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PLATINUM METALS REVIEW

A quarterly survey of research on the platinum metals and of developments in their applicaiion i n industry

VOL. 38 JANUARY 1994

Contents

Challenges in Emission Control Catalysis for the Next Decade

Nitric Oxide Catalysis as Applied to Vehicles

The New Kitsuregawa Technical Centre

Plastic Deformation and Fracture of Ruthenium Single Crystals

Extending the Life of Reactor Fuel Cladding Tubes

Platinum 1993 Interim Review

First European Congress on Catalysis

Methane Conversion Using Platinum Loaded Zeolites

Ruthenium-Niobium-Zirconium System

Hydrogen Material Science and Metal Hydride Chemistry

Optically Readable Hydrogen Sensor Uses Palladium

Precious Metals: ISSN 1004-0676

The Spanish Monopoly of Platina

Abstracts

New Patents

NO. 1

2

10

11

12

15

15

16

19

19

20

21

21

22

32

39

Communications should be addressed to The Editor, Platinum Metals Review

Johnson Matthey Public Limited Company, Hatton Garden, London ECl N 8EE

Challenges in Emission Control Catalysis for the Next Decade

1997 (LEV) 1997-2003 (ULEV)

By B. J. Cooper

0.075 0.040

- Johnson Matthey Catalytic Systems Division

F t h new automobile emission standards going into effect in Europe, and even tougher standards ready for implementation in California and the rest of the United Stares, automotive emission control systems are required to perform even better, in the ongoing effort to reduce vehicle emissions. Catalyst manufacturers, in collaboratioii with vehicle producers, have spent several years on the research, design, development and cesting of catalytic systems to meet the emission standards through to the end of this decade. This paper highlights key technical developments taking place in emission control catalyst technology.

In 1994 an ambitious programme will begin in California which specifies emission standards for transitional low emission vehicles (TLEV), low emission vehicles (LEV) and ultra low emission vehicles (ULEV); this emission reduction programme will extend into the next century.

Emission Standards In the last few years several important changes

in emission legislation have taken place which will define the requirements of the automotive industry for emission control technology. By far the most significant of them is the adoption, in California, of new, extremely stringent standards, see Table I. These standards call for reductions, kom current levels, by the year 2000, of 90 per cent in the emission of hydrocarbons,

50 per cent in the emission of carbon monoxide and 80 per cent in the emission of nitrogen oxides. United States federal standards are taking a similar firm position on emissions, but with a longer time frame. Similar stringent emission standards have been introduced in Europe, and in 1992 the first widespread, mandated use of catalytic converters came into effect. The California Ultra Low Emission Vehicle standards are more than twice as severe as the possible future European standards, and currently represent the most stringent legislation worldwide for catalytic converter technology.

A second impact on the design of emission control systems is from legislation on the U.S. Corporate Average Fuel Economy standard, and also the proposed carbon dioxide standards

Table I

U.S. and California Emission Standards

I Pollutant, g/mile

Year and standard 1 Hydrocarbons I Carbon monoxide I Nitrogen oxides

1990 us. 1994 U.S. 1993 California 1994 (TLEV)

0.41 0.25 0.25 0.125

3.4 3.4 3.4 3.4

1 .o 0.40 0.40 i 0.40

3.4 0.20 1.7 I 0.20

Platinum Metah Rev., 1994, 38, ( l) , 2-10 2

(ULEV)

in Europe. From this perspective, the use of a leaner burning engine with significantly improved fuel economy is extremely desirable and has significant impact on the design of emission systems and catalytic converters. As a result, the leaner burn diesel engine is expected to continue as a serious contender in the European Market, and as such has its own specific catalyst requirements (l) , and will be the subject of a future article in Platinum Metals Review. The lean burn gasoline engine, and the two-stroke engine are also likely to have some effect on emission control technologies towards the end of this decade.

Engines, Emission Control and Catalysts

Since the early 1980s, the primary emission control system for four-stroke passenger car gasoline engines has consisted of the three-way catalytic converter, which is capable of simultaneously reducing hydrocarbons, carbon monoxide and nitrogen oxides emissions, see Figure 1. The three-way converter reaches maximum efficiency close to the stoichiometric airfuel ratio. Therefore the engine has to function at around the stoichiometric airfuel ratio, and is controlled by means of a feedback system containing an oxygen sensor placed in the exhaust system. In addition, mass air sensors together with electronic fuel injection systems, which allow much more precise air:fuel meter- ing, are now common on modern emission controlled vehicles.

Lean burn versions of the four-stroke engine have been under development for some years. But because of the need to meet nitrogen oxides emission standards, a vehicle having an engine which operates at stoichiometry with a three- way catalytic converter is currently favoured. However, there is no doubt if an effective catalyst technology emerges, which could reduce nitrogen oxides under lean air:fuel ratios, that it would give a significant impetus to the development of the technology of lean burn four- stroke and two-stroke engines.

Advanced two-stroke gasoline engines, capable of meeting current emission control stan-

AIR: FUEL RATIO

Fig. 1 The effect of the air:fuel ratio on the catalyst performance for conventional three-way catalysts, demonstrating optimum pollution control at the stoichiometric air:fuel ratio

dards, are now under development. In contrast to the four-stroke engine, the two-stroke is a lean burn engine operating at air:fuel ratios between 20: 1 to 40: 1. It is clear that for these types of engines, the conventional three-way catalyst system would be incapable of reducing nitrogen oxides emissions, thus an alternate approach to control nitrogen oxides is required.

Fuel Effects In addition to the complexities of producing

new types of engine, further complications are emerging due to the proposed use of reformu- lated gasolines. Those gasolines with reduced sulphur content offer advantages in meeting lower emission targets, due to the removal of the inhibition of the catalyst by sulphur. Figure 2 shows the emissions from a vehicle measured over the U.S. Federal Test Procedure (FTP) using gasoline containing three different fuel sulphur levels (87, 355 and 735 ppm). Tests were conducted over palladium, palladium/ rhodium and platinumlrhodium catalyst systems.

In all cases the emissions increase as the fuel sulphur level increases. The greatest sensitivity to the fuel sulphur level is shown by the palladium-only catalyst for controlling nitrogen oxides. In contrast, the least sensitivity to fuel sulphur is also shown by palladium-only

Platinum Metals Rev., 1994, 38, (1) 3

Fig. 2 The effect of fuel containing 87, 335 and 735 ppm sulphur on the amount of pol- lutants remaining after the exhaust has been passed through, from left to right al- ladium, palladiumlrhodium and platiuumlrhodium catalysts. These results are from the U.S. FTP

l!

HYDROCARBONS CARBON MONOXIDE NITROGEN 0x1 DES

P d - 8 7 Pd-355 Pd-735

a PdlRn-87 Pd lRh-355 a PdlRh-735

P t l R h - 8 7 F? /Rh-355 P t l R h - 7 3 5

catalysts, for hydrocarbon control. The hydrocarbon control capability of palladium-only catalysts is currently attracting attention as an aid to meeting the stringent California hydrocarbon emission limits.

Systems Design The most immediate need, both in Europe

and the United States, is for catalysts that are more thermally durable. In the United States the achievement of the future emission standards is contingent upon increasing the efficiency of the catalytic converter system. The simplest approach to achieve that objective consists of mounting the catalyst close to the exhaust manifold so that the catalyst warms up faster. As a result, catalyst temperatures can be expected to be significantly higher, thus an improvement in the thermal durability of the catalyst is needed.

In Europe, a similar requirement has emerged due to the use of smaller capacity, high revolu- tion engines, which are used at much higher vehicle speeds. This, together with aiming to achieve stoichiometric calibration at all engine speeds, is resulting in a significant rise in the temperature of the exhaust and catalyst system.

The requirement for a reduction in hydrocarbon emissions promulgated in the California standards has focused serious attention on controlling vehicle emissions during cold start. Under these conditions, large quantities of hydrocarbons can be emitted prior to the catalytic converter attaining its light-off temperature.

To overcome this problem, several alternate technologies are under development. Catalyst research has concentrated on developing fast light-off catalysts, which minimise the time before which the catalyst becomes active. Electrically heated substrates are also available which heat the catalyst to above its light-off temperature either prior to or immediately after starting the engine.

An alternate approach to controlling the hydrocarbon emissions produced during cold start is to use absorbent materials in the exhaust, which trap the hydrocarbon emissions before the catalyst becomes active and later release the emissions at higher temperatures. Due to limitations in the trapping materials used, these systems require complex arrangements of valves or heat exchangers in the exhaust system, and an extremely low light-off catalyst is required


downstream to combust the emissions desorbed from the hydrocarbon trap.

Thus, a broad picture emerges where the major thrust in catalyst development is towards producing catalysts capable of+eacting extremely quickly after vehicle operation under cold start conditions. This results in an additional requirement for catalyst coatings of high thermal durability, for use in close coupled positions to the engine, and which can withstand harsh operating environments for up to 100,000 miles.

Catalyst Substrate Designs Virtually all emission control catalysts in use

today are based on a monolith substrate design. The monolith may be either a ceramic or metallic construction, with cordierite being the preferred ceramic material, and femtic steels being the preferred metallic material. The former is designed for low thermal expansion in order to maintain structural integrity and resistance to thermal shock. The latter is designed for oxidation resistance under high temperature conditions. Both substrates have a high surface area coating incorporating both base metals and noble metals to achieve the desired catalytic performance.

Moving a converter close to the manifold often produces space constraints within the vehicle, with the result that small converter shapes are being installed ahead of the main catalytic converter. The installation of small converters with smaller frontal areas produces flow constriction in the exhaust system and higher pressure drop. This results in power loss fkom the engine, which is often unacceptable to the automotive designer.

One approach to reduce the power loss is to develop thin walled substrate systems, which reduce the pressure drop. A significant increase in the intrinsic strength of the ceramic body is a necessary requirement for these thin walled substrates, so that they can withstand the can- ning pressures required during the insertion of the catalyst into the converter shell. This, in turn, requires a modification to the basic structure of the ceramic, especially with respect to its porosity, and also the development of adher- ent coatings for the new ceramic structure. All

Detaik of Hills lard2

Wdrocarbon Tailpipe Emissions, ppm I

Hill 1 Hil l 2

V 0

e 2 i 6 8 I0 1; 14 1 6 Is 2-0 22 HILL NUMBER

Fig. 3 Hydrocarbon tailpipe emissions produced during the U.S. FTP test for a vehicle being driven from a cold start and run over a number of hills

this has been successfully achieved, so that the efficiency of a thin walled substrate catalyst is comparable to that of a conventional catalyst.

Early problems with the mechanical integrity of metal substrate systems have now been largely resolved, by improvements in fabrication technology. Metal substrates are now finding application, particularly on vehicles with small engines, where space is at a premium. The inherent benefit of using metal supports of thin walled structure has been in the lower pressure drop, and this has helped metal substrates to be accepted for such applications.

At present, attention is focused on developing metal substrates as electrically heated supports. These may be used to treat emissions during vehicle cold start, when hydrocarbon emissions are high, see Figure 3. Two principal types of metal support structures are under development.

The first consists of insulated layers of metal foil, and the second consists of an extruded powder metal support, in which the electrically conducting path is controlled through slots in the substrate. Both types of support systems have been evaluated as electrically heated catalysts (EHC), operating in conjunction with


Table II

Results Using Electrically Heated and Conventional Three-Way Catalysts

US. FTP Emission results, g/mile

Metal support

Extruded metal EHC

Foil EHC

California ULEV standards

Non-methane hydrocarbons Carbon monoxide Nitrogen oxides

0.012 0.35 0.17

0.024 0.31 0.17

0.04 1.7 0.2

conventional three-way catalytic converters. Emission levels at or below those required for the California ULEV standards have been achieved on prototype systems, as Table I1 shows, and the durability of the systems are currently being evaluated. Future developments in this area are concentrating on reducing the power consumption required for electrical heating and on optimising battery and alternator systems.

Advances in Catalyst Design The most prominent three-way catalyst sys-

tem in use today typically consists of platinum and rhodium as the active catalyst ingredients supported on a stabilised alumina coating containing cerium oxide as an oxygen storage component. Nickel oxide can also be added to suppress the formation of hydrogen sulphide, which is produced from sulphur in the exhaust under rich air:fuel ratio conditions. It should be noted, however, that the use of nickel oxide in catalyst systems is generally avoided in the European market due to concerns over health hazards associated with nickel. In contrast, nickel oxide is used extensively in the U.S. market, as there is no evidence to support a loss of nickel from emission control catalysts.

Thermally Stable Catalysts As previously mentioned a major challenge,

for future catalyst systems, is to develop more thermally stable catalyst materials. This is due to the sintering of catalyst materials being significantly enhanced under typical close coupled

operating conditions. In the design of future emission systems it is desirable that the maximum operating temperature of the catalyst system is increased to around 950°C. Under such conditions it is expected that there will be significant loss of surface area and some crystallite growth. Thus, extensive research and development is being undertaken into methods of dispersing and stabilising the key catalytic materials for operation at higher temperatures. Incorporating these materials into new catalyst systems has given a significant improvement in high temperature durability when the system is aged at temperatures up to 1O5O0C, as is shown in Figure 4.

Palladium Catalysts In general the techniques described above, for

enhancing the thermal durability of a catalyst, are most beneficial in improving the efficiency of platindrhodium three-way catalysts for controlling emissions of carbon monoxide and nitrogen oxides after high temperature ageing. Although the platinum/rhodium catalyst generally retains good efficiency for hydrocarbon control, it is desirable to enhance it because of the future severe standards for hydrocarbons.

Developments in palladium catalyst technology have resulted in a significant improvement in hydrocarbon control, see Figure 5. Palladium catalysts will see application in close coupled converter systems, either as a single palladium catalyst, or as a palladium catalyst in combination with a platinudrhodium catalyst. Table


Reproduced with the kind permission of Corning Glass Works and Camet Company

Fig. 4 Conversion of hydrocarbons, carbon monoxide and nitrogen oxides a t the stoichiometric air:fuel ratio by a standard platinumlrhodium three-way catalyst, aged at 900 and 1050°C, and by a n advanced platinumlrhodium catalyst aged at 1O5O0C, showing that the advanced catalyst has much greater high temperature stability

c

8 90

80

f 7 0 e W > 60

50 e

STANDARD 900 STANDARD 1050 ADVANCSD 1050

CATALYST TYPE

Hydrocarbons Carbon monoxide a Nit rogen oxides

I11 shows a comparison of the relative performance of several converter combinations in two vehicles, employing palladium only and plat- inumkhodium catalysts in close coupled and underfloor converters. The optimum converter system design on these test vehicles appears to be a combination of palladium-only and plat- i n d r h o d i u m converters, to take advantage of the superior hydrocarbon control capability of palladium and the superior control of nitrogen oxides by platinudrhodium, Figure 5 .

Low Light-off Catalysts In the absence of further enhancements to the

thermal durability of catalyst systems, the second option is to design catalysts that are much more effective under low temperature exhaust conditions. In this case the emission system designer would then have the option of locating the converter in an exhaust position which is

more remote from the engine, thus avoiding excessively high exhaust temperatures. Substantial enhancements in catalyst light-off must also be achieved to produce a significant effect during the emission test.

New catalyst formulations under development in the Johnson Matthey laboratories have demonstrated a potential for significantly lowering the light-off temperature, when compared to a conventional platinudrhodium three-way catalyst. In Figure 6 the improvement in light- off achieved with a new catalyst formulation is shown, when measured in a laboratory reactor operating a t a gas hourly space velocity of 90,000. Installation of this catalyst on a vehicle has shown promising advantages for cold start control of emissions of hydrocarbons and carbon monoxide.

As a result of such new formulations, other options have emerged, for instance low light-off

Fig. 5 Comparison of the pollutant conversions by palla- diudrhodium and palladium- only three-way catalysts from U.S. FTP results for a 4.6 I vehicle, showing the superior performance of palladium for hydrocarbon control, and platinumlrhodium for nitrogen

u

u a 2' 0 e W

B J

8 I.

HYDROCARBONS CARBON MONOXIDE N I T R O G E N OXIDES D

Standard Pt lRh Standard P d l R h m Standard Pd-mly oxides control. In all cases the advanced catalyst gives superior results Advanced P t l R h Advanced PdlRh


Table 111

Comparison of Palladium-only and Platinudhodium Catalyst Efficiencies in Underfloor and Close-Coupled Positions

Pollutant

Hydrocarbons

Carbon monoxide

Nitrogen oxides

U.S. FTP 2.2 I vehicle I US. FTP 2.5 I vehicle

Catalyst positions Underfloor

catalysts could be used to improve the effectiveness of converters under the low speed portion of the European driving cycle, or could be utilised to improve the effectiveness of converters in meeting TLEV and LEV standards in California. They might also be used in conjunction with electrically heated catalysts or hydrocarbon traps to meet the ULEV standards in California, which are due for implementation at the end of the decade.

Non-Regulated Emissions of Hydrogen Sulphide

The decision to eliminate the use of nickel in catalyst formulations for the European market has presented a diEcult technical challenge to the catalyst designer, who must maximise the reduction of nitrogen oxides to nitrogen while minimising the reduction of sulphur dioxide to hydrogen sulphide. Tackling this selectivity problem has generally resulted in some lowering in catalyst performance for nitrogen oxides reduction, as hydrogen sulphide formation is suppressed.

The advantage which nickel oxide provided was its ability to absorb hydrogen sulphide and release the stored sulphur as sulphur dioxide in

Platinum Merals Rev., 1994, 38, (1)

oxidising conditions. This allowed the catalyst designer to formulate a catalyst composition to achieve maximum activity for the reduction of nitrogen oxides.

However, it is necessary to find an effective substitute for nickel, to suppress hydrogen sulphide emissions, for the European market. The progressive improvements in catalyst technology, which have been achieved by research and development in the Johnson Matthey laboratories over the past five years, for hydrogen sulphide suppression are shown in Figure 7. The formulations that have currently been developed

c 100,

Product ion catal yst

s$ 1 0 0 150 200 2 5 0 300 350 4 0 0 450 _ _ u u TEMPERATURE, .C

Fig. 6 Carbon monoxide conversion as a function of exhaust temperature showing the superior light-off temperature for an advanced catalyst formulation over that of a current production catalyst

8

Catalyst

Pd-only

1 1 :E3:: 1 87.7 1 Pt/Rh 1 85.1 1 :::: coupled Pd-only 91.0 Pd-only 92.8

Pt/Rh 90.9 91 .I Pt/Rh 91.9 89.6

Close- ‘‘1’’

Pd-only Pt/Rh Catalyst Pd-only Pt/Rh

90.1 87.8 Pd-only 90.5 89.0

I Pd-only 1 84.5 I 86.9 I Pd-only I 91.4 I 95.0

I Pt/Rh I 93.0 I 93.5 I Pt/Rh I 94.2 I 93.7

Pt/Rh 898.2 87.7689.6 885.1

Fig. 7 Hydrogen sulphide emissions from an unsuppressed three-way catalyst, and two suppressed catalysts produced in 1990, and 1993 demonstrating the progressive reduction in hydrogen sulphide emissions in non-nickel three-way catalysts

1400,

-16 0 16 32 4 8 64 80 96 112 128

TIME AFTER START OF DECELERATION, 5

are effective in suppressing emissions of hydrogen sulphide, while still maintaining a high converter efficiency.

Catalysts to Control Nitrogen Oxides under Lean Conditions

Emerging engine technologies have designs that operate at air:fuel ratios leaner than stoichiometric, giving benefits in fuel economy and a reduction in emissions of carbon dioxide, which is considered to be a serious contributor to global warming. In addition to lean burn four-stroke gasoline engines, diesel and two- stroke engines also operate at air:fuel ratios greater than 20: 1. Conventional three-way catalysts can control the carbon monoxide and hydrocarbon emissions at these airfuel ratios, but there is little ability to control emissions of nitrogen oxides. As a result, there is a tremendous interest in catalyst systems that can reduce nitrogen oxide emissions at lean calibrations.

A new range of catalyst materials has been

Copper1 zeolite

4 20 Hr - L

tO 150 200 250 300 350 4 0 0 ZV TEMPERATURE, 'C

Fig. 8 Nitrogen oxides conversion by an advanced platinum catalyst compared to a copperlzeolite catalyst under lean exhaust conditions, as a function of the exhaust temperature

developed which shows activity for removal of nitrogen oxides under lean operating conditions. The new "Lean NOx" catalysts are based on zeolites containing active metals exchanged within the zeolite structure. One of the most active materials evaluated to date is copper- exchanged ZSM-5 zeolite, but this material has shown limited durability. More active and durable materials - including the platinum group metals - are being sought as catalysts for nitrogen oxide control under lean conditions, see Figure 8.

Current "Lean NOx" catalyst systems are inef- fective for controlling carbon monoxide and hydrocarbons and, therefore, future systems utilising such catalysts would have to operate in conjunction with a platinum group metal catalyst to control the carbon monoxide and hydrocarbons. Measurable reductions in nitrogen oxides have been demonstrated by lean burn gasoline, diesel, and two-stroke engines using the new "Lean NOx" catalyst systems. This suggests that there will be a new approach to catalytic emission control towards the latter half of the decade, once issues of durability are solved.

Conclusions Significant progress is being made in the devel-

opment of emission control catalysts to meet the challenges arising from tightening emission legislation. These challenges will lead to new developments in emission control catalysts throughout the rest of this decade.

Advances are being made with new substrate designs, including the advent of elecnically heated substrates, for catalyst systems. The thermal


durability of catalysts is improving and enhancements in light-off temperature are being achieved with new catalyst formulations. It is likely that platinum and rhodium will continue to be the primary ingredients for controlling carbon monoxide and nitrogen oxides and that palladium will continue to emerge as an important contributor to control hydrocarbon emissions.

New horizons are now being opened for controlling nitrogen oxides under lean operating conditions, and it is felt that the most likely mar-

ket for such catalyst systems will be the lean burn diesel engine, and possibly the lean burn two-stroke engine. Both copper and platinum catalysts are under development, but problems with the durability of such catalyst systems remain to be resolved. However, this area gives the most challenging and intriguing possibilities for the design of future emission systems.

References 1 B. J. Cooper and S . A. Roth, Platinum Metals Rev.,

1991, 35, (4), 178-187

Nitric Oxide Catalysis as Applied to Vehicles A recent review paper by Kathleen C. Taylor

of General Motors covers the technical literature on nitrogen oxides automotive emission control published during the period 1982-1991 (Catal. Rev.-%. Eng., 1993,35, (4), 457-481). The paper concentrates on three-way catalysts applied on gasoline engine vehicles, but a brief summary is also presented of recent work on lean nitrogen oxides catalysts for lean burn engine vehicles. The requirement for further reduction in nitrogen oxides emissions from vehicles is highlighted by reference to the recent tightening of standards in the United States; as outlined in the above Platinum Metals Review article. The paper considers the fundamentals of three-way catalyst operation and describes rhodium as the preferred metal for nitrogen oxides control, due to its high activity for their reduction and high selectivity to form nitrogen rather than ammonia.

The paper states that wide adoption of rhodium replacements such as palladium or copper appears unlikely at this stage due to the stricter control standards coming into force. It references the use of platinum in three-way catalysts together with ceria, and describes basic work on the role of ceria and its operation in conjunction with platinum and rhodium. Ceria is shown to be capable of extending the time for nitric oxide decomposition over platinum/ rhodiudceria catalysts due to the fact that the ceria absorbs oxygen from nitric oxide decomposition. Thus, ceria prevents the noble metal catalyst becoming deactivated by the accumulation of surface oxygen. Ceria is also claimed to alter favourably the reaction kinetics of carbon monoxide oxidation and nitric oxide reduction, and to decrease the apparent activation energy of the carbon monoxiddnitric oxide reaction, so favouring high conversion at low temperatures. Lower ceria particle size enhances the reduction of nitric oxide over platindceria catalysts and this is attributed

to the increased platinum-ceria interaction. The paper addresses the recent interest in the

substitution of palladium for rhodium as a cost reduction move. It describes palladium as having a narrower air:fuel operating range for the control of nitrogen oxides emissions compared to platinum/rhodium, particularly under rich air:fuel conditions. This has been ascribed to poisoning of palladium sites by hydrocarbons in the exhaust, which can be alleviated by the addition of lanthanum and other additives.

The reduction mechanism for nitrogen oxides removal is described as a nitric oxide decomposition process over the noble metals, followed by the removal of oxygen from the noble metal surface via reaction with a reducing agent. Surface chemistry studies of reactions over rhodium surfaces have clearly identified the elementary steps necessary to complete this reaction process. Rhodium is found to be structure sensitive with particle size having a major effect, but crystallographic orientation only a moderate effect, on sensitivity.

The recent Auto/Oil Quality Improvement Research Program has clearly shown that fuel sulphur level can have a dramatic impact on nitrogen oxides emissions from a vehicle. During this study an increase of fuel sulphur from 49 ppm to 466 ppm showed a 9 per cent increase in the emissions with the higher sulphur content fuel. Laboratory studies have confirmed these results. Platinum and rhodium show rapid reversibility when the fuel sulphur level is lowered back to 49 ppm; however, palladium is slower to recover. The presence of ceria in the catalyst prolongs the recovery process due to sulphur adsorbed on the ceria surface.

The review is a useful compendium of the literature published during the period, particularly with respect to the mechanism and reaction of nitric oxide removal over rhodium based three-way catalyst systems. B.J.C.


The New Kitsuregawa Technical Centre JOHNSON MATTHEY PROVIDES TECHNOLOGICAL SUPPORT

AND EMBRYONIC MANUFACTURING FACILITIES IN JAPAN

In October 1993 Johnson Matthey opened its first Technology Centre in Asia. Located at Kitsuregawa, some seventy- five miles north-east of Tokyo, this new facility will enable Johnson Matthey to make their specialised expertise in the application of the platinum metals, and other high-technology materials, available more readily to industrial customers in Japan and hence to Japanese companies throughout the world.

In view of the global importance of the Japanese car manufacturers, the Centre includes a dedicated engine test and auto- catalyst evaluation laboratory. Johnson Matthey already supplies more than one-third of worldwide demand for automobile emission control catalysts, and will now be better placed to respond rapidly to the exacting demands of Japanese design engineers, whose requirements for catalyst information, testing and technical support are unsurpassed.

The Japanese electronics industry is a major user of advanced materials, the specifications of which are very precise, especially with regard to purity. Johnson Matthey has a great accumulation of knowledge and practical skills relating to the analysis and purification of noble and rare materials; these will be available

through the new electronic materials applications laboratory and manufacturing facility.

As a result of the research and development philosophy of both government and industry, Japan is now leading the world in the move towards commercial- isation of fuel cell electric generators. At the Kitsuregawa Technical Centre a pilot plant has been established which will provide fuel cell developers with samples of advanced catalyst materials formulated for this potentially important application.

With some limited facilities for fabri- cating platinum metals products, this new centre is well placed to serve the growing markets in Japan and Pacific rim countries.

Platinum Metals Rev., 1994, 38, (l), 1 1 1 1

Plastic Deformation and Fracture of Ruthenium Single Crystals By P. Panfilov and A. Yermakov Laboratory of Strength, Urals State University, Ekaterinburg, Russia

At the present time ruthenium, with its hexagonal close packed lattice, does not find wide application in industry when compared with platinum and iridium, due to its poor workability and its unsatisfactory resistance to corrosion at elevated temperatures (1-3). However, its high melting point, 225OoC, and relatively low cost suggest that some ruthenium-based compounds might possibly be considered as high temperature materials for aerospace applications (4).

Ruthenium is of interest to materials science since it has a low value for the ratio of the lattice constants c:a of 1.582 (1). In general hexagonal close packed metals obey an empirical rule, according to which structures with c:a > d(8/3) display basal slip behaviour, while those with c:a < d(8/3) show prismatic slip behaviour under deformation. The value of c:a = d(8/3) is determined from geometric considerations of the atomic stacking in the hexagonal unit cell (5). The value for ruthenium lies between the c:a ratio for titanium (1.587) and for beryllium (1 567) (1). Titanium is deformed at room temperature by prismatic slip while beryllium is deformed by means of basal slip, which is an exception to the empirical rule (5). Thus it would be very interesting to discover what is the main deformation mechanism in ruthenium single crystals at room temperature. This information may be helpful in specifying opti- mal regimes for processing ruthenium workpieces. Plastic deformation and fracture of ruthenium single crystals are considered here at room temperature.

Crystal Production Large single crystals of ruthenium have been

grown by electron beam melting at the Ekaterinburg Plant for Processing of Non-

Ferrous Metals, which is also the method for growing iridium crystals (6). They had sizes: 100 mm in length and 10 mm in diameter. The amounts of metallic impurities in compacted ruthenium workpieces for growing crystals and in the single crystals are given in the Table. X- ray analysis has shown that ruthenium crystals are grown along the c axis. Samples of single crystal ruthenium for use in mechanical tests have been cut from a large ruthenium crystal by means of spark erosion.

Crystals for tensile testing were parallelepipeds of size 10-1 5 x 2 x 0.5 mm, while crystals for compression were of size 3 x 2 x 2 mm. Mechanical tests were carried out at room temperature on Instron test machines; the traverse speed being 1 mm/min and hydraulic grips were used in tensile tests. Fracture surfaces of the crystals were examined by scanning electron microscopy.

The mechanical behaviour of single crystal samples with two orientations has been studied under both tensile and compression tests. The first orientation was favourable for basal slip and thus unsuitable for prismatic slip, while the second orientation was favourable for

I Metallic Impurities in Ruthenium, ppm

Element

Platinum Iridium Rhodium Palladium Silver

Scrap

100 800 900 -

$

Single crystal

10 140"

1 1 1

90'

$ content of non-noble metals IS approximately 300 ppm impurity has been estimated after analysis

Platinum Metals Rev., 1994, 38, ( l ) , 12-15 12

Fig. 1 The crystal geometry of ruthenium single crystal specimens for tensile and compres- sive teats. Favourable orientation for basal slip (unfavourable for prismatic slip): l a tensile axis is normal to c axis; l b compression axis is parallel to c axis. Favourable orientation for prismatic slip (unfavourable for basal slip): 2a tensile axis is parallel to c axis; 2b compression axis is uor- mal to c axis

7 I I I I

I I I I

I I I I I I I I I

I

I I

;=;.

c axis t

prismatic slip and unsuitable for basal slip. The crystal geometry of the samples is shown in Figure 1.

Results and Discussion Deformation curves of tensile testing and

compression for single crystal ruthenium samples are given in Figures 2 and 3, respectively. It is clear that crystals under tension, with orientation favourable for prismatic slip, fail without any preliminary plastic deformation. However, for crystals of orientation favourable to basal slip the deformation prior to failure can reach 20 per cent. In both cases, the fracture mode of the ruthenium crystals was attested as cleavage or brittle transcrystalline fracture, see Figure 4, and the morphology of the ruthenium crystal fracture surfaces resembled the mor-

phology of the fracture surfaces of iridium single crystals (7). Crystal geometry analysis shows that the fracture surface of these ruthenium crystals is macroscopically parallel to one of pyramidic planes.

Similar behaviour takes place during compression. Samples of ruthenium crystals with orientation favourable for basal slip can be deformed by up to 80 per cent of their original size. It should be noted that a number of small cracks appeared on their surfaces under loading, but this did not lead to single crystals being sep- arated. Crystal samples with an orientation favourable for prismatic slip changed the direction of their compression after the application of load they began to crack and fold, after which the crystals were deformed in the direction favourable for basal slip. Their fracture mode


5 10 6 20 DEFORMATION, per cent I

I l b

20 40 60 80 DEFORMATION, per cent

I Fig. 2 Deformation curves (tension) of ruthenium single crystals: l a favourable for basal

Fig. 3 Deformation curves (compression) of ruthenium single crystals: l b favourable for basal slip; 2b favourable for prismatic slip I slip; 2a favourable for prismatic slip

was also attested as cleavage or brittle transcrystalline fracture.

The results obtained may be briefly sum- marised as follows. Ruthenium crystals with an orientation favourable for basal slip are deformed quite well under both tensile and compression tests, while the plasticity of single crystals having an unsuitable orientation for basal slip is poor. When doing this, “plastic” ruthenium samples fail by cleavage under tension and crack under compression. In addition, is should be pointed out that the “re-orientation” of the crystals from unsuitable to favourable for basal slip direction of compression, takes place during compression tests.

Similar mechanical behaviour can be observed in single crystals of hexagonal close packed metals, such as zinc, which are deformed by basal slip and cleave under tension. Therefore, these findings provide a basis for stating that at room temperature the main deformation mode in ruthenium single crystals is by basal slip*. However, some insignificant contributions to their plasticity may be brought about by alternative deformation mechanisms, such as mechanical twinning and both prismatic and pyramidic slip. Consequently, ruthenium is the next metal to beryllium in the Periodic Table with hexagonal close packed structure and a low c:a ratio, which is deformed by basal slip.

By contrast in Ref. 8 it was stated that deformation of ruthenium occurs through slip along the planes of a prism, and the following arguments were presented: a low c:a ratio in ruthenium and observations of slip bands on the surfaces of compressed ruthenium single crystals.

This fact, contrasted with the above discussed empirical rule, will be the subject of further work.

At the present time, the physical mechanisms of cleavage in single crystals of hexagonal close packed metals’are unclear; they may be connected with both features of crystal structure and the influence of impurities. As a rule, cleavage fracture is observed in metals having basal slip as the main deformation mode (5). Usually, brittle fi-acme in crystals of these metals is connected with an insufficient quantity of slip planes in the lattice. In agreeing with these arguments it may be concluded that the inclination to cleavage fracture is an inherent property of rutheni-

Fig. 4 SEM micrograph of the fracture surface of a ruthenium single crystal stretched at room temperature (orientation la). This fracture mode was con- 6rmed as brittle transcrystalline fracture or cleavage


um single crystals. Indeed, experiments have shown that highly pure ruthenium single crystal workpieces crack during treatment at room

temperature. In so doing, the poor workability of polycrystalline ruthenium compacted from powder is caused by of different impurities.

References

1 A. V. Bobylev, “Mechanical and Processing 5 R. W. K. Honeycombe, “The Plastic Deformation of Metals”, (Edward Arnold, London), Russian Translation, MIR, 1972

Properties of Metals (Handbook)”, Metallurgia, Moscow. 1987. 207. (in Russian) , < .

2 R. W Douglass and R. I. Jaffee, h e . ASTM, 1962,

3 E. M. Savitskii, V. P. Polyakova and N. B. Gorina,

4 R. L. Fleischer, Platinum Metals Rev., 1992, 36,

~i?&?~~+l$-%~~~~’~, ?$;${ (aq;ply; 7 P. Panfilov, G. Baturin and A. Yermakov, Int. 3.

F ~ ~ ~ ~ ~ ~ ~ , 1991, 50, 153 8 E. M. Savitskii, V. P. Polyakova, N. B. Gorina and

N. R. Roshan, ‘‘Physical Metallurgy of Platinum Metals”, MIR, Moscow, 1975, (in Russian)

62,627

Platinum Metals Rev., 1979, 23, (2), 57

(3)s 138

Extending the Life of Reactor Fuel Cladding Tubes A number of factors determine the length of

time that nuclear fuel rods can safely be left in pressurised water reactors, although it is generally accepted that the most important of these is waterside corrosion of the zirconium alloy cladding that contains the fuel. Over the past twenty years standard Zircaloy-4 tubes have performed satisfactorily in reactors throughout the world, but the economic and environmen- tal constraints that determine the present day reactor operating parameters have changed somewhat, and now the fuel has to withstand more arduous working conditions for consid- erably longer times.

To ensure that fuel cladding materials are capable of meeting the requirements of reactor operators over the next decade a number of new zirconium alloys have already been developed. Now researchers in South Africa have reported the results of an investigation to establish if the oxidation resistance of Zircaloy-4 can be improved by alloying palladium into the surface layer (“Improvement in Oxidation Resistance of Zircaloy-4 by Surface Alloying with a Thin Layer of Palladium”, G. A. Eloff, C. J. Greyling and P. E. Viljoen, J. Nucl. Muter.,

A 2 pm thick layer of palladium was electrodeposited onto the surface of test samples cut from standard fuel cladding tube material, which were then vacuum annealed at 950°C for various times to diffuse the palladium into the Zircaloy-4 before they were vacuum quenched to room temperature. Selected samples were then oxidised at 450°C, the rates of oxidation being monitored at intervals by determining the increases in weight of the samples.

The study showed that a substantial improvement in the short term oxidation resistance of

1993, 202, (3), 239-244).

Zircaloy-4 was achieved when the electrodeposited palladium layer was diffused into the surface, by annealing for an optimum period of time. This resulted in a high concentration of intermetallic particles at the sub-grain boundaries of the a-Widmannstatten structured outer layer. It is suggested that this increases the plasticity of the oxide layer and permits a greater degree of deformation to take place before the onset of cracking occurs, from the outer surface of the oxide layer.

Platinum 1993 Interim Review During 1993 it is estimated that consumer

demand for platinum in the western world will grow by six per cent to 4.02 million ounces troy. Shipments of primary platinum are expected to grow to 4.21 million oz, so - despite a fall in Russian sales to a four-year low and reduced output from minor primary sources - a surplus of 190,000 oz will result. Demand for palladium amounting to 4.04 million oz will, however, exceed supplies by 100,000 oz. For rhodium, lower shipments and growing demand will leave the market virtually in balance. While a small increase in consumption of ruthenium is fore- cast, purchases of iridium are expected to be steady.

Supply and demand data, and a discussion of the many factors that determine the market for platinum metals, are presented and sum- marised in the latest issue of Johnson Matthey’s twenty-four page illustrated publication “Platinum 1993 Interim Review”.

Organisations requiring such information are invited to request a copy from: Alison Cowley, Johnson Matthey Precious Metals Division, New Garden House, 78 Hatton Garden, London EClN 8JP, England; Fax 071-269 8389.


First European Congress on Catalysis By Professor G. C. Bond Brunel University, Uxbridge, Middlesex

Thefirst European Congress on Catalysis ( E UROPACAT I ) , which was held at the CORUM Conference Centre in Montpellier, France, from the 12th to the 17th September, 1993 coincided with the formation of the European Federation of Catalysis Societies ( E F C A T S ) . The Congress and the setting up of the Federation marked the culmination of three years’ intensive planning by representatives of almost every European country where catalysis is practised and studied, including those of Eastern Europe and the Commonwealth of Independent States.

EUROPACAT I took the form of fifteen independent symposia covering all branches catalysis, with five running in parallel at any one time; each symposium was organised by one of the national catalysis societies, and a total of about 145 papers were presented. There were also extensive poster displays, the titles of no less than 735 being listed. The meeting was attended by more than 1000 participants, including many from Eastern Europe. The local organisation under the chairmanship of Professor Francois Figueras coped magnificently with this unexpectedly large attendance.

At least nine of the fifteen symposia featured catalysis by the platinum metals to some extent, and reference is made to some of these contributions below; but the overwhelming importance of this group of metals is well illustrated by the fact that in the symposium on “Catalysis by Metals and Bimetallics’’ no less than thirteen out of 6f- teen papers dealt specifically with them. Our attention in this review will therefore naturally be focused on the contents of this particular symposium. Within this group it was also evident that there is a continuing interest in bimetallic systems, which formed the subject of six of the papers.

Monometallic Catalysts Methods of catalyst preparation continue to

receive attention: detailed studies were reported on the interaction of Pt(acac)2 (1) and of Rh(x- allyl), (2) with common oxidic supports such as alumina, silica and titania, various intermedi-

ates in the conversion of these complexes to metallic particles being detected spectroscopi- cally. Koningsberger and colleagues (3) reported a most interesting study of the effect of reduction conditions on the structure and properties of supported metal particles. By the use of EXAFS (Extended X-ray Absorption Fine Structure) they found that at low reduction temperatures there was a layer of chemisorbed hydrogen between the metal (platinum) and the support, and this was irreversibly removed on reduction at 450°C. The capacity of the surface platinum atoms to chemisorb hydrogen was then lowered, because, according to the authors, there was a permanent change in the structure of the metal-support interface, which in turn changed the electronic properties of the metal particles.

Other questions concerning metal-support interactions, and the use of novel and unusual supports, continue to generate interest. Until recently the use of basic supports was not much favoured; it is however known that platinum supported upon magnesia converts alkanes to aro- matics with good selectivity, but it is now reported that palladium supported upon magnesia catalysts perform even better (4). This system was also investigated by a “model” technique, that is, condensing palladium vapour onto a mag- nesium (1 00) surface (5); the palladium particles had the unique shape of a truncated square pyramid. A first attempt has been made to use buckminsterfullerene as a support for a metal (6); it was first deposited onto a support ofhigher

Platinum Metals Rev., 1994, 38, (l), 16-19 16

area, and then Ru(acac)3 was used as a source of metal. The resulting catalyst was used for hydrogenation of cinnamaldehyde, giving selec- tivities to cinnamyl alcohol of about 80 per cent.

The so-called “strong metal-support interaction” still fascinates catalytic chemists. The modification of titania by incorporating higher- valent cations, such as W”, produces a support for a rhodium catalyst which is twenty times more active for carbon monoxide hydrogenation than is the unmodified support (7). A method for preparing mesoporous platinum supported upon titania aerogels from T~(O’BU)~ + PtC14 or Pt(acac)? was reported (8); the product contained anatase particles about 8 nm in size, and had an area of 200 m’lg. Further evidence for the encapsulation mode! was obtained by ion- scattering spectroscopy of rhodium supported on titania model catalysts (9).

Catalyst Characterisation In addition to the methods alluded to above,

a number of comparatively novel methods were described for charactensing the structure of metallic catalysts. EXAFS is finding ever wider application, but the theoretical interpretation of the observed oscillations is st i l l not firmly established, and failure to allow for the anharmonicity of the motion of atoms in the surface may lead, especially with lighter elements, to an underestima- tion of the particle size (1 0). ‘H NMR of hydrogen adsorbed on supported metal catalysts is another rich source of information; when applied to palladium catalysts in conjunction with measurements of uptake, it is capable of distinguish- ing between the stmnglydemisorbed + a-hydride phase and P-hydride phase (1 1). Metal surfaces are known to be labile and to reconstruct to minimise surface fkee energy; but what is surprising is that the background pressure in the residual vacuum under UHV conditions is sufficient to effect an adsorbate-induced reconstruction observ- able by Scanning Tunnelling Microscopy (1 2).

Bimetallic Catalysts The preparation of small, homogeneous alloy

particles on supports suitable for catalytic applications still poses a number of difficulties. One

approach is to use as precursor a compound in which the desired elements are linked; for example, the compound (pt01yl)~Cu~Rh~ was used to prepare supported CuRh particles which showed useful properties in liquid-phase reactions (1 3). Similarly the binuclear acetate-bridge bridged complex P ~ C U ( O A C ) ~ has been employed to make Pd-Cu/AlZO3 catalysts (1 4). Pt-Au/SiOz catalysts can be made by reacting a reduced platinum on silica catalyst with HAuC14, a process that can lead either to the random deposition of gold atoms on the platinum particles, or to a specific coverage of low- index planes, depending on the conditions used (1 5). Conventional impregnation of silica with solutions of the chlorides of palladium and gold produces materials, the homogeneity of which is uncertain, but careful X-ray Photoelectron Spectroscopy work reveals the presence of Sio close to the small alloy particles after reduction at only 380°C (16).

The ability of the platinum group metals to form sols of finely divided metal particles has been known for many years, but only recently have bimetallic sols been studied. Bimetallic palladium-copper sols, which are supported on carbon are effective catalysts for hydrogenating alkynic alcohols (1 7).

Applications as Catalysts Mention of metal sols as supported metal cat-

alyst precursors leads us naturally to their use in unsupported form; rhodium particles prepared under phase-transfer conditions show high stereoselectivity for reducing ortho-disubstituted aromatic rings to cis-disubstituted cyclohexa- nes (1 8). Crown ethers containing benzene rings fused into the macrocycle can be similarly reduced. A most interesting innovation is the use of an osmium tetroxide complex with an alkaloid, such as cinchonidine, incorporated in a polymeric matrix, as a catalyst for enantioselective di-hydroxylation of alkenes (1 9). Chiral palladium complexes containing neutral bidentate optically-active nitrogen ligands effect enantioselective allylic substitutions.

One symposium was devoted to “Catalysis and the Environment”, and not surprisingly the


selective reduction of nitrogen oxides featured in a number of papers. Although vanadia-titania catalysts and copper-exchanged ZSM-5 zeolite are effective, attention is now turning to lean- burn conditions, where catalysts based on the platinum group metals have potential (20). There were also several studies reported of the kinetics and mechanism of the nitric oxide-carbon monoxide reaction. On rhodium single crystal surfaces, nitric oxide is strongly chemisorbed and blocks access of carbon monoxide to the surface: their reaction is therefore slower than is the oxidation of carbon monoxide (21). Bimetallic combinations involving palladium were compared with rhodium; the palladium-chromium showed comparable activity, but palladium-silver was less active (22).

Fundamental investigations enlarging our understanding of catalysis were comparatively few in number. T h e use of transient kinetic methods to study the methane-deuterium equi- libration on Rh-Ag/Si02 catalysts revealed that the desorption rate of C, species was faster than over rhodium supported o n silica, and the strength of hydrogen chemisorption less (23). T h e reasons underlying t h e dependence of activity o n the size of metallic particles have long been questioned by catalytic scientists. It

now appears possible that the effect may have a n energetic rather than a geometric explanation, for a particle-size dependence of reaction kinetics in alkane hydrogenolysis has been traced to differences in hydrogen chemisorption strength (24).

The concept of using a semi-permeable membrane to overcome equilibrium limitations, for example, in dehydrogenations, is also not new, but no practical application on any scale has yet resulted: attempts to develop usable systems are however continuing. Palladium-silver membranes used for isobutane dehydrogenation are unfor- tunately quickly poisoned (25), but efforts to construct membranes fkom platinum supported on alumina are showing promise (26,27).

Conclusion It has only been possible to mention a few

of the highlights of the papers presented a t EUROPACAT-I, and scarcely any of the many posters which featured the platinum group metals. However, it is clear that they continue to dominate the catalytic scene, and that their efficiency in very many applications remains unchal- lenged. EUROPACAT-I1 will be held in Maastricht in September 1995: put that date in your diary now.

Speakers 1 S. Kohler, S. Trautmann, H. Doopsch and M.

Baerns, Universitat Bochum, Germany 2 P. Dufour, C. C. Santini, S. L. Scott and J. M.

Basset, I. R. C. and Ecole Superieure de Chimie Industrielle de Lyon, France

3 D. C. Koningsberger, M. Vaarkamp, F. S. Modica and J. T. Miller, Utrecht and Eindhoven Universities, The Netherlands, and Amoco Research Center, Napierville, IL, U.S.A.

4 E. G. Derouane, V. Jullien-Lardot, A. Pasau- Claerbout, N. J. Blom and P. E. Hejlund Nielsen, Facultes Universitaires, Namur, and Haldor Topsee Research Laboratories, Lyngby, Denmark C. R. Henry, C. Chapon, C. Duriez and R Monot, CNRS Campus de Luminy, Marseille, France, and EPFL, Lausanne, Switzerland

6 J. M. Planeix, N. Coustel, B. Coq, P. Kumbahr, R. Dutartre and P. Geneste, ENSCM, Montpellier, France

7 T. Ioannides, 2. Zhang, A. M. Efstathiou and X. T. Verykios, University of Patras, Greece

8 M. Schneider, T. Mallit, D. G. Duff and A. Baiker, ETH, Zurich, Switzerland

5

9 C. Linsmeier, H. Knozinger and E. Taglauer, Max-Planck-Institiit f u r Plasmaphysik, Garching, Germany, and Universitat Miinchen, Germany

10 B. S. Clausen, H. Topsae, L. B. Hansen, P. Stolze and J. K. Norskev, Haldor Topsee and Technical University of Denmark, Lyngby, Denmark

11 M. Polisset, D. Roubah, P. J. Levy, M. A. Springuel-Huet and J. Fraissard, Universite Louis Pasteur, Strasbourg, France

12 P. Legare, G. Maire, P. Bernhardt and F. Pflanz, Universite Louis Pasteur, Strasbourg, France

13 K. van Gorp, D. M. Grove, J. T. B. H. Jasuzebski, G. van Koten and J. W. Geus, University of Utrecht, The Netherlands

14 L. V. Nosova, V. I. Zaikovskii, A. V. Kalinkin and Yu. A. Ryndin, Institute of Catalysis, Novosibirsk, Russia

15 J. Barbier, P. Marecot, G. del Angel, P. Bosch and M. Dominguez, Universite de Poitiers, France, and Universidad Autonoma Metropolitana Iztapalapa and Instituto Mexican0 de Petroleo, Mexico


16 W. Juszczyk, Z. Karpkski, D. Lomot, J. Pielaszek and J. W. Sobczak, Institute of Physical Chemistry, Warsaw, Poland

17 N. A. Zakarina and M. K. Saimerdenova, Institute of Organic Chemistry and Electrochemistry, Alma Ata, Kazakhstan

18 K. Nasar, P. Drognat-Landre, F. Fache, M. Besson, D. Richard, P. Gallezot and M. Lemaire, VCBL and IRC, Villeurbanne, France

19 D. Pini, A. Petri and P. Salvadori, Universita di Pisa, Italy

20 R. Burch, P. J. Millington and A. P. Walker, University of Reading and Johnson Matthey Technology Centre, U.K.

21 Q. Gao, Y. Li, M. Bowker and R. W. Joyner, University of Liverpool, U.K.

Methane Conversion Using The ability to convert methane to higher alka-

nes directly would be of value industrially for the production of liquid fuels and chemicals. Recently a two-step process has been reported for higher alkane production &om methane using a platinum, ruthenium or cobalt catalyst supported on silica. In the first step the metal is exposed to flowing methane and in the second step the alkanes are released from the surface by flowing hydrogen. Related work on alkane production has also been reported when the second step was performed at a lower temperature than the first step. However, this is a stoichiometric reaction, and is not truly catalytic, and only one monolayer of C I is converted at each cycle. The methane also sweeps away hydrogen from the surface, allowing hydrogen deficient species to build up and carbon-carbon bonds to form. For this reaction large surface areas are needed, which will allow reasonable levels of methane conversion to occur.

One way to achieve large surface areas is by using zeolites and filling the cages with the reaction metals. Zeolites are extensively used as catalyst supports, particularly faujasites, as they produce very homogeneously dispersed catalysts with down to nearly atomic sized particles.

Therefore, preliminary work has been undertaken on methane conversion. (E. Mielczarski, S. Monteverdi, A. Amariglio and H. Amariglio, Appl. Cutul. A: Gen., 1993,104, (2), 215-228). Experiments were carried out by a methane adsorption and a hydrogenation step. Alkanes produced included ethane, propane, n- and i-butane, n-, cyclo- and i-pentane and n-, cyclo- and other isomers of hexanes and traces of hep- tanes. Hydrogenolysis was also monitored. At higher reaction temperatures, with Pt/HX, the total amount of homologated methane increased significantly with temperature, even though

22 A. el Hamdaoui, J. Massardier, M. Primet and A. Renouprez, IRC, Villeurbanne, France

23 L. Seyfried, J. M. Bastin, M. Nouinou and A. Frennet, Universite Libre de Brwelles, Belgium

24 G. C. Bond and J. C. Slaa, Brunel University, Uxbridge, U.K.

25 P. E. H~jlund Nielsen, S. Laegsard Jergensen and P. khrmann, Haldor Topsee, Lyngby, Denmark

26 J. Peureux, M. Torres, A. Giror-Fendler, H. Mozzanega, J. Sanchez and J. A. Dalmon, IRC and Lab. d’Automatique et de Genie de Procedes, Villeurbanne, France

27 G. Capanelli, A. Bottino, A. Grosso, A. Servida, G. Vitulli, A. Mastantuono, R. Lazzoroni and P. Salvadori, Universities of Genova and Pisa, Italy

Platinum Loaded Zeolites hydrogenolysis increased, at the expense of higher alkanes. On W H Y the amount of homologated methane reached a maximum at about 275°C but the yield decreased from 52 to 30 per cent when the temperature increased from 250 to 325°C. Hydrogenolysis occurred mainly in the range 250-350°C and was less for Pt/HX than for WHY. The results were compared to those for EUROPT-1 for the same 6 per cent platinum loading. The molar amount of methane homologated in identical operating conditions shows that the catalyst efficiencies are in the order Pt/HX > Pt/HY > EUROPT-1

It is concluded that the beneficial effects of using zeolites for direct methane conversion could be increased by using NaX or NaY zeolites, which should have less hydrogenolysis activity, by performing the reaction sequence at higher temperatures, and by adding a second metallic component to the platinum.

Ruthenium-Niobium-Zirconium System Efforts to improve the physical properties of

alloys have generally proceeded in a quasi- empirical way, but there is a need to improve on the trial and error approach particularly now that materials with special combinations of mechanical and electronic properties are required. As part of a programme to advance the design of intermetallics, a study has been made by researchers at The University of Texas at Austin of the phase stability for the three binary systems of the ruthenium-niobium-zirconium ternary system using first-principles methods 0. D. Becker and J. M. Sanchez, Mutet. Sci. Eng., 1993, A170, (1-2), 161-167).

The accuracy in calculating properties such as Debye temperature, formation energy and solubility, without empirical input, highlights the potential of this approach to alloy development.


Hydrogen Material Science and Metal Hvdride Chernistrv

J J

PLATINUM AND PALLADIUM ALLOYS FEATURED

Under the auspices of the National Space Agency of Ukraine, the Third Inter-Republic Conference on Hydrogen Material Science and Chemistry of Metal Hydrides was recently held from the 9th to the 15th October in the attrac- tive surroundings of the Conference Centre of the Ukrainian Academy of Sciences at Katsiveli near Yalta, in the Crimea.The conference was organised under the joint chairmanship of Professor V. A. Lavrenko and Dr D. V. Schur of the Institute for Materials Science of the Ukrainian Academy in Kiev, supported by an enthusiastic young committee. Approximately ninety contributions were presented with intermediate poster sessions. In an introductory address Professor B. Baranowski, of the Institute of Physical Chemistry of the Polish Academy in Warsaw, drew attention to the fact that the present conference was the first in the series at which some of the papers would be given in English, namely those originating from laboratories in the United Kingdom, Germany, Poland and Tiwan. Contributions delivered in Russian came from laboratories in the republics of Belarus, Russia, Kazakhstan, Uzbekhistan and Armenia, in addition to a majority from Ukraine. Excellent con- current translations in English and Russian were provided in all sessions.

Palladium and Palladium Alloys A main topic area of the conference concerned

hydrogen storage together with complementary issues such as developments in fuel cells and hydride batteries. Related current progress was discussed by Lavrenko who presented a com- prehensive introductory survey, including reference to the phase relationships of intermetallic compounds of the transition elements.

For palladium and palladium alloys, similari- ties between analogous factors in regard to the phase relationships, and to strain gradient effects

during hydrogen permeation experiments, were considered and discussed in two joint papers presented by R.-A. McNicholl and F. A. Lewis, Queen’s University, Belfast, X. Q. Tong, Burmngham University, K. Kandasamy, university of J&a and Y. Sakamoto, Nagasaki University. Similar problems in interpreting phase relationships were found for analogous studies on zirconium-vanadium alloys and palladium-zirconium alloys. These were discussed in two papers by I. U. Zavaly of the Department of Physics and Mechanics of the Ukrainian Academy in Lvov. Involvements of Gorsky Effects, produced by localised lattice strain gradients, could be inferred from electron microscopic observations during annealing of palladium containing low hydrogen contents. This was reported by T. P. Perng, from the Department of Materials Science and Engmeering, Hsinchu, National Academy, T~wan, Republic of China.

Structures and Hysteresis Phenomena Alternative structural change possibilities aris-

ing fkom dislocation production and associated structural damage, occunring concurrently on the introduction of hydrogen into palladium alloys, were dealt with in three papers on palladium-tung- sten, palladium-samarium, palladium-copper and palladium-platinum alloys from G. P. Revkevich, A. A. Katsnelson, I. V. Dolya, M. Mitkova and M. M. Kanyazeva of Moscow State University. Theoretical correlations between hydrogen pressure-composition-temperature relationships and regarding dependencies of various physical parameters on hydrogen content, in relation to hydrogen occupation of particular combinations of inter- stitial sites in palladium alloys, were discussed in a contribution by Z. A. Matysina and S. Yu. Zaginaichenko, of the Metallurgical Institute, of the State University in Dniepropetrovsk.

For palladium-hydrogen and nickel-hydrogen


systems the signilicance in the correlatioIls between their pressure-composition isothermals, in relation to hysteretic and critical point phenomena and also to magnetic parameters, was discussed in a contribution from I. Dugandzic and H. J. Bauer of the Physics Department, University of Munich. A particularly extensive discussion followed the presentation, by Baranowski, of a fresh

teretic effects in pressure-composition relationships and associated thermodynamic parameters of the nickel-hydrogen, and particularly palladium-hydrogen, systems.

Contributions to the conference are planned to be published in the Znternational Journal of Hydmgen Energy and it is anticipated that further conferences in the series will continue to take place

quantitative explanation for the size of the hys- on a biennial basis. F.A.L.

Optically Readable Hydrogen Sensor Uses Palladium A wide range of hydrogen-air compositions

explode on ignition, and may cause serious acci- dents. To avoid such situations arising a variety of hydrogen sensors has been developed. At present, the hydrogen concentration in an atmosphere is usually measured by monitoring changes in an electrical property of the sensor as reaction with the hydrogen gas takes place. To enhance the sensitivity of such sensors it is necessary to maintain clean surfaces, and therefore they are generally heated to temperatures above 15OOC. Thus there has been a need to develop an accurate hydrogen sensor which could operate at room temperature.

Researchers at Nagaoka University of Technol- ogy and at the university of Tokyo, Japan, had observed that the optical transmittance of palladium thin films depends strongly on the presence of hydrogen in the ambient atmosphere; now they have developed a hydrogen sensor which utilises this phenomenon and operates at room temperature. (Y.-S. Oh, J.-I. Hamagami, Y. Watanabe, M. Thta and H. Yanagida,J. C a m . SOC. JPn., 1993, 101, (6), 618-620).

The sensor consists of a palladium thin film deposited on a glass substrate by radio-frequency magnetron sputtering. When a sample is exposed to hydrogen the optical transmittance to light of wavelength 780 nm increases and becomes saturated at a constant value, but on exposure to dry air the transmittance returns to its original value. It is reported that these reactions are per- fectly reversible even after multiple repeats. For a thin film of specified thickness, the optical transmittance of the sensor was found to depend on the hydrogen concentration; with an increase in hydrogen concentration the relative change in transmittance increased, the response time decreased, and the recovery time increased.

This new optically readable palladium thin-film hydrogen sensor has excellent sensitivity and is compatible with fibre optics.

It is suggested that this novel palladium sensor may be selective only to hydrogen. Further- more, the dependence of optical transmittance on the hydrogen concentration in the ambient atmosphere has also been observed for radio- frequency sputtered platinum films.

Precious Metals: ISSN 1004-0676 Since 1980 the Institute of Precious

Metals, Kunming, China, has been producing a quarterly scientific periodical entitled R.eciOur Metals. Sponsored by the China National Nonferrous Metals Industry Cor- poration, the journal reports important research achievements in precious metals research in China. Publication is in Chinese, although English translations are given of the contents table, a brief abstract of each paper and associated key-words, and some figure captions. As may be deduced from the title, the journal covers gold and silver in addition to the six platinum group metals. The scope of the journal is somewhat

wider than that of Platinum Metals Review, in that the subject matter includes: explo- ration, mining and mineral dressing, extraction, separation, purification and analysis, and the recovery of precious metals from secondary resources. Also covered are measurements of physical properties, the use of precious metals and alloys by the chemical, dental, electronics and jewellery indus- tries; and the study of precious metals chemicals, complexes and drugs. More information about Precious Metals may be obtained from the Precious Metals Editorial Panel, Institute of Precious Metals, Kunming, (650221), Yunnan, People’s Republic of China.

Platinum Metals Rev., 1994,38, (1) 21

The Spanish Monopoly of Platina STAGES IN THE DEVELOPMENT AND IMPLEMENTATION OF A POLICY

By Professor Luis Fermin Capitiin Vallvey Department of Analytical Chemistry, University of Granada, Spain

The discooery of platina towards the middle of the eighteenth century in allutial gratvls worked for gold in the Spanish South American viceroyalty of Nett! Granadn, and the interest which this new metal aroused among European scientists as its presence became known, eoentually induced the authorities to recognise the situation and then to take action to control it by means of a royal monopoly. Here, in the first of this two-part paper, goarrnmental action is related to European discoceries up until the time when the usefulness of platina was firmly established.

For much of the eighteenth century platinum was at the centre of attention of people carrying out chemical research. Ever since word of the existence of this new metal had reached Europe there had been an extraordinary surge in curiosity about it among European researchers; indeed, practically all the great eighteenth century chemists worked with, or were interested in, platina. Valentin Foronda, an enthusiast of the physical and natural sciences who had travelled extensively throughout Europe and who was a friend of Joseph Louis Proust, wrote in 1793:

“The news of this new metal brought about the same effects on chemists throughout all of Europe as that spawned by electricity produced in a human circle when successfully touching the Leyden jar: everyone felt the immediate effects of being over- taken by the desire to discover the essence of this new material.” (1)

Since the beginning of the eighteenth century it had been known locally within the viceroyalty of New Granada that platinum occurred in the Choc6 gold deposits. However, it was not until the publication of the results of a Spanish-French expedition set-up to measure the meridian arc, and in which the two young scientifically trained Spanish naval officers Don Antonio de Ulloa and Don Jorge Juan participated (2), that this knowledge reached Europe, this being at a time when there was great interest in learning more about the natural sciences.

The initial demand for platina was relatively small and increased only gradually; at the beginning small amounts were required for the first research studies and later larger quantities were needed for the manufacture of jewellery, trinkets, and scientific and technical instruments. Of course, this growing demand could only be satisfied from the viceroyalty of New Granada, either by the legitimate trading route through Spain or as contraband smuggled from Latin America. Splitting platina - as the ore of the platinum group elements was then known - into its six components requires considerable technical and scientific know-how. The lack of any knowledge of the presence of the other elements and the infusibility of the ore could be the reasons why the material was considered to be worthless, for legitimate purposes, when it was first observed in gold-panning sites in New Granada. Its high density provided an oppor- tunity for fraud in that it could be added to, or not removed from, gold when producing ingots. In such circumstances the platina remains widely dispersed in the gold matrix, causing only slight variations in the density of the material or the results of cupellation analysis.

In response to this type of fraud the colonial authorities eventually decided to recall all the platina in circulation and throw it into deep rivers or ravines, while mines producing large proportions of the white-coloured metal were

Platinum Metals Rev., 1994, 38, ( l) , 22-31 22

closed. In time, improved methods for separating gold and platina (3) modified the attitude of the authorities, and work was permitted at some of the gold-panning sites provided the pro- portion of platina was not excessively high and as long as all the platina was removed from the gold at the miner's expense (4). The presence of platina made the refining process consider- ably more expensive; in one reported case refining costs were increased by 20 per cent (3). Thus it was only when the existence of platina became known in Europe that every imaginable method was used in an attempt to obtain the metal.

The Spanish government tried to keep abreast of the situation by founding a royal monopoly, which controlled the platina collection system in New Granada and its shipment to Europe, and by establishing a dedicated factory in Madrid where the metal was processed. Various problems, including the low price paid for unprocessed platina and the international polit- ical circumstances at the end of the eighteenth century, largely frustrated Spanish plans and favoured direct trade between other parts of Europe and America.

The Spanish contribution to the study and supply of platina has already been considered on a number of occasions (5-1 3) but the founding of the royal monopoly has not been researched previously. Here we will approach the topic by linking European scientific dis- coveries with the Spanish bureaucratic man- agement which led to the creation of this monopoly. The founding of the platina handling system and the Madrid refinery will not be considered.

European Scientific Activity and Platina

During the eighteenth century a total of 92 articles on platina were published in periodical scientific journals alone, that is excluding any other type of publication, and this number increased to 264 by the year 1820. By study- ing the period from 175 1 , the year in which the first paper was published, to 1820, when William Hyde Wollaston discontinued his production of platinum, it appears that the total number of papers published increased exponentially; a relatively important initial period was then followed by a 13-year lapse, see Figure 1.

d '

'15

YI W

U

K -10 F

3 " [:I

5

- 1750 1775 1800

YEAR

Fig. 1 A study of the number of articles about platina published in scientific periodicals between 1751 and 1820 shows that the total increased exponentially, left-hand scale. The experimental points are joined to form a continuous line. The continuous curve represents data adapted to fit the equation log N = -46.351 + 2.685 x 1O3x Y, where N is the accumulated number of papers, Y is the year; fit standard deviation 6.88 X 10". The number of articles published each year is indicated on the right-hand scale


Two insignificant positive deviations occurred in the plot of the accumulated paper numbers; the first ofthese, between 1780 and 1793, cor- responds to increased interest in refining and smelting. The second is somewhat more pro- nounced and took place between 1803 and 18 10, and is attributed to the discovery of the other elements of the platinum group and also to controversy generated mainly between France and England (1 4). This pure exponential depen- dency collapses around 18 10 when the accumulated index falls, which could suggest that we then have a logarithmic curve, indicating saturated exponential growth, which is charac- teristically found in science (1 5). Thus two stages can be distinguished in the

platina research carried out in the last quarter of the eighteenth century, the so-called Century of Enlightenment, and the early years of the nineteenth century. Only a meagie number of papers were published during the first stage, which ended with Pierre Francois Chabaneau’s success in refining platina. An increased over- all interest in the elements of the platinum group was evident during the second stage, which was ended in Spain by the French invasion in 1808 and in the rest of Europe with the discontinu- ation of platina imports into England by Wollaston in 1820.

During the first stage (1755-1786) the most

elementary observations were made about platina, some properties were established and it was defined as a noble metal. Efforts were concentrated on overcoming refining difficulties and a number of applications were tenta- tively suggested. At this time European requirements for platina were small. As can be deduced &om the distribution of published papers according to country and geographic area, see Figure 2, that the largest contribution was made by France (56.3 per cent) which was therefore the country with the greatest need for the metal.

The activity in the second stage (1787-1820) was again focused primarily on the refinement of platina, with the aim of endowing the metal with the malleability required for any probable use. Applications began to grow, modestly at first but with greater vitality later. The research effort was now shared between France and England, with the emphasis being on applications for the platinum group metals, rather than on establishing the properties of platina, as occurred during the first stage.

Spanish Government Activity Regarding Platina

The brief report about platina that was given by Ulloa and Juan in their “Historical Account” (2) spread rapidly, aided by official support for the dissemination of news of their achievements (1 6).

ENGL

SWEDEN 10

SPAIN 2.1 ENGLAND 3 0 6

I

PWSSIA 171

FRANCE 56.3

1755-1786 1787-1820

Fig 2 In the period up to 1786 preliminary observations about platina were being made and some properties established. European requirements for platina were small and a breakdown of the number of papers published according to country of origin shows that France made the largest contribution. From 1787 to 1820 applications for platina were being actively sought with France, and England, again at the forefront of these investigations


This information which was published in 1748, together with the results of work carried out on platina by Charles Wood and reported to the Royal Society in 1750 by William Watson (17), marks the beginning of European research on platina .

In 175 1 Hensik Theophil Scheffer expounded his findings about platina to the Swedish Academy of Sciences (1 8). Between 1754 and 1757 William Lewis presented four papers on platina to the Royal Society (19), and in 1754 Andreas Sigismund Marggraff reported his work to the Prussian Royal Academy of Sciences, in Berlin (20). In France, work by J. J. Le Frangois de Lalande (2 l), and by Pierre J. Macquer and Antoine BaumC (22), appeared in 1758.

News of the discovery of platina spread to widely read, informative publications. In 175 1 two letters on platina written by W. Watson to Georg Mattias Bose, professor of natural philosophy at the University of Wittenberg, appeared in the recently founded journal Physikalische Belustigungen (23). Just months later two articles on the same topic were published in the French Journal Oeconomique (24). In 1764 another article on platina appeared in the Gaceta & Madrid (25).

The studies reported are indicative of the state of opinion, and of the interest aroused in the European scientific community, by the presumed existence of a new noble metal in the Spanish dominions. This interest made it necessary for the Spanish Government to become informed of the location and the amount of this metal.

The Initial Spanish Response At first very little was done in Spain about

platina, with the exception of a paper which Bowles supposedly wrote in the 1750~~ at the request of Ulloa, but which was not published until 1782 (26).

In 1765 the platina issue had become suffi- ciently important to interest the Junta General de Comercio (Board of Trade), the Spanish fis- cal authorities, it now having been established that platina was a new noble metal analogous to gold in some respects (1 8). On June 14th, 1765 the Marquis of Esquilache sent a repre-

sentative from the Board of Trade to Julian de Arriaga, Secretary to the Office of the Indies, requesting information on platina; specifically its geographical location and the possibilities of mining it (27). The answer, dated July 30th, gave all the information then available at the “Casa de la Moneda” or mint. This included its appearance, size, colour, high density, infusibility, feeble attraction to magnets, and the fact that it did not alloy with gold. In report- ing how to separate it from gold only fusion and amalgamation were mentioned, not the method of inquartation which was also used (3).

Furthermore, this answer indicates that the use of platina was not prohibited, “since it is good for nothing”, but it warned that precau- tions should be taken to prevent its fraudulent use for adulterating gold. This observation confirms the varying attitude of the colonial authorities, which ranged from initial prohibition, when the metal was put to fraudulent use, to subsequent tolerance, when a particular mine did not have an excessively high platina content (4). Finally it proposed that experiments should be undertaken to try to establish possible uses for platina.

In the margin of this reply a short note, possibly written by Arriaga, states:

“Having been duly informed of the information herein contained, Sir Squilace [the Marquis of Esquilache], relating all that is on file at this Secretariat: instruct the Viceroy to ship Platina.”

With the exception of the petition made by Juan Wendlingen in 1757, which was never ful- filled, th is was the first occasion on which platina was oficially requested to be shipped to Spain. A quintal of platina, or four arrobas, was explic- itly requested (28), although in the subsequent regal mandate dated 30.07.1765 a request was made for two quintals (29). [One arroba contains 25 pounds, thus one quintal is 100 pounds].

In response to this, on January 18th, 1766, Viceroy Messia de la Cerda sent one arroba and 22 pounds of material which was then in his possession to Spain via Cartagena de Indias (30), and ordered more platina from Choco to enable the shipment of two quintals to be completed (31). The reason that some platina


had not been pitched into a deep river but was then available at the Santa Fe de Bogota Mint was due to a request made eight years earlier by the Jesuit Friar Juan Wendlingen, Chief Cosmographer of the Indies, who in 1757 had requested platina for his studies, but never received it “for not having taken the necessary measures to do so” (32).

The summary of the answer sent by the viceroy to Arriaga had the following note written in the margin:

“having arrived, the requested item shall be placed at the disposal of the Board: and inform the viceroy that what was requested shall not be shipped until thorough experimentation proves whether or not it is a worthwhile object.” (31).

If Arriaga was instructing the viceroy not to ship any more until further notice (33 ) , it would appear that a sufficient quantity of platina had already been received to enable a study to be made of its usefulness. The platina arrived in May 1767 and was delivered to the Board of Trade (34). As far as is known, however, no investigation was carried out and the whole affair was put off until the proverbial “tomorrow”.

Introductory Observations on the Second Shipment

The platina issue was revived seven years later by a letter dated June 15th, 1774, from Manuel de Guirior, the new viceroy of New Granada which announced the success of another attempt to melt down and work platina. As proof of this claim the viceroy sent to Julian de Arriaga, for delivery to the king, two platina medallions each carrying an effigy of Charles 111. One was made in platina and copper, in the ratio of 1: 1; the second was all platina (35).

An anonymous report entitled “Ynforme sobre la Platina”, describing the current position regarding platina, and its possible uses and advantages, probably accompanied the letter and the medallions. This report is not mentioned in the letter, however, nor does it appear with the rest of the documents in the General Archives of the Indies. None the less two factors support the belief that it was sent.

The first is a hand written note, signed by Jose

Don JosC Celestino Mutis 1732 - 1808

Initially going to New Granada as physician to the Viceroy Messia de la Cerda, Mutis studied principally the flora and the mineral deposits of this viceroyalty, including platina. His reports and correspondence serve as a valuable source of information about platina, including the fact that two platina medallions depicting King Charles 111 were produced in Santa Fb by Francis0 Benito and despatched to Spain in 1774

Celestino Mutis, which appeared at the end of a copy of the report, and which indicated that the medallions were dispatched together with the report written by the viceroy on June 15th, 1774. Two copies of this report are conserved at the Madrid Royal Botanical Gardens, one of them being signed by Mutis (36). The second piece of evidence is the fact that this report is the only place where mention is made of Francisco Benito. He was the engraver at the Santa Fe Mint and the man whom the Madrid authorities considered to be solely responsible for the innovative work.

In addition to Benito, the only other person mentioned was the vicereine who was reputed to be the promoter of the work, although her only contribution was to commission the


production of the medallions from the metal supplied. The research took place in Santa Fk (39, possibly at the Mint and under the direction or with the direct assistance of Mutis who lived in Bogoti &om 1770 to 1777, which would explain why he wrote the final report. It is assumed that platina fusion, not refinement, was carried out via the formation of alloys, so reducing the fusion point significantly and increasing the malleability of the metal, although not without problems.

In his report Mutis demonstrated that he was well informed on the researches carried out in Europe on platina. He mentioned that Ulloa was responsible for foretelling the discovery of platina, and he was familiar with the work of Morin - “La platine, l’or blanc, ou le huitieme mttal” (37) - although he did not quote it by its title. He confirmed his knowledge of the work of Morin by reference to a translated version of the book “A Collection of Experiences with Platina” which he claimed was being translated in Bogota by a devotee, who was, perhaps, himself. Significantly this title concurs with the sub- title of Morin’s book “Recueil d’Experiences faites dans les Academies Royales”. Additionally, Mutis also referred to experiments on platina undertaken in Sweden, London and Venice, which had also been mentioned in Morin’s publication.

Mutis was interested in advancing the “knowledge, change and use of the precious and extremely rare metal” and suggested several uses for it, all of which had been proposed previously by Morin. To justify the introduction of platina Mutis claimed that it was easy to melt down, but what he assumed to be pure platina - “a highly brittle and hard metal” - must, in fact, have been an alloy since at that time the technical facilities available were not capable of melting platina, especially if it was in an unrefined state.

None the less this apparent demonstration of the use of platina revived interest in it. As a result a government official, Francisco de Zalamea, travelled from Santa F k de Bogota to Choc6 to obtain further facts about platina and its uses. The information that he obtained

about the sites where the unwanted metal was dumped was to be made use of at the end of the 1780s to facilitate platina extraction (38). The letter written by the viceroy and the two

medallions were sent by Arriaga to the Board of Trade, for the attention of Miguel de Muzquiz, Minister of the Treasury, on September 30th, 1774 (39).

In his reply dated January 26th 1775, Mkzquiz admitted t o Arriaga that the investigations ordered in 1767 had not been carried out on the platina received, but said that they would now go ahead (40). This newly initated research, however, was not carried out but a series of measures involving platina were taken and resulted in a royal mandate dated 3.02.1775 (41). Inthis Benito was requested to provide detailed information about the processes used but not to dis- close them to anyone else and for maintaining his silence he was to be awarded compensation, determined by the viceroy. With regard to platina, Guirior ordered that

“it is not to be pitched as has been the custom to date, but rather it is to be safeguarded by royal officials, as metal belonging to H.M.”

and furthermore that no one in all of America is to work with the metal.

On the other hand, as a matter of urgency he requested the viceroy of Peru and the President of Chile to provide details about the existence of any platina mines in their respective territo- ries, and the value attached to the metal (42).

All the official notes sent to the viceroys, and their replies, are archived - except for those relating to the method used by Benito. This does not appear in any of the documents consulted, although it is recorded that the viceroy’s reply was received on September 2nd, 1775, together with an additional series of samples (43). The only information available alludes to the fact that “ [platina] had been able to be melted down with several alloys ....” (43), while another mes- sage mentions that “samples of the experiments carried out with platina melted down solely with copper and brass” (44). This confirms what had been noted previously; that the melting of platina had been achieved by the formation of alloys which have significantly reduced melting points.


It is interesting to speculate whether the claim to have melted platina was made with fraudulent intentions, and if so by whom. Alternatively, if the claim was made in good faith, did a combination of errors, ignorance and pure chance lead to the apparent fusion of platina? To date, the information necessary to answer these queries is not available, although it is likely that if it had been by chance the phenomenon would only have occurred on a single occasion, and this does not appear to have been the case.

This was not the first time that attempts to melt platina had been made in New Granada,

ments and trinkets as a cheap substitute for silver, a fact mention by Mutis in one of his reports:

The use of platina alloyed with copper, anti- mony and other metals was confirmed by Jean Baptiste Leblond, a Frenchman who travelled through the viceroyalties in the 1780s; by which time production had ceased because of the high contribution that manual labour costs made to the final price (45).

Further corroboration is contained in the first review written in Spain about the new metal by Munibe, who reports that:

“Around the year 1730, Nobleman Jorge de Villalonga was given a sword guard and a set of platina buckles by the first viceroy of Santa Fe as a gift although it can be assured that they did not

it was a brittle metal, heavier than gold in which it is intermixed.” (46)

Returning to the medallions referred to by Mutis, it must be emphasised that the involve- ment of the Board of Trade was not well known,

it having been used previously for making orna- possess sufficient bonding or consistency and that

‘‘Albeit the fact that small portions of platina used to be melted down in this city for making cere- monial sword hilts, boxes and shoe buckles, none of these pieces can be sighted nowadays, simply because the inhabitants have come to consider this invention absolutely worthless, and because of the requests and petitions generated by foreigners who aspired to verify its irresolute ability to be melted down, have disappeared entirely.” (36)

This reference coincides with the opinion expressed by Watson to the Royal Society in 1750, when presenting Wood’s studies on platina, when he mentions that:

“It is very probable that there is a great Plenty of this semi-metal in the Spanish West-Indies, since

since on June 27th, 1776 a new letter was received from the viceroy, which had been written on September 2nd, 1775, with the pur- pose of “re-examining this important matter” (43). Muzquiz responded to this on November 15th, 1776, excusing himself as the ordered investigations had still not been carried out (47). The interest of the Ministry of the Indies is made clear in an official note dated January 24th, 1779 in which Muzquiz reminded the recipients that he was still waiting for the report, so that he could act upon it (48).

trinkets made of it are very common. A gentleman of Jamaica bought five pounds of it at Carthagena for less that its weight of silver, and it was formerly sold for a much lower price ........ But the Spaniards have a way of melting it down, either alone, or

Eventually this report must have been sent to the General Board of Trade and Currency, but it has not been found. It is possible that it could have supported the idea of continuing

by means Of Some flw, and cast it into sword-hilts, buckles, snuff-boxes, and other utensils.. ...”. (1 7)

research on platina and the need to establish a royal monopoly. This would have justified the

As noted earlier, the facilities for melting platina did not exist then, so it must be assumed that these objects were made of platina alloyed with either copper or silver. Thus they would consist of platina dispersed in a metal matrix, and the material would have poor mechanical properties. In all probability the objects would be silver-coloured, because otherwise Watson would have mentioned the colour, and this suggests that if the matrix was copper then the platina content must have exceeded 60 per cent.

new request for platina which was sent to New Granada in December 1781 (49), and which resulted in the dispatch of a second shipment which arrived in Madrid in June 1784.

The delay in sending the second shipment of 12,937 castellanos of platina may have been due to the death of Viceroy Manuel Antonio de Flores. He was replaced by Juan de Torrezal Diaz Pimienta who died shortly afterwards and, in turn, was replaced in 1782 by Antonio Caballero y Gongora, Archbishop of Santa Fe


Antonio Caballero y G6ngora 1723 - 1796

While Archbishop of Santa FB de Bogotai, Antonio Caballero became Viceroy in 1782 and began his rule with a general amnesty for those involved in the com- munard’s revolt, and with the reorganisation of the army. He encouraged public education and religious missions. In 1783 he mounted, initially without royal authorisation, the Botanic Expedition to the Kingdom of New Granada under the leadership of Mutis. He was also the director of the Spanish plan for the collection and despatch of platina to Spain

de Bogota. Be that as it may, in the meanwhile the metal was stored in strongboxes (caja real) in Cartagena de Indias (50).

Spanish Studies on Platina During the last few years of the period 175 1

to 1786, the studies of platina undertaken in Europe had one main objective, to refine the metal and render it malleable enough for fabrication. Such attempts were made by A. Baume (51), N. A. de 1’Isle (52), K. von Sickingen (53) and Count de Milly (54).

The Spanish government was aware of the studies being carried out by Casimiro G6mez Ortega (1 740-1 8 1 €9, a professor of botany and an influential figure in the scientific world. Around 1776177, on his return from a trip to Europe he visited the Ministry of the Indies and emphasised the need to foster studies of the ductility of platina, because of the tremendous interest shown by European chemists. In September 1780 he sent the results of the Count de Milly’s study of platina refining to the Ministry (54), together with several objects manufactured in malleable platina. According to G6mez Ortega,

the results published by de Milly were very encouraging, but the problem remained unsolved (55).

As a result the Spanish government knew that if platina was to find use, a method of making the material malleable had first to be found. It is very likely that Jose de Galvez, the Marquis of Sonora and Secretary to the Indies, promoted the attempt to develop platina mining, in the belief that if this was successfully achieved other developments would follow.

What is still not clear is why work on platina refining did not begin in Spain until 1786, since all the necessary information had been available for at least a decade prior to this. Platina existed in abundance, the need to refine the metal was well known, and the lines along which European researchers had been working were heading in the right direction even though they had not yet been successful.

The delay was possibly due to the fact that at that particular time there was no chemical or metallurgical specialist in Spain capable of solving the basic problem; indeed, G6mez Ortega recognised this difficulty (55).


Another explanation could be that it was not entirely clear to the Spanish government if platina really was a noble metal, or not.

Spanish studies on platina refining were to be carried out at the Royal Basque Patriotic Seminary of the Basque Society of Friends of the Country, an organisation founded in 1763. In 1767 they had proposed the establishment of a learning centre and this was inaugurated ten years later. Because of lack of financial resources, however, each department could only offer general teaching. The remaining chairs of chemistry, metallurgy, mineralogy and mining were set up on the basis of an agreement signed by the Secretary of the Sea, and was intended to rehabilitate the Spanish military metallurgical industry (56) .

Louis Proust became responsible for chemistry and metallurgy, Fausto de Elhuyar for mineralogy, and Franqois Chabaneau for physics; the latter chair being funded by the Basque Society in order to complete the teaching staff. Apart from the teaching function, which is not considered here, both Chabaneau and Elhuyar carried out several research projects during their stay at Vergara; but Proust did not, possibly

because he was there for only a short time. When responsibility for Vergara was trans-

ferred from the Secretary of the Sea to the Secretary of the Treasury, it became the centre for investigations on platina and work com- menced immediately. At the beginning of 1786 the Secretary of the Indies, Jose de Galvez, Marquis de Sonora, put Chabaneau and de Elhuyar in charge of platina refining investigations and by May of that year the technical and financial studies of the methods of platina refining had been completed.

Some of the platina used for these studies had been donated to Vergara earlier by the Marquis of Castillejos so that potential uses for platina could be established (57); and part of the two shipments sent from America were also used.

Thus a significant change of emphasis had taken place. It was no longer a question of finding out if platina was useful; the metal was highly valued abroad, Spain exclusively controlled its availability and had established a process by which it could be refined. The new tasks were to organise the extraction and shipment of platina from America to Spain for refining. These will be considered in Part I1 of this paper.

References 1 V. Foxunda, “Disertaaon sobre la platid’, pp. 7940,

in “Mscelanea o coleccion de varios discursos”, 2nd Edn., Madrid, 1793, pp. 76-94

2 A. de Ulloa and J. Juan, “Relaci6n Historica del viaje a la America Meridional”, A. Marin, Madrid, 1748, reprinted by Fundacion Universitaria Espafiola, Madrid, 1978, Vol. I, p. 606

3 L. F. Capitin Vallvey, “Separating Platinum from Gold During the Early Eighteenth Century”, Platinum Metals Rev., 1989,33, (2), 73-80

4 L. F. Capitin-Vallvey, “Las autoridades coloniales y la platina neogranadina a comienzos del siglo XVIII”, Quipu, 1989,5, (3), 429443

5 J. F. ill^^, ‘ ‘ D ~ ~ Antonio de Ulloa el des- cubrimiento de la platina”, Las Ciencius, 1939, 4, ( a , 1 - 4 R. D, Antonio de Ulloa. La medicion del arco terrestre, La historia del platina,,, Rev. Arch, Bib, Mus,, 2, 27, (2), 29C333; ibid, 2nd part, 1913,28, (l), 58-91

7 F. Yoldi Bereau, “El aislamiento del platino y el Real Seminario Pamotico de vergm”, An. Fis.~ @im., 1945,41,19%200 A. R~~~~ de hmas, “ ~ a ~~~l ~~~~~l~ de Mineralogia de Madrid (1789-1808)”, Hispania, 1979,39, (142), 301-335

9 J. L. Howe, “Chabaneau: an early worker on platinum”, Chem. News, 1914,109,229-231

10 L. Silvan, “El Laboratorium Chemicum de Vergara y la Real Sociedad Bascongada en las investigaciones sobre la purificacion de la platina”, Bol. R. SOC. Basc. Amigos Pair, 1969,25, 165-189

1 1 D. McDonald and L. B. Hunt, “A History of Platinum and its Allied Metals”, Johnson Matthey, London, 1982

12 F. Arag6n de la Cruz, “Los laboratorios de purificacion del platino en Madrid en el siglo XVIII”, IV Congress of the Spanish Society on the History of Science and Technical Know-How, “Estudios sobre la Historia de la Ciencia y de la Tecnica”, Valladolid, Sept. 22-27, 1986, Junta de Castilla y Leon, 1988; F. Aragon de la Cruz, “La inves- tigacion sobre el platino en la Espafia del siglo XVIII”, I Congress of the Spanish Society of the History of Science and Technical Know-How, Madrid, Dec. 14-16, 1978

13 F. Aragon de la Cruz, “Los hermanos Elhuyar Y la investiga cion del platino en la Espafia del siglo XVIII”, in “Homenaje a 10s hermanos Delhuyar en el bicentenario del aislamiento del wolframio”,

“,,. Jorge

1983 14 Op. cir., (Ref. l l ) , pp. 150-159


15 D. J. S. Price, “Hacia una ciencia de la ciencia”, Barcelona, Editorial Ariel, 1973

16 J. P. Merino Navarro, and M. M. Rodriguez San Vicente, “Introduccion” in “La relacion historica del viaje a la America Meridional” by A. de Ulloa and J. Juan, Madrid, Fundacion Universitaria Espaiiola, Vol. I, 1978

17 W. Watson, “Several Papers Concerning a New Semi-Metal called Platina”, Phil. Trans., 175 1,

18 H. T. Scheffer, “Det hvita Gullet, eller fjunde Metallen, kalladt i Spanien, Platina del Pinto, pintos fma Silfver, belkrifvit ti1 fin natur”, Kungl. Wtensk. Akad. Handl., 1752, 13, 269-275;

19 W. Lewis, “Experimental Examination of a White Substance, said to be found in the Gold Mines of the Spanish West Indies, and there known by the Appellation of Platina, Platina di Pinto, Juan Blanca (Solution, alloys, purification)”, Phil. Trans., 1754, 48, 638-689; ibid, 1757, SO,

20 A. S. Marggraf, “Versuche mit dem neuen min- eralischen Koerper Platina del Pinto genannt”, Nouv. Mern. Acad. Roy. Sci., Berlin, 1755, 31-60; Chem., Schrifer, Berlin, 1768, 1, 1-42

21 J. J. Delalande, “Lettre a Messieurs les Auteurs du Journal des Scavans, sur un Nouveau Metal Simple; appelle Platine”,J des Scavanr, Jan. 1758,

22 P. J. Macquer, “Memoire sur un Nouveau Metal connu sous le nom d’or blanc ou de Platine”, Mern. Acad. Roy. Sci., Paris, 1758, 119-133

23 W. Watson, “Two letters to Bose”, Phys.

46,584-596

276-278

148-166

46-59

Belustigungen, 1751, (l), 107-108; ibid:, 1751, (4), 285-287

25 26

27

28

29

30

31

32

33

24 J. Oeconomique, May, 1751, 93-94; ibid., July, 1755, 148-149 Gaceta de Madrid, Tuesday, Jan. 3, 1764 G. Bowles, “Disertacibn sobre la platina”, in “Introduccion a la Historia Natural y a la Geografia Fisica de Espaiia”, Madrid, 1782, p. 207 Archivo General de Indias, Santa Fe, leg. 835, 14.06.1765, Esquilache to Arriaga, ff., 59r-60r Archivo General de Indias, Santa Fe, leg. 835, 30.06.1765, Secretario de Indias to Esquilache, ff., 61r-64r Archivo General de Indias, Santa FC, leg. 835, 30.07.1765, Arriaga to Messia de la Cerda, f., 57r Archivo Historic0 Nacional de Colombia, Cauca Mines, Vol. 5, 4.2.1766, Royal Officials from Cartagena to Messia de la Cerda, f., 843rv Archivo General de Indias, Santa Fe, leg. 835, 18.01.1766, Messia de la Cerda to Arriaga, ff., 68r-69r Archivo General de Indias, Santa Fe, leg. 835, 30.07.1765, Arriaga to Messia de la Cerda, f., 57r Archivo General de Indias, Santa Fe, leg. 835, 19.07.1766, Arriaga to Messia de la Cerda, ff., 70r-71r

34 Archivo General de Indias, Santa Fe, leg. 835, 5.05.1767, Arriaga to Muzquiz, f. 77rv

35 Archivo General de Indias, Santa FC, leg. 835, 15.06.1774, Guirior to Arriaga, f. 99rv

36 Real Jardin Botanic0 de Madrid, documents belonging to J.C. Mutis, “Report of Platina”, Santa Fk de Bogota

37 Morin, “La Platine, I’or blanc ou le huitieme metal”, Paris, 1758

38 Archivo General de Indias, Santa Fe, leg. 835, 21.08.1786, Caballero to Galvez, ff., 167r- 1 69v

39 Archivo General de Indias, Santa Fe, leg. 835, 30.9.1774, Arriaga to Muzquiz, ff. ,105-106v

40 Archivo General de Indias, Santa Fe, leg. 835, 26.01.1775, Muzquiz to Arriaga, ff., 101r-104r

41 Archivo General de Indias, Santa Fe, leg. 835, 3.02.1775, Arriaga to Guirior, f., 108rv

42 Archivo General de Indias, Santa Fe, leg. 835, 3.02.1775, Arriaga to Virrey del Peru and Presidente de Chile, f. 107r

43 Archivo General de Indias, Santa Fe, leg. 835, 27.06.1776, Arriaga to Muzquiz, ff., 114r-11%

44 Archivo General de Indias, Lima, leg. 1623, 26.09.1776, Note to the Juan Gregorio Pineyro y Sarmiento representatives

45 J. B. Leblond, “Memoire sur la platine ou or blanc”, Obs. sur Phys., 1785, 21, 362-373

46 Extracts from the Royal Basque Society of the Friends of the Country general board meet- ings, 1775, 70-71, (see Ref. 57)

47 Archivo General de Indias, Santa Fe, leg. 835, 15.11.1776, Muzquizto Arriaga, ff., 116r-117r

48 Archivo General de Indias, Santa FC, leg. 835, 24.01.1779, Arriaga to Muzquiz, ff., 123r-124r

49 Archivo General de Indias, Santa FC, leg. 835, 21.12.1781, Galvez to Virrey de Santa Fe, f., 143r

50 Archivo General de Indias, Santa FC, leg. 835, 7.10.1783, Caballero to Galvez, f., 148r

51 A. Baume, ”Chymie Experimentale et Raisonne”, Paris, 1773, 3, pp. 189-194

52 B. C. Sage, “Elements de Mineralogie”, Paris, 1777, 2, p. 361

53 K. H. von Sickingen, “Versuche uber die Platine”, Mannheim, 1782

54 Count de Milly, “Memoria ... sobre 10s exper- imentos e investigaciones que habia practicado con la platina. .. .”, Royal Palace Library, Ayala Collection, 47, 2860

55 C. Gomez Ortega, “Jnforme de D..... sobre la importancia del us0 de la platina. ..”, Royal Palace Library, Ayala Collection, 55, 2873

56 A. P. Whitaker, “The Elhuyar mining missions and the Enlightenment”, Hispanic A m . Hist. Rev. , 1951, XXXI, 557-585

57 J. Fages y Virgili, “Los quimicos de Vergara y sus obras”, Acceptance speech upon admittance to the Academy of Sciences, Madrid, 1909, p. 41


ABSTRACTS of current literature on the platinum metals and their alloys

PROPERTIES Optical Properties of Coloured Platinum Inter metallic Compounds J. HURLY and P. T. WEDEPOHL, 3 Muter. sci., 1993, 28,

The optical properties of PtAl, were changed by addition of 5-25 % Cu by mass. The colour of PtA1, changed from brass-yellow through orange to copper-pink. Adding Cu increased the lattice parameter of the simple fluorite structure PtAl, by - 0.8 %, but not its structure. Also the addition of Cu produces a progressive lowering of the reflectivity at the red end of the visible spectrum.

Phase Equilibria in the Pt-In-P System c. F. LIN, s. E. MOHNEY and Y. A. CHANG, 3 Appl. Phys., 1993, 74, (7), 4398-4402 Phase equilibria in the Pt-In-P system have been determined at 725 and 600°C by XRD and electron probe microanalysis. The observed binary phases were con- sistent with data in the literature; three ternary phases were found. A tie-line transition from InP-Pt,In, at low temperature to In-PtP, at high temperatures was found between 600 and 725°C from both bulk phase equilibria and PtIn,/InP thin film samples. Enthalpy of formation of PtP, at 298 K was --350 f 40 kJ/mol. From the phase equilibria, Pt,In, may be useful as a stable contact material to InP.

Quasicrystalline (A1,Pd)-Phase in Dilute AI-Si-V-Pd Films for Use as Reliable Metallizations in Ultralarge Scale Integration A. G . DIRKS and A. E. M. DE VEIRMAN, Scr. Metall. Muter., 1993, 29, (8), 1017-1022 A study of the Al-Si-V-Pd alloy has been performed to assess its use in ULSI, and to examine its high resistance to electromigration, which occurs at a current density of 2.106 Ncm, at 180°C. In DC magnetron sputtered Alga ,V, ,Pdu I alloy films (Al, I'd) pre- cipitates were observed upon annealing at 450"C, being located at the Al grain boundaries.

Feffd Nano-Multilayers Prepared by Vapour Deposition, and Their Magnetic Anomaly F. PAN, T. YANG, J. ZHANG and B. x. LIU, 3. Phys.: Condens. Maner, 1993,40, (3, L507-L514 The magnetic properties of FePd nano-multilayers prepared by electron beam vapour deposition are reported. The magnetic moment per Fe atom in the multilayers was greatly enhanced when the Fe layer thickness was < 6.5 nm: up to 3.27 F~ at an Fe layer thickness of 1.6 nm, and there was an increased tendency towards perpendicular magnetisation as the thickness of the Fe layer decreased. The enhancement may be due to the formation of a Fe-enriched phase with f.c.c. structure, at the FePd interfaces.

(20), 5648-5653

The Reflectance of Solid-Phase Epitaxial Pd/Ge Film on GaAs and Its Application for VCSELs Array

GUAN and Q.-x. CHEN, Solid State Commun., 1993,88, (6), 461-463 A novel technique for producing vertical cavity surface-emitting lasers (VCSELs) arrays is described, which uses solid-phase epitaxial PcUGe thin films as ohmic contacts to GaAs. The PcUGe ohmic contact to GaAs had a resistivity of 5 x 10 '/cmz on 10Vcm' n-GaAs. The reflectivity of the non-alloyed Pd/Ge film on GaAs is suitable for use as both the reflec- tors and electrodes in the laser array.

Structural Analysis of Polymer-Protected Palladium/Rhodium Bimetallic Clusters Using EXAFS Spectroscopy M. HARADA, K. ASAKURA, Y. UEKI and N. TOSHIMA, J. Phys. Chew., 1993,97, (41), 10742-10749 Structures of colloidal dispersions of PcURh bimetallic clusters prepared by refluxing solutions of their salts in H,O/EtOH in the presence of poly- (N-vinyl-2-pyrrolidone) were investigated by EXAFS. The Pd-Rh bond distance, - 2.7 8, in the alloy foil, is equal to that of Pd-Pd and Rh-Rh in Pd and Rh foils, respectively. Peak height dserences between the Pd foil and the PdiRh(li1) alloy foil and between Rh foil and the same alloy foil show that the disorders are all about the same, even at room temperature.

Electrical Resistance and Thermoelectric Power of Ordered Fe,Pd7,,Au, Alloys N. I. KOUROV, L. N. TYULENEV and YU. A. VERESHCHA- GIN, Fiz. Metal. Metallov., 1993, 75, ( 6 ) , 75-79 The electrical resistance and thermoelectric power of ordered Fe,,Pd,, .Au, alloys, where x 5 37.5 at. %, were studied at intervals between 4.2-1300 K. The dependencies of the temperature and concentration characteristics were established during the phase transfer from ferromagnetic (x < 7.5 at.%) to antiferro- magnetic (x > 15 at.%) alloys, and also on the bound- ary of stability of the modified phases (x 225 at.%).

The Specific Volumes of Pd,,Ni,,P,, in the Liquid, Glass, and Crystallized States K. c . CHOW, s. W o N G a n d H. w. KUI,J Appl. Phys., 1993,

The specific volumes of Pd,,Ni,,P,,, in the liquid (827-1 196 K), glass (300-593 K), and crystallised state (30Ck593 K) are reported. Purity was very important for the molten state measurements. The inter- section points of the specific volume curves of the liquid (both stable and metastable), glass and crystallised state are 573 f 80 and 492 f 80 K (extrapolated values), respectively. The specific volume of the relaxed glass is 0.25% above that of the crystallised state.

W.-X. CHEN, P.-F. JIAO, J.-H. ZHAO, S.-M. WANG, S . 4 .

74, (9), 5410-5414


The Shape Memory Effect in a Tiad% Alloy

HORIKAWA, scr. Metall. Muter., 1993, 29, (lo),

High temperature tensile tests for the Ti5,Pd,, alloy, which exhibits the highest transformation temperatures are reported using a button of the alloy made by plasma melting. To improve the shape memory characteristics the critical stress for slip has to be increased by adding a ternary element, and the parent phase has to be strengthened by age hardening, and by a heat-mechanical treatment. Adding Ni to the Ti-Pd alloy system improved the shape memory characteristics.

Magnetic Order in Pd,TiIn: A New Itinerant Antiferromagnet?

and K. R. A. Z I E B E C K , ~ M a p . &. Magn. Muter., 1993,

The bulk magnetic properties of the intermetallic compound Pd,TiIn which has the Heusler L2, structure are reported. The material orders antiferromagnetically at < - 110 K. The effective paramagnetic moment obtained from the Curie-Weiss behaviour of the susceptibility is 4.9 pB. which is much higher than can be expected from a localised moment associated with the Ti atoms. This suggests that the material is probably an itinerant antiferromagnet with finite-temperature properties characterised by spin fluctuations.

Characterization of Mechanical Properties in the Ir-Nb-Zr Intermetallic System A. M. GYURKO andJ. M. SANCHEZ, Mazer. sci. Eng. , 1993,

The mechanical properties of very high melting intermetallic compounds in the Ir-Nb-Zr system are examined. Two related high temperature L1, intermetallic compounds Ir,Nb (1) and Ir,Zr (2) have similar lattice parameters, and melting points of 2450 and 2280°C, respectively. (1) has twice the strength of (2). A ternary compound Iro,7,Nbo,,iZro.u8 has a high temperature strength greater than that of either (1) or (2). Total energy electronic structure calculations con- fumed the similariry in the cohesive properties of the binary compounds and suggest that differences in the density of states at the Fermi level may explain their dissimilar mechanical behaviour.

The Magnetic Properties of Iridium in Mixed-Metal Oxides

Compd., 1993,201,73-84 The magnetic susceptibilities of Ir mixed metal oxides have been measured as functions of temperature and applied magnetic field. Oxides Sr41r06, BaLaNiIr06 and BaLaCoIr06 order antiferromagnetically at 12, 87 and 56 K, respectively. BaLaFeIrO, has a spin-glass transition at 65 K. La,NiIrO, and La,CuIrO, order as weak ferromagnets at 80 and 70 K, respectively. La2Mg,.,Zn,IrO6 changes from antiferromagnetism, with T, = 11.7 K, when x = 0, to ferromagnetism with T, = 9.5 K and b, = 0.4 ps, when x = 1.

K. OTSUKA, K. ODA, Y. UENO, M. PIAO, T. UEKI and H.

1355-1 358

K. U. NEUMANN, J. CRANGLE, R. K. KREMER, N. K. ZAYER

127, (1-2), 47-51

A170, (1-2), 169-175

A. V. POWELL, J. G. GORE and P. D. BATTLE, 3 Alloys

Phase Diagram and Electrical Behavior of Silicon-Rich Iridium Silicide Compounds c. E. ALLEVATO and c . B. VI"G,J. Abys Corn@., 1993,

The Ir-Si phase diagram on the Si-rich side has been investigated by XRD, density, DTA, metallography and other techniques. An attempt to prepare eight Si-rich compounds was made; however, only IrSi, Ir&, Ir& 1 r S 5 and IrSi-, were identified. Ir&, Ir4Si7 and IrSi2 were not found. IrSi, was polymor- phic with orthorhombic and monoclinic unit cells in the high and low temperature forms. IrSi and IrSi, exhibit nearly temperature-independent electrical resistivities of (5-10) x ohm m. Ir4Si5 and I r S , have metallic behaviour, and Ir& is semiconduct- ing. A eutectic alloy with 80 & 1 at.% Si was observed between IrSi, and Si.

200,99-105

ELECTROCHEMISTRY A Study of Cathodic Oxygen Reduction at Platinum Using Microelectrodes D. PLETCHER and s. SOTIROPOULOS, J. Electroanal. Chem., 1993, 356, ( 1 and 2), 109-119 Cathodic reduction of 0, was studied at a Pt rotating disc electrode and Pt microelectrodes in neutral and basic aqueous solutions. The limiting current densi- ties for the reduction waves at the Pt electrodes are explained by the fact that the apparent number of electrons involved in the reduction is a strong function of the mass-transfer coefficient, k, and the reduction changes from a 4-electron to a 2-electron process with increasing rate of mass transport. H20, is the major product where there is a large k,.

Ellipsometry of Hydrous Platinum Oxide Layers and Electrodispersed Platinum Surfaces Resulting from Their Electroreduction

Films, 1993, 232, (l), 63-67 The ellipsometric characteristics of relatively thick (40C700 nm) hydrous Pt oxide layers (HPtOLs) produced by oxidation-reduction cycling at 0-2.4 V in 1 M H2SOI were studied, together with the surface topography of electrodispersed Pt electrodes (EDPtEs) obtained by electroreducing the HPtOLs, at 25°C. The H 2 0 content of HPtOLs increases with increasing layer thickness.The EDPtE has a rough structure with a metal : void ratio of - 0.5.

Preparation and Characterization of a Composite Palladium-Ceramic Membrane J. P. C o u s a n d J . D. WAY, Ind. Eng. Chem. Res., 1993, 32, (12), 3006-3013 Composite Pd-ceramic membranes with Pd films of 11.4-20 pm were made by depositing Pd film inside asymmetric tubular ceramic membranes by elecuoless plating. The membranes had both high H permeabil- ity and selectivity. The H,M, selectivity for a membrane with a 11.4 pn Pd film was 380 at 823 K at a transmembrane pressure difference of 1500 kPa.

J. 0. ZERBINO, C . PERDRIEL and A. J. ARVIA, Thin Solid

Platinum Metak Rev., 1994, 38, (1) 33

Electrochemical and Corrosion Behaviour of Intermetallide Systems of Ti,Pd and TiPd

Low-Temperature Chemical Vapor Deposition of Ruthenium Dioxide from Ruthenium

and Ti with Electrdispersed Palladium Layers L. P. KORNIENKO, N D. TOMASHOV and G. P. CHERNOVA, Zashch. Met., 1993, 29, (3), 359-367 Studies of the dissolution rates of T i and Pd electrodes, and also of T i and Pd from intermetallides Ti,Pd and TiPd, in anodic and cathodic regions were performed under corrosion potentials in 10 % HSO, at 100°C. Intermetallides Ti,Pd and TiPd formed on the Ti surface during the electrodispersion of Pd alloys, followed by annealing, appeared to be an effective cathode, giving corrosion protection to the system.

Capability of Permeate Hydrogen through Palladium-Based Membranes for Acetylene Hydrogenation N. ITOH, w.-c. xu and A. M. SATHE, Ind. Eng. Chem. Res.,

Hydrogen permeation through pure Pd, Pd,,Ni-, Pd,,Ru, and Pd,,Ag,, membranes was used to hydro- genate C,H, at 373 K and atmospheric pressure. H, was supplied by a permeation mode thrbugh the membrane and a premixed mode. For higher G H , conversions the order in the membranes was Pd > Pdq,Ni- 5 Pd,,Ag,, > Pd9,Ru7. The H, which permeated through the Pd-based membrane is more active than H, from the premixed mode.

1993,32, ( l l ) , 2614-2619

PHOTOCONVERSION A New Linkage Isomer of RhCI,(DMSO),: Photochemical Synthesis, Crystal Structure, and Reactivity of rner,truns-RhCI,(DMSO), (DMS 0) E. ALESSIO, P. FALESCHINI, A. s. SANTI, G. MESTRONI and M. CAUIGARIS, Inorg. Chem., 1993, 32, (25),

The photochemical isomerisation of the title compound (1) to the new linkage isomer mer,trans- RhCl,(DMSO),(DMSO) (2) was performed in order to study the effect of light on the equilibria between the neutral Rh-DMSO isomers. Complex (2) is thermo- dynamically unstable compared to (1). The two isomers react stereospecifically with N ligands by following different paths and produce isomeric products.

5756-5761

ELECTRODEPOSITION AND SURFACE COATINGS Iridium Coatings on Carbon-Carbon Composites Produced by Two Different Sputtering Methods: A Comparative Study K. MUMTAZ, J. ECHIGOYA, T. HIRAI and Y . SHINDO, 3. Marer. Sci. Lett., 1993, 12, (18), 1411-1412 High modulus C fibres were used to make C-C composite substrates. Ir was r.f. and DC sputtered onto one side of the composite. DC sputtering produced interconnected islands and some uncovered substrate. The r.f. sputtered coatings were extremely fine and uniform before and after high-temperature heat treatment.

Tetroxide: A Simple Approach to High-Purity RuO, Films Z. YUAN, R. J. PUDDEPHATT and M SAYER, Chem. Mater.,

RuO, is a good precursor for the CVD of high purity RuO, films. Films were prepared by annospheric pressure CVD of RuO, on glass, Al and Si(100) substrates held at 150°C. The films were shiny with excellent adhesive. The resistivity of a film of 1 pm thickness is - lo-, R cm. The films were assessed for ferroelectric applications by depositing 0.3 pm thick Pb zir- conate titanate films on a 1 pm thick RuO, layer. After firing and annealing the films were crack-free, crystallised in the perovskite phase, with a ferroelectric hysteresis loop.

RuO, Films by Metal-Organic Chemical Vapor Deposition J. SI and S. B. DESU, 3. Mazer. Res., 1993, 8, (lo),

An optimised hot wall MOCVD process for producing pure and conducting RuO, thin films on Si, SiOJSi and quartz substrates at temperatures as low as 550°C was developed. R u ( C ~ H ~ ) ~ was used as a precursor. Either pure RuO,, pure Ru or a RuO, + Ru mixture could be obtained, depending on conditions. As- deposited pure RuO, films were specular, crack-free and well adhered to the substrate. AES showed good composition uniformity across the bulk of the films.

1993, 5, (7), 908-910

2644-2648

APPARATUS AND TECHNIQUE A Potentially Selective Methane Sensor Based on the Differential Conductivity Responses of Pd- and Pt-Doped Tin Oxide Thick Layers

RILLO, I. SAYAGO, J. GUTIERREZ and J. A. DE AGAPITO, Sens. Actuators B, 1993, 16, (1-3), 384-389 A sensor selective to CH, has been constructed from screen printed layers of SnO, doped with either Pt or Pd, which have different conductivities at the temperature of operation for such a device. The sensor has long-term stability and exhibits an important differential response to EtOH, which is the reverse of that for CH,. The device is insensitive to changes in relative humidity, gas flow and ambient temperature.

Detection of Sub-ppm H,S Concentrations by Means of SnO,(Pt) Thin Films, Grown by the RGTO Technique G. SBERVEGLIERI, S. GROPPELLI, P. NELLI, C. PEREGO, G. V A L D R ~ and A. CAMANZI, Sens. Actuators B, 1993, 15, (1-3), 86-89 The effect of Pt deposited onto the wrinkled surface of SnO, thin films grown by the RGTO (rheotaxial growth and thermal oxidation) technique was examined for detecting concentrations of 100 ppb-10 ppm H,S. A RGTO-prepared film with a layer of 35 A Pt could detect H,S concentration of 5 100 ppb. The response time was 20 s and recovery time 80 s to 1 ppm H S .

P. DUTRONC, C. LUCAT, F. MENIL, M. LOESCH, M. C. HOR-


Epitaxial Growth of Pt on Basal-Plane Sapphire: A Seed Film for Artificially Layered Magnetic Metal Structures R F. C. FARROW, G. R. HARP, R. F. MARKS, T . A. RABEDEAU, M. F. TONEY, D. WELLER and S . S . P. PARKIN, 3 Cryst. Growth, 1993, 133, (1/2), 47-58 The epitaxial growth of thin (I 250 A) Pt films on basal-plane sapphire (000 1) by molecular beam epi- taxy is described. Pt nucleates as islands at 600°C, which have Pt(l1 l)llsapphire(0001) but with two in-plane orientations related by a 180" rotation about the [l 1 11 axis. Films as thin as -30 A are structurally and electrically continuous and of high quality.

Glucose Quantitation Using an Immobilized Glucose Dehydrogenase Enzyme Reactor and a Tris(2,2'-bipyridyl)ruthenium(II) Chemiluminescent Sensor A. F. MARTIN and T. A. NIEMAN, Anal. Chim. Acta, 1993, 281, (3), 475-481 Glucose was detected using a flow injection analysis method. Glucose dehydrogenase was immobilised by glutaraldehyde cross-linking to pore glass to form an enzyme reactor. Ru(bpy)," was immobilised in a Nafion film on a Pt elenrode and acted as a regenerable chemiluminescent sensor. Optimum operating conditions were determined for pH - 6.5. The upper limit for glucose detection depends on the concentration of (p- nicotinamide adenine dinucleotide)' and the lower detection limit is 10 pM glucose.

JOINING Barium TitanatelNoble Metal Laminates Prepared by the Oxidation of Solid Metallic Precursors M. M. m N Y and K. H . SANDHAGE,J Mater: Res., 1993,

Solid metallic precursors were oxidised to produce multicomponent electronic ceramics and ceramic- metal composites for dielectric BaTiOJPd or Ag, laminates from Ba-Ti precursor powders. The Ba-Ti precursor was sealed in Pd or Ag tubes and rolled to form thin Ba-Ti/Pd laminates. Exposing the Ba-Ti core to 2300°C in pure O2 caused rapid oxidation, and annealing at 2 900°C gave dense BaTiOJPd laminates of dielectric constant 650 at room temperature and 1 kHz.

8, (1 l), 2968-2977

HETEROGENEOUS CATALYSIS Pt-Catalyzed Combustion of CH,-C,H, Mixtures A. BAIAKRISHNA, L. D. SCHMIDT and R. ARIS, Chem. Eng.

The effect of different amounts of C,Hs on the bifur- cation features of CH, catalytic combustion in air was studied over Pt foil. The behaviour can be predicted by a one-step global kinetic scheme.For some fuel ratios the system ignited directly h m the extinguished state to the complete-reaction state without passing through the intermediate propane-reactive state.

SCL, 1994, 49, (l), 11-18

Catalysts for the Selective Dehydrogenation of High Molecular Weight Paraffins

Pt, PtSn, PtGe and PtPb catalysts supported on y-Al,O, doped with alkaline metals were characterised and tested in n-decane dehydrogenation. When alkaline metals were added to Pt/A1203 a promoting effect on selectivity to olefins was observed. For PtSn/Al,O,- doped catalysts the performance depends on the alkaline metal used as dopant, the Sn content and the preparation method. Bimetallic catalysts give a better olefin yield and a lower selectivity to gases and aro- matics than monometallic Pt catalysts.

Surface Features and Catalytic Performance of PlatinumlAlumina Catalysts in Slurry- Phase Hydrogenation

ARNAIZ-AGUILAR, J . A. GONZALEZ-MARCOS and J. R. GONZALEZ-VEIASCO, Ind. Eng. Chem. Res., 1993, 32,

Pt catalysts supported on commercial y-A1203 were prepared by impregnation and anionic exchange with aqueous solutions of H2PtCI,, characterised and tested for activity in the slurry-phase hydrogenation of benzene. Support type and preparation method influ- enced the dispersion. The activity for catalysts prepared by impregnation did not depend on the support, however, the activity of catalysts prepared by anionic exchange varied with the support. T-126 supports presented pore-diffusion problems for catalysts with higher metallic contents, due to its small average pore radius of 2.9 nm and sharp pore-size distribution.

Stabilization and Sintering of Porous PtlSiO,: A New Approach w. zou and R D. GONZALU, Appl. C a d . A: Gen., 1993,

Pt/SiO, catalysts with well defined pore size distrib- utions were prepared by the sol-gel method, using tetraethoxysilane (TEOS) and Pt(AcAc), as precursors. Pore size distribution was controlled by varying the H,O:TEOS ratio during synthesis, and pores of 3.5-7.5 nm were obtained. Surface areas > 800 m2/g and high Pt metal gas-phase exposure were also obtained. When particle size was matched to the average pore diameter, the resulting PdSi02 catalysts were structurally stable and resistant to sintering in 0, at up to 675°C. To avoid sintering the metal loading was reduced to 0.2-0.3 wt.%.

Preparation of Alumina Fiber-Type Catalyst for Methane Combustion by Sol-Gel Method Y. MIZUSHIMA, M. SEKINE and M. HOIU, 3, Ceram. SOC. Jpn., 1993, 101, (9), 1057-1061 Porous A120, fibres were prepared by the sol-gel method, and Pd was supported on the fibre by dipping or by mixing, the latter using Pd(OAc)2 which was mixed with a sol before spinning. Mixing gave better dispersion of Pd particles in the fibre. The Pd/Alz03 fibre catalysts had higher activities for CH, combustion than commercial granular-type A1203, although the fibre had a 1/50 th smaller surface area.

A.A.CASTR0, catal. kc., 1993, 22, (1, 2), 123-133

M. A. GUTIERREZ-ORTIZ, M. P. GONZALEZ-MARCOS, S.

(1 l), 2457-2463

102, (2), 181-200


Selective Hydrogenation of Styrene on Pd-Ho/YAl2O3 and Pd/yAl,O, Catalysts

c. ENACHE and E. ANGELESCU, Bull. SOC. Chim. Belg.,

Pd-Ho/y-Al,O, catalysts exhibit higher activity than Pd/y-Al,O, for styrene hydrogenation. Adding Ho to Pd changes the place of the Pd impregnation front, depending on the state of the supported Pd. Oxidised Ho aluminate is formed as a result of the interaction between Ho and the Pdly-ALO, support. The Ho aluminate is catalytically inactive, but represents adsorption centres for styrene. On Ho containing catalysts hydrogenation occurs between the styrene adsorbed on basic centres and H spilled from the I’d particles.

Wacker-Type Oxidation of Cyclohexene over Palladium-Supported Heteropoly Compounds H. SOEDA, T. OKUHARA and M MISONO, Nippon Kagaku Kuishi, 1993, (8), 917-923 The liquid phase oxidation of cyclohexene by 0, has been studied using Pd-supported heteropoly compounds and homogeneous catalysts. Pd-supported Cs, ,H, ,PMO,W~O~~ (1) was eficient for the reaction, producing cyclohexanone (Wacker-type oxidation) and cyclohexenone (allylic oxidation), while PdC1,- CuC1, had very low activity under the same conditions. Using (l), at 80°C and 8 arm of 0, the turnover frequency for the total products reached - 25 with respect to the Pd atom, which is greater than that for a homogeneous Pd(N0,)2-H,PMo,W,0,u system.

Preparation and Catalytic Efficiency of Mixed Noble Metal Catalysts on Electrochemically Activated Carbon Fibre Supports A. D. JANNAKOUDAKIS, P. D. JANNAKOUDAKIS, N. PAGA- M S and E. THEODORIDOU, 3: Appl. Electrochem., 1993, 23, ( l l ) , 1162-1168 Supported binary Ag-Pd catalysts were prepared on electrochemically activated C fibres by repetitive cation exchange between acidic groups (-COOH and -OH) and noble metal salts, followed by cathodic reduction of the exchanged metal ions to the metallic state. Catalytic efficiencies for hydrogenation of nitrobenzene in MeOH solution and nitrobenzene electroreduction were compared. The mixed Ag-Pd/C systems were more stable than double Pd-PdC deDositions

V. I. PARWLESCU, V. P.&VULESCU, L. FRUNZA, N. GRECU,

1993, 102, (6), 391-398

Hydrosilylation of Alkenes Catalysed by Rhodium Complexes Immobilized on Silica via a Pyridine Group M. CAPKA, M. CZAKOOVA and u. SCHUBERT, Appl. Organomet. Chem., 1993, 7, (6), 369-372 A series of Rh carbonyl complexes bound to SiO, via a pyridine group was prepared using 2-(2- trimethoxysilylethy1)pyridine and (3-methacryloxy- propy1)triethoxysilane from Rh,(CO),CI,(Rh,). The prepared immobilised complexes were either surface-bonded or bonded in the silicate matrix. The Rh complexes efficiently catalysed the hydrosilylation of octene by triethoxysilane, and were more active than both the homogeneous analogues and complexes immobilised on organic polymers. The present catalysts suggest alternative types of immobilisation.

Partial Oxidation of Methane over Ruthenium Catalysts M. G. POIREQJ. TRUDELand D GUAY, c a d . ktt., 1993, 21, (1,2), 99-111 The catalytic partial oxidation of CH, with O2 to produce syngas was studied under various conditions over Ru supported catalysts. A catalyst with as little as 0.015 wt.% RdAl,O, gave a higher synthesis gas selectivity than a catalyst having 5% Ni/SiO,. Ru was produced by reduction from RuO, early during the experiments. Ru is more stable than Ni, does not form volatile carbonyl under experimental conditions, as Ni does, is less susceptible to be reoxidised during reaction and does not lead to C deposition.

An X P S Study of Ru-Promotion for ColCeO, Fischer-Tropsch Catalysts

Sci., 1993, 72, (l) , 55-65 XPS was used to examine the reduction of co-pre- cipitated Co,OJCeO, (1) and Ru promoted (1). The Co,O, lowered the reduction temperature of CeO,, and after reduction at 550°C, the stoichiomeny of the oxide in (1) was CeOl 7 7 * 0 0 1 . Promotion with Ru lowered the reduction temperatures of both the Ce and Co con- stituents and a reduction of CeO, to CeOl u t o O , occurred at temperatures as low as 170°C.

M. HOANG, A. E. HUGHES and T. W. TURNEY, Appl. s U ? f

HOMOGENEOUS CATALYSIS and retained their mechanical stability andcatalytic activity even after prolonged storage in aqueous or methanolic solutions and after ultrasonic treatment.

From Surface Science to Catalysis: Surface “Explosions” Observed on Rh Crystals and Supported Catalysts

and Mechanism Of Reactions in Aqueous Iodide Sohtions of Platinum. III. Hydroiodination and Reduction of Acetylene in Pt(II)-NaI-H+-H,O System S . A. MITcHENKo, v . v . ZAMASHCHIKOV and 0. N. PRYADKO, Kinet. Katal., 1993, 34, (3), 484487

T. J. CASSIDY, M. D. ALLEN, Y. LI and M. BOWER, Catal. Lett., 1993, 21, (3,4), 321-331 Surface “explosions” for acetate species on Rh single crystals and on Rh/Al,O, catalysts under ambient pressure conditions are reported, for decomposition reactions shown by a narrow peak of 3 K wide, by TPD. The “explosions” are classed as second order autocat- alytic surface processes, where free surface Rh sites and coadsorbed adatoms are essential to the reaction.

. . . _ . A catalytic hydroiodination and reduction of C,H, in the system Pt(I1)-I-H-H,O has been discovered; the main feature being the conversion of C2H, by B-iodi-platinising which forms B-iodivinyl Pt(II) complexes. After protolysis of Pt(II)CH=CHI vinyliodide is formed. Another reaction with C,H, formed binuclear Pt(II)CH=CHPt(IV) compounds which were reduced by iodide ions to the 0-vinyl of the Pt(II), followed by protolysis of the final fraction.


Acetylene kinetics

Selective Homogeneous Oxidation of Allylic Alcohols with Palladium (11) Salts v . BELLOSTA, R. BENHADDOU and s. CZERNECKI, Synlen,

An efficient process for the selective oxidation of allylic alcohols with PdCl, and Pd(OAc), in the presence of other hydroxyl functional groups is described. When D-glucal was oxidised by Pd(OAc), in the presence of NaOAc and DMF solvent for 2 h, a 95% enone yield was obtained. Testosterone was produced in good yield from steroidal allylic alcohols under similar reaction conditions. The high degree of selectivity of the reactions is explained by a fast hydride transfer from C to Pd in the allylic Pd alcoholate initially formed by ligand exchange.

Palladium-Catalyzed Annulation of 1 , P - Dienes Using Ortho-Functionally-Substituted Aryl Halides R. C. LAROCK, N. G. BERRIOS-PENA, C. A. FRIED, E. K. W M , C. TU and W. LEONG,J. org. Chem., 1993, 58, (1 7), 4509-4510 The annulation of 1,4-dienes by aryl halides with ortho-heteroatoms and carbanion-stabilising groups, catalysed by Pd(OAc),, gave high yields of monocyclic and bicyclic 6-membered ring heterocycles and car- bocycles. The process involved aryl Pd formation and addition to the diene, Pd migration and intramolec- ular n-ally1 Pd displacement.

1993, ( l l ) , 861-863

Rhodium- Catalyzed Ring-Opening Silylformylation of Epoxides Leading to R-Siloxy Aldehydes Y. FUKUMOTO, N. CHATANI and s. MURAI, 3. Org. Chem., 1993,58, (16), 4187-4188 Epoxides reacted with a hydrosilane and CO in the presence of [RhCI(CO),], and 1-methylpyrazole, to produce a ring-opening silylformylation leading to 0-siloxy aldehydes. The ring opening of 1-butene oxide occurred preferentially at the primary C to give a 77:23 mixture of 3-(dimethylphenylsi1oxy)pentanal and 2- [(dimethylphenylsiloxy)methyl]butanal in a com- bined yield of 60%. An epoxide with a bulky sub- stituent underwent a completely regioselective silylformylation.

Rhodium Complex-Catalyzed Desilylative Cyclocarbonylation of 1-Aryl-24 trimethylsi- 1yl)acetylenes: A New Route to 2,3-Dihydro- 1 H-inden- 1 -ones R. TAKEUCHI and H. YASUE, 3 org. Chem., 1993, 58,

A novel cyclocarbonylation of l-aryl-2-(trimethylsi- 1yl)acetylene involving the C-H activation of an aromatic ring is reported during the RhCI(PPh,),-catalysed reaction of l-phenyl-2-(trimethylsilyl)acetylene under H,O gas shift reaction conditions, giving 2,3-dihydro-lH-inden-l-one (1). The products were obtained in good to excellent vield whether the sub-

(20), 5386-5392

- stituent on the aromatic ring was electron-donating

Hemilabile eo-Ligands in or electron-withdrawing. Various Rh complexes with CatalYsed c-c Linkages: Codimerization of excess triphenylphosphine in the presence of Et,N Ethylene and Styrene and Cooligomerization produced good yields of (1). A new and general syn- of Ethylene and Carbon Monoxide thesis of (1 ) is presented. G. 1. P. BRITOVSEK, w. KEIM, s. MECKING, D. SAINZ and T. WAGNER,^ Chem. SOC., Chem. Commun., 1993, (21),

Neutral and cationic Pd ally1 complexes with biden- fate ligands Ph,P(CH,),,CO; (where n = 1-3) or Ph,P(CH,),,CO,R (n = 1-3; R = Me, Et) were prepared and used as catalysts for the codimerisation of C,H, and styrene, and for the co-oligomerisation of C,H, and CO. A dramatic effect for anionic as compared with neutral P,O-ligands was observed, which may be due to the hemilabile behaviour of the C0,R- group. Under catalytic conditions the 0-Pd bond dis- sociates giving free co-ordination sites for catalysis.

Chiral Rhodium Complex-Catalyzed Asymmetric Cyclization and Its Application to the Synthesis of Natural Products K. S A K A I , ~ . Synth. Org. Chem. 3pn. , 1993, 51, (8), 733-743 The Rh(1)-catalysed cyclisation of substituted 4-pen- tenals into cyclopentanones has been developed into a highly diastereoselective and enantioselective asymmetric cyclisation by using the Rh(1)-complex with chiral ligands, such as BINAP, and (+)-DIPMC. Cationic Rh(1) with BINAP gave the best asymmetric cyclisation in chemical yields and enantioselectiv- ity as well as diastereoselectivity. The Rh(1) complex also catalysed the cyclisation of oct-6-enal with the crj-cyclohexane-l,2-dioxy function at the C3 position.

1632-1634

Complete Reversal of Stereoselectivity in Rhodium Complex-Catalysed Hydrosilylation of Alk-1-yne R. TAKEUCHI and N. TANOUCHI, 3 Chem. soc., Chem. Commun., 1993, (7), 1319-1320 [Rh(cod)Cl],-catalysed hydrosilylation of hex-1-yne with Et,SiH in EtOH or DMF is highly selective for the formation of (2)-vinylsilane, whereas [Rh(cod)Cl],-PPh, in MeCN or Pr"CN is highly selective for the formation of (6-vinylsilane in 97 % selectivity. The active species for cis addition is a Rh' cationic complex produced in situ.

Effective Asymmetric Hydroboration Catalysed by a Rhodium Complex of 1- (2-Diphenylphosphino-1-naphthyl) iso- quinoline 1. M. BROWN, D. I. HULMES and T. P. LAYZELL, 3 Chem. SOC., Chem. Commun., 1993, (22), 1673-1674 The hydroboration-oxidation reaction of vinylarenes with the title Rh catalyst gives corresponding 1-arylethanols in I 99% chemoselectivity and 94% e.e. The reactions proceeded at 20°C and the best results were obtained when the Rh complex was repre- cipitated before use. The result showed the potential of using chelating P-N ligands in asymmetric hydroboration, adding to their promise in Pd-catalysed allylic alkylation revealed earlier.

Platinum Merals Rev., 1994, 38, (1) 31

Palladium

Reduction of Ruthenium and Iron pMethylene Complexes with Hydrosilanes Producing Alkane: A Model System for Methanation via the Fischer-Tropsch Mechanism M. AKITA, T. OKU, R. HUA and Y. MORO-OKA,~. Chetn. SOC., Chem. Commun., 1993, (22), 1670-1672 Alkane (RMe) was produced by reduction of the Ru and Fe pmethylene complexes [M,(C,H,),(p-CHR)- (p-CO)(CO),], where M = Ru, R = H; M = Fe, R = CH,Ph, with hydrosilanes by way of dinuclear hydrido-methylene and methyl intermediates. This reaction sequence can be used as a model system for methanation via the Fischer-Tropsch mechanism.

FUEL CELLS Enhanced Electrocatalysis of Oxygen Reduction on Platinum Alloys in Proton Exchange Membrane Fuel Cells s. MUKERJEE and s. SRINNASAN, J. Electroanal. Chem., 1993,357, (1 and 2), 201-224 The electrocatalysis of the 0, reduction reaction on some binary Pt alloys (Pt+Cr, Pt+Ni and Pt+Co) was studied at their interfaces with the PEM of perfluo- rinated sulphonic acids. The results, when compared to Pt/C electrocatalysts (electrodes with the same 0.3 mg/cm2 Pt loading) showed enhanced activities, lower activation energies and different reaction orders for all the alloys. The alloys had lattice contractions, the pre- dominant phase being Pt,M f.c.c. crystallite.

An Advanced Proton Exchange Membrane Electrolyzer with an Improved Three- Dimensional Reaction Zone

APPLEBY and 0. J. MURPHY, Int. J. Hydrogen Energy,

Improved proton exchange membranes (PEM) for H,O electrolysis, using impregnated Nafion to create a 3-dimensional reaction zone at the electrodelPEM interfaces, were studied. The anode electrocatalyst is a mixnue of Ru, Ir and Ta oxide and the cathode electrocatalyst is electrodeposited Pt black on Ti and stainless steel gauze. At 85°C and current density 1 Akm2 the cell potential was 1.85 V, being constant for 1000 h. When operated as a fuel cell H, was best oxidised at the Ru,IrTaO, and 0, reduced at the Pt black elecuodes.

K. PETROV, K. XIAO, E. R. GONZALEZ, S. SRINNASAN, A. J.

1993, 18, ( l l ) , 907-913

ELECTRICAL AND ELECTRONIC ENGINEERING Writemrase Cyclability of Copt Disks K. FUJIMOTO and s. HASHIMOTO, J. Magn. & Magn. Muter., 1993, 126, (1-3), 587-589 The writelerase cyclic characteristics of ColPt disks have been studied. A disk with a quadri-layer structure (substrate1SiN 85 nm/Co/Pt 18 nmlSiN 100 nmlAl40 nm) on a glass substrate and Curie temperature of 355°C achieved 1 O6 writelerase cycles with a constant carrier:noise ratio.

Reduction of Leakage Current and Minority Carrier Lifetime in Platinum-Diffused p n Diodes P. SAGALA and H. KUWANO, 3pn. J . Appl. Phys., 1993,

A method to control the depth profiles of Pt-related trap concentration in Pt-diffused Si pin diodes and to improve their electrical properties is proposed. Pt was introduced into Si wafers and the p’n diodes by a 1- or 2-step heat treatment. The leakage current and minority carrier lifetimes can be simultaneously min- imised. With the 2-step heat treatment the trap concentrations near the surface decrease, and those in the bulk increase, to more than those of the as-diffused diodes with increased annealing temperature.

Resistance Adjustment with Short-Pulse Nd:YAG Laser for Ru0,-Based Thick-Film Resistors Buried in Polyimide Film E. GOFUKU, T. OHNAWA, M. KOHARA and M. “OSHITA, IEEE Trans. Cotnponents, Hybrids, Manuf. Technol.,

The resistance of thick film resistors (TFRs) buried in polyimide film was adjusted by a new process using short-duration pulses from a Nd:YAG laser to irra- diate the TFRs through the polyimide film. When a pulse optimised for duration and power density is applied to the buried TFR, the polyimide film is not degraded, but the TFR surface is modified effectively. The resistance is decreased by increasing the number of laser pulses. The modified TFR has a thin glass layer which is heavily doped with Ru impurities during the rapid thermal process.

The Reaction between Ruthenium Dioxide and Aluminium Nitride in Resistor Pastes c. KRETZSCHMAR, P. OTSCHIK, K. JAENICKE-ROSSLER and D.SCHLiiFER,3j Muter. Sci., 1993,28, (21), 5713-5716 DTA, TG, mass spectroscopy and XRD tests were performed to evaluate the reaction between RuO, and AlN in the presence of “non-reducible” glasses. RuOt can react with AlN in the presence of glass under the firing conditions used to produce thick film pastes. The reaction may cause bubbles in the resistor layers.

32, (9A), 3760-3763

1993, 16, (6), 592-597

TEMPERATURE MEASUREMENT Use of Proximity Effect in Iridium-Gold Superconducting Phase Transition Thermometers U. NAGEL, A. NOWAK, E. KELLNER, H:J. GEBAUER, P. COLLING, S. COOPER, D. DUMMER, P. FERGER, M. FRANK, P. FREUND, G. FORSTER, J. IGALSON, A. NUCCIOTTI, F. PROBST, A. RULoFS, w . SEIDEL and L. STODOLSKY, 3j h Temp. Phys., 1993,93, (3/4), 543-548 The proximity effect was used to reduce the critical temperature of Ir to below its usual value of 1 12.5 mK, by overlaying the Ir with Au. Measured critical temperatures for the Ir-Au bilayer films as a function of the layer thicknesses were compared to theoretical ones. Superconducting phase transition thermometers which worked in the range 30 to 100 mK were achieved.


NEW PATENTS CHEMICAL COMPOUNDS

Noble Metal Hydrosol to Colour Leather TODA KOGYO CORP Japanese Appl. 511 5 5,629 The hydrosol contains noble metal colloid selected from Pt, Pd, Rh, Ru, Au or Ag salts, such as water soluble chloride or nitrate, including platinic acid chloride, Pd(I1)-, Rh(II1)- and Ru(II1)-chlorides, etc., and an anionic surfactant comprising the alkaline salt of an aromatic group based sulphonic formalin con- densate. The hydrosol has a pH of 2.5-4.0. The hydrosol can be used to colour artificial leather.

ELECTROCHEMISTRY Oxygen Generating Electrode TDK CORP. European Appl. 560,338A An 0, generating electrode comprises a conductive substrate with either a first metallic layer containing 20-1 Pt and 80-99 Ta oxide layer (in mol YO, calcu- lated as the metals), or a 14-8.4 Ir oxide and 8691.6 Ta oxide layer, and a second Ir oxide and Ta oxide layer containing 80-99.9 Ir and 20-0.1 Ta. The electrode has good long term performance, low anodic potential at high current density and is used as an anode in aaueous solution electrolvsis, such as for

ELECTRODEPOSITION AND SURFACE COATINGS

Currentless Deposition of Metal Coatings BAYER A.G. European Appl. 562,393A A currentless deposition of adhesive metal coatings involves coating the surface with a UV-hardenable formulation, hardening by W radiation and currentless metallisation of the UV-hardened layer. In addition, the formulation contains 0.5-5 wt.% of a noble metal compound, preferably Pd, which acts as a metallisation activator, and a filler or solvent. Metallic coatings can be deposited on pressed circuits, foil key- boards, switching mats, sensors and screen surfaces.

Palladium-Nickel Alloy Electroplating Solution YAZAKI CORP. European Appl. 563,587A A Pd-Ni alloy plating solution comprises an aqueous solution of a Pd(I1) salt, a Ni(I1) salt, NH,, an NH,‘ salt and 3-pyridine sulphonic acid. The Pd compound may be PdC12 or PdSO, but preferably PdC12(NH3)2. The Ni(I1) salt is NiCl,, NiSOa, Ni(OAc),, or double or complex salts. The solution gives a uniform elec- wdeposited film with excellent gloss at a high electric current density. - -

acid, alkali or salt recovery, electrowinning of Cu, etc. Preparation ofFilm for Hydrogen Separation Electrode for Seawater Electrolysis ISHIHUKU KINZOKU KOGYO K.K.

Japanese Appl. 51156,481 The electrode comprises a Ti alloy body coated with thin TiO,, and fired, a porous Pt layer of 8-19 glcm’ apparent density, followed by a layer of an Ir0, and Pt composite comprising 10-90 mol% IrO, and 90-10 mol% Pt. The electrode gives a high Clr generation rate while maintaining a stable performance under a poor potential condition.

Corrosion Resistant Insoluble Electrode

An insoluble electrode comprises a first layer of valve metal, a second layer of valve metal and Ir oxide and a third layer of IrO,, and preferably a fourth layer of porous Ir02 having 5-30% or void. In an example, a Ti sheet was coated with IrO, (1 000 A) by reaction sputtering. The electrode has high corrosion resistance even after an electrolysis at a current density o f t 150 Ncm’.

Electrode with High Durability for Electrolysis

Japanese Appl. 51230,682 The electrode is produced by coating with an active layer, possibly Ir, onto a conductive electrode base and placing between an intermediate Pt layer and a layer containing oxides of Ti, Ta, Nb, Zr or Sn. The electrode has high durability and stability in reactions accompanied by cathode polarisation.

NIPPON STEEL COW. Japanese Appl. 51209,299

PERMELEC ELECTRODE LTD.

MlTSUBISHI KAKOKI KAISHA Japanese Appl. 51137,979

Film for separating H, is prepared by electroles plating Pd film (1) onto a non-conductive finepored material (2) such as AlrO, and Si02-Alr0,, then electroplating with a second I’d layer (3). (1) and (2) contain 1-50 wt.% of one of Ag, Ni, Co or Cu. The total thickness of (1) and (3) alloy films is 2-50 l m . The film is used to separate H, from gas produced by steam- reforming or partial oxidation of natural gas.

Platinum-Palladium Alloy Coating Solution BIKUTORIA K.K. Japanese Appl. 51163,595 A Pt-Pd alloy coating solution is prepared by dissolving salts of metallic Pt and Pd, such as diamino nitrides of Pt and Pd, and by adjusting the pH to 2 12 using ethylenediamine. In an example, the layer consisted of 82% Pt-18% Pd. The solution provides a mirror gloss and white coloured coating.

Conductive Film for Electrocasting TANAKA KlIUNZOKU KOGYO K.K.

Japanese Appl. 51195,281 Conductive film is formed on a brazing body for electrocasting by employing several cycles of dipping the brazing body into an aqueous solution containing PVA and Pd chloride; and then into a catalysing solution of Pd chloride-stannous chloride, followed by electroless plating with Cu. The film is used as the mother mould to produce precious metal ornaments. The body is pretreated to form a conductive film and the mould can be easily melted off.


Palladium Alloy Electroless Plating Bath

A bath for plating Pd-Ni alloy, comprises an aqueous solution containing 0.0001-0.5 mol/l Pd compound, 1-500 mol/l organic compound containing divalent S, 0.01-50 g/l surfactant, 0.001-8 mol/l NH, and/or amine compound, and 0.005-2 mol/l of at least one of phosphite, hypophosphite and borohydride. The above bath is used to apply electric contact points to electronic components.

Electroless Platinurn Plating Bath

ISHIHARA YAKUHIN K.K. Japanese Appl. 5/214,55 1

NIPPON ELECTROPLATING ENG. K.K. Japanese Appl. 5/222,543

A Pt plated article is made by placing the article to be coated in an electroless Pt plating bath, to form a lus- trous Pt film on the surface. The bath contains a tetravalent Pt amine salt of Pt(NH,),X, preferably Pt(NH,),Cl, or Pt(NH,),(OH),.

APPARATUS AND TECHNIQUE High Intensity Discharge Lamp GTE PROD. CORP. U S . Patent 5,225,733 A Sc halide and alkali metal halide discharge lamp has enhanced colour rendering index and emission spectrum during operation due to inclusion of Pt in the chemical fill of the arc tube. The improved high intensity discharge lamp uses a chemical fill of Hg, inert gas and ScI,, andNaI, LiI or CsI. Pt metal is added to maintain the lamp luminosity during operation and to reduce the tendency to discolour.

Oxygen Sensor with Good Low Temperature Activity NGK INSULATORS LTD. Japanese Appl. 5/133,931 An 0, sensor comprises a substrate made of 0 ion conductive solid electrolyte (l) , and a pair of cer- met electrode (2) with at least one of them containing a Pt layer, added by electrolytic plating. The 0, sensor has good low temperature activity over a long time. The sensor can be used to control the airfuel ratio of an engine, minimising the fluctuations.

Electrochemical Detector for Saccharides SHIMADZU CORP Japanese Appl. 5/ 149,9 17 An electrochemical detector for saccharides utilises an electrode reaction with the working Rh electrode. The Rh acts as a catalyst for the oxidation of saccharides in an alkaline solution, but the saccharides do not stick to the surface of the electrode. Thus, the detector detects saccharide with high sensitivity and good reproducibility. It is used in flow injection analysis, capillary elecwphoresis, etc.

Oxygen Sensor NOK CORP. Japanese Appl. 5/ 164,73 1 An oxygen sensor with a t h i i e d stabilised ZrO, layer is made by forming a porous Pt electrode, with a stabilised ZrO, layer and porous ceramic layer on a metallic substrate, and etching the metallic substrate. It is used for 0, detection in a solid electrolyte, giving shorter response time by thinning stabilised ZrO,.

Deodorising Unit for Refrigerators MATSUSHITA ELEC. IND. CO. LTD.

Japanese Appl. 51223,438 The deodorising unit comprises a catalyst layer of activated Al,O,-SiO, and a Pt group metal on a mesh heated section of a housing above a tubular deodorising heater, which is in the path of circulating air. Radiation and convected heat from the defrosting heater are transferred to a condenser to prevent a drop in the defrosting performance of the refrigerator. Odour in the circulating air is cleaned by the catalyst.

HETEROGENEOUS CATALYSIS Ruthenium Catalyst for Lower Polyhydric Alcohol Production MONTECATINI TECNOLOGIE S.P.A.

European Appl. 553,815A A new Ru based hydrogenation catalyst is prepared by suspending granulated activated C, adding Ru chloride, adjusting the pH to 4 . 5 8 by adding alkali, heating, filtering, suspending the solid in alkaline solution, heating, bubbling H, through, and separating the solid from the suspension. Lower polyhydric alcohol are produced at 220-270°C. The catalyst is used for hydrogenolysis of higher polyhydric alcohols under pressure, continuously, in a fixed bed reactor.

Dimethyl Naphthalene Production for Plastics

European Appl. 5 54,704A Dimethyl naphthalene (1) is produced by cyclisation-hydrogenation of 5-tolyl-pent-2-ene in the presence of Pd and/or Pt catalysts supported on crystalline aluminosilicate, such as a zeolite, Si02-Al,0, and/or Al,O, at 150400°C. (1) is obtained in high yield in a single step without any side reactions.

Cyclohexene Production BASF A.G. European Appl. 554,765A Production of cyclohexenes comprises partially hydrogenating benzene with H, in the presence of H 2 0 and Ru catalysts modified with Ni in the liquid phase at lOCb2OO"C. The Ru-Ni alloys preferably contain 1-30 wt.% Ni. The amount of H,O is 5-90 wt.% and is neutral or weakly acidic, and contains dissolved cations of transition metals of Groups 11-VII and a promoter, such as ZnSO,. The process gives improved space-time yields and increased selectivity to cyclohexenes.

Dehalogenation of a-Halogenated Carboxylic Acids ELF ATOCHEM. S.A. European Appl. 557,169A A catalyst to dehalogenate a-halogenated carboxylic acids or their esters, comprises activated charcoal, as either cylindrical particles of 0.3-1.5 mm diameter and 0.3-5 mm long, or spherical particles of 0.3-2 mm diameter containing a Pt group metal, preferably Pd. The catalyst can remove dichloro-acetic acid from monochloroacetic acid (1) and some trichloro-acetic acid arising from the industrial synthesis of (1). The catalyst has good selectivity. The reaction can be carried out continuously on fixed or fluidised beds.

MITSUBISHI GAS CHEM. CO. INC.


High Selectivity Dialkyl Carbonate Preparation BAYERA.G. European Appls. 558,996A and 559,001A Dialkyl carbonates of formula OC(OR), are prepared h m alkyl nimtes and CO over Pt metal halide catalyst on an amorphous AI,O,-SiO, carrier containing 30-80 at.% Al ( based on Al and Si) in a continuous gas phase reaction at 50-1 50°C. The catalyst may also contain at least one of Sb, Bi, Al, Cu, V, Ni, Ta, Sn, Fe, Co and/or Ni. The dialkyl carbonates are produced with selectivity of > 97%. The catalyst has a long working life, with better mechanical stability and abrasion resistance, and is able to retain activity and selectivity for long periods.

Denitrification Catalyst for Lean Diesel Exhaust DEGUSSA A.G. European Appl. 559,021A A catalyst for deniuification of lean, especially diesel engine, exhaust gas comprises an M,O, coat, of large surface area, optionally stabilised with rare earth metals andlor SiO,, andlor CeO,, and contains Pt and Ir in 1: 10-1 0: 1 weight ratio, and also a thermostable mordenite coat containing Cu and/or Fe. The catalyst gives ultra high conversion rates at 225-4OO0C, with NOx being reduced to N,, even in an 0, rich exhaust gas environment.

Platinum Catalyst for Lean Burn Vehicles CATALERIND. CO. LTD. European Appl. 562,516A The catalyst which is used for purifymg exhaust gases from lean burn vehicles comprises Ba oxide, La oxide plus Pt supported on a porous carrier. At least part of the oxides is presented in the catalyst as a composite oxide. The catalyst has high efficiency and durability and removes CO, HC and NOx from exhaust gases in an 0, rich atmosphere.

Catalyst for Hydrogenolysis of Polyhydric Alcohols MONTECATINI TECHNOLOGIE S.R.L.

World Appls. 93114,866-67A A catalyst composition, on a granulated activated C support of specific surface area 600-1000 m’lg, comprises (a) 0.5-5 wt.% Ru; (b) 1-10 wt.% Pt, Rh or Pd; and (c) 0.5-2.5 wt.% Cu, with the amount of Cu less than metal in (b). The catalyst can produce lower polyhydric alcohols, such as ethanediol, 1,2-propy- lene diol, butanediol, etc., from higher polyhydric alcohols obtained from renewable materials.

Cycloolefin Production in High Yield and Selectivity CATALYTICA INC. World Appls. 93116,971-72A Cycloolefin production comprises contacting H, with an aromatic feedstock of mono- or polycyclic aromatic hydrocarbon(s) in a partial hydrogenation which uses Ru catalysts on a composite support and an aqueous solution containing a Group VIII, IB or IIB promoter cation. The feedstock preferably comprises benzene, toluene, 1-4 C alkyl benzene or xylenes, etc. Cycloolefin is obtained in high yield with high selectivity, productivity and efficiency.

Naphtha Reforming EXXON RES. & ENG. CO. U S . Patent 5,221,465 A catalyst (1) containing 0.1-1.0 wt.% Pt, 0.1-1.0 wt.% Ir and 0.02-0.4 wt.% Sn uniformly dispersed throughout an inorganic oxide support, is used to upgrade the octane quality of naphtha at 100-700 psig and 700-10OO0C. The reforming unit comprises serially connected reactors, including a lead reactor and a tail reactor, each of which contains a Pt catalyst, with the tail reactor containing (1). The obtained catalyst has high activity and selectivity, giving yields of at least 5C liquid reformate.

Production of Methoxy -Naphthyl-Buteneone

The production of 4-(6’-methoxy-2’-naphthyl)- 3-buten-2-one comprises reacting 2-bromo-6- methoxy-naphthalene (1) with methyl vinyl ketone in the presence of a Pd(I1) catalyst at 50-200°C. (1) may then be hydrogenated in the presence of a Pd/C catalyst to form 4-(6‘-methoxy-2’-naphthyl) butan-2-one (2). The reaction is typically carried out under an inert atmosphere to prevent oxidation and the formation of by-products. (2) is a known non-steroidal anti-inflammatory agent and is obtained in nearly quantitative yields.

Dehydrogenation of Propane and Butane UOP U S . Patent 5,227,566 Propane or butane is dehydrogenated in the presence of a supported Pt catalyst under severe conditions which promote rapid deactivation of the catalyst; therefore the catalyst is regenerated by oxidations during redispersion, involving CI, gas and reduction. A drymg step and the presence of O2 in the redispersion step improves the operation by shifting the equilibrium between HC1 and O,, and H,O and Cl,, to favour the production of Cl,.

Steam Dehydrogenation of Hydrocarbons UOP U S . Patent 5,233,118 Steam dehydrogenation of 2-1 6C hydrocarbons occurs at 400-9OO0C, 0.1-10 atm and liquid hourly space velocity of 0. l-lOOih, and utilises a catalyst comprising a 8-.4l,O, support and a Pt group metal, alkali and/or alkaline earth metal and Sn, Ge, Pb, In, Ga andlor TI. The catalyst preferably contains 0.01-5.0 wt.% Pt, 0 . 1 4 wt.% Cs and 0.01-5 wt.% Sn. The obtained catalyst has high selectivity and conversion for hydrocarbon dehydrogenation, giving products used to manufacture various detergents, plastics and high octane gasoline.

Lanthanum and Palladium Binary Oxide Catalyst FORD MOTOR CO. US. Parent 5,234,881 The catalyst comprises as active agent, an outer coating of La,Pd,Or or LaJ‘dO, binary oxide, calcined and supported on a substrate, such as Al,O,, SiO,, and ZrO,. The amounts of binary oxide are equiva- lent to 15-1 50 g Pdft’ of the substrate. The catalyst is a three-way automotive emission catalyst for CO, NOx and hydrocarbon removal at 800-1050°C.

HOECHST CEIANESE CORP U s . Patent 5,225,603


NOx Decomposition and Removal MlTSUI KOZAN K.K. Japanese Appl. 51220,350 NOx contained in various industrial exhaust gases are decomposed and removed by using a catalyst of a complex oxide containing at least one of Rh20,, Coz03; or a mixture of a Cr, Mo, W or compounds; or a mixture of alkali(ne earth) metal compounds, by contacting with gas at 150-600°C. In an example, Co-Rh-Cr-KOH catalyst was packed in a quartz reaction tube. The catalyst maintains a high denitration rate stably over long times.

Three-Way Catalyst Preparation DAIHATSU MOTOR CO. LTD.

Japanese Appl. 51 220,39 5 A catalyst for cleaning car engines is prepared by impregnating an aqueous solution of Pt, Pd, Rh, Ir or Ru, preferably Pd, of pH 10 into a carrier, drying and calcining it. The carrier is a composite oxide of perovskite structure of formula Ln..A.MO,, where Ln is a rare earth metal except Ce; A is Ce or alkaline earth metal; M is a transition metal of Mn, Fe, Co, Ni, Cu, Pd, Ru, etc. and x is 0-1. The catalyst is used to clean CO, HC, NOx, etc., from the exhaust gas of gasoline engines. It has excellent cleaning activity at lower temperature. To operate at temperatures of > 9OO"C, an auxiliary catalyst can be added.

Catalyst for Steam Reforming Hydrocarbons

Japanese Appl. 5/220,397 A catalyst to steam reform hydrocarbons to produce H, and syngas consists of an active Ru component and an auxiliary catalyst of a Zr sol precursor of Zr oxide supported on Al oxide or A1 oxide containing, preferably, a Ca, Ba or Mg aluminate. The amount of Ru is preferably 0.02-5.0 and Zr oxide is 0.2-20 parts by weight, based on 100 parts by weight of the catalyst. It has improved and stabilised activity.

Exhaust Gas Catalyst

NISSAN GADORA SHOKUBAl K.K.

TOY0 KOGYO CO. Japanese Appl. 51228,342 The apparatus comprises a catalyst, preferably A-type zeolite impregnated with Pt, for oxidising NO, and another catalyst, preferably ZSM-5 zeolite ion- exchanged with Cu ions, for reducing NOx, downstream of the first catalyst. A third catalyst is y-AlzO, supported Pt, Rh, Pd or Ir. The apparatus is used for cleaning the exhaust gas of internal or external combustion engines, and can efficiently reduce NOx from high hydrocarbon content exhaust.

Catalyst to Remove Nitrites and Nitrates from Water SOLVAY UMWELTCHEMIE G.m.b.H.

German Appl. 4,207,959 A catalyst used in the separation of nitrites and/or nitrates from H,O by selective N, formation, comprises Pd andlor Rh, or Pd and a metal of the Cu group, impregnated in a porous inorganic carrier. The carrier contains a 0 and K modified Al oxide with only traces of a, but no y and 6 modifications. The car- rierlcatalyst is abrasion resistant.

Menthol Production BAYER A.G. German Appl. 4,208,443 D,L-Menthol is produced by continuous hydrogenation of unsaturated compounds, especially thy- mol, in a stationary bed over a Pd alloy catalyst of PdRu, PdRh or Pd/Ru/Pd containing 10-95 % Pd on a support containing lanthanide and Mn with alkali metal hydroxide and/or sulphate at 160-220°C and at least 25 bars pressure. D,L-Menthol is used in the perfume, flavouring and pharmaceutical indus- tries. The catalyst can be easily produced, is durable and ecologically acceptable.

HOMOGENEOUS CATALYSIS Preparation of 2-Pyridyl Methanol Derivatives

European Appl. 5 5 3,7 7 8A The preparation of a-(2-pyridyl)-2,8-bis(trifluo- romethyl)-4-quinoline methanol (1) comprises asymmetric hydrogenation of the corresponding 2-pyridyl- ketone in the presence of a Rh diphosphine complex catalyst, (Rh(X)(Y)(LO,1,2)) 1,2, where X = halide, ZCOO, phenolate or halogenated phenolate; Z = lower alkyl or phenyl; Y = a chiral atropisomeric diphosphine ligand. The (R) and (S) forms of (1) are prepared by this process.

Biphenyl Tetracarboxylic Dianhydride Production MITSUBISHI KASEI cow. European Appl. 556,806A A simple process to produce biphenyltetracarboxylic acid dianhydrides (BPDA), which are used as monomers for preparing polyimides, comprises heating phthalic anhydride (1) at 135-3OO0C in the presence of a Pd catalyst to dimerise (1). The catalyst is a Pd salt of an organic acid and is used in amounts of 0.01-0.5 mol in terms of the amount of Pd per mol of (1).

Production of 2-Methyl-Naphthol KURARAY CO. LTD. European Appl. 558,069A Production of 2-methyl-1-naphthol (1) comprises conversion of 2-methylene-1-tetralone (2) to (1) by isomerisation in the presence of H, treated I'd-, Rh- or Ru-based catalyst, at 50-1 50°C. The amount used is 0.1-20 ratio by weight, based on (2). (1) is an intermediate for pharmaceuticals, the process is simple and economical using inexpensive raw material with good conversion and selectivity without excessively high temperatures.

Preparation of &-Olefin Intermediates NISSAN CHEM. IND. LTD. European Appl. 560,532A A czs-olefin (1) is prepared by reduction of an alkyne of formula RlCCR2, having substituents of ester, silyl, carboxy, cyano, phenyl, with formic acid and a Pd catalyst. The catalysts used include Pd(PPh,),, Pd(PBu,),(CH,=CH,), PdCl(CH,)(COD), and so on, where COD = cyclooctadiene, in amounts of 1-10 mol% based on moles of (1). The cis-olefins are used as intermediates for the synthesis of fine chemicals, especially bioactive materials.

F. HOFFMANN LA ROCHE & GO. A.G.


Carboxylic Acid Preparation SUMITOMO CHEM. CO. LTD.

European Appl. 560,656A Lower carboxylic acids are prepared by reacdng alkane with CO in the presence of 10-100 ml/mmol of Pd catalysts andor Cu catalysts, in a solvent, and salts of peroxy acids at 0-100°C and 1-100 atm, for 1- 50 h. The Pd catalyst may be Pd(O,CCH,),, Pd(O,CC,Hr),, Pd(O,CCH,H,), or PdC1,. The Cu catalyst is Cu acetate or Cu sulphate. The process is efficient with very little by-product, and yields acetic, propionic, butanoic and pentanoic acids.

Regioselective Hydroformylation of Olefins UNIV. OTTAWA World Appl. 931 1 4,057A Aldehyde is prepared by reaction of an olefin in the liquid phase at 70-120°C with CO and H, and/or reducing agent, in the presence of zwitterionic Rh complex or its precursors and a bidentate phosphine ligand. The catalyst allows regioselective production of linear or branched products.

Preparation of Adipic Acid E.I. DU PONT DE NEMOURS & CO.

US. Patent 5,218,144 The preparation of adipic acid involves the hydro- carboxylation of pentenoic acid, using an Ir catalyst, iodide, H20, CO and carboxylic acid solvent. The reaction takes place at 100-200°C and 0-2000 psig; the Ir concentration is 100-5000 ppm and the iodide concentration is 500-8000 ppm of the reaction mixture, with a molar ratio iodide:Ir of 1-5: 1. The process gives yields of > 97 % and high linear selectivity. The process avoids use of halocarbons and simplifies the production.

Anhydride Preparation CHEVRON RES. & TECHNOL. CO

U S . Patent 5,220,060 Preparation of carboxylic acid anhydrides comprises reacting a carboxylic acid ester of formula, R,COzR,, where R, = 1-1OC alkyl and R, = H, 1-1OC alkyl, phenyl, 7-1OC alkylphenyl or 7-1OC phenylalkyl, and CO in the presence of a catalyst system containing a Pd compound, an iodide promoter and a proton donor, at 50-300OC. Methylene and oxymethylene bis-ester products are formed, and are useful for pre- serving moist grain during storage. Unreacted components and products can be recycled for further use in the process.

Carboxylic Acid Production CHINA PETROCHEMICAL DEV. COW.

US. Patent 5,227,519 Carboxylic acid production comprises carbonylat- ing an alcohol of formula ROH (where R is 1 4 C saturated hydrocarbyl) with CO and a catalyst containing a Rh compound, a halogen source, an iodide salt and a separately added trihaloacetic acid promoter. The reaction takes place at 180-220°C at a CO partial pressure of 1.4-60 kg/cm’. The catalyst can convert MeOH to acetic acid at > 95% selectivity and space time yields > 23.

Osmium Catalysed Asymmetric Dihydroxylation of Olefins MASSACHUSETTS INST. TECHNOLOGY

US. Patent 5,227,543 Osmium catalysed asymmetric dihydroxylation of an olefin comprises combining olefin, a cinchona alkaloid chiral ligand, an organic solvent, H,O and an oxi- dant to oxidise 0 s species to OsO+ The amount of 0s-containing catalyst and the amount of cinchona alkaloid or its derivative, are 0.3 mol% and 3 mol%, respectively, relative to the amount of olefin. The method can synthesise chiral intermediates, and achieves improved rates and turnover numbers.

Preparation of Mixtures of Acetals and Hemiacetal Esters AIR PROD. & CHEM. MC. US. Patent 5,239,112 Mixtures of acetals and hemiacetal esters, used as plasticisers and solvents, are prepared by reacting vinyl ester and an alcohol, using a solvent of dielectric constant 5-50, and a Pd or Pt-containing catalyst without active support. The process can prepare acetals from vinyl acetate and isopropanol, yielding acetals of secondary and tertiary alcohols. Conversions of loo%, acetal yields of 95%, and product selectivity of 99% are obtained.

Silicone-pol yether Copolymer Production GENERAL ELECTRIC CO. US. Patent 5,247,044 Silicone-polyethers are prepared by Pt group metal catalysed ring-opening polymerisation of epoxides. This involves mixing the epoxide, a Si-H functional Si compound and a complex of Pt, Pd, Rh, Ir, 0 s or Ru and holding at 25-1 2OoC for a suitable time. The curable silicone-polyethers are used in cosmetics, floor and automobile polishes, lubricants, mould releases, emulslfylng agents and viscosity additives. The process can be carried out at room temperature.

Telomerisation of Conjugated Alkadiene HENKEL KG.a.A. German Appl. 4,242,467 Telomerisation of conjugated alkadiene with sugar involves the preparation of a mixture containing sugar, solvent comprising saturated aliphatic secondary or tertiary alcohol and H20, a catalytic amount of Pd catalyst and part of the alkadiene, followed by heating the mixture to 40-100°C and continuous addition of the remaining alkadiene. The catalyst is Pd(I1) acetylacetonate with 2 equivalents of Ph,P, etc., as lig- and. The products are sugar-alkadienyl ethers for emulsifiers, lubricants, thickeners and cosmetics. The process gives high yields.

FUEL CELLS Electrocatalyst for Fuel Cell Anode STONEHART ASSOC. INC. European Appl. 556,535A The electrocatalyst comprises a Pt-Ni-Co ternary alloy, preferably containing 10-50% Pt, 10-50% Ni and 10-50% Co, supported on an inorganic support. The electrocatalyst is used for an anode in a fuel cell, has good anti-poisoning against CO, and the fuel cell can be operated at lower temperature.


Internal Reforming Molten Carbonate Fuel Cell TONEN COW. Japanese Appl. 51190,194 The fuel cell has a Pt group metal, Pt, Pd, Rh and Ir, or their mixture, preferably Rh or Ru, catalyst on a ZrO, based support. An electrolyte uses a binary system of Li and Na carbonates or a mixture of the binary system and carbonate. The catalyst has a higher reaction activity and less coking than usual. The resulting fuel cell has improved durability.

ELECTRICAL AND ELECTRONIC ENGINEERING Thick Film Resistor Composition for Hybrid Microelectronic Circuits E.I. DU PONT DE NEMOURS & CO.

European Appl. 548,865A The thick film resistor composition comprises in wt.%. finely divided particles of : (a) 10-50% of Ru oxide-based compound; (b) glass containing SO,, CaO, B20,, PbO and AL0, (in total 2 95% of the glass); and (c) PbO containing Pb silicate glass; all dispersed in a liquid organic medium. The composition is used for microelectronic circuits or chip resistors; has a small length effect on the temperature coefficient of resistance, and little variation in the resistance value and TCR on firing with a glass overcoat.

Multilayer Film for Magneto-Optical Recording JOHNSON MATTHEY P.L.C. European Appl. 549,246A The sputtered PtICo multilayer film materials system has a polar Kerr rotation of 2 0.1, a square polar Kerr hysteresis loop, and a room temperature coercivity > 2000 Oe. It comprises a glass substrate with a layer of Si of Si nitride, a metal interlayer of S 200 A Pt, and a PtlCo multilayer. The film allows reading and writing from the substrate side.

Magneto-Optical Thin Film Production MITSUBISHI CABLE MD. LTD.

Japanese Appl. 51140,791 A magneto-optical thin film is prepared &om an anode of an Al alloy substrate with a porous coating formed by anodisation. A Pt-Mn-Sb alloy is deposited in the pores by applying a voltage between the anode and a counter electrode in the electrolytic solution which contains Pt, Mn and Sb ions. This is followed by polishing, and heat treatment to remove any stress. The uniform and densely filled PtMnSb alloy con- tributes to regeneration of recorded information, and the fully crystallised alloy improves the S:N ratio.

Magnetic Recording Medium

A magnetic recording medium comprises a substrate and a Cr ground layer sputtered on the substrate, and a magnetic layer made of alloys containing Co, Cr, Pt, Ta and B in quantity: 70-85, 5-20,2-15, 2-10, and 2-7 at.%, respectively, sputtered on the ground layer. The thickness of the layer is - 20-80 nm.

HITACHI METALS LTD. Japanese A@[. 51205,239

Laminated Type Piezoelectric Actuator TOKIN COW. Japanese Appl. 512 18,5 16 Polyalkyl alkenyl siloxane containing a 1-18C alkyl group and a 2-8C alkenyl group is reacted with polyalkyl hydrogen siloxane containing a 1-18C alkyl group by using a catalyst comprising a Pt compound. The resulting resin is used in laminated type piezoelectric actuators and greatly improves the electrical insulation; the actuator has high reliability.

Highly Electrically Conductive Substrate OTSUKA KAGAKU YAKUHIN K.K.

Japanese Appl. 51221,763 The substance, for ink, paint, films, fibres, and shaped articles of high conductivity, comprises an electrically conductive Sn oxide-Sb oxide having an attached layer containing S 30 wt.% of Pt, Pd, Rh, Ru, Au, Ni, Co, Cu, Cr, Sn, andor Ag. The light weight conductive substance has electrical resistivity of lO-’-l O4 Rcm.

Paste for Thick Film Resistor SUMITOMO METAL MINING CO.

Japanese Appl. 51242,722 The paste comprises conductive particles, coated with one or more oxides of Ru, Ir, and Rh; glass frit and an organic vehicle. The metal oxide layer covers a part or all of the surface of the particles. The paste is used to form thick film resistors for hybrid IC or thick film chip parts.

MEDICAL USES Platium for Thrombus Formation TARGET THERAPEUTICS World Appl. 9311 6,650A An endo-vascular electrolytically detachable wire for thrombus formation has a Pt wire or tip inserted into the vascular cavity, and the tip is fuzzed out to pack the tip to obstruct blood flow. A conical section joins a reduced diameter section covered with Teflon to prevent contact with blood. A stainless steel coil is soldered to the end of a Pt secondary coil.

Jawbone Mounted Dental Implants WILKMSON CO. US. Patent 5,217,685 A hard, Zn-free alloy for an abutment base for jawbone mounted dental implants contains by weight %: 64 Au, 22 Pd, 9 Ag, 4.5 Pt and 0.5 Ir. The abutment base alloy is compatible with the oral environment and with implant materials. The alloy has high structural strength and ductility to withstand the stresses on a dental implant.

Dental Amalgam Compositions W. J. O’BRIEN US. Patent 5,242,305 Dental amalgam compositions comprise by weight: 40-60% Ag base powder (1) with 1-27% Cu; 1-10% Pd base powder (2); and 40-60% Hg. (2) is an alloy containing 2 50% Pd, and is coated with Cu, Ag, Au, Pt or In. (2) may be replaced by a thin foil of Pd in combination with the above metals.

The New Patents abstracts have been prepared from material published by Derwent Publications Limited.


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