platinum metals - johnson matthey

PLATINUM METALS REVIEW

A qirurterly survey of research on the platinum metals arid of

developments in their application in industry

V O L . 11 J A N U A R Y 1 9 6 7

Contents

The Manufacture of Nitric Acid

Further Increase in Platinum Production at Rustenburg

A Rhodium-Platinum Thermocouple for High Temperatures

Platinum Metal Electrocatalysts for Fuel Cells

Measuring Electrodeposit Thickness

Osmium-coated Tungsten Cathodes

Platinum Metals in Homogeneous and Heterogeneous Catalysis

One Hundred and Fifty Years

Metal-Ligand Reactivity and Homogeneous Catalysis

Abstracts

New Patents

NO. 1

2

9

10

12

13

I S

16

18

30

31

39

Communications should be addressed to The Editor, Platinum Metals Review

Johnson, Matthey & Co., Limited, Hatton Garden, London, E.C.1

The Manufacture of Nitric Acid THE ROLE OF PLATINUM ALLOY GAUZES IN THE AMMONIA OXIDATION PROCESS

By H. Connor, B S ~ . Johnson Matthey & Co Limited

Nitric acid production by the oxidation of ammonia on platinum gauzes con- stitutes one of the world’s major chemical industries. In this article the author outlines some of the principal features of this process, and describes in some detail the chemical reaction taking place at the platinum surface. He also discusses the changes that occur in the gauze leading to metal loss during operation. Handling and repairing the gauzes on a plant site and platinum dust recovery byJilters are among other aspects of interest to plant

operators with which the author deals.

Thomas Malthus (1766-1 834) maintained that the world’s population increases more rapidly than its food supplies, and only disease, war, poverty and vice prevent large- scale starvation. He could not foresee the world of the twentieth century, nor the role to be played by platinum gauzes in producing fixed nitrogen fertilisers without which his gloomy predictions might well be realised.

I t is now estimated that the total world output of nitric acid has risen from about 18.3 million tonnes (100 per cent HNO,) in 1962-63 to just under 23.5 million tonnes in 1965-66 (I). At this level of production the world’s nitric acid plants are believed to operate at an average of 82 per cent of all available production capacity. The estimated production of the major manufacturing countries is shown in Table I (I) . It may also be estimated that this total plant capacity represents a platinum gauze inventory of

Platinum Metals Rev., 1967, 11, (l), 2-9 2

around 200,000 oz troy (about 6250 kg), excluding the weight of spare gauzes that most plants hold.

The manufacture of nitrogen fertilisers represents by far the largest proportion of the use of nitric acid. These fertilisers, generally with high nitrogen contents, provide the active nitrogen in the form of ammonium nitrate or as nitrophosphate formed by the action of nitric acid on phosphate rock. For these processes “weak” nitric acid (55 to 65 per cent HNO,) is usually employed. Certain territories, such as Japan, are exceptions to this generalisation, since nitrate fertilisers for domestic agriculture may not be suitable there, and consumption of the acid by the explosive and chemical industries is thus more important. In the U.S.A., about 65 per cent of the nitric acid produced is consumed in the manufacture of fertilisers, for example, ammonium nitrate, and an additional 4 to 5 per cent is used for products such as potassium nitrate and nitrophosphates. The remainder

Table I The World’s Output of Nitric Acid (I)

(Millions of tonnes 100 per cent HNO,)

U.S.A. 3.4 4.7 U.S.S.R. 2.5 3.7 West Germany 2.2 2.55 France 1.73 2.2 Italy 1.05 1.3 Norway 1 .o 1.25 Netherlands 0.7 0.95 United Kingdom 0.6 0.90 Rest of the world 5.1 2 5.85

18.30 23.40

1962-63 1965-66

- -

Fig. 1 Three ammonia converters installed in a modern nitric acid plant operated by Imperial Chemical Industries Limited. Each converter has three rhodium-platinum catalyst gauzes, 114 inches in diameter,

woven by Johnson Matthey & Co Limited.

(about 30 per cent) is used by the explosives, plastics and chemical industries. Table I1 shows an estimated breakdown of the world’s use of nitric acid (I).

I n 1962-63 nitric acid represented about 25 per cent of the world’s fixed nitrogen production, but this proportion had dropped to an estimated 22.5 per cent by 1965-66. This decline is probably temporary, and is largely attributed to the sustained expansion of fertilisers obtained directly from ammonia, in particular urea and complex fertilisers based on ammonium phosphate. Low-cost ammonia from very large modern plants employing new processes based on hydrogen obtained from petroleum fractions (output about 1000 tonnes per day), together with increasingly large nitric acid plant facilities (about 500 tonnes per day), can be expected to effect substantial reductions in nitric acid production costs. Such reductions may have significant effects on potential applications in which price considerations have limited or prohibited the use of nitric acid until now.

Table II I The World’s Usage of Nitric Acid (I) Millions of Tonnes

100 per cent HNO, 1962-63 1965-66

Fertiliser production 14.6 (80%) 18.9 (81%)

Explosives, plastics and chemical industries 3.7 (20%) 4.5 (19%)

One such sector is the manufacture of nitrophosphate-type fertilisers.

With a world population that is expected to be about 7000 million by the end of this century, and with two-thirds of them under- nourished by even the most frugal standards, the outlook for nitrogen fertiliser production seems assured, and nitrate fertilisers based on nitric acid are likely to play a very major role in fulfilling total fertiliser demand.

The Nitric Acid Process The foundation of the modern nitric acid

process was laid by Kuhlmann in 1838 when he filed a patent for the catalytic oxidation of

Platinum Metals Rev., 1967, 11, (l), 3

ammonia over platinum sponge, although Milner had earlier oxidised this gas to nitric oxide over manganese dioxide in 1789. Pilot plant scale experiments were carried out by Ostwald and Brauer in the period 1901 to 1904, and the first plant to produce 300 kg of nitric acid per day was commissioned at Gerthe, near Bochum, in 1906. A tenfold increase in production was achieved by 1908. These early plants used crimped platinum strips wound into a coil, but in 1909 Kaiser filed a patent for the use of platinum in the form of a gauze woven of wire 0.06 mm diameter with 1050 apertures/cm2, and such gauzes are still used today. The contribution of Ostwald and his co-workers to the development of the nitric acid process, and the trials that led to the establishment of this new technology, have been described elsewhere

Until the early 1920s ammonia was obtained from gas works liquors and the impurities it contained - mainly sulphur and arsenic - resulted in comparatively short catalyst lives. The really large-scale production of nitric acid had to await two other major technological developments : the availability of cheap, high-purity synthetic ammonia from the Haber process, and stainless steel as a material of construction for efficient absorption systems working under pressure. The contribution the latter development has made to plant design may be judged by the fact that in 1919 a U.S.A. plant to produce 280 tonnes per day of nitric acid required 24 atmospheric pressure acid absorption towers, each 35 ft square and 60 ft high - a total volume of 1.63 million cubic feet, not counting 12

large oxidation towers (4). The modern nitric acid process proceeds

essentially in three stages : I Liquefied ammonia is vapourised and

pre-heated before being mixed with pre- heated air. The mixture at about 3oo0C, and usually containing 10.5 to 12 volume per cent of ammonia, is passed downwards through a pad of platinum alloy gauzes in a converter. Nitric oxide is

(2, 3) .

formed as a result of an extremely rapid, highly exothermic reaction at the platinum surface in accordance with the overall equation

4 NH,f50,+4 N 0 + 6 HZO + 2 16.7 kcal/mole

This reaction will be discussed in fuller detail in a later section.

2 The nitric oxide that is produced at the platinum gauze is oxidised further by means of secondary air reacting honio- geneously in the gas phase in accordance with the overall equation

2 NO+O,+N,O, Formation of dinitrogen tetroxide proceeds via an intermediate nitrogen dioxide, NO,. The nitric oxide oxidation reaction has a negative temperature coefficient, hence low temperatures favour high yields. Elevated pressures also raise the yields of the tetroxide, making possible the production of higher strengths of acid.

3 Dinitrogen tetroxide is absorbed in water with the formation of nitric acid in accordance with the simplified equation

+z NO, (recycled for re-oxidation).

The absorption proceeds at greater rates, and with higher efficiencies, at elevated pressures and low temperatures.

In a modern plant the heat liberated by the ammonia oxidation reaction is usually recovered, enabling the plant to be self-supporting for its power requirements once the reaction has reached optimum conditions and capacity working is attained.

Modern Proprietary Processes There is no universally optimum overall

design of a nitric acid plant; conditions of pressure, temperature, flow rate and other factors for each stage in the process may be varied to suit particular local requirements and situations. At least fifteen proprietary nitric acid processes are available now; the choice presented to operators is wide, and the selection of the “best” process to suit a given

3 N,O,+Z ~ , 0 + 4 HNO,


requirement involves the evaluation of numerous technical and economic factors (5, 6).

The principal design variables for the ammonia oxidation and subsequent stages of the plant are temperature, pressure and gas flow rate. Their main effects in these sections are shown in Table I11 (7). Since the oxidation of nitric oxide and the absorption stages are always carried out at pressures in the range 4 to 9 atmospheres, plants are generally described by the pressures within the ammonia oxidation coverter : low, or atmospheric, medium (3 to 5 atmospheres) or high (5 to 9 atmospheres). Ammonia oxidation at low pressures results in higher conversion efficiencies and lower platinum metal losses compared with medium or high pressure oxidation. Longer operating periods between shut-downs for gauze maintenance are also possible, but such converters are bulkier, more expensive and require costly hot-gas compressors to raise the gas pressure after oxidation to that required in the subsequent stages.

The American high pressure plants-all derived from the Du Pont process-operate with a converter pressure around 8 atmospheres and with a gauze pad temperature in the range 900 to 950°C. They also have high

gas flow rates per unit area of gauze, and hence the platinum loss rates are high, in practice running to 250 to 400 mg/ton IOO per cent HNO,. Among the European process licensors, Uhde and Stamicarbon also offer high pressure plants with the gauze pad operating at temperatures about 900°C. These, however, have lower gas flow rates and the platinum losses are correspondingly reduced to 180 to zoo mg/ton. Medium pressure converters with gauze temperatures of 845 to 880°C generally experience platinum losses from 85 to 125 mg/ton, while converters operating at atmospheric pressure with gauze temperatures about 80o"C have the lowest metal loss rates, around 50 mg/ton (5, 8). It must be mentioned that process licensors' claims for platinum loss rates generally appear to be conservative in the light of actual operating experience.

Table IV summarises the principal features of some commercial nitric acid processes available to operators under licence. I t is based on licensors' specifications and is re- produced by courtesy of the Noyes Develop- ment Corporation, New York (7).

The cost of producing ammonia has fallen recently following the introduction of new processes for manufacturing low cost hydro-


Table IV

Principal Features of Some Commercial Nitric Acid Processes

Approximate operating Product pressures, atmospheres acid Typical requirements

Name (abs) per cent per tonne of 1 0 0 ~ o Distinctive features Combustion Oxidation Absorption HNO, HNO,

.__._.__~__~__I___._- --- -~

Bamag (Monopressure)

Bamag (Combination)

Chemico

c & I

Grand Paroisse

Hercules

Kuhlmann

Montecatini

Pechiney- St Gobain

SBA (Socihti Belge de 1'Azote)

SBA

Stamicarbon

Uhde (normal strength)

Uhde (high strength)

Weatherly

1,4 o r 8

1,4 o r 8

8 t o 9

8

3 t o 4

8

1

4 t o 5

4 fO 5

1

3.3

1

7 t o 8

(a) 4.5 (b) 1

9.5

1.4 o r 8

4 o r 8

8 t o 9

8

7 t o 8

8

4

4 t o 5

4 t o 5

3 t o 5

3 t o 5

5 to 6

7 t o 8

4 t o 5 4 t o 5

9.0

1,4 o r 8

4 o r 8

8 t o 9

8

7 t o 8

8

5

4 t o 5

4 t o 5

3 t o 5

8

5 t o 6

7 t o 8

4 t o 5 4 t o 5

9.0

55 t o 70 dependent on pressures Uses perforated plate towers used with cooling water coils on

the plates

55 t o 7 0 NH3 280 kg Similar to above Pt 45 mp, cooling HIO 170 m pure H,O 100 kg

55 t o 65 (steam turbine and 51OoC (with steam turbine and plus expander) 68OOC plus expander) NH, 287 kg N H 3 287 kg Pt 128mg Pt 128 mg cooling HIO 135 m 3 cooling H20 100 ma pure H,O 500 kg pure H,O 540 kg

55 t o 67 NHI 292 kg Uses cascade cooling and a plus Pt 170mg single tower for oxidation/

cooling H,0 117 ma absorption/bleaching pure H20 400 kg

56 t o 7 0 NHI 282 kg Oxidation towers cooled ex- Pt 100mg ternally by water. Absorp- cooling H,O 200 m s t ion tower cooled by internal pure H20 710 kg water coils. 5 unit, single

shaft, turbo-compressor used

5 7 t o 60 NH, 285 kg Uses high gas superheat t o Pt 174mg obtain maximum power re- cooling HzO 85 t o 95 ma covery. Specially designed pure HaO 500 ke water-cooled absorwion

55 t o 70 NH, Pt cooling H,O

53 t o 62 NH, Pt cooling H,O

normally NHI up t o 60 Pt

58 t o 70 (for55% HNO,) NH, Pt cooling H,O pure H,O

50 t o 70 Similar t o above

50 t o 6 5 NH, Pt cooling H,O pure H,O

Pt cooling H,O

55 t o 6 0 NH,

60 max. NH, 68 min. Pt

cooling H,O pure H,O

55 t o 6 0 NH, (or Pt

higher) cooling H,O pure H,O

I trays ensure a minimum'99% absorption efficiency

280 kg Uses a specially designed 45 mg tray t o induce oxidation and

150 m3 absorption in the l iquid phase

286 kg Uses separate oxidation and 100 mg absorption towers fitted w i th 100 m a refrigerated trays

286 kg Uses specially designed 100 mg water-cooled trays in oxida-

t ion absorption columns

Packed columns for 5874 281 kg acid. Additional plate-type 45mg columns used for 70% acid

150 ma 650 kg

Similar t o above. Uses catalytic tail-gas combustion for maximum energy recovery

Specially designed plate cool- ers used i n conjunction w i th

285 kg 45 mg

250 m' packed columns 730 kg

285 kg 79% of steam produced used 200mg for driving air compressor, 150 ms 1 1 ~ . f o r heating tail-gas,lO%

as product steam. Bubble tray atsorbers used

283 kg Uses multi-stage, packed 60 mg oxidation and absorption

165 m3 columns: each stage fitted 250 kg w i th own cooler and pump.

Figures listed refer t o process

284 kg Uses butted heat-exchanger 165mg assembly and a single oxida- 142 ma t i o n /absorpt ion/bleaching 750 kg column fitted w i th bubble

trays

(4

Note: The above table is intended as a general, comparative guide only. It i s based on licensors' specifications, and actual plant performances depend on variable and individual plant features such as daily capacities, water temperatures, types of drive and other associated items selected t o suit local conditions.


gen from petroleum fractions. With low ammonia costs, the advantages of higher conversion efficiencies achieved by atmospheric pressure converters may no longer outweigh the relatively high capital and operating costs of such mixed-pressure plants. There is a trend in Europe, therefore, to follow American practice and to adopt constant-pressure processes in which the converter and the following sections of the plant operate at the same pressure (usually in the range 3 to 9 atmospheres). The selection of the economically optimum operating pressure depends on a number of factors, for example, ammonia costs, steam credit value and local tax situations (9).

The Gauze in Operation The heart of the nitric acid plant is the con-

verter where ammonia is oxidised to nitric oxide. Consisting essentially of a reactor shell wherein the pre-heated ammonia-air mixture generally flows vertically downwards through the gauze pad, it is usually situated immediately on top of the waste heat boiler. A baffle or diffuser system located in the top of the converter ensures that the gas mixture reaching the gauzes is homogeneous, and provides an even gas distribution over the entire gauze surface. This is important in order to avoid “hot spots” with attendant risk of local gauze damage, and becomes more difficult to achieve with increasing converter diameter.

Stainless steel or an aluminium-magnesium alloy are used as constructional materials for the ammonia pre-heater, the mixed-gas ducts leading to the converter and the converter hood itself. This is to ensure that ammonia at the pre-heat temperature (250 to 300°C) does not come into contact with surfaces capable of catalysing its decomposition into nitrogen and hydrogen before making contact with the platinum gauzes. Iron oxide-used as an ammonia synthesis catalyst, and equally capable of catalysing the reverse reaction-is particularly liable to cause ammonia losses by pre-decomposition. I t should be carefully excluded from the system by avoiding the use of mild steel components liable to rust forma-

tion. The interior surface of the converter hood is heated by radiation from the gauze pad and external water cooling is required, especially for high pressure converters whose gauzes operate at temperatures up to about 950°C. Fig. 2 illustrates the marked effect of temperature on the decomposition of ammonia on various metal surfaces (10). At normal pre-heat temperatures, ammonia decomposes about 10 times faster on mild steel than on stainless steel. It is estimated that from 1.5 to 3 per cent of the ammonia fed to most plants may be lost by pre-decomposition and thus never reach the platinum gauzes.

The Ammonia-Air Mixture The ammonia feedstock is vaporised, super-

heated and filtered to remove any dust or oil particles before pre-heating. Atmospheric air may be scrubbed with water and is then care-


fully filtered before being pre-heated in a separate heat exchanger. Good mixing of the gases is essential, and for this purpose venturi-type or sparge-type mixers are usually employed.

In certain proportions, ammonia and air form explosive mixtures. At I atm. pressure, the lower explosive limit is 13.8 volume per cent NH,, falling to 13.0 and 12.4 volume per cent at 5 and 8 atm. pressures respectively. The stoichiometric composition for the reaction

is 14.2 volume per cent NH,, although a somewhat more important ratio is the kinetic-stoichiometric composition, at which the collision chances for oxygen and ammonia molecules are in the ratio 9 4 : I. This ratio corresponds to an ammonia concentration of 12.7 volume per cent in air. In practice, ammonia concentrations in the range 10.5 to 12 volume per cent are used, and in this region it is apparent that there is very little excess oxygen supplied to the reaction system. The variation in the NH, : 0, ratio as the reaction proceeds is illustrated in Fig. 3 (I I).

The Reaction at the Gauze The oxidation of ammonia is a typical

example of a very fast heterogeneous reaction with residence times from I O - ~ to ro-4 seconds and hourly space velocities exceeding 108. Such conditions entail considerable linear gas velocities, often greater than 20

metres/minute. Since the mean free path of ammonia molecules under the pressure and temperature conditions normally encountered in a converter is of the order of 0.3 micron, compared with a wire diameter around 60 microns and even larger aperture diameters, ammonia mass transfer is not influenced by molecular diffusion limitations. The physical transport of the ammonia molecules to the platinum surface is the rate-determining fac-

4 NH,+S 02-24 NO-I 6 HSO


tor during the greater part of the reaction period.

If ammonia and oxygen were allowed to react under equilibrium conditions, nitrogen and water would be the only products. Reaction conditions are such, however, that nearly every molecule that hits the platinum gauze surface is converted to nitric oxide in accordance with the overall equation

4 NH,+s O,+4 NO]-6 H,O If the gas flow rate is too high, some un-

reacted ammonia passes through the gauze pad, and will then react with nitric oxide (12)

4 NH,+6 NO+s N,+6 H,O If the rate is too low, some nitric oxide will

decompose on the hot platinum surface (13) 2 NO+N,+O,.

Since about 80 to go per cent of the reaction is completed on the upper gauze of a 3- to 5- ply pad, or in the top 20 per cent of the layers in a thick pad used in high pressure converters, the gas leaving this zone will contain both ammonia and nitric oxide. In order to reduce to a minimum the reaction between these gases, it is necessary to provide very good

contact between individual gauzes and to avoid any free spaces between them. This is achieved by using gauzes that are perfectly flat and free from folds or buckles that could separate them from each other.

Numerous studies of the kinetics of the principal reaction have been made (14,1516). Among the postulated intermediates are hydroxylamine, nitroxyl, NHO, and the radical NH. It is generally agreed that reaction proceeds between ammonia and an activated oxygen boundary layer that covers most of the platinum surface.

The formation of nitric oxide is favoured by low operating pressures and, since the reaction bas a positive temperature coefficient, also by high temperatures. The optimum temperature, moreover, increases with the rate of gas flow.

The concludingpart of Mr Connor’s article, dealing principally with the problem of platinum losses from gauzes during operation and with the production and handling of gauzes, will be published in the April issue of Platinum Metals Review.

References I Private communication, Nitrogen, published

by the British Sulphur Corporation, London

z L. €3. Hunt, Platinum Metals Rev., 1 9 5 8 , ~ ~ I29 3 A. Mittasch, Saltpetersaure aus Ammoniak,

4 A. M. Fairlie, Chem. Met. Eng., 1919, 20, 8 5 D. C. Oosterwijk, The Choice of a Nitric Acid

Plant, Trans. Inst. Chem. Eng., 1966,44, ( z ) , CE.38

6 Anon,Chem. Proc. Engng., 1966,47, ( I ) , 11-17 7 Nitrogen Fertiliser Chemical Processes, Noyes

Development Corporation, New York, 1965 8 E. Bahari, Chem. G.’ Proc. Eng., 1965, January,

16 9 A. Horton, European Chemical News, Large

Plant Supplement, September 30, 1966, 76 10 D. A. Spratt, Chem. SOC. Special Publication,

11 A. P. Oele, Chemical Reactor Engineering, Ed. K. Rietema, Pergamon Press, London, I957

12 H. Wise and M. F. Frech, J . Chem. Phys., 1954, 2% I463

13 L. Andrussow, Z. Angew. Chem., 1926,39,32z 14 E. Molinari et al., J . Catalysis, 1965, 6, (3),

15 J. Zawadski, Faraday SOC. Discussions, 1950,

16 R. H. Harrison and L. A. Lobe, Chem. Eng.

VerIag Chemie, Weinheim, 1953

1% I957

34 1-3 53

8,140

Prog., 1953, 49, 349

Further Increase in Platinum Production at Rustenburg

Any concern felt by users of platinum about the availability of metal to meet their future needs should have been relieved by the announcement recently made by Rustenburg Platinum Mines of their further plans to increase production.

Temporary measures introduced last year to secure a relatively quick increase in output are to be replaced with permanent facilities giving an annual capacity ofabout 600,000 ounces of platinum by the autumn of this year.

Preliminary work has been started on a further scheme, involving the acceleration of shaft sinking programmes, further extension to the reduction works and smelter plant and the expansion of numerous mining facilities. This, together with the extension of refining plant now being undertaken by Johnson Matthey and by Matte Smelters, will result in a refined platinum capacity of some 750,000 ounces a year. This increased flow of metal, which compares with an output of about zoo,ooo ounces a year in 1963, will begin to reach users in 1969 and will be fully effective by 1971.

permit production at this rate well beyond the turn of the century. The estimated ore reserves available to Rustenburg are considered to be sufficient to

Platinum Metals Rev., 1967, 11, (l) , 9-9 9

A Rhodium-Platinum Thermocouple for High Temperatures A REFERENCE TABLE FOR THE “SIX-THIRTY” COUPLE

The thermocouple formed by two rhodium- platinum alloys containing 6 per cent and 30 per cent of rhodium respectively was first introduced in Germany some thirteen years ago by Degussa of Hanau for temperature measurements in molten steel. Since then it has been widely used in other high temperature applications; J. A. Stevenson (I), for example, has recently given an account of its use in the control of glass melting furnaces in Russia.

The “Six-Thirty” thermocouple, as it is commonly known, was developed because the standard platinum : 10 per cent rhodium- platinum and platinum : 13 per cent rhodium- platinum thermocouples were found to have limitations when used much above 1500°C. The pure platinum limb becomes extremely weak mechanically and is very susceptible to contamination by rhodium from the alloy limb. The “ Six-Thirty” thermocouple over- comes these disadvantages by the use of two rhodium-platinum alloys that enable it to be used for continuous temperature measurements up to 1700’C and intermittently up to about ISOO~C, the limiting temperature being the melting point of the 6 per cent rhodium- platinum limb at 182oOC.

The thermocouple is very stable under clean oxidising conditions. Walker, Ewing and Miller ( 2 ) have shown this couple to be more stable than any other rhodium-platinum alloy combination. The use of two rhodium- platinum alloys produces a lower e.m.f. output, but above IOOO”C the sensitivity of the “Six-Thirty” closely approaches that of the platinum : 10 per cent rhodium-platinum thermocouple and may thus be used without any appreciable sacrifice in the accuracy of measurements. At room temperature the

e.m.f. and sensitivity are so low that below 50°C cold junction correction may be neg- lected for all but the most precise measurements.

The growing importance of this thermocouple led to the redetermination of basic values, and new and more accurate reference tables compiled by Obrowski and Prinz of Degussa (3) were published in 1962. These tables are now regarded as standard values in Europe.

In the U.S.A. the “Six-Thirty” has become the preferred thermocouple for high temperature measurements and to facilitate its use and calibration in America reference tables have been derived by George W. Burns and John S. Gallaher (4) of the National Bureau of Standards. I n a commendably detailed paper the authors describe how their test programme was conducted using thermocouples from three major American manu- facturers and one from Degussa. The compositions chosen, 6.12 per cent and 29.6 per cent rhodium respectively, reflect the desire to avoid creating a new and conflicting set of standards, since these alloys had been previously found to generate e.m.f.s that conform closely to the values determined by Obrowski and Prinz.

The American reference table is therefore similar to the 1962 table and the differences between them, shown graphically in the dia- gram, are claimed to be less than the differences found between the couples being tested.

Burns and Gallaher give a full account of the techniques used to calibrate their thermocouples; these include comparison with a platinum resistance thermometer, comparison with a platinum : 10 per cent rhodium- platinum thermocouple and comparison with


Reference Table for 6 per cent Rh-Pt : 30 per cent Rh-Pt Thermocouples (Temperature in "C (IPTS 1948); electromotive force i n absolute

millivolts; reference junction 0°C

+ 4 0 -

0 { t 3 0 -

> t20- 8

0

10

20

30

40

50

60

70

80

90

100 -

+ 3oc _ L _ _ _ _ _ _ _ - ------ ___- - - -

*_- - -/-

1000

z

w 2 -10-

:: -20- n LL -30-

5 -40-

4.844

4.936

5.029

5.1 22

5.21 6

5.31 1

5.406

5.502

5.598

5.695

5.793

0.092

0.093

0.093

0.094

0.095

0.095

0.096

0.096

0.097

0.098

. . -. --._ - .- .-._

--- -..-____ - - - - _ _ _ ---__ -- -- - - 3 o c

1100

5.793

5.891

5.990

6.090

6.190

6.290

6.391

6.492

6.594

6.697

6.800

0.098

0.099

0.100

0.100

0.100

0.101

0.1 01

0.102

0.103

0.103

an optical pyrometer.

1200

6.800

6.904

7.009

7.114

7.220

7.326

7.433

7.541

7.649

7.757

7.866

0.1 04

0.1 05

0.1 05

0.106

0.106

0.107

0.108

0.108

0.108

0.109

1300

7.866

7.976

8.086

8.196

8.307

8.41 8

8.530

8.641

8.754

8.866

8.979

0.110

0.110

0.110

0.1 11

0.111

0.112

0.111

0.1 13

0.112

0.113

-

1400

8.979 0.114

0.1 13

0.114

0.114

0.1 15

0.114

0.1 15

0.115

0.116

0.115

9.093

9.206

9.320

9.434

9.549

9.663

9.778

9.893

10.009

10.124

A large number of e.m.f. determinations were also carried out on each limb of the thermocouples under test, the e.m.f.s being measured with respect to platinum reference wires. In addition a study was made of the effect of variations in the rhodium content on the temperature-e.m.f. relationship. The results of this and other parts of the test programme are shown con- cisely in graph form.

After averaging the results of the calibra- tions three quartic equations were derived

1500

10.124

10.240

10.356

10.471

10.587

10.704

10.820

10.936

11.053

11.169

11.286

0.1 16

0.1 16

0.1 15

0.1 16

0.117

0.1 16

0.116

0.117

0.1 16

0.1 17

1600

11.286

11.403

11.519

11.636

11.753

11 369

11.986

12.1 03

12.220

12.336

12.453

0.117

0.116

0.117

0.117

0.116

0.117

0.1 17

0.117

0.1 I 6

0.117

~

1700

I 2.453

12.570

12.686

12.803

12.91 9

13.035

13.1 52

13.268

13.384

13.500

13.616

0.117

0.1 16

0.117

0.1 16

0.1 16

0.117

0.1 16

0.1 16

0.1 16

0.1 16

1800

13.616

13.731

13.847

0.115

0.1 16

with the aid of an IBM 7094 digital computer. In common with previous investigators, Burns and Gallaher found that no equation of simple form will adequately describe the e.m.f.-temperature relationship over the entire temperature range.

The authors emphasise the arbitrary nature of their reference table, but conclude that the thermocouples used by Obrowski and Prinz had essentially the same characteristics as those of American manufacture. Thus thermocouples made to comply with the earlier table

L 1 5 0 0 1000 1500

TEMPERATURE 'C


Difference between the NBS reference table and the 1962 Degussa reference curve for the "Six-Thirty" thermocouple

1000 1000

of Obrowski and Prinz will comply with the American table to within similar tolerances.

The authors conclude their paper with a discussion of the results obtained and a consideration of the uncertainties in the measurements. Burns and Gallaher estimate that they do not exceed&z°C at 14ooOC and about f3 or 4°C at 1750°C.

It is interesting to note that the American results are based almost entirely on comparison techniques, whereas Obrowski and Prinz used the fixed melting point technique. If criticism of this paper may be made it is that the value of the work would have been given more weight if more than one set of batches from each manufacturer had been tested.

Apart from this one reservation the authors have presented an extremely competent and valuable paper and the publication of these tables underlines the international recognition of the “Six-Thirty’’ thermocouple as an accurate, sensitive and stable sensor for the measurement of high temperatures.

P. H. w. References

I J. A. Stevenson, Platinum Metals Rev,, 1966, 10, 128-131

2 B. E. Walker, C. T. Ewing and R. R. Miller, Rev. Sci. Instrum., 1962, 33, (IO), 1029-1040

3 W. Obrowski and W. Prinz, Archiv Eisen- hiittenwesen, 1962, 33, (I), 1-4; Plarinum Metals Rev., 1962, 6 , 96-97

4 George W. Burns and John S . Gallaher,J. Res. NBS, 1966,70C, (z), 89-125

A high proportion of the papers dealing with fuel cell developments presented at the Fifth International Power Sources Sym- posium at Brighton in September again focused attention on the use of platinum metals as electrocatalysts. Among these contributions was an analysis by A. L. Harrison and G. R. Lomax of Electrical Power Storage of the economic factors determining the role that fuel cells will play in the future as electricity generating devices. This gave some quantitative expression to the most likely areas of fuel cell application, which might include power generation for radio repeater stations, submarines, marine buoys and certain electric vehicles such as fork lift trucks. A I kW hydrogen-air fuel cell battery employing a supported palladium catalyst and equipped with full instrumenta- tion to record all aspects of its successful operational life of 2000 hours was also described in detail by M. I. Gillibrand and J. Gray of the same company. Such a battery has also been built into an electrically driven factory truck.

Recent advances in internal reforming methanol-air cells were described by C. G. Clow, J. G. Bannochie and G. J. W. Pettinger of Energy Conversion Limited. Such systems reform methanol with water to yield hydrogen in a reaction chamber immediately adjacent to a silver-palladium membrane that acts as the anode. The hydrogen thus formed

Platinum Metal Electrocatalysts for Fuel Cells diffuses through the anode to the potassium hydroxide electrolyte side, and is consumed as the fuel. A bi-porous nickel cathode is employed, and an integrated unit to provide 6 kW was described. In order to make more economical use of the silver-palladium alloy, a tri-foil developed by Johnson Matthey and consisting of a nickel/silver-palladium alloy/ nickel “sandwich” having an overall thickness of 0.005 inch with the alloy thickness of about 0.00003 inch formed the basis of a new “window” electrode structure for such a cell. This development consists of electrolytically removing small windows of nickel on the tri-foil, leaving the thin silver-palladium membrane exposed but supported mechanically by the surrounding nickel overlay.

Activation of Raney-nickel anode electrocatalysts by small amounts of platinum or palladium was demonstrated by M. Jung and H. H. V. Dohren of Varta AG, Germany, to provide a satisfactory technique for providing highly active anodes with low polarisations. Platinum loadings as low as 0.58 mgm/cm2 proved effective.

A contribution from the U.S.S.R. by V. S. Bagotzky described the mechanism and kinetics of cathodic oxygen reduction on platinum electrodes. Different forms of chemisorbed oxygen, as well as some pene- tration by oxygen into the upper atomic layers of the metal, could be demonstrated.

H. C .


Measuring Electrodeposit Thickness A BETA BACK-SCATTER METHOD FOR THE PLATINUM METALS

In the electrodeposition of the platinum group metals it is particularly important that electrodeposit thicknesses are accurately known. Excessively thick electrodeposits are costly; insufficiently thick deposits may lead to breakdown in service. The average thickness of electrodeposits used industrially is O.OOOZ inch, while in decorative applications the average is much lower. Small errors at these thicknesses often amount to a relatively large proportion of the total thickness, and there is thus a need for a process control technique capable of checking electrodeposit thicknesses rapidly and non-destructively.

The conventional methods of measuring electrodeposit thicknesses by microsectioning or by “strip and weigh” methods are in- accurate on thin deposits and are only accurate to about 20 per cent on thick deposits, while they are also time-consuming.

To find a more accurate measuring method that could be quickly used without damaging the electrodeposit a project was initiated in the Johnson Matthey Analytical Laboratories which led to the development of a prototype beta back-scatter thickness gauge (I). Further

development work carried out in conjunction with Panax Equipment Limited has now resulted in a commercial apparatus, known as the Beta 750 Thickness Gauge and available to industry from Johnson Matthey. One of these units has been in use for over two years and has already paid for itself in the metal economies it has effected. This instrument is based on the principle that beta particles, when they pass through matter, collide with the electron shells of the atoms they encounter and after many collisions some emerge from the surface they entered. The beta particles that emerge are described as back-scattered. The intensity of the beta back-scatter from a material is proportional to its atomic number or aggregate atomic number. The amount of back-scattered radiation can be used as a means of determining the thickness of one electrodeposited layer on a different basis metal. A variation in coating thickness will give a change in overall atomic number, and in back-scatter intensity below a limiting value that represents the maximum thickness of deposit which can be measured with a particular isotope.

Fig. I For the accurate and non-destructive measurement of plating thicknesses of the platinum group metals the Beta 750 provides a simple and compact instrument, using the principle of “back- scatter” of beta particles


14C

135

- 0 0 o_ X - l3C ln t- z 2 s

125

12c 50 I00 I so

PLATINUM THICKNESS (MICRO INCHES1

The Beta 750 comprises a krypton 85 source, which emits only beta particles, contained in a metal cylinder which is mounted above a radiation detector. The detector is connected to an electronic counter. In use the sample to be measured is positioned above the source. The beta particles back-scattered from the sample are collected by the detector and a count made over a certain period i s referred to the calibration graph for the particular electrodeposit and the thickness read off. The points on the calibration graph are plotted by recording the count obtained on the instrument, using the same sample

Fig. 2 A typical calibration graphfor use with the Beta 750. This shows the thickness of platinum plating on titanium obtained from measurement of standard specimens. (Aperture 0.06 inch x 0.2 inch; counting time 60 seconds)

holder, from a number of standards. The standards have known thicknesses of the electrodeposit on the same basis metal.

There are several factors to take into account in using this method of measurement. The electrodeposit must differ by at least 3 in atomic number from the basis material. The energy of the beta radiation is sufficient to measure normal plating thicknesses. The beta source has a half life of 10.6 years, which allows stable calibration graphs to be drawn for a large number of metals and non-metals. The geometry of the source is such that it can be used to measure thicknesses over very small areas, down to I mm in diameter. This allows the instrument to be used for measuring thicknesses on curved surfaces with little loss of accuracy.

A typical calibration graph, shown in Fig. 2, gives the curve for platinum on titanium, while Fig. 3 shows the curve for palladium on copper.

There is an optical arrangement allowing the exact point being measured to be seen even though the board is face down to the beta source. The thickness of rhodium electrodeposits on nickel, often used as in electronic

122 ' j4r- -____-

PALLADIUM THICKNESS (MICRO INCHES)

Fig. 3 A calibration graph for palladium plating on copper (Aperture 0.06 inch

)O diameter; counting time 60 seconds)


Fig. 4 A close-up view of the measuring head being used to determine the thickness of a rhodium electrodeposit on nickel

contact applications, can be measured, but because the atomic numbers of rhodium and silver only differ by one the unit cannot distinguish between them.

to the platinum group metals but also to other metals will shortly be published elsewhere (2).

References I B. S. Cooper and W. Westwood, B.P. Appln.

A fuller account of the development of this equipment and of its applications not only

5942165

Metal Finishing, in the press 2 S. P. G. Melrose and B. S. Cooper, Trans. Znst.

Osmium-coated Tungsten Cathodes Thermionic valves, and a number of related

devices such as klystrons and magnetrons, depend for their operation on the control of a stream of electrons generated by a thermionic emitter. A common form of emitter consists of a porous tungsten substrate in association with a reservoir of barium calcium aluminate which, by mutual reaction, provides a supply of barium to the emissive surface.

The total work function of the assembly depends on the work functions of both the substrate and the adsorbate and on the degree of surface adsorption and, as it is considered that no better adsorbate than barium exists, attention has been directed in recent years towards alternative substrates.

Recent theoretical work led to the pre- diction that, paradoxically, a higher work function of the substrate could lead to a reduction in the total work function of the whole system and, in a recent paper by P. Zalm and A. J. A. van Stratum, of the Philips Research Laboratories (Philips Tech. Rev., 1966, 27, (3/4), 69-75), results are given for systems in which rhenium, ruthenium, iridium and osmium were investigated, the

metals being applied as thin coatings to the tungsten substrates. I t was confirmed that the work function of the emitter decreased as the work function of the substrate coating increased and more detailed investigation of the most promising assembly containing osmium revealed that the reduction in work function was so marked that, for example, at 800°C a current density ten times that of a normal cathode was possible.

It is considered that the use of osmium cathodes with their higher performance will be of considerable practical advantage in magnetrons, reflex klystrons and disc-seal triodes and further, as a consequence of the lower operating temperature for a given performance, these cathodes may find application where the expense of initial purchase and replacement is an important consideration.

During this investigation the work functions of iridium and osmium have been determined as 5.50fo.00~ V and 5.93fo.05 V respectively, and although the work function of ruthenium was not determined it is known to be in excess of that of tungsten at 4.54 V.

J. E. H.


Platinum Metals in Homogeneous and Heterogeneous Catalysis A REVIEW OF PAPERS PRESENTED AT THE AMERICAN CHEMICAL SOCIETY MEETING

The catalytic properties of the platinum group metals and their salts featured signi- ficantly in two symposia held as part of the one hundred and fifty-second meeting of the American Chemical Society held in New York in September. The first symposium, on the subject of “Mechanisms of Heterogeneous Catalysis”, was arranged by the Division of Petroleum Chemistry and occupied two days. Most of the papers relating to metal catalysis were concerned with the use of deuterium as a tracer in understanding mechanisms of hydrogenation.

Isotopic Tracer Studies F. Hartog (Dutch State Mines) reported

results on the reaction of benzene with deuterium on all the Group VIII metals. All catalysed multiple exchange of the benzene, giving CGDG as a primary product, this process being most favoured by ruthenium and least by platinum. Additional exchange occurred in the hydrogenation step, and completely deuterated cyclohexanes were observed.

A paper by A. W. Weitkamp (American Oil Company) described a study of the interaction of naphthalene with deuterium using charcoal- supported noble metal catalysts. This system is complex by reason of the large number of possible products : in addition to exchanged naphthalene and tetralin, there are four possible octalin isomers and two decalin isomers. Palladium in particular gives high yields of tetralin, with little exchange of naphthalene, suggesting that the latter molecule behaves more like a diolefin and a benzene ring than t ~ 7 0 fused benzene rings.

Four papers described the interaction of

Platinum Metals Rev., 1967, 11, (l), 16-17

olefins with deuterium. G. C. Bond and J. M. Winterbottom showed that when deuterium interacted with the n-butenes over alumina-supported palladium in the region of room temperature, the isomerised butenes contained much less than one deuterium atom per molecule: the results strongly suggested that dissolved hydrogen and deuterium atoms play an important role in reactions catalysed by palladium. J. J. Phillipson and R. L. Burwell (Northwestern Universityj described their attempts to simplify the study of the olefin-deuterium reaction by assisting the removal of adsorbed hydrogen atoms, which would otherwise have gone into the alkane, by means of deuterated solvents. They used cyclopentene as the olefin and a platinum-alumina catalyst : using CH,OD containing some deuterated ethanol- amine they obtained over 60 per cent cyclopentane-d, and only 3 to 4 per cent cyclopentane-do.

G. V. Smith and J. A. Roth (Illinois Institute of Technology) reported that a phenyl substituent at an olefinic double bond leads to preponderant I, 2-cis addition relative to other processes such as exchange and double-bond migration which normally occur with facility over palladium catalysts : the effect was attributed to rr-bonding of the aromatic ring to the catalyst surface. E. Selke, W. K. Rohwedder, C. R. Scholfield and H. J. Dutton (U.S. Department of Agriculture, Peoria) reported a detailed study of exchange and isomerisation of methyl oleate catalysed by palladium : this is another complex system, for double-bond migration leads to a large number of olefinic products, but by careful use of several different analytical techniques

16

the authors were able to form a satisfactory picture of the principal reaction mechanisms.

Homogeneous Catalysis The symposium arranged by the Division

of Industrial and Engineering Chemistry entitled “Homogeneous Catalysis-Industrial Applications and Implications” also occupied two days and aroused wide interest. J. Halpern (University of Chicago) and G. C. Bond both gave general reviews of the field, the latter emphasising the correlations between homogeneous and heterogeneous catalysis : G. Szonyi (CIBA) reviewed the present commercial status of homogeneously catalysed reactions, and A. W. Gessner (Lummus Company) discussed some aspects of mass and heat transfer pertaining to such reactions. K. A. Taylor (ICI, Runcorn Heath) associated the activity of d8-complexes with their ability to exist in either four- or five fold co-ordination, and reported on the catalytic hydrogenation properties of diphosphine complexes of Ir’ and Rh‘.

Olefin oxidation by palladous chloride commanded much attention. P. M. Henry (Hercules Powder Company) discussed the kinetics of ethylene oxidation and contrasted Pd”, which yields acetaldehyde, with TIrr which yields ethylene glycol in addition. R. G. Schultz and D. E. Gross (Monsanto) had studied the vinylation of acetic acid by hexenes and reported that product distribu- tions were sensitive to the concentration of acetate ion: some new reaction mechanisms were suggested. The same subject arose in a small symposium on “New Chemistry of Ethylene”: D. Clark and P. Hayden (ICI, Heavy Organic Chemicals Division) described how the products of vinylation of acetic acid by ethylene could be controlled by variation of the solvent chosen: in acetic acid acetaldehyde and ethylidene diacetate predominated, whereas in dimethylacetamide, vinyl acetate was the major product. In the same symposium, J. Tsuji and K. Ohno (Toyo Rayon Company) showed that palladous chloride catalyses the carbonylation of olefins and

decarbonylation of aldehydes and acyl halides : the latter reactions are also catalysed by tris (triphenylphosphine) rhodium chloride.

It is now well known that rhodium chloride catalyses the polymerisation of butadiene to trans-I, 4-polybutadiene: two papers presented at the Division of Polymer Chemistry, one by M. Morton and B. Das (Institute of Polymer Science, Akron) and the other by V. A. Kormer and colleagues (U.S.S.R.), reported studies of the reaction, the mechanism of which shows signs of being complex. R. E. Rinehart (U.S. Rubber Company) showed that noble metal-olefin complexes were also polymerisation catalysts.

Werner Centenary Symposium In the Werner Centenary symposium,

under the auspices of the Division of Inorganic Chemistry, several papers were presented which related to noble metal complexes of actual or potential interest as homogeneous catalysts. Thus J. C . Bailar (University of Illinois) described complexes of paIladium and platinum possessing the ability to catalyse the reduction of all but one olefinic double bond in a polyolefin: such complexes are of great interest in the fat-hardening process. L. Vaska (Clarkson College of Technology) summarised his spectroscopic examination of iridium carbonyl hydride and deuteride complexes.

Homogeneously-catalysed processes are clearly in a period of rapid development. Two such processes are already operating commercially and more are likely to follow soon. Homogeneous catalysts have the potential advantages over heterogeneous catalysts of greater specificity and more economic use of the noble metals. The size of the current research effort in this field was amply demonstrated at this meeting and is a testimony to the great promise which this field holds out. It has particular relevance to the rapidly-growing petrochemicals industry, where conversion of cheap olefin feedstock to more valuable products is urgently being sought. G. C. B.


One Hundred and Fifty Years AN ANNIVERSARY REVIEW OF JOHNSON MATTHEY’S ROLE IN THE ECONOMIC HISTORY OF PLATINUM

By Donald McDonald Johnson Matthey 8z Co Limited

January Ist, 1817, is generally accepted as the date of the beginning of the business that is now Johnson Matthey & Co Limited. It was on this day that Percival Norton Johnson, in partnership with his younger brother, took over the assaying house of his father, John Johnson, in Maiden Lane, London. This arrangement only lasted a few months when the father returned and Percival really started his own separate office in the house next door. The parental business had bought and sold native platinum and he himself had done some research on its solubility in nitric acid when alloyed with silver and had published the results (I). But little was possible in the confined space of Maiden Lane and his interest was largely directed to the work of his friend, Thomas Cock, who had learned chemistry in William Allen’s famous laboratory at Plough Court, Lombard Street, and had assisted his em- ployer in his work on platinum (2); he later worked out a method for making platinum malleable and published it (3). He and Johnson came together when they married two sisters and thereafter Cock, who was a man of means and became neither employee nor partner, helped Johnson towards the refining and fabrication of the metal. Little was or could be done until Johnson moved in February 1822 to larger premises at 79 Hatton Garden and from then on the work progressed.

At that time the only native platinum available came from the Choco district of Colom- bia, whence it was smuggled by speculators who found some sale for it in Europe. There had been successful conversion to malleable

Since its inception a century and a half ago the Jirm of Johnson Matthey has played a leading part in the extraction, rejining and supply of platinum and its allied metals. To mark this anniversary, Mr McDonald has prepared a full account of the growth of these activities from the days when Percival Norton Johnson established his business, through the early years when the uses ofplatinum were virtually conjned to the laboratory, and on to more recent times when industrial applications are of major importance. I n this article the ebb and jlow of demand and supply are clearly traced, with Johnson Matthey growing steadily to its present dominant position, jointly with Rustenburg Platinum Mines, as the world’s largest supplier

of the platinum metals

metal in Spain (1786-1804) (4) and a larger use in France, which was increasing (5). In London W. H. Wollaston was working on it scientifically and commercially but in secrecy (6). The demand was for scientific apparatus, for weights and measures and, started by Wollaston and carried on by the French, for boilers for concentrating sulphuric acid. Johnson, with the aid of Cock and later in partnership with the latter’s nephew, W. J. Cock, expanded his operations slowly in the various commercial directions just mentioned. A new source of raw material became available about 1825 with the discovery of quantities of native platinum in the Russian Urals; this


quickly grew and displaced the Colombian product, which dwindled to a very small supply for some eighty years.

Apart from Johnson’s small contribution, the French became the main source of fabricated platinum until the middle of the century, when they were challenged by young George Matthey and his partners who were about to succeed Johnson on his retirement in 1860. Matthey had been collaborating with the French scientists, Deville and Debray, who had invented a new and easier method of melting platinum by means of their oxy- hydrogen blowpipe, and had very much improved the commercial methods of refining it. This led him to the invention of joining the metal by fusion welding which much simplified the problems of fabrication. In ten years his firm had supplanted the French as the principal world suppliers (7).

Supplies from Russia The general position about 1860 was that

the Russian mining interests were supplying all the native platinum that was required. The main refiners were Johnson Matthey in London, Desmoutis Quennessen in Paris and a new-comer (1851) in Heraeus in Germany. For a time (1826-1846) (8) the Russians were refining at St Petersburg and turning the product into coins but, owing to currency difficulties, they gave this up, called in all the coins that they could get and stored the whole stock in the vaults of the Imperial State Bank. The other refiners continued to draw their supplies from the Russian mines, with occa- sional contributions from the stock. Vigorous attempts were made to persuade the Russians to sell this but all failed until 1872, when George Matthey’s partner, John Sellon, managed to secure the whole lot, then amount- ing to 378,000 02. This heavily overstocked the market for the next ten years and had two far-reaching effects. First, since its quantity was far too much for a single firm to finance and use, it was split among the three refiners and so helped to bring them together in a loose alliance. Second, it practically ruined

Percival Norton Johnson 1792-1866

In January 181 7 Johnson set up as an assayer and rejiner in London, so founding theJirm of Johnson Matthey & Co Limited. He continued to direct the affairs of his growing business until his retirement in 1860, by which time the firm had for many years been recognised as leading refiners and fabricators of platinum. H e was elected a Fellow

of the Royal Society in 1846 (From a portrait dared 1829 by G. J . Robertson)

the Russian platinum mining industry and drove those concerned to give thought as to how they could become less dependent on these foreign refiners.

This Russian reaction also worked in two directions. First, there was determination to set up means for study of the platinum metals and the methods of refining them, so that one day Russia would be able to staff a refinery of its own. This began in a small way but was kept up, so that by the turn of the century there was in existence a definite laboratory under Professor L. A. Chugaev teaching people the chemistry of the platinum metals. So, when the opportunity at last came in 1917, there was a man (Baraboshkin) available to take it. The second and more immediate reaction was to bring the Russian producers together, if possible into a single unit, and


George Matthey

Joining Johnson in 1838 as a young apprentice, George Matthey was taken into partnership in 1851 and became senior partner in 1860. He combined a brilliant scienti$c understanding with sound business ability and made a great contribution to the company’s success in the latter half of the nineteenth century. He too was elected a Fellow of

the Royal Society (From a portrait painted at the age of twenty)

1825-1913

then to protect its operations by taxation and duties. This dithered for many years and eventually it became obvious that the necessary finance could not be raised in Russia. Recourse was had to Paris, and a French company was formed based on French and Belgian finance. This was called the Com- pagnie Industrielle du Platine and the wry result of the attempt to unite the Russian producers was the formation of an almost monolithic institution financed by the abhor- red foreigner (9). This company continued to function, and controlled go per cent of the output, until the 1914 war cut off its supplies.

The reaction of the three older refiners, then often referred to as the Allied Houses, to the operations of the CIP was also two- fold. They were in a position of some strength since, at any rate until the latter built its own refinery, as they were the only available re-

finers and the only outlet for its product. They were therefore able to prevent it from entirely dominating the business. In 1912, in order still further to strengthen this position, they began to toy with the idea of erecting a joint refinery in Russia at Ekaterinburg (now Sverdlovsk) in the neighbourhood of the mines to secure the product of any miners disgruntled by the present situation. Heraeus was to supply a suitable resident engineer, Desmoutis was to arrange and collect the finance, and Johnson Matthey were to design the buildings and plant, to provide the know- how and to prepare and ship the equipment. The first local collaborator was the largest un- committed mining concern in the field, the Nikolai-Pavdinsky Mining Co, and they were to find the site and build the refinery. Many delays occurred and it was not until after the outbreak of war in August 1914 that building began. Difficulties mounted, with the labour being called up for service in the Rus- sian forces, while the equipment had to come in via Archangel, so that it was not until late in 1915 that refining began. In the meantime, the young man Baraboshkin had “presented himself to the builders and asked to be employed as manager”. Under the circumstances, his offer was welcome and he took up the work for which some forty years of destiny had prepared him. In March 1917 the refinery was nationalised by the Kerensky Government of Russia and again in February 1918 by the Soviet Government, when it became the first unit of the infant Soviet platinum industry and passes out of this story for a few years (10).

The American Market The second reaction of the Allied Houses to

the CIP was a decision to develop jointly the growing market for platinum in the U.S.A., and to keep the new-comer out of it. Until then each house had maintained its own mobile agent but the rate at which industriali- sation was spreading made the idea of a joint organisation attractive. In I 894 Heraeus’ agent and relative Charles Engelhard, who


The old houses in Hatton Garden from which the business of .Johnson Matthey was conducted i n the earlier years of its history

(From an engraoing by Wilfred Loue)

had been in America since 1891, had been appointed manager of the joint interests. In 1901 he acquired a small wire business and followed this in 1904 by taking over the larger firm of D. W. Baker & Sons, of Newark, New Jersey. In the new Baker & Co, the Allied Houses (as a unit) and the Baker family had 299 shares each while Engelhard had 100; the Directors were a Baker or two, a repre- sentative of Johnson Matthey, and Engelhard representing Heraeus and himself (the French did not appoint a Director). This arrangement continued until 1917, when the U.S.A. joined in the war and the Heraeus shareholding was sequestrated as enemy property. Engelhard,

Between 1828 and 1844 Russia made use of its platinum resources as a coinage metal and some 485,000 ounces of platinum were struck as 3, 6 and 12 rouble pieces but were later withdrawn. ln 1872 John Sellon, George Matthey’s partner, succeeded i n securing the greater part of the stock of coins for rejining by Johnson Matthey

who in the meantime had become an American citizen, bought it. Later, in 1926, he was able to acquire the French holding as well and, in 1928 Johnson Matthey, not wishing to continue as minority holders, sold theirs to him as well. This gave him control of the company and henceforward he was a major factor in the platinum market.

Meanwhile there was great anxiety every- where about the future of platinum supplies. This had begun long before and was to some extent another reaction of the market to the activities of the CIP as well as to an increasing demand from the chemical and electrical industries. At first almost the


A hundred years ago-at the .Paris Exhibition of 1867-Johnson Matthey demonstrated this platinum boiler, designed to handle jive tons a day of sulphuric acid. Made by autogenous welding of the metal by direct fusion in a blowpipe jlame, a process introduced by George Matthey, boilers of this type became a permanent feature of sulphuric acid plants until the

introduction ofthe contact process after the turn ofthe century

only significant result was a revival of interest in the original pre-Russian source in Colom- bia. Production there had fallen to a very low level in the hands of native prospectors but in I907 there were enquiries for capital in London. These reached Consolidated Goldfields of South Africa who immediately approached their friends Johnson Matthey, with the result that a joint company, the Anglo-Colombian Development Co, was formed in 1911. This went to work very quickly but, for reasons first of economy and later for safety in war conditions, the growing product went direct to Baker & Co in New Jersey and this house equipped itself with a refinery to deal with it, at first, of course, on behalf of the Allied Houses. Unfortunately, however, as time went on the Anglo-Colom- bian company found itself in heavy competition with strong American interests and eventually had to give up and in 1922 was taken over by them. By that time the total output was a steady 40,000 oz per year.

A New Source in Canada During the first decade of the century

there came the beginning of what later became a very important source of platinum and indeed for a time the main supplier of the world. The English Mond Nickel Co had started to work an enormous deposit of nickel-copper ore at Sudbury, Ontario, and soon discovered that there were traces of the platinum group metals in it. These concentrated with the nickel in the smelting operations and, after the application of the Mond refining process, remained in a solid residue to the extent of several per cents. As Johnson Matthey had done all the early assaying it was natural that they should be asked to under- take the extraction. In 1909 a contract was made and this was renewed periodically until 1919 when the Mond Co took over the work themselves and in 1923 opened their own London refinery at Acton, which later also took over an output from the International


Nickel Co, a neighbour of Mond at the Sudbury mines. I n 1919 also, in view of the growing importance of the American market, the selling of the products was transferred from Johnson Matthey to Engelhard and thereafter took place in New York.

The outbreak of war in August 1914 practically stopped the regular supply of Russian platinum to the Western countries. A few shipments got through in 1915 and in 1916 and even a last one in JuIy 1917, but the Soviet nationalisation of the mines put a final stop to these. From then on for about seven years the world had only the Colombian and Mond outputs plus a few oddments from Australia and the turning-over of its own scrap. Fortunately this just sufficed. Mean- while great speculation went on as to what would happen after the war. The news from Russia was thought to be too bad to be true and anyhow sooner or later the Soviets would need foreign currency. Nothing was known about Baraboshkin and the Nikolai-Pavdinsky refinery and all that was left was hope.

The first contact between the West and the Soviets came in 1921 when negotiations about an exchange of prisoners of war began. On behalf of Johnson Matthey, A. B. Coussmaker met Maxim Litvinov, the chief negotiator, and learned that the Russians were fulIy aware of the value of their platinum and intended to work it for themselves and to refine and fabricate it. Three years later they were in need of foreign currency and offered refined platinum of excellent quality in ingots. Johnson Matthey having through Coussmaker obtained their confidence, took up this business and between 1924 and 1926 negotiated three contracts covering 130,000 oz of metal in all. This they distributed to Engelhard, Heraeus and the French according to their respective requirements. In 1926 the Russians decided that they wanted to do their own selling and set up an organisation (the Edelmetalle Vertriebs AG) in Berlin for this purpose. The operations of this had a very serious effect on the market already suffering from marked lack of demand owing to the

widespread world depression in trade and to strong rumours of the discovery of a new source in South Africa. The price of platinum fell and fell until in April 1931 it reached its nadir at A4 13s per ounce.

The Stable Price Policy At this point it is desirable to pause for a

moment to consider the influence of various factors on the platinum market. At the beginning of the present century, when an industrial demand for the metal first became evident, it also began to attract the attention of speculative buyers, whose operations caused severe fluctuations in its price. At that time Coussmaker, already Johnson Matthey’s chief adviser on the subject, urged that the future of the metal was likely to depend more on its industrial use than on the speculative, and that users would be discouraged if the price that they obtained for their scrap was much less than the price at the time of buying because of variations caused by speculation. From then onwards it was always Johnson Matthey’s policy to do their best to keep the price steady. This brought them into conflict with their great rival, Charles Engelhard, who believed that it was in the best interest of everyone if the price was allowed to move according to supply and demand, wherever the latter came from. Johnson Matthey’s policy, therefore, could not be fully implemented until 1958, when their suppliers became the principal factor in the market and gave them the supplies to maintain it.

Another point to be mentioned here before resuming the main course of the story is that after the end of the war the French platinum industry had all but disappeared. By 1910 the old business of Desmoutis Quennessen had become very weak and by 1918 it was in the hands of its bankers. In 1926 it went into liquidation and the relics were taken over by a younger and more energetic company, the Comptoir Lyon Alemand. They gradually rationalised the platinum situation in France and then did the same for the bullion business


so that, by the outbreak of war in 1939, a lively industry was again active in French and continental markets in both of these fields.

The name of A. B. Coussmaker has already been mentioned and now a second resolution of his must be brought forward. He always took the view that Johnson Matthey’s position before 1914 was a weak one of dependence on the goodwill of the CIP for its supplies and he persuaded the company to make great efforts to find alternative sources. The only result before the war was the Colombian development already described and then there followed the complete cutting-off of the Russian supplies and in 1921 the end of hopes that their refining might one day return. Coussmaker then made his great resolution that he would work tirelessly in the search for new sources until he had restored to Johnson Matthey the position that they had held in the platinum market a generation before.

The South African Discoveries He made personal prospects in Canada,

Australia and New Zealand, but nothing important came to light until 1925, when Dr Merensky discovered the platinum- bearing rock complex in South Africa that bears his name. This is part of an enormous system and outcrops over about forty miles on its eastern side (Lydenburg) and seventy miles on its western side (Rustenburg and Pot- gietersrust). At once he went to investigate and in 1926 he made an exhaustive examination of the whole of the outcrop and designated the localities which he considered to hold out the best prospects. It has so happened that those which he named then are the only ones where mining has subsequently taken place successfully. The deep-seated ore is a complex nickel-copper sulphide carrying the platinum metals as arsenide and other compounds and, at the actual outcrop and for a certain distance below it, this had weathered and lost most of its copper and nickel. It was therefore at first relatively easy to collect and handle and a boom of small prospectors got to work in

Arthur Blakeney Coussmaker A Director of Johnson Matthey from 1925 until 1964, A . B. Coussmaker devoted himself to securing adequate supplies of rejinable platinum materials for his company. He was responsible jirst for negotiating contracts with the Soviet Government between 1924 and 1926, and a little later for encouraging the South African interests to

consolidate their mining enterprises (From a portrait by David Jagger)

1926. But the weathered material was soon exhausted and the boom petered out; by 1928 only two mining companies were still at work, and conditions became more and more dis- couraging to them as the market price of platinum continued to fall. Those two sur- viving mines were owned by two strong companies, Consolidated Goldfields of South Africa Ltd and the Johannesburg Consoli- dated Investment Co Ltd, and the two men chiefly concerned were J. A. Agnew, the Chairman of the former, and J. G. Lawn, the mining expert of the latter. Coussmaker was by now fully convinced that South Africa could offer the supplies of platinum that were necessary to put Johnson Matthey back into their former position in the market.


With the formation of Rustenburg Platinum Mines in 1931, with Johnson Matthey as its technical advisers, smelters and rejiners, a process for treating the output was developed and

a smelting works in which to carry it out was built at Brimsdown

To implement this he must keep these two companies in action and persuade them to combine to form a single producer in their two neighbouring mines in preparation for the better days which his experience told him would surely come. He succeeded in communicating his faith to Agnew and together they persuaded Lawn, so that in September I931 the jointly-owned Rusten- burg Platinum Mines Ltd was formed and got to work, with Johnson Matthey as its technical advisers, smelters and refiners, with responsibility for marketing all the platinum metals it produced. Coussmaker was on the road to honour his brief.

But meanwhile the handling of the South African product had not been free from difficulties. The oxidised material at first available presented much the same sort of problems as had the Mond Nickel CO’S concentrate of twenty years before. Johnson Matthey soon produced a process for treating it and put up a works on the eastern outskirts

of London at Brimsdown in which to carry it out, but a number of failures took place elsewhere. The commencing output of Rusten- burg Mines was to be 91,000 tons milled per annum, but they were hardly allowed a full year of it. The state of the market was such that both mines and treatment plant had to be shut down in April 1932, a state of affairs that lasted until August 1933. This was not entirely a bad thing because it coincided with the fact that before long Rustenburg would have come to the end of their oxidised zone of mineral and would be confronted with the unchanged sulphide ore. This called for new and different methods of concentration, smelting and refining, since there were now quantities of copper and nickel to be recovered and marketed as well as the values. The shut- down gave opportunity for the necessary research and planning both in South Africa and at Brimsdown, so that when everything did reopen, progress was uninterrupted and the South African platinum industry moved


I n 1934 a new source of platinum appeared when dredging began at Goodnews Bay in Alaska. A . B. Coussmaker secured the rejining of the output from this operation for Johnson Matthey’s American sub-

sidiary J . Bishop & Co

steadily forward to great success. That it did so at so early a period is without doubt due to Coussmaker’s initiative, Johnson Matthey’s technical experience, the faith of Agnew and the mining resources of his and Lawn’s companies. Undoubtedly the industry would have been developed at some time, but it would have been much later, probably during or after the 1939-45 war, and at the hands of other people.

The prolonged depression in the platinum market with its continuous fall in the price had of course given rise to great anxiety among the producers, particularly those who had recently made heavy investments in their works. Coussmaker had been energetic- ally putting forward his views about the need to maintain a steady and reasonable price to encourage a wider use of the metal in industry. T o see if there was any possibility of arriving at a common policy, a meeting of producers took place in the summer of 1931 in London and there he was supported by R. C. Stanley, the President of the International Nickel Co, who had similar views about the price of nickel. As a result of this, in October I931 a small company was formed in London called Consolidated Platinums Ltd, with a capitali-

sation of iC;~,ooo in ten shares of LIOO. The Chairman was Lord Brabourne, of Consoli- dated Goldfields and the Directors J. G. Lawn, D. Owen Evans, of the Mond Nickel Co and J. E. Jansen, of Edelmetalle Vertriebs AG representing the Russians. There was a Committee of Management, all producers’ men, and three distributors (Johnson Matthey, Baker & Co and Edelmetalle Vertriebs AG), each dealing on behalf of the principal with whom he normally worked. Initially the price of the metal was fixed at $30 (say L7) per ounce and the system worked reasonably well for about a year. Then, in October 1932, trouble began with the appear- ance in America of considerable quantities of so-called “secondary” platinum. The Ameri- cans insisted in selling this at a lower price and the whole arrangement broke down in the free-for-all that followed.

The affair of Consolidated Platinums, associated with the devaluation of sterling, and followed by the New Deal in the U.S.A. and then a breath of rearmament, brought about a turn of the tide in the platinum market and a slow and fluctuating climb back to the pre-slump prices until by 1934 the figure was steady at iC;7 15s per 02. In the meantime


Johnson Matthey had been quietly consoli- dating their interests in the United States in face of the strong position occupied by Charles Engelhard and Baker & Co, who had at their disposal not only the steady output of the Colombian mines but also the rapidly increasing output of platinum from the Mond Nickel Co and the International Nickel Co (since I929 merged under the latter’s name), resources which gave them a virtual control of the market, with the Russians almost the only other supplier.

In 1919 Johnson Matthey had formed a small buying-and-selling company in New York (Johnson Matthey & Co Incorporated) but it had no refining or fabricating resources until 1930 when they bought a controlling interest in the old established American company, J. Bishop & Co Platinum Works of Malvern, Pa. This was of very great value to them in face of later events. In the meantime, however, their sources of raw material were very meagre. There was a small one in Ethiopia which went on for several years at about 6,000 oz per year and, of course, after 1933 the South African product began to be significant. In 1934, however, a new source appeared in Good-

news Bay, Alaska, and, in face of strong American competition, Coussmaker was able to obtain for Bishop the refining of this output which, by 1938, had reached 38,000 oz per year.

Growth of Industrial Uses The revival of the demand for platinum

after 1933 was firmly based on industrial uses. The speculators had vanished and the jewellery use continued to be small. The need for chemical apparatus increased with the growth of research, both academic and industrial, and in the thirties the demand for electrical parts, particularly wires and contacts, kept the workshops busy. But increasingly important was the catalytic use, especially that for the production of nitric acid for artificial fertilisers, and this was to grow rapidly and force the expansion of resources. It soon became apparent that the American supply was reaching its peak, before a possible decline, but that the South African production was capable of very great expansion. The first step in that direction was taken in 1938 when the milling capacity of the Rustenburg mines was raised to I million tons per annum and some of the preliminary

Operations at Rustenburg Platinum Mines have been extended many times over the last thirty years and now provide the largest source of the platinum metals in the world. Further expansion plans recently

announced will increase output to approximately 750,000 ounces of platinum a year


I n 1937 a rebuilding p l a n was started f o r Johnson Matthey's administrative headquarters. T h i s head o$ce building now incorporates the site of the original houses f r o m which P. N.

Johnson and his jun ior partners worked to establish themselves as plat inum refiners

smelting operations were transferred from to replace the old one but, in the event, the Brimsdown to Rustenburg. But when the latter had to continue working as well for war came in 1939 there was still not enough manyyears. and an entirely new works had to be designed, In 1947 an entirely new mine was opened built and equipped at Brimsdown. This was some sixty miles north of Rustenburg, on a

Further expansion in p la t inum refining activity resulted i n 1956 in the building of a completely new refinery at Royston. I n this part of the plant , p la t inum and palladium are taken into solution, leaving

rhodium, ruthenium, ir idium and osmium as insoluble residues to be treated separately


This section of the Royston rejinery-the largest of its kind in the world-handles the precipitation, re-dissolving and re-precipitation of platinum and palladium. It is arranged on the cascade system to

facilitate the movement of solutions

site designated by Coussmaker in 1926 as next most favourable to Waterval and Potgieters- rust, by a new company, The Union Platinum Mining Co. This worked the mine indepen- dently for two years and then, in 1949, merged with the Rustenburg company.

New Refineries These extensions put a great strain on

refining capacity; the methods had been considerably improved but the seams were burst- ing. Final relief did not come until 1956, when a completely modern refinery, equipped with the latest devices in chemical engineering, was opened at Royston in Hertfordshire. And it was this latest expansion of output that finally put Rustenburg Mines and Johnson Matthey into the position of being the largest suppliers of platinum in the world and enabled them at last to carry out their joint policy of an industrial price without interference by anybody.

It remains to mention one vital factor in the great increase in demand for the metal which actuated these great expansions, and that was the fact that in 1952 the mineral oil

business discovered the power of platinum to reform the hydrocarbons of their crude oil with the production of high-octane petrol, a discovery which revolutionised the enormous business in that commodity. In 1954 Johnson Matthey entered into partnership in a joint company with Universal Oil Products of the U.S.A. who owned the main patents concerned. This undertook the production of the necessary catalysts for the whole of the sterling area, work which is still expanding at a rapid rate.

References I P. N. Johnson, Phil, Mag. 1812, 40, 3-4 2 D. McDonald. A History of Platinum, Lon-

3 A. and C. R. Aikin. A Dictionary of Chemistry

4 D. McDonald, lac. cit. pages 62-72 5 D. McDonald, lac. cit. pages 50-57, 127-139 6 D. McDonald, Platinum Metals Rev., 1966,

7 D. McDonald, A History of Platinum, pages

8 D. McDonald, loc. cit. pages 159-167 9 N. K. Visotsky, Estestvennie proizvoditelnie

silni Rossii. Moscow, 1923, Vol. 4, Part 11, Section X, pages 67-68

10 0. E. Zviaginstev, Zzvestiya Znstituta iz Zzucheniyu Platini 1927, 5 , 5-22

don, 1960; pages 89-94

and Mineralogy, London, r807-r814

10, 101-106

197-224


Metal-Ligand Reactivity and Homogeneous Catalysis The Oxford Inorganic Discussion, an annual meeting sponsored by the Chemical Society and designed to aford an opportunity for inorganic chemists to meet and discuss topics of common interest, was held this year on September 30th. The subject under consideration, metal-ligand reactivity and homogeneous catalysis, was one of obvious interest to those concerned with the chemistry of the platinum group metals.

The meeting was opened by Professor Geoffrey Wilkinson (Imperial College) with a lecture entitled “Homogeneous Hydrogena- tion of Olefins using Rhodium Catalysts”. The preparation and structure of the rhodium (I) complex tristriphenylphosphine rhodium (I) chloride was described. Its dissociation in solution and the take-up of hydrogen and solvent molecules was discussed with reference to its catalytic activity. The mechanism of its function as a remarkably active catalyst for the hydrogenation of olefins was considered in detail and its reactions with hydrogen, deuterium and hydrogen-deuterium mixtures both alone and in presence of olefins were described and discussed.

“A Comparison of Homogeneous and Heterogeneous Catalysts” was the subject introduced by Dr G. C . Bond, of Johnson Matthey. The function of metals of Group VIII in heterogeneous catalytic reactions such as hydrogenation, oxidation and hydrogenolysis was outlined, stressing the importance of electronic and geometric structure of the metal. Important factors governing the behaviour of salts and complexes in homogeneous catalytic reactions of olefins such as the oxidation state of the metal, electronic configuration, and ligands surrounding the metal atom were discussed and illustrated with reference to the use of the carbonyls of cobalt and iron, rhodium chloride, palladium chloride, phosphines and platinum-tin complexes in isomerisation, the pentacyanocobalt (111) anion, iron carbonyl, platinum-tin com-

plexes, tristriphenylphosphine rhodium (I) chloride and Vaska’s iridium compound in hydrogenation, palladous chloride in the Wacker process for oxidation of ethylene to acetaldehyde and rhodium trichloride in the polymerisation of butadienes.

Dr D. N. Clark, of Imperial Chemical Industries, considered “Palladium-catalysed Oxidation in Nonaqueous Solvents” with particular reference to the oxidation of ethylene by oxygen in solutions of palladous chloride in such solvents as methanol and acetic acid. The distribution of the products of the reaction such as vinyl ether, vinyl acetate, acetal and vinylidene chloride when the oxidation was carried out in acetic acid was described and the marked effect on this distribution of the addition to the system of dimethyl acetamide was stressed. The yield of vinyl acetate increased with increasing additions of this compound so that finally IOO per cent yield could be obtained. Mechan- isms to explain the reactions were postulated and the effects of other solvents considered.

“The Activation of Small Inert Molecules” was the subject of Professor J. Chatt (Uni- versity of Sussex) with particular reference to the nitrogen molecule in the context of atmospheric nitrogen fixation. The difficulty of breaking the N=N bond was stressed and explained from energy considerations. This emphasised the problems involved in devising methods for nitrogen fixation, a problem in- explicably solved by the bacterium, azobacter.

P. M. L.

Platinum Metals Rev., 1967, 11, (1),30-30 30

ABSTRACTS of current literature on the platinum metals and their alloys PROPERTIES Presence of Depleted Zones in Platinum M. J. ATTARDO and J. M. GALLIGAN, Phys. Rev. Letters, 1966, 17, (4), 191-193 Field ion microscopy of annealed Pt before and after irradiation by neutrons revealed large dis- turbances of the lattice apparently introduced by isolated damage events.

A Field Ion Microscope for Operation at 4.2"K M. J. ATTARDO, J. M. GALLIGAN and J. SADOFSKY, J . Sci. Instrum., 1966,43, (8), 607-608 A field ion micrograph of Pt with the tip at 4.2'K shows striking uniformity of intensity over the specimen surface, generally increased intensity and better resolution. Details of the liquid He and N cooling system for the instrument are described.

The Activity of Oxygen in the Liquid Fe-Pt Alloy System E. s. TANKINS and w. A. SIPES, A.S.M. Trans. Q., 1966, 59, (3)> 535-543 Equilibrium studies of H,(g) +O =H,O(g) at 15oo-17oo"C in liquid 10 and 30% Pt-Fe alloys enabled measurement of the standard free-energy changes when the standard state was 1% dissolved 0, solution. The equilibrium constant was determined for compositions up to 60 wt.% Pt at 1550°C. The interaction parameter E =

-1-0.004 is valid for compositions up to 20 wt.% Pt.

Nonstoichiometric A15-type Phases in the Systems Cr-Pt and Cr-0s R. M. WATERSTRAT and E. c. VAN REUTH, Trans. Met. Soc. A.I.M.E., 1966, 236, (8), rz3z-1~33 Nonstoichiometric AIS-type phases were observed in the Cr-Pt and Cr-0s systems. X-ray and metallographic studies established that they occur at 21+1 at.:/, Pt after vacuum annealing for a week at 1200'C and at 2 8 i 1 at.% 0 s after annealing for a day at 1400°C.

The Rate of Diffusion of Hydrogen through Palladium

Khim., 1966, 40, (7), 1450-1456 Rate of H, diffusion through Pd oc .\/(incident H, pressure). log(permeabi1ity) cc I/T at 300- 500"C, but not always at lower temperatures. Pd permeability is highly dependent on its surface area and preparation. It is greatest and most re- producible when the Pd foil is sealed by clamping between Cu gaskets. Soldering or welding the foil in air or in a poor vacuum sharply reduces its

A. A. RODINA and N. I . DORONICHEVA, Zh. Fiz.

permeability, which only recovers after repeated heating in H,. Permeability of Pd foil produced by rolling pure Pd monocrystals differs by 20% from that of commercial grade Pd.

Investigation of Changes of the Properties of Palladium and Some of its Alloys during Reactions with Hydrogen A. A. RODINA, M. A, GUREVICH, v. A. STROEVA and N. I. DORONICHEVA, Ibid., (9), 2046-2052 Except for 50 wt.% Ag-Pd, the permeability for H, of the alloys tested is greater than that of Pd above 300°C. The permeability of 18.5 wt.% Ag-Pd increased with use. Greatest stability after repeated heating and cooling in H, was obtained with 5 wt.% Ni-Io wt.% Ag-Pd, 10 wt.% Au-Pd and 35 wt.% Ag-Pd. X-ray analysis showed that the low stability of 18.5 wt.% Ag-Pd after similar treatment is due to increase of cr-phase lattice spacing, and to a& phase conversion, which reduced the contact between the alloy and H, during heating and cooling.

Stabilising a Spacecraft by Sunlight R. L. SOHN, New Scientist, 1966,31, ( ~ I o ) , 425-426 A suggested stabiliser consists of solar sails with an honeycomb steel core and Pd plate surfaces. H, is contained in the core under pressure and diffuses through the Pd surfaces at a rate dependent on the heat from solar radiation. The gas diffusion creates a reaction which maintains the spacecraft in the desired attitude.

Hydrogen in Palladium Alloys H. BRODOwSKY and H. HUSEMANN, Ber. Bunsen- gesell. Phys. Chem., 1966, 70, (6), 626-630 H, absorption isotherms of 4.78 at.% Sn-Pd, 5 at. % Pb-Pd, 5 at. % Rh-Pd and 16.7 at. % Ni-Pd at 30-175"C, 1-800 Torr were measured gas- volumetrically. Thermodynamic excess functions of these systems are discussed. The effect of alloy additions suggests that the four outer electrons of Sn and Pb compete with electrons of H, in filling the &band but that Rh increases the number of vacancies in that band. Strain energy for proton entry into octahedral holes is reduced by alloy additions with relatively large atomic volume, and vice versa.

Speed of Sound in the Alloys Pd-Rh and

0. BELMAHI, M. MERCK, E. PERREARD, M. PETER, E. WALKER and J. R. SCHRIEFFER, Helv. Phys. Acta,

Impulses from piezoelectric and magnetostrictive transducers were used to measure the transverse, torsional, longitudinal and extensional speeds of

Pd-Ag

1966, 39, (4), 338-354

Platinum Metals Rev., 1967, 11, (1),31-39 31

sound at 77 and 300'K as a function of the mean atomic number of Rh-Pd and Ag-Pd alloys. 5% Rh-Pd shows maxima in the electronic contribution of the specific heat y and in the susceptibility Xd, and its bulk modulus CL shows a slight minimum. Ax: a(300'K) - ~(77'K) shows a broad maximum. Temperature increment of the shear modulus A G =G(300"K) - G(77"K) shows a narrow peak which correlates with the temperature increment Axd of the susceptibility.

Ordering Effects in Equiatomic Au-Pd Alloys v. I. IVERONOVA and A. A. KATSNEL'SON, Kristallo- grafiya, 1966, 11, (4), 576-580 Ordering of equiatomic Au-Pd alloy samples increased during successive 0.5 h annealings at temperatures up to SOOT and analogously affected the Hall effect and electrical conductivity of specimens. Plastic deformation sharply decreased ordering.

The Effect of Periodic Antiphase Domain Structure on the Mechanical Properties of Copper-Palladium Alloys v. I . SYUTKINA and E. s . YAKOVLEVA, Fiz. Tverd. Tela, 1966, 8, (9), 2688-2694 The presence of periodic antiphase domain struc- tures strongly affects the behaviour of Cu-Pd alloys under stress. Strengthening mechanisms are discussed.

Magnetic Susceptibility of Iron-rich Face- centred Cubic Iron-Palladium Alloys s. ARAJS, Phys. Status Solidi, 1966,15, (2), 501-506 Mass magnetic susceptibilities of I .o, 3.0, 4.9, 7.9, 10.0, 11.9, and 15.3 at.% Pd-Fe f.c.c. alloys and of pure f.c.c. Fe, measured at 15oo"K, do not follow the Curie-Weiss law. I/XT plotted against I/T, where X is magnetic susceptibility and T is absolute temperature, indirectly reveals the antiferromagnetic nature of Fe, which is gradually reduced by alloying with Pd.

Close Order and K-Effect in the Pd-W and Pd-CO Alloys SH. A. ALIMOV and A. A. KATSNEL'SON, Fiz. Met. Metalloved., 1966, 22, (3), 468-470 Ordering in 11.3 at.% W-Pd and in 15 and 25 at.% Co-Pd was studied. Annealing of the alloys increases the effect and also, for 25 at.%] Co-Pt, the electrical resistivity p. Raising the annealing temperature from 700 to 900°C causes no notice- able change of resistivity. The K-effect occurs in the Co-Pd as well as in W-Pd alloys.

X-ray Diffraction and Thermo-analytical Investigation of the Palladium-Phosphorus System L. 0. GULLMAN, J . Less-Common Metals, 1966, 11,

(3), r57-167 X-ray diffraction and differential thermal analysis

of the Pd-P system at 300-1100°C revealed the phases Pd,P, Pd,P, Pd,.,P, Pd,P, Pd,P,, P d p , and PdP,. Pd,.,P, Pd,P and probably PdP, melt congruently; the others decompose peritectically on heating. On cooling, Pd,.,P decomposes eutectoidally into Pd,P and Pd,P. Limits of the homogeneity region, cell parameter/composition curves and density/composition data were determined for Pd,P. Pd,.,P is monoclinic with a=~.oo59 f0.0003 A, b=7.6082+0.0005 A, c-8.4199~0.0005 a, p=95.640&0.005".

The Magnetic Susceptibilities of Pd-Cd, Pd-Sb, and Pt-Cu Binary Alloys D. J. LAM and K. M. MYLES, J . Phys. soc. Japan,

Magnetic susceptibilities of Pd-Cd, Pd-Sb and Pt-Cu alloys were measured at 300-4.2'K and plotted against their compositions. Factors con- tributing to the susceptibility were assessed. Spin paramagnetic susceptibility is discussed in terms of the rigid-band model of alloying.

Nitrogen Adsorption on Iridium and Rhodium v. J. MIMEAULT and R. s. HANSEN, J . Phys. Chem.,

No N, adsorption occurred during flashing of I r and Rh filaments previously dosed with N, for 15 min at 3oo"K, 4 x IO-' Torr but some did occur after thermal excitation of N, at > 20m°K on W filaments in an ionisation gauge. A model of this is based on dissociation of N, to atomic N on W with subsequent adsorption rate proportional to atomic N concentration.

On Intermediate Phases in Alloys of Titanium with Iridium, Rhodium and Osmium v. N. EREMENKO, T. D. SHTEPA and v. G . SIROTENKO, Poroshkovaya Met., 1966, (6), 68-72 Studies of the Ti-Ir, Ti-Rh and Ti-0s systems throughout the range of concentrations revealed the existence of y, 6 and E phases in the Ti-Ir system, y, 6 and E phases in the Ti-Rh system, but only S phase in the Ti-0s system. Ti,Ir is y phase, TiIr is y phase and TiIr, is E phase. The S phase in the Ti-Rh is monoclinic with a=2.96 to.03, b=2.86&0.03, c-3.4rho.02 A, p = 90'37'.

Magnetic Properties of Rh-rich FeRh Alloy E. M. HOFER and P. cUCKA, .7. Phys. Chem. Solids,

Magnetic moment per alloy atom decreases from I,73 I*.B for 51% Rh-Fe to 0 . 1 8 ~ ~ for 63% Rh-Fe. The transition temperatures rise from 26" to 78°C over the same composition range. The paramagnetic Curie point remains almost steady around 36743°C. The decrease in paramagnetic Curie point remains almost steady around 367*3"C. The decrease in magnetic moment is probably due to increasing content of paramagnetic y phase.

1966,21, (8), 1503--I507

1966, 70, (9), 3001-3003

1966, 27, (9), 1552-1555


Elastic Properties of Polycrystalline Sc, Re, Ru and Pt-21 Ir H. L. BROWN, P. E. ARMSTRONG and c. P. KEMPTER J . Less-Common Metals, 1966, 11, (2), 135-140 Polycrystalline Sc, Re, Ru and 21 Ir-Pt tested at 23°C have Young's moduli 0.770, 4.63, 4.47 and 2.18 x IoGkg/cm2 respectively; shear moduli 0.294, 1.78,, 1.73 and 0.899 x l o G kg/cm2; bulk moduli 0.672, 3.78, 3.65 and 1.25 x I O ~ kg/cm2; Poisson's ratios 0.31,0.30,0.30 and 0.21; specific electrical resistivities 86.6, 17.4, 7.06 and 29.9 pQcm at 20°C.

CHEMICAL COMPOUNDS Acetylenic Complexes of Palladium E. 0. GREAVES and P. M. MAITLIS, J. Organomet. Chem., 1966, 6, (I), 104-106 Rapid polymerisation of acetylenes by Pd(I1) compounds prevents the formation of complexes of the type RC,R'PdIICl,X, where X=Cl, amine, etc., but it has proved possible to replace two phosphines in (Ph,P),Pd by acetylenes bearing strongly electron-withdrawing substituents.

Chlorination of Rhodium and Thermal Conversion of the Trichloride YA. I. IVASHENTSEV and R. I. TIMONOVA, Zh. Fiz.

Khim., 1966, 11, (IO), 2189-2192 Reactions of Rh with Cl,, HCl and CC1, were studied at 50o"C. Dilution of C1, by 0, to > 20% C1, prevented formation of RhCl,. RhCl, melted in a stream of C1, and partially sub- limated and dissociated. Its crystal hydrate can be dehydrated in one stage at 105-14o~C. H, reduced anhydrous RhCl, to Rh but air decomposed it to oxide.

Production and Properties of Osmium Heptafluoride a. GLEMSER, H. w. ROESKY, K.-H. HELLBERG and H.-U. WERTHER, Chem. Ber., 1966, 99, (X), 2652-2662 Pale yellow OsF,, formed by heating 0 s with F, at 350-400 atm, 500-600°C, is extremely hygro- scopic and F, begins to separate above 100°C. OsF,+OsF,+:F, occurs slowly at room temperature. Mass spectra, magnetic susceptibility measurements, ESR measurements and I r spectra indicate the possible existence of OsF, and show that OsF, has the configuration D6h, that of a pentagonal bipyramid.

High Pressure Synthesis of Arsenopyrite- type Ternary Compounds M. D. BANUS and M. C. LAVINE, Mat. Res. Bull., 1966, 1, (I), 3-12 OsSbSe, OsSbTe, OsBiSe and RuBiSe were synthesised for the first time at 35-50 kbar. The 0 s compounds are monoclinic. Resistivity measurements on OsSbSe and on OsSbTe suggest that they are extrinsic semiconductors.

Structural Investigations of P-RuCl,, RuBF, and RuI,

H. K. BREITBACH and G. THIELE, J . Less-Common Metals, 1966, 11, (4), 288-289 The three compounds are of the TiI, structural type with hexagonal crystals and the following lattice parameters: P-RuCl,, a=6.12~, c=5.65&, c/a=o.gz3; RuBr,, a=I2.924, c=5.860 A, c/a=o.453; RuI,, a=6.982, c=6.23r, c/a=o.892.

Metallocene Polymers. XV. Polymers Con- taining the Ruthenocene System E. W. NEUSE, J. Organomet. Chem., 1966, 6, (I), 92-95 Ruthenocene-containing polymers with a structure in which r,2-, x,3-, and I,I'-C,,H,RU groups are interlinked in a random sequence distribution by CH, or variously substituted methinyl bridges have been obtained by ZnC1,- catalysed melt condensation of ruthenocene with aldehydes, as previously done with ferrocene- aldehyde condensations, but more rigorous reaction conditions were required.

H. G. VON SCHNERING, K. BRODERSEN, F. MOERS,

ELECTROCHEMISTRY The Reversible Oxygen Electrode

A review of the mechanisms occurring at the Pt surface of the reversible 0, electrode. (17 refs.)

Some Effects of Nitric Acid on Pt/O, Cathodes J. P. HOARE, s. G. MEIBUHR and R. THACKER, J. Electrochem. Soc., 1966, 113, (IO), 1078-1082 0, and not N, causes the improved polarisation characteristics of Pt/O, cathodes treated with HNO,. It is dissolved in the surface layers of the metal as an alloy of Pt and 0 atoms several layers deep. This surface is a good catalyst for 0, reduction and H,O, decomposition. It retains its activity for 0, reduction over extended periods. Attempts to make a porous electrode of this type by similar techniques as for bright Pt failed.

The Rate of Ionisation of Hydrogen on Semi-immersed Platinum Electrodes in Al- kaline Solutions E. A. OSTROVIDOV and A. L. ROTINYAN, Zh. Priklad- noiKhim., 1966,39, (8), 1742-1747 Studies showed that, for high polarisation, ionisation of H, is not a film mechanism. Results indicated kinetic problems and suggested that ionisation of H, only occurs at active centres on the Pt electrode depending on the amount reaching them.

Area Changes of Electrodeposited Platinum Black

Measurements of area changes of Pt black

J. P. HOARE, Nature, 1966,211, (5050), 703-705

R. THACKER, Nature, 1966, 212, (5058), 182-183


deposited on Pt wires in gM 0-H,PO, at 25 and 80°C demonstrated the effects of time, temperature and electrode composition, including addi- tives, on the sintering properties of Pt black electrodeposits in aqueous solution. Recrystallisa- tion of unsupported Pt blacks occurs slowly at ambient temperatures but more quickly at en- hanced temperatures.

The Permeation of Electrolytic Hydrogen through Platinum E. GILEADI, M. A. FULLENWIDER and J. O'M. BOCKRIS, J . Electrochem. SOC., 1966, 113, (9), 926-930 Absorption and permeation of electrolytic H, through Pt foils was observed directly by an electrochemical method at 50-80°C. Diffusion coefficient at 70°C was 3.4x10-~ cm2/sec.; apparent energy of activation was 9.6 kcal/g atom. Concentration of absorbed H, just below the cathode surface was 2.7x10-~ g atom/cm3. Atomic H tended to concentrate in areas of high strain within the metal where it could be in a lower energy state. H, permeation was detectable only when the cathodic surface of the membrane became poisoned. H, embrittlement phenomena resembled those in Fe and steel. Variation of cathodic overpotential with time was related to the change in H, concentration in the metal near the cathodic surface.

Electrode Kinetics of Oxygen Evolution and Dissolution on Rh, Ir, and Pt-Rh Alloy Electrodes A. DAMJANOVIC, A. DEY and J. O'M. BOCKRIS, Ibid., (71, 739-746 Determinations of electrode kinetics of Rh, Ir and Pt-Rh electrodes showed that each possesses two regions of constant S(ln ianodic) /SV. Catalytic activity above - r.4V (versus NHE) was ipt< ipt-Rh<iRh<iIr. The anodic side of the alloy behaved like Rh; the cathodic side like Pt. Time decay was conventional except that the anodic side of Pt-Rh behaved like Pt. Stoichiometric numbers were -2. After anodic polarisation, Pt-Rh electrodes behaved as if the substrate was an individual area of Pt and Rh oxides.

ELECTRODEPOSITION AND SURFACE COATINGS Kinetics of Pd" Cementation on Sheet Copper in Perchlorate Solutions E. A. VON HAHN and T. R. INGRAHAM, Trans. Met. SOC. A.Z.M.E., 1966, 236, (S), 1098-lro3 Studies on cementation rates of PdII in 0.02-0.1 mM concentration in aqueous HClO, on electro- polished Cu cylinders, rotated at various high speeds to minimise thickness of the diffusion layer, showed that in 0.1 M HC10, the cemented Pd is dense, adherent and shiny. First stage of this cementation is first order with respect to


PdII concentration but the second stage is much slower. In 0.001 M HClO, only the first stage is evident and the cementation rate is faster, due to (PdOH)+ ions predominating over unhydrolysed PdIr. This deposit is porous and loose. Pd-Cu alloys rather than pure Pd constitute the deposits. Activation energies are 9.5 kcal/mole in 0.1 M HClO,, 7.4 kcal/mole in 0.001 M HC10,.

Investigation of the Mechanism of Anodic Dissolution and Electrodeposition of Palla- dium in Chloride Electrolytes V. I. KRAVTSOV and M. I. ZELENSKII, Elektrokhimiya, 1966, 2, (IO), 1138-1143 Studies on 3M H,SO, solutions of Pd containing various amounts of C1- and PdC1,- showed that the orders of the processes are: C1-(cathodic) 2.6; Pd2+(cathodic), 0.91; Cl-(anodic), 2.14. The results partially explain the electrochemical reactions which occur on Pd surfaces and in Pd complexes. The mechanism of slow electrochemical reactions is discussed.

LABORATORY APPARATUS AND TECHNIQUE Gases in Underground Plants and Their Detection J. 0. COLYER, R. THARBY and R. c. SENIOR, Post Off. Elect. Erig. J., 1966, 59, (2), 80-84 Indicator, Gas, No. 5 is sensitive to the common property of flammability of gases which are dangerous in underground spaces. Samples of the atmosphere to be tested are passed over a heated Pt filament forming part of a Wheatstone bridge circuit. Catalytic action in the presence of flammable gases raises the filament temperature and unbalances the bridge. This method is faster than the older sodium-chlorpalladite tester.

Negative Staining with Osmium Tetroxide Vapour

(5057), 84-85 Collagen fibres to be studied by electron microscopy were stained negatively by OsO,, which gave delicate outlines of better contrast than other techniques.

P. BARLAND and M. ROJKIND, Nature, 1966, 212,

CATALYSIS Surface Catalysis of the Hydrogen-Oxygen Reaction on Platinum at Low Temperatures P. LEDER and J. B. BUTT, Am. Inst. Chem. Eng. J.,

Data from low-temperature H,-0 , conversions over dilute Pt/Al,O, indicated a strong effect of product H,O on reaction rate and second-order dependence of rate on pHZ in the presence of excess 0,. Stable activity levels lower than previously reported were consistent with a chemi-

1966, 12, (4), 718-721

sorbed 0, mechanism and with reaction conditions at a dilute catalyst. Activation energy at 100°C was IO+ 2 kcal/mole.

Catalytic Oxidation of Hydrogen - Intra- pellet Heat and Mass Transfer J. A. MAYMO and J. M. SMITH, Zbid., (5), 845-854 High rates of oxidation of H, over 1.86 cm pellets of Pt/Al,O, particles mixed with A1,0, showed temperature differences > 300°C between centre and surface of pellets and also large temperature variations at their surfaces, depending on position. Intrapellet heat and mass transfer resistance were both important but only heat transfer resistance was significant between pellet and gas. A new method was devised for measurement of effective diffusivity under reaction conditions. Predictions gave results 776 greater than the experimental effectiveness factor.

The Mechanism of Hydrogenolysis and Isomerisation of Hydrocarbons on Metals. 11. Mechanisms of Isomerisation of Hexanes on Platinum Catalysts

J. Catalysis, 1966, s, (3), 428-445 Isomerisation of n-hexane, 2-methylpentane and 3-methylpentane over Pt films, Pt/A1,0, and Pt/ pumice, when compared with hydrogenolysis of methylcyclopentane, indicated that a common cyclopentane intermediate was involved in both reactions and was adsorbed on metal sites of the catalysts. Formation of z,j-dimethylbutane from hexanes and of C,H, from methylcyclopentane also occur on Pt films. Only aromatisation occurs when 1,1,3-trimethylcyclopentane reacts with H, on Pt film at 300°C.

Chemisorption and Catalytic Properties of Supported Platinum J. A. CUSUMANO, G. w. DEMBINSKI and J. N. SINFELT, Zbid., 471-475 Chemisorption studies for H, on Pt/AI,O, and Pt/SiO,-Al,O, showed that Pt dispersion is greater on Pt/Al,O,. Catalysts were prepared by impregnation of the supports by H,PtCl, followed by reduction in H,. The rate of dehydrogenation of cyclohexane on these catalysts is also higher on Pt/AI,O, which is attributed to the greater Pt dispersion. Adsorption of H, on Pt at 70% surface coverage is 7-8 kcal/mole exothermic for Pt/A1,0,.

On the Specific Activity of Platinum Catalysts

DOUGHARTY and c. G. HARKINS, Ibid., 6, (I), 92-99 Cyclopropane hydrogenations at 0°C showed that specific activity is independent of Pt content in Pt/q-Al,O, and Pt/y-Al,O,, and of whether the support is A1,0, or SiO,. It is almost the same in highly dispersed Pt catalyst samples as in Pt foil. Such samples were merely twice as active as

Y. BARRON, G. MAIRE, J. M. MULLER and F. G. GAULT,

M. BOUDART, A. ALDAG, J. E. BENSON, N. A.

sintered, less dispersed or foil catalysts but their specific surface area varied by > 4 orders of magnitude. They were also more susceptible to 0, poisoning.

The Mechanism of Heterogeneous Catalysis R. L. BURWELL, Chem. Engng. News, r966,44, (36), 56-67 A review of present knowledge of heterogeneous catalysis in which the importance of the Pt metals is outstanding. (9 refs.)

Some Agents Influencing the Surface Area of Platinum in Reforming Catalysts Z. JAWORSKA-GALAS and J. WRZYSZCZ, Chem. Stosowana, Ser. A, 1966, 10, (I), 105-112 The specific surface of Pt/A1,0,, determined by H, reduction of 0, chemisorbed on it, was 2.5- 190 m2/g, depending on A1,0, preparation, method of Pt impregnation and calcination temperature. Pt surface area decreased in use but oxidising regeneration restored or even augmented the original area. Preparation included impregnation of dried or hydrated A1,0, with H,PtC1, or PtS, followed by drying and calcination for 2-4 h at 500-80o"C. C1 content was 1-2%, depending on the preparation.

On the Damaging of Platinum Catalysts in Their Large Scale Use

E.-R. STRICH, I<. BECKER and G. WEIDENBACH, Chem. Tech., 1966, 18, (8), 449-454 Results are reported of a year-long study designed to increase the life of Pt reforming catalysts. Studied were ways in which catalysts are damaged during installation and by S-, N- and O-complexes and by inorganic components during use. The effect of the conditions during regeneration was studied also.

The Role of Hydrogen in the Dehydrogena- tion of Cyclohexane on Platinum v. A. DRUZ', N. I. UTEGULOV and D. v. SOKOL'SKII, Zh. Fiz. Khim., 1966, 40, (7), 1483-1488 Potentiometric studies indicated that the degree to which the Pt catalyst surface is charged with H, increases with higher temperature and faster process rate. Dehydrogenation of cyclohexane on Pt occurs when the surface is comparatively highly charged with H, and when the potential variation is 20-80 mV. Increased H, adsorption on Pt dis- places C,H, and restricts hydrogenation of C,H,.

Catalytic Conversion of Dicyclopentylmeth- ane on Pd-, Pt-, Co-Alumina Catalysts in Catalytic Reforming Conditions N. I. SHUIKIN and I. I. VOZNESENSKAYA, Zzv. Akad. Nauk S.S.S.R., Ser. IZhim., 1966, (S), 1455-1456 Conversions of dicyclopentylmethane were carried out at 450"c, 30 atm H,, volume rate 0.3 h-l, H,: hydrocarbon=s:I over 0.5% Pd/AI,O,,

H. BLUME, C. SZKIBIK, F. PFEIFFER, H . KLOTZSCHE,


0.5% Pt/Al,O,, IOU/, Co/Al,O,. Isomerisation to decalin occurs most easily on the Pd catalyst. Hydrogenolysis of both rings to form C,,H,, iso- alkanes occurs on the Pt catalyst together with the formation of methylcyclopentane and cyclopentane. Slight isomerisation occurs on the Co catalyst and formation of various alkylcyclo- pentanes.

Study of Supported Catalysts by the Exoelec- tronic Emission Method. VI. Platinum on Magnesium Oxide and Chromium Oxide

and N. I. KOBOZEV, Zh. Fiz. Khim., 1966, 40, (8),

Increase of Pt concentration on the surface of the support in Pt/MgO and Pt/Cr,O, catalysts leads to increases in both catalytic activity and exoelectronic emission. The oxides have similar surface electronic properties. Exoelectronic emission is first order with respect to paramagnetism for these samples.

A. S. SHASHKOV, V. M. MOZZHUKHINA, I. V. KRYLOVA

1965-1968

The Modification of Raney Nickel Catalysts by Additions of Transition Metals. 111. Electro-oxidation of Hydrogen and Catalytic Hydrogenation on Raney Nickel-Platinum Alloys A. B. FASMAN, A. ISABEKOV, D. v. SOKOL’SKII, A. A. PRESNYAKOV and K. T. CHERNOUSOvA, Ibid., (9),

Pt added to Raney Ni considerably increases its electrochemical activity as anode for the oxidation of H, and its catalytic activity for the hydrogenation of potassium maleate, o-nitrophenol and n-quinone. During manufacture Pt forms a solid solution with NiA1, and Ni,Al,, which leads to growth in the lattice parameters of the Raney Ni.

2086-2093

The Isomerisation of Aliphatic Hydrocarbons over Evaporated Films of Platinum and Palladium J. R. ANDERSON and N. R. AVERY,J. Catalysis, 1966, 5, (3), 446-463 Paraffins reacted over Pd films are mainly hydrocracked whereas over Pt films on mica or on NaCl there is considerable isomerisation. The mechanisms of these reactions are discussed for oriented and unoriented films.

Investigation of the Mechanism of Catalytic Decomposition of Formic Acid Vapour on Palladium A. A. KHOMENKO, L. 0. APEL’BAUM and M. I. TEMKIN, Kinetika i Kataliz, 1966, 7, (4), 671-678 Studies of HCOOH dehydrogenation on Pd membranes at 225-275’c, PHC~~H=O.OI-O. r atm showed that reaction rate cc pg:&,; activation energy = 16.2 kcal/mole. Studies involving Hh excluded a bond mechanism but a dissociative

mechanism applied to calculations for an heterogeneous surface explained the kinetic equation produced.

Hydrogenation of Ethylene and Propylene over Palladium Hydride R. J. RENNARD and R. J. KOKES, J . Phys. Chem,

Studies of the rate of C,H, hydrogenation as a function of H, concentration, temperature, P C ~ H ~ and P H ~ over Pd hydride and deuteride show it to be nearly zero order in pCzHl and pHZ at 78°C but first order in hydride concentration. The first order rate constant decreases with hydride concentration but activity increases. An inverse isotype effect occurs with D,; the main deuterated product is C,H,D,. The slow step is probably addition of adsorbed H atoms to adsorbed C,H, or adsorbed ethyl radicals. Similar studies were carried out using C,H,.

Catalytic Oxidation of Methane on Palladium- Gold Alloys J. G . FIRTH, Trans. Faraday Soc., 1966, 62, (9),

A microcalorimetric method for the determination of rates, orders and apparent activation energies of heterogeneous catalytic reactions was applied to the complete oxidation of CH, on Pd-Au alloys and indicated that the &orbitals of the catalyst take part in the reaction. A relatively stable adsorbed intermediate appears to be part of the reaction sequence. Changes in the apparent activation energies seem due partly to changes in the heat of formation of this intermediate. Two types of microcalorimeter were used : one consists of catalyst deposited on an A1,0, bead in which is embedded a Pt coil connected to a Wheatstone bridge circuit; the other possesses a Pt alloy thermocouple in place of the coil.

The Catalyst Platinum/Polyvinyl Alcohol D. v. SOKOL’SKII, 0. A. TYURENKOVA, v. A. DASHEVSKII and G. P. YASTREBOVA, Zh. Fiz. Khim., 1966,409 (9L 2243-2249 As the polyvinyl alcohol content of colloidal Pt / polyvinyl alcohol increases the rate of hydrogenation at first increases and then begins to fall. The catalyst with 20 mg Pt and 250 mg of polyvinyl alcohol in 10 ml solution has maximum activity. Pt separates out if the polyvinyl alcohol content falls below 2 mg/Ioo ml solution. Catalyst activity drops off according to the solvent in the order H,>o.oI% NaOH>50%C,H60H. The catalyst is more active at room temperature than at 40°C. Reaction rate increases rectilinearly with catalyst content. Hydrogenation of ally1 alcohols is zero order; reduction of C,H,NO, is first order. Rate of reduction of C,H,NO, in solvents falls in the order : H,O > CH,OH > dioxane > C,H,OH>acetone. The catalyst is regenerated by precipitation with alcohol and subsequent dissolution in H,O.

1966, 709 (8), 2543-2549

2566-2576


Nonenzymatic Conversion of Penicillins to 6-Aminopenicillanic Acid D. A. JOHNSON, c. A. PANETTA and R. R. SMITH, J. Org. Chem., 1966, 31, (8), 2560-2564 Nonenzymatic conversion of several o-nitrophenyl- substituted penicillins to 6-aminopenicillanic acid occurred by spontaneous cleavage of the side chain at room temperature after reduction to the substituted amine with H, over Pd/C, or, preferably, to the hydroxylamine with alkali boro- hydride in the presence of Pd/C.

Homogeneous Catalysis. 111. Isomerisation of Deuterio Olefins by Group VIII Metal Com- plexes J. F. HARROD and A. J. CHALK, r. Am. Chem. soc.,

D , movements were studied during isomerisation of vinyl- and allyl-deuterated I-olefins by homogeneous Rh- and Pd-complex catalysts in the presence and without an unlabelled olefin. With RhCl,, D, was redistributed to all C atoms in the allylic system, and intermolecular D , exchange to all C atoms of the unlabelled olefin occurred. With bis(benzonitri1e)dichloropalladium catalyst the double-bond shift occurred by shift of D or H from C, to C,. Less intermolecular D, exchange occurred with less D, attached to doubly-bonded C atoms.

The Mechanism of Isomerisation of Olefins with Transition Metal Catalysts R. CRAMER and n. v. LINDSEY, Ibid., 3534-3544 The proposed mechanism for olefin isomerisation with Rh, Pd, Pt, Ni or Fe catalysts and various cocatalysts involves rearranging a kinetically stable metal hydride with co-ordinated substrate olefin to a metal alkyl and then to the metal hydride complex of the isomeric olefin. The method of initial hydride formation depends on the cocatalyst and the oxidation state of the metal but isomerisation and hydride regeneration pro- ceed via a reversible reaction involving the reduction of proton to hydride with concurrent two- electron oxidation of the metal.

1966,88, (IS), 349i-3497

The Synthesis of Olefinic Cyanides from Olefins by Means of Palladium(I1) Cyanide Y. ODAIRA, T. OISHI, T. YUKAWA and s. TSUTSUMI, Ibid., (17), 4105-4106 The first reported synthesis of olefinic cyanides from olefins was carried out efficiently using Pd(CN) ,, probably by n-complex formation. CuCN and Ni(CN), were less effective.

The Mechanism of the Reaction of Nucleo- philes with Alicyclic Olefin Palladium Com- plexes M. GREEN, R. N. HASZELDINE and J. LINDLEY, J. Organomet. Chem., 1966, 6, (I), 107-108 PdC1, catalyses the reaction of cyclohexane with

CH,COONa in CH,COOH at 20°C in the presence of benzoquinone to yield 76% of cyclohex-a-enyl acetate and 24% of cyclohex-j- enyl acetate rather than cyclohex-I-enyl acetate. CuC1, hardly affected this result. The mechanism is discussed.

Hydride Transfer Reactions Catalysed by Metal Complexes

RhCl, catalysed the dehydrogenation of iso- C,H,OH to acetone at a decreasing rate as Rh was precipitated during the reaction. This involved the reversible transfer of an hydride ion from the crC atom of the alcohol to form a Rh hydride intermediate which either reacted with a proton to give H, or decomposed to give Rh metal. No Rh precipitation occurred when using a RhC1,-SnC1, complex.

Kinetics and Mechanism of the Homo- geneous Catalytic Activation of Carbon Monoxide in Solutions. I. Catalytic Activity of Bromide Complexes of Pd(I1)

KUSHNIKOV, v. F. VOZDVIZHENSKII and v. A. GOLODOV, Zh. Fiz. Khim., ~ 9 6 6 ~ 4 0 , (7), 1468-1474 CO reacts with bromopalladate(I1) in aqueous solution by its introduction into the co-ordination sphere of the complex with subsequent oxidation therein. Bromopalladate(I1) was studied by spectrophotometry in aqueous and acetonitrile solutions with [Br-] /[Pdz+] =4-6000. Quantity of catalyst, temperature, concentrations of Br-, H+, and HBr, and p c o all affect the activity of [PdBr,] during CO reduction of cr-naphtho- quinone in 3 :7 H,O-dioxane. [PdBr,H,O]- anions have most activity. The mechanism may be formation of an intermediate Pd(I1) carbonyl- bromide complex, which decays to [PdBr,] z-n.

11. Effect of the Concentration of Cations and Anions on the Kinetics of the Reduction of N-Benzoquinone v. D. MARKOV, v. A. GOLODOV, G. G. KUTYUKOV and A. B. EASMAN, Ibid., 1527-1532 The concentrations of H+, C1- and Br- affect the activity of K,PdCl, and K,PdBr, solutions for the CO reduction of N-benzoquinone. The effect of acidity on activity was determined by the change amount of Pd (11) acidocomplex. Bromide complexes were 3-4 times as active as chloride corn- plexes. Maximum activity of the solutions occurs in the range of conversion from [PdL,H,O]- to [PdL,Ia-. 111. Investigation of the Catalytic Activity of Compounds of the Transition Metals v. D. MARKOV and A. B. EASMAN, Ibid., 1564-1570 Oxidation of CO in aqueous solutions at low temperatures was studied using metallic ions as catalysts. Pd(I1) acido complexes showed the maximum activity.

H. B. CHARMAN, Nature, 1966,2I2, (5059), 278-2,79

G. G. KUTYUKOV, A. B. FASMAN, A. E. LYUTS, YU. A.

Platirzum Metals Rev., 1967, 11, (l), 37

The Reaction of Vinyl Halide-Palladium(I1) Chloride Complexes with Nucleophiles : Catalytic Vinylation E. W. STERN, N. L. SPECTOR and H. P. LEFTIN, 7. Catalysis, 1966, 6, (I), 152-153 PdCl, catalysed the reactions of vinyl chloride and CH,COOH in iso-octane at room temperature, 2 atm pressure and of vinyl chloride and isopropyl alcohol under similar conditions, to form vinyl acetate and isopropyl acetal respectively. In these and similar reactions the reduction of PdCl, to Pd did not occur. The mechanism of these reactions is believed to involve complex formation.

Hydrogenation of Phosphatides on Palladium Catalysts in Solvents G. A. POTLOVA and D. v. SOKOL'SKII, Izv. Akad. Nauk Kaz. S.S.R., Ser. Khim., 1966,16, (I), 48-54 Cephalin fractions of soya phosphatides were hydrogenated at normal pressure and low temperature on Pd/CaCO,, Pd/BaSO,, Pd/SiO, and Pd/C. Degreased soya phosphatides were hydrogenated similarly on 51% Pd/CaCO,. Kinetic studies on mixed solvents in the latter reaction showed that the rate of hydrogenation is greatest when one solvent is C,H,.

Hydrogenation of Rosin on a Palladium Catalyst I. I. BARDYSHEV and E. B. SMIRNOVA, Gidrolizn. i Lesokhim. Prom., 1966, 19, (4), 4-6 Disproportionation to tar acids was the main reaction during the hydrogenation of rosin in COHO solution in the presence of Pd catalysts at I~o'C, p,,$< 40 atm and <O.I%> I'd per unit wt. of rosin. Hydrogenation of rosin occurred at 15o"C, p,,,~50-60 atm in the presence of 0.2-0.4%, Pd with ) I mol. H, per mol. tar acid. Further increases of pHs and catalyst concentration gave no further significant rosin hydrogenation. Lower rate of hydrogenation occurred at lower temperatures and above 150°C the rate of disproportionation increased. Catalyst deactivation was prevented by adding one part of catalyst to remove poisons in the rosin and a further part to catalyse hydrogenation of pure rosin.

The Hydrogenation of Acetylene. 111. The Keaction of Acetylene with Hydrogen Catalysed by Alumina-supported Rhodium and Iridium G. c. BOND and P. B. WELLS,^. Catalysis, 1966, 5, (3h 419-427 Hydrogenations of C,H, over Rh/A1,0, at 18- 150°C and over Ir/Al,O, at 45-185T were - first order in H,; zero (Rh) or negative (Ir) order in C,H,. Under comparable conditions Rh was always more selective for C,H, production. Selectivity depended on all experimental variables. C,H, formation over both metals decreased

with increasing initial p ~ * and decreasing pCSH2 and temperature. Olefin hydrogenation was slow in the presence of C,H,, rapid in its absence. Rh, Ir, Pd, Pt catalysts for C,H, hydrogenation are compared.

The Use of Supported Solutions of Rhodium Trichloride for Homogeneous Catalysis G. J. K . ACRES, G. c. BOND, B. J. COOPER and J. A. DAWSON, Ibid., 6, (I), 139-141 Advantages of combining heterogeneous and homogeneous catalytic techniques were studied by dissolving RhC1,.3H,O in ethylene glycol, adding this solution to Silocel suspended in CH,OH, evaporating the latter to form a powdered catalyst, and using it to catalyse isomerisation of I-C,H,, to cis- and truns-2-C5H,,.

Hydrogenation of Phenylacetylene on Rhodium A. M. SOKOL'SKAYA and K. K. KUZEMBAEV, Izv. Akad. Nauk Kaz. S.S.R., Ser. Khim., 1966, 16, (I), 78-84 Studies of the hydrogenation of phenylacetylene on 5'X Rh/BaSO, and on Rh black at 5, 15 and 30°C in CH,OH and in 0.1 N HC1 and KOH methanolic solutions showed that the first mol. H, was added much more slowly than the second. The hydrogenation was not strictly selective; before 0.5 mol. H, was added, ethylbenzene was detected. During the hydrogenation the catalyst surface was almost fully covered by H,. The catalyst retained its activity after 5 or 6 successive hydrogenations of phenylacetylene.

Organic Syntheses by Means of Noble Metal Compounds. XXV. Palladium-catalysed Car- bonylation of Ethyl Acetylenemono- and -dicarboxylates J. TSUJI and T. N O G I , ~ . org . Chem., r966, 31, (8),

PdC1, and 10% PdjC catalysed the room temperature carbonylation in C,H,OH of ethyl acetylenemonocarboxylate to ethyl fumarate, ethyl-ethenetricarboxylate, ethyl-~,~,z-ethanetri- carboxylate and ethyl- I ,3-butadiene- I ,I ,4,4- tetracarboxylate, and of the dicarboxylate to ethyl-ethenetricarboxylate, ethyl-1,1,2-ethane- tricarboxylate and ethyl-1,1,2,2-ethanetetra- carboxylate. HC1 in the medium affected the yields. XXVII. Decarbonylation of Acyl Halides Catalysed by a Rhodium Complex and Pre- paration of Acylrhodium Complexes by a Novel Addition Reaction of Acyl Halides J. TSUJI and K. OHN0,y. Am. Chem. Soc., 1966,88, (14),3452-3453 Decarbonylation of acyl halides with RhCl(Ph,P), proceeds smoothly and efficiently to yield olefins, HCl and RhCICO(Ph,P), under mild conditions. The new acylrhodium complex RCORhCl,

2641-2643


(Ph,P) , can be isolated by carefully controlling the reaction conditions. Electrophilic attack on the Rh by the carbonyl C is thus possible. XXIX. Decarbonylation of Acid Halides and Carbonylation of Alkyl Halides Catalysed by Rhodium Complex Ibid., Tetrahedron Letters, 1966, (39), 4713-4716 (PPh,),RhCOCl efficiently catalyses the homogeneous decarbonylation of acyl and aroyl halides to olefins and aryl halides respectively, and the carbonylation of some alkyl halides, e.g. benzyl chloride to phenylacetyl chloride in C,H, at 15o"C, roo atm pco.

CATHODIC PROTECTION Corrosion Protection of Drying Cylinders in Paper-making Machines by Cathodic Polari- sation

205-225 Electrochemical theory and practical details of the method of protecting cast iron drying cylinders using a Pt anode. (See Platinum Metals Rev.,

A. ALMAR-NAESS, Corrosion sci., 1966, 6, (S),

I966,10, (2), 48-51).

CHEMICAL TECHNOLOGY Selective Reductions with Electrolytically Produced Hydrogen J. B. LEE and P. CASHMORE, Chem. Q Ind., 1966,

An electrolytic cell containing 5% H,SO,, an anode of Pt gauze and a cathode of Ag-Pd alloy tube produced H, which reduced acetylenes to the corresponding olefins, and acetylenic alcohols and acids to the olefinic compounds. No trans olefins were produced. Neither were other types of compounds reduced.

(42), 1758-1759

NEW PATENTS METALS AND ALLOYS Palladium Alloy Tubes J. BISHOP & CO. U.S. Patent 3,254,956 An improved process for the production of ultra -pure H, utilises a reaction tube made of porous ceramic impregnated with Fe, Ni or Pt and lined with a thin-walled Pd-alloy tube, preferably made of Pd-Ag alloy.

Nuclear Fuel Element

U.S. Patent 3,261,757 A nuclear fuel element for use in a chemonuclear

ATOMIC ENERGY COMMISSION

TEMPERATURE MEASUREMENT Fifty Years of Temperature Measurement J. A. HALL,J. sci. Instrum., 1966, 43, (8), 541-547 A survey of developments in thermometry since 1916 discusses the accuracy and reproducibility of the temperature scale itself and then the accuracy with which practical measurements may be made in terms of that scale. Pt metal thermocouples and the Pt resistance thermometer have become increasingly important and more accurate.

Silver-Palladium as an Indicator of Thermal Gradients in Pellet Induration H. w. HITZROT, L. v. FEGAN and R . A. LIMONS, Trans. Soc. Mining Eng. A.I.M.E., 1965, 232,

Ag-Pd wires with specific melting points from 2000 to z5oo"F indicate pellet-bed temperatures in travelling-gate or shaft furnaces. Wires are encased in ceramic capsules which accompany a sample of green pellets in a Nichrome wire basket during firing. After exposure, each capsule is recovered from the basket and examined to find the maximum temperature attained. Disad- vantage of the method is that it is not continuous but it is cheaper than thermocouples.

The Total Hemispherical Emittance of Coated Wires D. BRADLEY and A. G. ENTWISTLE, Br. J . Appl. phys., 1966, 17, (9), 1155-1164 A theory for the derivation of hemispherical spectral emittance and hence total hemispherical emittance, for a uniformly coated cylinder is applied to fine 10% Rh-Pt wires coated in fused SiO, at 340-1350"C and agrees with experiment. Effect of coating thickness is discussed.

(2)> 95-99

Platinum Metals Rev., 1967, 11, (l), 3 9 4 4 39

reactor comprises an inner core composed of an alloy of 50-98 wt.lX Pd, 1-30 wt.% U and 1-20 wt.% Pt and a 0.2-6p external coating of Pt.

ELECTROCHEMISTRY Electrolytic Technique for Hydrogen Re- covery AMERICAN CYANAMID co. British Patent 1,039,41 I An electrolytic process for separating and recover- ing H, from a gaseous mixture, where the gas- permeable anode is made of, or contains a Pt group metal, preferably Pt, Pd or Rh. See also 1,039,412.

Electrodes for Electrolytic Cells DAVID J. EVANS (RESEARCH) LTD. British Patent 1,045,816 A bipolar electrode for an electrolytic cell com-

then is treated at I,OOO"C in moist H, before the coating is intensified by electrolytic plating and the moist H, treatment is repeated.

prises two sheets of Pt, Rh, Ru, TI or Ni coated with Pt which are seaarated bv a alate of elec- LABORATORY APPARATUS trically insulating material extending beyond the edges of the metal sheets. The metals sheets are corinected together through the insulating plate.

AND TECHNIQUES Weights for ~~l~~~~ A~~~~~~~

Platinum-coated Electrodes J. BISHOP & CO. U.S. Patent 3,254,015 The over-voltage of a Pt-coated anode for a C1, cell is lowered by first charging the Pt with H, by electrolysing it cathodically in a solution which is free of Pt until evolution of H, occurs on its

SARTORIUS-WERKE A.G. German Patent 1,223,169 The accuracy of balance weighing with two arms is increased by exclusion of the air buoyancy effect by pairing weights of identical volume but different density on both arms. Suitable materials are pure I r and a 64y0 Rh-36% Ni alloy.

surface and then heating the anode at 7oo-1,000°F so that there is at least some recrystallisation of Pt.

Platinum Group Metal Electrodes for a Brazing Alloys

UNION CARBIDE COW. U S . Patents 3,255,044-5 British Patent 1,044,379 A redox couple radiation cell has a carbon porous cathode and a Pt metal anode, preferably Pt coated with a finely divided Pt black. See also 3,255,046.

BRAZING

Radiation Cell WESTINGHOUSE BRAKE AND SIGNAL CO. LTD.

A brazing alloy useful in the manufacture of semiconductors comprises 4-10 wt.%> In, Sn or Ga, 20-40 wt.% Cu, 5-20 wt.% Pd and balance Ag.

ELECTRODEPOSITION AND SURFACE COATINGS Electrodeposition of Palladium

British Patent 1,040,410 An electrolyte for the electrolytic deposition of Pd at p H 4-5, 23-65°C and 3.6-4.6 A/fP comprises an aqueous solution containing 0.01-0.121 moles/l Pd and, for each mole of the latter, about 2 moles complexing agent and a suitable buffer.

Production of Metallic Coatings on the Surfaces of Other Metals

British Patent 1,042,816 Non-metallic surfaces are provided with con- ducting or magnetic coatings by pretreatment with a seeding metal compound, preferably a Pd compound, followed by electroless plating.

Palladium Electroplating Bath

French Patent 1,436,451 The electrolyte is an alkaline or neutral aqueous solution of a Pd compound and an NH, salt of a weak acid which does not form an insoluble product with the Pd compound.

Platinum Plating of Molybdenum

German Patent 1,221,518 Mo wire in particular is chemically plated as it passes through a bath, at 125-z50 m/h, containing 350-500 g/1 H,PtCl, and 20-30 g/1 HgCl, and

INTERNATIONAL BUSINESS MACHINES CORP.

INTERNATIONAL BUSINESS MACHINES CORP.

JOHNSON MATTHEY & CO. LIMITED

VEB BERLINER GLUHLAMPEN-WERK

CATALYSTS


Hydrogenation of Salts of Phthalic Acids

British Patent 1,037,693 Salts of phthalic acids are hydrogenated to the corresponding salts of the hexahydrophthalic acids at I ~ o - ~ ~ o ' C , 50-350 atm, in the presence of Pt, Pd, Ru and/or Rh catalyst and in the presence of a salt of the isomer of hexahydrophthalic acid which is not desired.

Manufacture of 1,4-Benzodioxanylalkylam- ino-ethanols IMPERIAL CHEMICAL INDUSTRIES LTD. British Patent 1,038,335 1,4-Benzodioxan derivatives are produced by reducing r,4-benzodioxan-2-ylglyoxal or its hydrate by catalytic hydrogenation in the presence of Pt catalyst, an amine or its acid-addition salt and an inert diluent.

Hydrogenation of Quinoline

British Patent x,o38,644 5,6,7,8-Tetrahydroquinoline is produced by contacting quinoline and/or 1,2,3,4-tetrahydroquinoline with H, at above 3 0 0 ° C and in the presence of a Pt or Pd catalyst.

Organopolysiloxane Process GENERAL ELECTRIC co. British Patent 1,038,876 The molecular weight of a mixture of at least two organopolysiloxanes, one of which has Si-H bonds and the other Si bonded vinyl and/or ally1

BADISCHE ANILIN- & SODA-FABRIK A.G.

ALLIED CHEMICAL CORP.

radicals, is increased by contacting it with a complex (PtCl,.olefine) , or H(PtCl,.olefine).

Improved Hydrocracking Conversion Catalyst and Process

British Patent 1,039,167 An improved catalyst for the hydrocracking of hydrocarbons at 5oo-800°F and 300-5,ooo psig which comprises 0.05-5 wt.% Pt group hydrogenation component composited with crystalline synthetic mordenite zeolite.

Production of Isoprene

ET LUBRIFIANTS British Patent 1,039,255 In the production of isoprene the crude 4,4-dimethyl-1,3-dioxan is treated with H, at up to 20ooC and in the presence of Ni, Rh, Pt or Pd as hydrogenation catalyst.

Production of Hydroxylamine INVENTA A.G. British Patent 1,039,866 Hydroxylamine is produced by the reduction of NO by H,, in acid solution, at 65-80°C and in the presence of the hydroxylamine salt of the acid and a Pt group metal deposited on activated C and impregnated with AgNO,.

ESSO RESEARCH & ENGINEERING CO.

INSTITUT FRANCAIS DU PETROLE, DES CARBURANTS

Autofining of Petroleum Hydrocarbons

British Patent 1,040,298 White spirits are produced by contacting at 550-820'F and 100-600 psig, a S-containing straight run petroleum naphtha of 3o-20o0C boiling range with a refractory metal oxide supporting 0.01-5 wt.7: Pt group metal.

Process for the Production of Hydroxylamine Snlphate Solution INVENTA A.G. British Patent 1,040,500 An hydroxylamine sulphate solution is produced by the continuous reduction of NO with H,, at 30-85°C in an aqueous H,SO, solution and in the presence of a Pt group metal catalyst.

Production of Hydrogen Peroxide IMPERIAL CHEMICAL INDUSTRIES LTD. British Patent 1,041,045 H, and 0, are reacted in the presence of a solid Group IB or VIII catalyst, e.g. an Au-Pd mixture, in the presence of liquid H,O, an acid and a non- acidic organic compound containing 0,.

Oxidation of Hydrocarbons and Alcohols IMPERIAL CHEMICAL INDUSTRIES LTD. British Patent 1,041,046 Aldehydes or ketones are produced by oxidation in contact with a crude H,O, solution in H,O, acid and a solid Group IB or VIII metal catalyst, e.g. palladised SiO,.

THE BRITISH PETROLEUM CO. LTD.


Production of Glyoxal

British Patent 2,041,376 Ethylene is reacted with HNO, in aqueous medium in the presence of a Pd salt catalyst in an amount of more than 0.0001 wt.% of the reaction mixture. Preferably the salt is PdCl, or Pd(NO,),.

Regenerating Lead-Contaminated Catalytic Composite UNIVERSAL OIL PRODUCTS British Patent 1,041,751 A catalyst containing a Group IB, VA, VIA or VIII metal deposited on a refractory oxide support is regenerated by treatment with an aqueous synthetic detergent solution and drying. The catalyst especially consists of O.OX-XO wt.o/, of Pd, Ru, Rh, I r or 0 s on an oxide support.

Diamides

British Patent 1,042,482 In the production of dipeptide derivatives, hydrogenolysis of the corresponding N-benzyloxy- carbonyl-L-aspartyl-L-phenylalanine-amides is carried out over Pd/C. See also 1,042,485-6.

New Fused Polycyclic Hydrocarbon Deriva- tives ROUSSEL-UCLAF British Putent 1,042,631 Hydroindane compounds useful in steroid synthesis are obtained by a process involving catalytic hydrogenation over a Pd catalyst which does not cause isomerisation. See also 1,042,632-3.

Preparation of Cyclic Polyolefinic Hydro- carbons E. I. DU PONT DE NEMOURS & CO. British Patent 1,043,800 8-r6C non-conjugated polyolefinic hydrocarbons are hydrogenated selectively, to the corresponding cyclic mono-olefines by reacting them at 25-15Ooc and 1-100 atm with H, in the presence of 0.1-5 wt.7' Pd or Pt catalyst and 50-150 wt.yo H,O based on the weight of hydrocarbon.

Improved Hydrocracking Process

British Patent 1,045,397 Hydrocarbon fractions boiling above 300°F are hydrocracked by contacting them at 500-800°F with H, and a catalyst comprising a Pt group metal supported by a 6-15 A pore size zeolite which has been base exchanged to reduce its Na,O content below 10% and maintaining initially a high concentration of catalyst poison and reducing it as the process proceeds.

Preparation of Chlorine, Bromine and Iodine

British Patent 2,046,313 CI,, Br, and/or I, are prepared by contacting a


IMPERIAL CHEMICAL INDUSTRIES LTD.


SHELL INTERNATIONALE RESEARCH MIJ. N.V.

mixture of hydrogen halide and 0, with a catalyst comprising o . I - x ~ ~ ~ Ru or a compound thereof on a suitable carrier, at 250-500°C and 0.1-100 atm.

Rhodium Oxide Hydrogenation Catalyst

U.S. Patent 3,253,018 Aldehydic esters are prepared by reacting dienes with CO and coreactant containing H bonded to a non-carbon atom in the presence of Rh,O,.

Platinum Group Metal Catalysts in the Production of Esters

U.S. Patent 3,253,020 An unsaturated ester is produced by reacting a hydrocarbon olefine with a medium consisting of the carboxylic acid, less than 10 wt.% water, 0.001-5 wt.% Pt group metal and 0.05-2 wt.yo soluble bromide.

Platinum Group Metal Isomerisation and Hydrocracking Catalysts

US. Putent 3,253,oss Paraffinic hydrocarbons are subjected to hydro- catalytic conversion by contacting them with H, at 205-400°C and 100-500 psi and in the presence of A1,0, which has been contacted with a halogen-generating compound and supports 0.01- 5 wt.% Pt group metal.

Platinum Group Metal Catalysts for the Conversion of Exhaust Gases

U.S. Patent 3,254,966 A catalytic element for the oxidation of combustion engine exhaust gases comprises a housing with perforated walls within which are disposed small perforated containers. The housing is filled with crimped metal ribbons coated with a Pt group metal and the containers are filled with a Pt group metal or alloy supported on a refractory metal oxide material.

Platinum Group Metal Hydrogenation Catalysts

U.S. Patent 3,255,200 Imidazole is produced by contacting a mixture of H,, formamide and ethylenediamine at 340- 480°C with a catalyst comprising a sorptive refractory oxide and 0.1-2 wt. Yn Pt group metal, preferably Pt or Pd.

Platinum Group Metal Hydrogenation Catalysts SHIONOGI & CO. LTD. U.S. Patent 3,256,286 The hydrogenation of morphinon derivatives is carried out in the presence of supported or unsupported Pt, Pd or Ni catalysts.

ESSO RESEARCH AND ENGINEERING CO.

UNION OIL CO. OF CALIFORNIA


UNIVERSAL OIL PRODUCTS CO.

AIR PRODUCTS AND CHEMICAL INC.

Platinum Metals Rev., 1967, 11, (l),

Noble Metal Catalysts for the Treatment of Automobile Exhaust Gases

U.S. Patent 3,257,163 The exhaust gases formed by the combustion of leaded petrol are purified by contacting them with a scavenger, e.g. alkali or alkaline earth metal vanadates, Al, Co, etc., and a Pt, Rh, Pd or Ru catalyst.

Palladium Decarbonylation Catalyst THE QUAKER OATS co. U.S. Patent 3,257,417 Furfural is decarbonylated in the liquid phase to furan by contacting it at 190-225°c with more than 0.01 mole Ca acetate in the presence of a Pd catalyst.

Platinum Group Metal Reforming Catalysts SINCLAIR RESEARCH INC. U.S. Patent 3,258,420 A hydrocarbon feedstock of 90-450"F boiling range is reformed by passing it and H, over a fixed bed of refractory metal oxide particles supporting 0.3-x wt.% Pt group metal, preferably Pt, at 900-980°F and 150-250 psig.

Platinum-Fluorine-Alumina Reforming Catalyst PHILLIPS PETROLEUM co. U S . Putent 3,258,503 Pt-F,-Al,O, catalyst is preferred in the production of C,H, from 6-9 C cycloparaffins.

Waste Gas Combustion Treatment

U.S. Patent 3,259,454 The effectiveness of a Pt/A1,0, catalyst in burning waste gases is improved by adding a tertiary di- carboxylic acid to the gas.

Isomerisation Process PHILLIPS PETROLEUM co. U.S. Patent 3,260,762 The isomerisation of cyclohexane to methyl cyclopentane is catalysed by a Pt metal supported on an oxide or oxides.

Diene Production

U S . Patent 3,260,767 Aliphatic dienes are produced from hydrocarbons by dehydrogenation over a supported PdO catalyst.

Alumina Supported Palladium Catalyst L'AIR LIQUIDE, S.A. French Patent 1,428,528 Oxygenated H,O is produced by a cyclic process involving partial oxidation of anthraquinone in the presence of 2% Pd/A1,0, catalyst.

Platinum Hydrogenation Catalyst INVENTA A.G. French Patent X,429,133 Nitrogen oxide is hydrogenated in an acid medium and in the presence of 2% Pt /C catalyst, which is periodically reactivated by contact with HF.

E. I. DU PONT DE NEMOURS & CO.

UNIVERSAL OIL PRODUCTS CO.

PETRO-TEX CHEMICAL CORP.

42

Trimeric Ruthenium Tetracarbonyl LONZA S.A. French Patent 1,430,131 Hydroquinone is produced by reacting C,H, and CO at roo-300°C and 150-350 atm in the presence of organic solvent, H, and trimeric Ru(CO), catalyst.

Platinum Group Metd Hydrocarbon Con- version Catalysts

French Patent 1,431,985 A hydrocarbon conversion catalyst comprises crystalline mordenite of at least 5 A pore size and 0.01-10 wt.% Group VI or VIII metal, including the Pt group metals.


Alumina-supported Noble Metal Catalysts

French Patent 1,432,084 The gas formed during the course of the manufacture of electrodes for the electrolytic production of A1 is purified by contacting it with an 0, containing gas and A1,0, supporting a noble metal, preferably Pt or Pd.

METALLGESELLSCHAFT A.G.

Noble Metal Oxide Polymerisation Catalysts

French Patent 1,433,069 Amongst the catalysts which are used in the polymerisation of vinyl alkyl ethers are the reaction products of concentrated H,SO, and Ru, Rh, Pd, Os, I r or Pt oxides.

THE GOODYEAR TIRE & RUBBER CO.

Selective Acyl Dione Hydrogenation

The hydrogenation of the 2-acyl group of 2-acyl- cyclopentane-I ,3-diones to an a-alkyl group is accomplished using finely divided Pt, Pd, Rh or Ir.

UNION CARBIDE CORP. French Patent 1,434,085

Platinum Group Metal Isomerisation Catalysts THE PURE OIL CO. French Patent 1,437,357 n-Pentane and/or n-hexane are isomerised without any hydrocracking by treating them with H, at 37r-38o0C, 7-8.7 kg/cm2 pressure and in the presence of a catalyst comprising 0.1-1 wt.% Pt group metal, preferably Pd or Rh, up to 5 wt.% combined Fa, and a SiO,/Al,O, support containing 50-95 wt.% SO,.

Hydroxylamine Sulphate Production INVENTA A.G. German Patent 1,219,453 NO is reduced with H, in the presence of Pt catalyst (e.g. Pt/C) and H,SO,.

Beta-pinene Production

German Patent 1,221,218 The isomerisation of a-pinene at 140-200°C in

FARBWERKE HOECHST A.G.


the gas phase in the presence of 1-5 ~ 0 1 . ~ ~ H, is catalysed by 0.5-10 wt.% Pd/C.

Carboxylic Ester Production

German Patent 1,221,224 The reaction of at least 3C olefines with CO and alcohols or phenols is catalysed by L,PdX, where L is phosphine, NH,, amine, RCN or unsaturated hydrocarbon, X is anion, and m and n are I or 2, e.g. (PPh,),PdCl,.

Vinyl Compound Production

German Patent 1,221,637 The reaction of C,H,, 0, and nucleophilic compounds is catalysed by PdO, preferably on a support.

Production of Ally1 Chloride

German Patent 1,222,913 Olefines with 3-4C atoms are reacted with 0, and HC1 at 20-35"C using PdO as catalyst. French Patent 1,435,688 is almost identical but additionally covers the use of any Group VIII noble metals. See also 1,224,301.




FUEL CELLS Catalytic Electrode for a Fuel Cell

British Patent I ,038,300 A fuel cell electrode comprises 1-75 wt.% finely divided Group 111, IV or V metal oxide, a binder- waterproofing agent and a Pt group or other noble metal. After shaping, the electrode is leached to a 0.01-10 wt.% oxide content and optionally is additionally electroplated with a Pt group metal, preferably Pt.

Gaseous Fuel Cell GENERAL ELECTRIC co. British Patent 1,038,884 A fuel cell for use with carbonaceous gases has an electrolyte in the form of an aqueous solution of Cs and/or Rb hydroxide, carbonate and/or bi- carbonate positioned between and in direct electrical contact with a pair of gas-permeable conductive electrode elements containing a Pt group metal as the catalytic constituent.

Fuel Cell Electrode AIR PRODUCTS AND CHEMICALS INC. and

British Patent 1,039,604 A fuel cell electrode is produced by impregnating a porous, electroconductive support material with compounds of Pt and Ag, Au, Ru, Os, Rh, Ir or Pd promoter metal taken in I : 2 to 2 : I molar ratio, drying the support, reducing the noble metal compounds to precipitate the metals and washing the impregnated electrode.

AMERICAN CYANAMID CO.

NORTHERN NATURAL GAS CO.

Fuel Cells LEESONA CORP. British Patent 1,040,343 A fuel cell for the direct generation of electricity comprises a non-porous H, diffusion membrane made of an alloy of 5-40 wt.% Au and Pd, a cathode and an aqueous electrolyte.

Fuel Cell Electrode AIR PRODUCTS AND CHEMICALS INC. and NORTHERN NATURAL GAS CO. British Patent 1,040,681 An electrode is manufactured by plating Pt on to a base from a salt solution using a Pt auxiliary electrode and a low frequency pulsating electric current.

Fuel Cells

British Patent 1,044,872 A fuel cell includes an 0, electrode in the form of Pd, Pd-Ag alloy or Pt or conductive material coated with such metals and is formed as a membrane which is permeable to H, but not to other gases.

Fuel Cell Electrodes Containing Platinum Group Metals AMERICAN CYANAMID co. U S . Patent 3,252,839 A fuel cell electrode comprises carbon, 0.1-40 wt.yu Pt group metal and a waterproofing agent and an electrodeposited layer of 0.1-10 wt.% Pt group metal, preferably Pt.

Noble Metal Fuel Cell Electrodes VARTA A.G. and SIEMENS-SCHUCKERTWERKE A.G. U.S. Patent 3,253,956 An improved fuel cell includes electrodes consisting of activated C and 1-20 wt.% Pt, Pd and/or Ir.

Combined Fuel Cell Electrolyte and Noble Metal Electrodes

U S . Patent 3,257,239 A fuel cell is made by mixing finely powdered carbonates of at least one alkali or alkaline earth metal with finely powdered refractory material, pressing the mixture into a flat plate, coating one face with a suspension of finely divided Group IB metal, e.g. Ag, and the other with a Pt group metal, evaporating the suspension medium and finally sintering the plate to form thin coatings of noble metals on its faces.

Porous Fuel Cell Electrodes

French Patent 1,430,123 A porous fuel cell electrode is produced by inti- mately mixing a binder, a charge which decomposes giving a gaseous product and a supported or unsupported Pt group metal or alloy, shaping the mass at elevated temperature and then heating

SIEMENS-SCHUCKERTWERKE A.G.

INSTITUTE OF GAS TECHNOLOGY


the shaped electrode to cause evolution of gas and pore formation.

Fuel Cell-Electrode H. L. C. HYRAUD French Patent 1,434,265 A new form of H electrode is thin and flexible, e.g. Pd or Pt deposited on a paper support.

GLASS TECHNOLOGY Apparatus for Melting Glass

RENNIES DE LOING British Patent 1,045,604 An apparatus for melting glass comprises a Pt or Pt alloy crucible which acts as one electrode, a heating inductor surrounding the crucible and forming part of the oscillatory circuit of a high frequency generator and another electrode which makes it possible to pass electric current directly through the vitreous materials in the crucible.

STE. DES VERRERIES INDUSTRIELLES

ELECTRICAL AND ELECTRONIC ENGINEERING Fuse Member SIGMUND COHN CORP. British Patent 1,038,059 A fuse member comprises an intimate unalloyed mixture of (i) 20-95 wt. parts Pt, Pd, Rh, Ru, Ir and/or Au and (ii) 5-80 wt. parts A1 and/or Mg.

Electrical Resistor

U.S. Patent 3,252,831 A film-type electrical resistor comprises an electrically insulating substrate resistant to high temperatures and a deposited metal-glass film containing Ag, Au and/or metal component, preferably 25-65 wt.% Ag, 20-45 wt.O/U Pt and 5-35 wt.% Au.

Composite Alloy Electric Contact Element J. corn et al. U.S. Patent 3,254,279 An electrically conductive contact is composed of an alloy comprising 0.3-6 wt.% Ga, 0.1-20 wt.% Pt and/or 0.055-11 wt.% Pd and the balance Ag and/or Au.

Use of Noble Metals in the Manufacture of Semiconductors

U.S. Patent 3,261,075 In the manufacture of a semiconductor device comprising a siliconiferous crystal bounded by a circumferential edge and having at least one n-p junction terminating at said edge, a thin coating of Pt, Pd, Rh, Ir, Ru, Os, Au, Ag or their alloys is applied to the conductive leads, a thin bonding layer of Ag, Pt, Pd or their alloys is fused to the crystal face following which the leads are bonded to the crystal and the assembly is encased in glass.

ELECTRA MANUFACTURING CO.

CARMAN LABORATORIES INC.


platinum metals - johnson matthey

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