research article size control of iron oxide nanoparticles...

Hindawi Publishing CorporationJournal of ChemistryVolume 2013 Article ID 781595 10 pageshttpdxdoiorg1011552013781595

Research ArticleSize Control of Iron Oxide Nanoparticles UsingReverse Microemulsion Method Morphology Reductionand Catalytic Activity in CO Hydrogenation

Mohammad Reza Housaindokht and Ali Nakhaei Pour

Department of Chemistry Ferdowsi University of Mashhad PO Box 9177948974 Mashhad Iran

Correspondence should be addressed to Ali Nakhaei Pour nakhaeipourayahoocom

Received 8 May 2013 Revised 15 August 2013 Accepted 6 September 2013

Academic Editor Mohamed Afzal Pasha

Copyright copy 2013 M R Housaindokht and A Nakhaei Pour This is an open access article distributed under the CreativeCommons Attribution License which permits unrestricted use distribution and reproduction in any medium provided theoriginal work is properly cited

Iron oxide nanoparticles were prepared by microemulsion method and evaluated in Fischer-Tropsch synthesis The precipitationprocess was performed in a single-phase microemulsion operating region Different HLB values of surfactant were prepared bymixing of sodium dodecyl sulfate (SDS) and Triton X-100 Transmission electron microscopy (TEM) surface area pore volumeaverage pore diameter pore size distribution and XRD patterns were used to analyze size distribution shape and structureof precipitated hematite nanoparticles Furthermore temperature programmed reduction (TPR) and catalytic activity in COhydrogenation were implemented to assess the performance of the samples It was found that methane and CO

2selectivity and

also the syngas conversion increased as the HLB value of surfactant decreased In addition the selectivity to heavy hydrocarbonsand chain growth probability (120572) decreased by decreasing the catalyst crystal size

1 Introduction

Nanoscale materials exhibited novel properties includingquantum size effect on photochemistry nonlinear opticalproperties of semiconductor and new catalytic properties ofmetallic nanoparticles [1] Therefore synthesis of nanopar-ticles is of a great interest field during the past few yearsAs compared to their bulk counterparts nanoparticles oftenhave superior or even new catalytic properties following fromtheir nanometer size [2] Hence the size of the nanoparticlesis pivotal in determining the catalytic properties and under-standing how size may affect the catalytic properties remainsa central goal in nanocatalysis research [3]

Many methods have been reported for preparation ofnanoparticles [2 3] Preparation of metallic nanoparticlesusing microemulsion has been well established [4ndash7] Dueto the specific structure of the microemulsion system it wasexpected as a suitable environment for producing small metalnanoparticles with narrow size distribution A microemul-sion is defined as a system of water oil and amphiphile(surfactant) [4ndash7] In some respects microemulsions can

be considered as small-scale versions of emulsions that isdroplet type dispersions either of oil-in-water (ow) or ofwater-in-oil (wo) with a size range in the order of 5minus50 nmin drop radius In the hydrophilic interior of these droplets acertain amount of water-solublematerial can be dissolved forexample transitionmetal salts that then serve as precursor(s)for the final metal particles As for simple aqueous systemsmicroemulsion formation is dependent on surfactant typeand structure A surfactant substance reduces the surfacetension of a liquid in which it is dissolved [4ndash7] Hydrophilic-lipophilic balance (HLB) is an important concept whichrelates the molecular structure to the interfacial packingand film curvature It is generally expressed as an empiricalequation based on the relative proportions of hydrophobicand hydrophilic groups within the molecule If the structureof the surfactantmolecule is designed precisely the surfactantfilmmay spontaneously adopt a natural radius of curvature ofthe interface which has a direction and magnitude withoutany need for an energy input [4ndash7]

Recent studies revealed structure sensitive properties ofmany catalytic reactions like CO hydrogenation process in

2 Journal of Chemistry

Fischer-Tropsch synthesis (FTS) [8ndash12] Murzin reportedthat FTS reactions on the supported cobalt based catalystsshow many sensitivities to the catalyst particle size [13 14]Moreover many new results showed that nanosized ironparticles play an essential role to achieve high FTS activity [8ndash12] Iron-based catalysts are preferred for utilizing synthesisgas derived from coal or biomass because of the excellentactivity for the water-gas-shift reaction which allows usinga synthesis gas with a low H

2CO ratio directly without an

upstream shift-step [15 16] In our previous works we triedto show structure sensitivity of unsupported iron catalysts[10 11 17]

In this the present work feasibility of iron nanoparticleformation in the microemulsion systems with different HLBvalues was investigated Moreover effects of HLB values onthe particle size were investigated Then catalyst character-ization and catalytic FTS reaction are examined at differentparticle sizes

2 Experimental

21 Catalyst Preparation Fe-Cu nanoparticles were preparedby coprecipitation in a water-in-oil microemulsion [11ndash15] The precipitation was performed in the single-phasemicroemulsion operating region For this purpose a watersolution of metal precursor Fe(NO

3)3-9H2O (Fluka puriss

pa ACS 98ndash100) and Cu(NO3)2-4H2O (Fluka purum

pa gt 97) were added to a mixture of an oil phase(Chloroform Aldrich gt99) and mixed surfactants containTriton X-100 and SDS The HLB values of Triton X-100 andSDS are 134 and 40 respectively Besides 1-butanol as acosurfactant was added to system in order to obtain a propermicroemulsion

For preparation of various sizes of hematite nanoparticlesreverse microemulsions were prepared with different HLBvalues through varying the weight ratio of Triton X-100 andSDS For a quaternary system of surfactant (119878 g) oil (119874 g)alcohol (119860 g) and water (119882 g) the following symbols weredefined 120572 represents the mass fraction of oil in water plus oil120572 = 119874(119882 + 119874) 120573 the mass ratio of surfactant in the wholesystem 120573 = 119878(119882 + 119874 + 119878 + 119860) and 120576 the mass fraction ofalcohol in the whole system 120576 = 119860(119882 + 119874 + 119878 + 119860) [4ndash7]In the prepared microemulsion system the parameters are120572 = 062 120573 = 003 and 120576 = 028 After stirring well andstabilizing for 24 h a transparentmixturewas obtainedThenhydrazine was added to reducemetal precursorThe resultingmixture was decanted overnight The solid was recoveredby centrifuging and then washing thoroughly with distilledwater and ethanol for several times Lanthanum promoterwas added by wet impregnation method with La(NO

3)3

precursor on its optimal value after treatment in air asdescribed previously [10ndash12 17]The promoted catalysts weredried at 383K for 16 h and calcined at 723K for 3 h in air Thecatalyst compositions were designated in terms of the atomicratios as 100Fe564Cu2La

22 Catalyst Characterization Elemental analysis was per-formed to determine the composition of the elements in

the bulk of catalysts The surface area was calculated fromthe Brunauer-Emmett-Teller (BET) equation and pore vol-ume average pore diameter and pore size distribution ofthe catalysts were determined by N

2physisorption using a

micromeritics ASAP 2010 automated system A 05 g catalystsample was degassed in the micromeritics ASAP 2010 at100∘C for 1 h and then at 573K for 2 h prior to analysis Theanalysis was done using N

2adsorption at 77K Both the pore

volume and the average pore diameter were calculated byBarrett-Joyner-Hallender (BJH)method from the adsorptionisothermAssuming that the Fe

2O3particles are spherical the

corresponding particle size (119889BET) can be estimated as [18]

119889BET =6

120588119860

(1)

where 120588 is the true density of Fe2O3 that is 524 gcm3 and

119860 is the specific surface area of samplesThe XRD spectrum of the catalysts was collected by an

X-ray diffractometer Philips PW1840 X-ray diffractometerusing monochromatized CuK

120572radiation (40 kV 40mA)

and a step scan mode at a scan rate of 002∘ (2120579) per secondfrom 10ndash80∘ XRD peak identification was recognized bycomparison to the JCPDS database software The averagecrystallite size of samples 119889XRD can be estimated from XRDpatterns by applying full-width half-maximum (FWHM) ofcharacteristic peak (104) Fe

2O3located at 2120579 = 333∘ peak to

Scherrer equation

119889XRD =09120582

FWHMcos 120579 (2)

where 120582 is the X-ray wavelength (15406 A in this study) and120579 is the diffraction angle for the (104) plane

Temperature programmed reduction (TPR) measure-ments of the calcined catalysts were recorded by using aMicromeritics TPD-TPR 2900 system The catalyst samples(50mg) were purged with argon at 473 for 30min and cooledto 323K The samples were heated from 350 to 1100K at arate of 10 Kmin under flow of 51 hydrogen in argon gasmixture The consumption of hydrogen was monitored by athermal conductivity detector (TCD)

The morphology of prepared catalysts was observed witha transmission electron microscope (TEM LEO 912 ABGermany) An appropriate amount of Fe

2O3suspension

directly taken from the reaction solution was dropped ontothe carbon-coated copper grids for TEM observation Theaverage particle size (119889TEM) and particle size distributionwere determined by TEM images considering more than 100particles

23 Catalytic Performance The catalysts were tested in afixed-bed microreactor A detailed description of the exper-imental setup and procedures has been provided elsewhere[15 16] The catalyst samples (30 g catalyst diluted with 12 gquartz 100ndash180 120583m) were activated by a 5 (vv) H

2N2

gas mixture with space velocity of 151 nl sdot hminus1 sdot gFeminus1 at

01MPa by increasing temperature from ambient to 673Kat 5 Kmin then maintained for one hour and subsequently

Journal of Chemistry 3

20 30 40 50 60 70

Inte

nsity

(a)

(b)

(c)

(d)

2120579

012

104

110

113

024

116

018

214

300

Figure 1 X-ray diffraction patterns of the prepared catalysts aftercalcinations ((a) HLB = 139 (b) HLB = 237 (c) HLB = 312 and (d)HLB = 40)

reduced to 543K The pretreatment was followed by thesynthesis gas stream with H

2CO = 1 and space velocity

of 307 nl sdot hminus1 sdot gFeminus1 for 24 h in 01Mpa and 543K After

catalyst pretreatment synthesis gas was feed to the reactorat 563K 17 bar (H

2CO)feed = 1 and a space velocity of

49 nl sdot hminus1 sdot gFeminus1

The products were analyzed by means of three gas chro-matographs a Shimadzu 4C gas chromatograph equippedwith two subsequent connected packed columns Porapak Qand Molecular Sieve 5A and a thermal conductivity detector(TCD) with Ar as carrier gas for hydrogen analyzing AVarian CP 3800 with a chromosorb column and a thermalconductivity detector (TCD) were used for CO CO

2 CH4

and other noncondensable gases A Varian CP 3800 with aPetrocolDH100 fused silica capillary column and a flame ion-ization detector (FID) were used for organic liquid productsso that a complete product distribution could be provided

3 Results and Discussion

31 Catalyst Characterization Nanostructure iron catalystswere characterized by X-ray diffraction (XRD) measurementafter calcinations (Figure 1) As shown in Figure 1 XRDpatterns of samples very close to the ones with cubic hematitestructured Fe

2O3crystal in JCPDS database The character-

istic peaks corresponding to (012) (104) (110) (113) (024)(116) (018) (214) and (300) planes are located at 2120579 = 243333 358 408 496 541 576 641 and 656∘ respectivelyDiffraction data indicates that the presence of lanthanumand copper and also subsequent treatment by dried airdo not affect the hematite crystalline phases in differentcatalyst preparation methods This shows that the formed

Table 1 Average particle size determined by TEM BET and XRDtechniques

HLB dBET (nm) dXRD (nm) dTEM (nm)139 168 154 14237 203 188 17312 221 206 2140 263 248 24

Table 2 Textural properties of prepared catalysts

HLB BET surface area(m2g)

Average pore size(nm)a

Pore volume(cm3g)a

139 682 162 014237 564 196 016312 518 223 01940 435 259 021aThese values were calculated by BJH method from desorption isotherm

hematite structure remains stable during subsequent aqueousimpregnation and thermal treatment It was also shown inFigure 1 that the microemulsion system only modules thephysical properties of reactionmediumwithout changing thereaction paths and arrangements of crystal structure Thecharacteristic peak at 2120579 = 333∘ which corresponds to thehematite 104 plane was used to calculate the average metalparticle size by the Scherrer equation The calculated valuesof 119889XRD of the samples are listed in Table 1

Textural properties and pore size distributions of the freshiron-based catalysts are shown in Table 2 and Figures 2 and 3respectively N

2adsorption-desorption isotherms of catalysts

are presented in Figure 3 As shown in this Figure theprepared catalysts show type IV of Brunauerrsquos classificationisothermswithH

1-type hysteresis loop at the relative pressure

of 1198751198750= 08ndash095 This hysteresis loop is characterized as

hexagonal mesoporous materials with cylindrical channels[19]

The pore size distributions of the catalysts which werecalculated by Barrett-Joyner-Halenda (BJH) method foradsorption step are presented in Figure 3 and Table 2 Sinceall pore size values are fairly close to the dimension ofparticles it deduces that the measured pore size is mainlycaused by the inter particle voids

The TEM photographs for the prepared samples aredemonstrated in Figure 4 and Table 1 and also the particlesize distribution determined by TEM images are shown inFigure 5 The average particle size (119889TEM) and particle sizedistribution were obtained from TEM images by consideringmore than 100 particles As shown in Figures 4 and 5 theaverage range of particle size and particle size distributionincreases as HLB value increases

The particle size of samples which were determined byXRD BET and TEM techniques are summarized in Table 1Particle sizes which were estimated by different techniquesprovide different physical explanation The particle sizeobtained from XRD pattern (119889XRD) indicates the average


0

100

50

150

00 05 10Relative pressure (PP0)

Volu

me a

dsor

bed

(cm

3g

STP

)

(a)

0

100

50

00 05 10

Relative pressure (PP0)

Volu

me a

dsor

bed

(cm

3g

STP

)

(b)

0

100

50

150


Volu

me a

dsor

bed

(cm

3g

STP

)

(c)

0

100

50

00 05 10


Volu

me a

dsor

bed

(cm

3g

STP

)

(d)

Figure 2 N2adsorption-desorption hysteresis at 77 K of prepared catalysts after calcinations ((a) HLB = 139 (b) HLB = 237 (c) HLB = 312

and (d) HLB = 40)

00

02

04

1 10 100Pore diameter (nm)

(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(a)

00

02

04


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(b)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(c)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(d)

Figure 3 Adsorption BJH pore size distribution of prepared catalysts after calcinations ((a) HLB = 139 (b) HLB = 237 (c) HLB = 312 and(d) HLB = 40)


10nm

(a)

10nm

(b)

(c)

20nm

(d)

Figure 4 TEM image of prepared catalysts after calcinations ((a) HLB = 139 (b) HLB = 237 (c) HLB = 312 and (d) HLB = 40)

crystallite size of particles The 119889BET value is calculated fromsurface area which is measured by nitrogen adsorption-desorption assuming that the particles are spherical andnonporous The 119889XRD and 119889BET possess the cumulative andcomprehensive information on particle size although theyare derived indirectly However the 119889TEM value is a directevidence of average particle size of Fe

2O3suspension and thus

in this work it has been used for further calculationsAs shown in Table 1 the particle size is increased and the

particle size distribution becomes wider with the increase ofHLB value In fact nanoparticles are formed in the internalstructure of the microemulsion which is determined bythe HLB value of surfactant The results show that the sizeof different droplets determines the hematite particle sizedepending on the HLB value of surfactant

The effects of the iron particle size on the reductionbehavior of the catalysts were measured by H

2-TPR The

profiles of H2-TPR are presented in Figure 6 As shown in

Figure 6 all catalysts present two main reduction peaks atabout 700 and 900K in the H

2-TPR profiles It has been

postulated that the first stage corresponds to the reductions

of 120572-Fe2O3to magnetite (Fe

3O4) and CuO to Cu whereas

the second stage corresponds to the subsequent reduction ofFe3O4to metallic iron (120572-Fe) [15 16] It is also found that the

first stage can be further separated into two peaks the firstpeak corresponds to the reduction of the solid solution ofCuO and part of 120572-Fe

2O3to Cu and Fe

3O4 and the second

small peak is ascribed to the reduction of the residual 120572-Fe2O3to Fe3O4 The presence of Cu in iron catalyst reduces

120572-Fe2O3to Fe3O4at lower temperature rather than Cu-

free samples As CuO reduces Cu crystallites nucleate andprovide H

2dissociation sites which in turn lead to reactive

hydrogen species capable of reducing iron oxides at relativelylow temperatures [8 9]

The TPR profiles in Figure 6 clearly show that the firstreduction peaks of the catalysts shift to the lower temperaturewith the decrease of the iron particle sizeTheprobable reasonis higher interaction between iron and copper oxides inhomogeneous phase of the catalyst prepared via microemul-sion system This suggests that the microemulsion techniquepromotes the dispersion of Cu promoter which subsequentlyenhances the effect of Cu promoter improves the reduction


000

020

040

060Re

lativ

e fre

quen

cy

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(a)

000

020

040

060

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(b)

000

020

040

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(c)

Size range (nm)

000

020

040

Rela

tive f

requ

ency

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(d)

Figure 5 Relative particle size distribution of prepared catalysts after calcinations ((a) HLB = 139 (b) HLB = 237 (c) HLB = 312 (d)HLB = 40)

of the 120572-Fe2O3 and decreases the reduction temperature for

first peak in H2-TPR profile

The amount of the consumed H2during different reduc-

tion stages which is obtained from integrating the area of thecorresponding reduction peak is summarized in Table 3 Theoverall H

2consumption [molH

2molM(Fe +Cu)] of the first

reduction peaks can be assigned to the reduction of CuO andalso the reduction of 120572-Fe

2O3to Cu and Fe

3O4 respectively

In the first stage of reduction CuO and Fe2O3reacted with

hydrogen based on the following reactions

3Fe2O3+H2997888rarr 2Fe

3O4+H2O

(

molH2

mol Fe= 0166 for complete reduction)

(3)

CuO +H2997888rarr Cu +H

2O

(

molH2

molCu= 1 for complete reduction)

(4)

The peaks at 851 K (molH2mol Fe) correspond to the reduc-

tion of Fe3O4to Fe as below

Fe3O4+ 4H2997888rarr 3Fe + 4H

2O

(

mol H2


(5)

The peaks at higher temperature (above 900K)may be due tothe reduction of FeO to Fe and the H

2consumptions which

are consistent with theoretical valuesAs shown in Figure 6 and Table 3 smaller crystal size of

the catalyst has also influence on the reduction of Fe3O4to


450 550 650 750 850 950 1050 1150Temperature (K)

H2

upta

ke

(a)

(b)

(c)

(d)

Figure 6 TPR profiles of prepared catalysts after calcinations ((a)HLB = 139 (b) HLB = 237 (c) HLB = 312 and (d) HLB = 40)

0

05

1

15

2

25

3

35

4

45

0 2 4 6 8 10 12 14 16 18

OlP

a rat

io

Carbon number

HLB = 139HLB = 237

HLB = 312HLB = 40

Figure 7 Olefin-to-paraffin ratio in products after 35 h time-on-stream reaction conditions 583 K 17 bar (H

2CO)feed = 1 and

space velocity of 49 nl sdot hminus1 sdot gFeminus1 ((a) HLB = 139 (b) HLB = 237

(c) HLB = 312 and (d) HLB = 40)

120572-Fe as well as first reduction step The results show that theamount of the catalyst reduction increased with decreasingthe catalyst crystal size

32 Catalytic Activity The effect of the catalyst particle sizeon catalyst activity product selectivity and hydrocarbondistribution at the same time-on stream is listed in Table 4It was found that the CO and H

2conversion was increased

while the HLB value of surfactant decreased It is also shownin this table that the methane and CO

2selectivity increased

while the catalyst particle size decreased Moreover higherhydrocarbon selectivity and chain growth probability (120572)decreased when the crystal size decreased

Olefin-to-paraffin ratio in products and olefin and paraf-fin production rates after 35 h time-on-stream are shown inFigures 7 and 8 As listed in Table 4 and shown in Figures 7and 8 olefin selectivity is decreased by reduction of the HLBvalue of the surfactant (catalyst particle size decreased) Alsoas shown in Figures 7 and 8 olefin selectivity decreases withincreasing the olefins carbon number

The catalytic properties of nanoparticles depend on thesize of catalysts active site Thus different sizes of nanopar-ticles have different catalytic activity and selectivity Thedynamic surface restructuring of nanoparticles should alsodepend on their size that is smaller nanoparticles havehigher surface energies For the heterogeneous catalyticreactions adsorption equilibrium constant of feed increasedwith decreasing the particle size [13 14] By increasing theadsorption equilibrium constant of hydrogen and carbonmonoxide on surface of iron catalysts in small particles thecatalyst reduction and FTS reaction increased Also higheractivity of the iron catalyst with lower particle size (Table 4)may be related to the reduction ability of the catalysts thatincreased with the particle size (Figure 6 and Table 3)

It is postulated that 1-alkenes are primary products ofthe FTS reaction over iron-based catalyst and may be trans-formed to paraffin by hydrogenation as a secondary reaction[20 21] Secondary reactions occur when primary productsdesorbed from a site and then interact with another catalyticsite before leaving the catalyst particles Secondary reactionscan influence the type and molecular weight of the hydro-carbon products Hydrogenation of 1-alkenes to paraffin isthe most famous secondary reaction in FT synthesis Thusthe extent of secondary reactions can also be observed fromthe dependency of the 119874

119899119875119899ratio or olefin content on chain

length The ratio of olefins to paraffins depends on catalysttype structure and the reaction conditions Slow removalof reactive products (eg 120572-olefins) due to the reductionof diffusion coefficients with increasing chain length caninfluence the FTS reaction rate and selectivity The resultspresented in Table 4 show that the olefinparaffin ratios aredecreased with increasing catalyst particle size

Van der Laan and Beenackers emphasized the solubilityimpact (vapor-liquid equilibrium) over diffusion as the maincontributor on secondary reactions [21] As shown in Table 4the secondary reactions are increased (119874119875 decreased) inthe lower iron particle size because of some difficulties ofolefin diffusion in nanoparticles with narrow pores On theother hand the steric hindrance can limit the competitiveadsorption of bigger molecules on smaller crystal sizesThus increasing the adsorption equilibrium constant bydecreasing iron particle size is more for hydrogen than thatof carbon monoxide [8ndash12] Higher hydrogen concentrationson smaller particles enhance the hydrogenation of olefinTheresults presented in Figures 7 and 8 and Table 4 show thatthe olefinparaffin ratios are decreased with increasing thecatalyst particle size of the samples

Anderson-Schultz-Floury (ASF) distribution of FTSproducts on catalysts is presented in Figure 9 Product


00

05

10

15

20

25

30

35

40

0 4 8 12 16Carbon number

HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)

Figure 8 Olefin and paraffin production rates after 35 h time-on-stream and reaction conditions 583 K 17 bar (H2CO)feed = 1 space

velocity of 49 nl sdot hminus1 sdot gFeminus1 ((a) HLB = 139 (b) HLB = 237 (c) HLB = 312 and (d) HLB = 40)

Table 3 Quantitative results of H2 consumption for catalysts in H2-TPRa

HLB Peak (K) H2 consumption Reductionmol H2mol Mb mol H2mol Fe

139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106

aThe H2 consumption was measured from the area under the corresponding peakbM = Fe + Cu


Table 4 Catalysts activity and products selectivity after 35 h time-on-stream

HLB XCOa HCb OPc

120572d CO2 ()e Products selectivity

CH4 C2ndashC4 C5ndashC12 C12+

40 672 213 11 083 313 137 417 350 96312 715 222 10 08 322 146 476 315 63237 752 228 10 078 331 156 532 274 38139 775 235 09 075 345 176 575 228 21Reaction conditions 563K 17Mpa and H2CO = 1 and space velocity = 49 nl sdot hminus1 sdot gFe

minus1aCarbon monoxide conversion (mol)bHydrocarbon production gCH2gFes (times10

5) and CH4 freecOlefin to paraffin ratiodChain growth probabilityeCO2 selectivity selectivity to oxygenates was negligible (lt20) in all cases

0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40

Figure 9 Overall products distributions on catalysts after 35 h time-on-stream reaction conditions 583 K 17 bar (H

2CO)feed = 1 space

velocity of 49 nl sdot hminus1 sdot gFeminus1 ((a) HLB = 139 (b) HLB = 237 (c)

HLB = 312 and (d) HLB = 40)

distribution shows a slight shift to the lower molecularweight hydrocarbons by decreasing the HLB value of thesurfactant The trend lines are plotted to determine the chaingrowth probability 120572 As listed in Table 4 the chain growthprobabilities were 083 08 078 and 075 for 40 312 237and 139 HLB value of surfactant respectively This confirmsthe higher molecular weight hydrocarbons production usinghigher HLB value of surfactant in preparation of catalystAs mentioned in the previous section higher HLB value ofsurfactant produced higher particle size of catalysts

Figure 9 and Table 4 also show the effects of the catalystparticle size on the selectivity of Fischer-Tropsch synthesisproducts Comparison of the product distributions of thecatalysts clearly shows that the product distribution shiftto the lower molecular weight hydrocarbons by decreasingthe HLB value of the surfactant (or decreasing the catalystparticle size)

The most accepted mechanism for FTS reaction is C1

insertion which leads to the carbide theory [21] These C1

species have various hydrogenation degrees as follows COHCO HCOH CH and CH

2 Literature results [19 20] have

discussed that light hydrocarbons are built up by monomersthat exhibited higher degree of hydrogenation that is CH

2

Obviously heavy hydrocarbons are built up due tomonomersexcept CH

2species with lower degree of hydrogenation

With increasing the hydrogen concentration on the surfaceof the catalyst the concentration of C

1monomers with

higher degree of hydrogenation are increased Increasing theconcentration of hydrogen on the surface of the catalysts as aresult of reduction of the catalyst particle size increases theconcentration of C

1monomers and ultimately leads to the

higher selectivity to the lower hydrocarbons being enhanced

4 Conclusion

Nanosized iron oxide particles have been successfully synthe-sized by reverse microemulsion with different HLB valuesThe iron oxide particle size and particle size distribution areincreased by decreasing of HLB values It was found that theCO and H

2conversion is increased as the HLB value of the

surfactant is reduced Also the methane and CO2selectivity

is increased at the same time as the catalyst particle size isdecreased In addition higher hydrocarbon selectivity andchain growth probability (120572) show a descending trend incarbon number when the crystal size decreases

Acknowledgment

Financial support of the Ferdowsi University of MashhadIran (P153691-8985) is gratefully acknowledged

References

[1] A T Bell ldquoThe impact of nanoscience on heterogeneouscatalysisrdquo Science vol 299 no 5613 pp 1688ndash1691 2003

[2] J Y Ying ldquoDesign and synthesis of nanostructured catalystsrdquoChemical Engineering Science vol 61 no 5 pp 1540ndash1548 2006

[3] X Zhou W Xu G Liu D Panda and P Chen ldquoSize depen-dent catalytic activity and dynamics of gold nanoparticles at


the single-molecule levelrdquo Journal of the American ChemicalSociety vol 132 no 1 pp 138ndash146 2010

[4] P Kumar and K L MittalHandbook of Microemulsions Scienceand Technology Marcel Dekker New York NY USA 1999

[5] S Eriksson U Nylen S Rojas andM Boutonnet ldquoPreparationof catalysts from microemulsions and their applications inheterogeneous catalysisrdquoApplied Catalysis A vol 265 no 2 pp207ndash219 2004

[6] I Capek ldquoPreparation of metal nanoparticles in water-in-oil (wo) microemulsionsrdquo Advances in Colloid and InterfaceScience vol 110 no 1-2 pp 49ndash74 2004

[7] G Guo Y Sun Z Wang and H Guo ldquoPreparation of hydrox-yapatite nanoparticles by reverse microemulsionrdquo CeramicsInternational vol 31 no 6 pp 869ndash872 2005

[8] T Herranz S Rojas F J Perez-Alonso M Ojeda P Terrerosand J L G Fierro ldquoHydrogenation of carbon oxides overpromoted Fe-Mn catalysts prepared by the microemulsionmethodologyrdquo Applied Catalysis A vol 311 pp 66ndash75 2006

[9] A Sarkar D Seth A K Dozier J K Neathery H H Hamdehand BHDavis ldquoFischer-Tropsch synthesismorphology phasetransformation and particle size growth of nano-scale particlesrdquoCatalysis Letters vol 117 no 1-2 pp 1ndash17 2007

[10] A Nakhaei Pour S Taghipoor M Shekarriz S M K Shahriand Y Zamani ldquoFischer-tropsch synthesis with FeCuLaSiO

2

nano-structured catalystrdquo Journal of Nanoscience andNanotech-nology vol 9 no 7 pp 4425ndash4429 2009

[11] A Nakhaei Pour M R Housaindokht S F Tayyari and JZarkesh ldquoFischer-Tropsch synthesis by nano-structured ironcatalystrdquo Journal of Natural Gas Chemistry vol 19 no 3 pp284ndash292 2010

[12] A Nakhaei Pour M R Housaindokht S F Tayyari and JZarkesh ldquoEffect of nano-particle size on product distributionand kinetic parameters of FeCuLa catalyst in Fischer-Tropschsynthesisrdquo Journal of Natural Gas Chemistry vol 19 no 2 pp107ndash116 2010

[13] D Y Murzin ldquoSize-dependent heterogeneous catalytic kinet-icsrdquo Journal ofMolecular Catalysis A vol 315 no 2 pp 226ndash2302010

[14] D Y Murzin ldquoThermodynamic analysis of nanoparticle sizeeffect on catalytic kineticsrdquo Chemical Engineering Science vol64 no 5 pp 1046ndash1052 2009

[15] ANakhaei Pour SMK ShahriH R Bozorgzadeh Y ZamaniA Tavasoli and M A Marvast ldquoEffect of Mg La and Capromoters on the structure and catalytic behavior of iron-basedcatalysts in Fischer-Tropsch synthesisrdquo Applied Catalysis A vol348 no 2 pp 201ndash208 2008

[16] A Nakhaei Pour Y Zamani A Tavasoli S M K Shahri andS A Taheri ldquoStudy on products distribution of iron and iron-zeolite catalysts in Fischer-Tropsch synthesisrdquo Fuel vol 87 no10-11 pp 2004ndash2012 2008

[17] A Nakhaei Pour M R Housaindokht S F Tayyari J Zarkeshand M R Alaei ldquoDeactivation studies of Fischer-Tropschsynthesis on nano-structured iron catalystrdquo Journal ofMolecularCatalysis A vol 330 no 1-2 pp 112ndash120 2010

[18] H I Chen and H Y Chang ldquoHomogeneous precipitation ofcerium dioxide nanoparticles in alcoholwater mixed solventsrdquoColloids and Surfaces A vol 242 pp 61ndash69 2004

[19] A Ramirez and L Sierra ldquoSimulation of nitrogen sorptionprocesses in materials with cylindrical mesopores hysteresisas a thermodynamic and connectivity phenomenonrdquo ChemicalEngineering Science vol 61 no 13 pp 4233ndash4241 2006

[20] M E Dry ldquoThe Fischer-Tropsch synthesisrdquo inCatalysis Scienceand Technology J R Anderson and M Boudart Eds SpringerNew York NY USA 1981

[21] G P van der Laan and A A C M Beenackers ldquoKinetics andselectivity of the Fischer-Tropsch synthesis a literature reviewrdquoCatalysis Reviews Science and Engineering vol 41 no 3-4 pp255ndash318 1999

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


Fischer-Tropsch synthesis (FTS) [8ndash12] Murzin reportedthat FTS reactions on the supported cobalt based catalystsshow many sensitivities to the catalyst particle size [13 14]Moreover many new results showed that nanosized ironparticles play an essential role to achieve high FTS activity [8ndash12] Iron-based catalysts are preferred for utilizing synthesisgas derived from coal or biomass because of the excellentactivity for the water-gas-shift reaction which allows usinga synthesis gas with a low H

2CO ratio directly without an

upstream shift-step [15 16] In our previous works we triedto show structure sensitivity of unsupported iron catalysts[10 11 17]

In this the present work feasibility of iron nanoparticleformation in the microemulsion systems with different HLBvalues was investigated Moreover effects of HLB values onthe particle size were investigated Then catalyst character-ization and catalytic FTS reaction are examined at differentparticle sizes

2 Experimental

21 Catalyst Preparation Fe-Cu nanoparticles were preparedby coprecipitation in a water-in-oil microemulsion [11ndash15] The precipitation was performed in the single-phasemicroemulsion operating region For this purpose a watersolution of metal precursor Fe(NO

3)3-9H2O (Fluka puriss

pa ACS 98ndash100) and Cu(NO3)2-4H2O (Fluka purum

pa gt 97) were added to a mixture of an oil phase(Chloroform Aldrich gt99) and mixed surfactants containTriton X-100 and SDS The HLB values of Triton X-100 andSDS are 134 and 40 respectively Besides 1-butanol as acosurfactant was added to system in order to obtain a propermicroemulsion

For preparation of various sizes of hematite nanoparticlesreverse microemulsions were prepared with different HLBvalues through varying the weight ratio of Triton X-100 andSDS For a quaternary system of surfactant (119878 g) oil (119874 g)alcohol (119860 g) and water (119882 g) the following symbols weredefined 120572 represents the mass fraction of oil in water plus oil120572 = 119874(119882 + 119874) 120573 the mass ratio of surfactant in the wholesystem 120573 = 119878(119882 + 119874 + 119878 + 119860) and 120576 the mass fraction ofalcohol in the whole system 120576 = 119860(119882 + 119874 + 119878 + 119860) [4ndash7]In the prepared microemulsion system the parameters are120572 = 062 120573 = 003 and 120576 = 028 After stirring well andstabilizing for 24 h a transparentmixturewas obtainedThenhydrazine was added to reducemetal precursorThe resultingmixture was decanted overnight The solid was recoveredby centrifuging and then washing thoroughly with distilledwater and ethanol for several times Lanthanum promoterwas added by wet impregnation method with La(NO

3)3

precursor on its optimal value after treatment in air asdescribed previously [10ndash12 17]The promoted catalysts weredried at 383K for 16 h and calcined at 723K for 3 h in air Thecatalyst compositions were designated in terms of the atomicratios as 100Fe564Cu2La

22 Catalyst Characterization Elemental analysis was per-formed to determine the composition of the elements in

the bulk of catalysts The surface area was calculated fromthe Brunauer-Emmett-Teller (BET) equation and pore vol-ume average pore diameter and pore size distribution ofthe catalysts were determined by N

2physisorption using a

micromeritics ASAP 2010 automated system A 05 g catalystsample was degassed in the micromeritics ASAP 2010 at100∘C for 1 h and then at 573K for 2 h prior to analysis Theanalysis was done using N

2adsorption at 77K Both the pore

volume and the average pore diameter were calculated byBarrett-Joyner-Hallender (BJH)method from the adsorptionisothermAssuming that the Fe

2O3particles are spherical the

corresponding particle size (119889BET) can be estimated as [18]

119889BET =6

120588119860

(1)

where 120588 is the true density of Fe2O3 that is 524 gcm3 and

119860 is the specific surface area of samplesThe XRD spectrum of the catalysts was collected by an

X-ray diffractometer Philips PW1840 X-ray diffractometerusing monochromatized CuK

120572radiation (40 kV 40mA)

and a step scan mode at a scan rate of 002∘ (2120579) per secondfrom 10ndash80∘ XRD peak identification was recognized bycomparison to the JCPDS database software The averagecrystallite size of samples 119889XRD can be estimated from XRDpatterns by applying full-width half-maximum (FWHM) ofcharacteristic peak (104) Fe

2O3located at 2120579 = 333∘ peak to

Scherrer equation

119889XRD =09120582

FWHMcos 120579 (2)

where 120582 is the X-ray wavelength (15406 A in this study) and120579 is the diffraction angle for the (104) plane

Temperature programmed reduction (TPR) measure-ments of the calcined catalysts were recorded by using aMicromeritics TPD-TPR 2900 system The catalyst samples(50mg) were purged with argon at 473 for 30min and cooledto 323K The samples were heated from 350 to 1100K at arate of 10 Kmin under flow of 51 hydrogen in argon gasmixture The consumption of hydrogen was monitored by athermal conductivity detector (TCD)

The morphology of prepared catalysts was observed witha transmission electron microscope (TEM LEO 912 ABGermany) An appropriate amount of Fe

2O3suspension

directly taken from the reaction solution was dropped ontothe carbon-coated copper grids for TEM observation Theaverage particle size (119889TEM) and particle size distributionwere determined by TEM images considering more than 100particles

23 Catalytic Performance The catalysts were tested in afixed-bed microreactor A detailed description of the exper-imental setup and procedures has been provided elsewhere[15 16] The catalyst samples (30 g catalyst diluted with 12 gquartz 100ndash180 120583m) were activated by a 5 (vv) H

2N2

gas mixture with space velocity of 151 nl sdot hminus1 sdot gFeminus1 at

01MPa by increasing temperature from ambient to 673Kat 5 Kmin then maintained for one hour and subsequently


20 30 40 50 60 70

Inte

nsity

(a)

(b)

(c)

(d)

2120579

012

104

110

113

024

116

018

214

300









2 CH4











Pore volume(cm3g)a













0

100

50

150


Volu

me a

dsor

bed

(cm

3g

STP

)

(a)

0

100

50

00 05 10


Volu

me a

dsor

bed

(cm

3g

STP

)

(b)

0

100

50

150


Volu

me a

dsor

bed

(cm

3g

STP

)

(c)

0

100

50

00 05 10


Volu

me a

dsor

bed

(cm

3g

STP

)

(d)


and (d) HLB = 40)

00

02

04


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(a)

00

02

04


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(b)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(c)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(d)



10nm

(a)

10nm

(b)

(c)

20nm

(d)







2-TPR The









2O3to Cu and Fe

3O4 and the second








000

020

040

060Re

lativ

e fre

quen

cy

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(a)

000

020

040

060

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(b)

000

020

040

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(c)

Size range (nm)

000

020

040

Rela

tive f

requ

ency

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(d)






2consumption [molH



2O3to Cu and Fe

3O4 respectively




3O4+H2O

(

molH2


(3)


2O

(

molH2


(4)



Fe3O4+ 4H2997888rarr 3Fe + 4H

2O

(

mol H2


(5)


2consumptions which




450 550 650 750 850 950 1050 1150Temperature (K)

H2

upta

ke

(a)

(b)

(c)

(d)


0

05

1

15

2

25

3

35

4

45

0 2 4 6 8 10 12 14 16 18

OlP

a rat

io

Carbon number

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 and


(c) HLB = 312 and (d) HLB = 40)















00

05

10

15

20

25

30

35

40


HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)





139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106




HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


20 30 40 50 60 70

Inte

nsity

(a)

(b)

(c)

(d)

2120579

012

104

110

113

024

116

018

214

300









2 CH4











Pore volume(cm3g)a













0

100

50

150


Volu

me a

dsor

bed

(cm

3g

STP

)

(a)

0

100

50

00 05 10


Volu

me a

dsor

bed

(cm

3g

STP

)

(b)

0

100

50

150


Volu

me a

dsor

bed

(cm

3g

STP

)

(c)

0

100

50

00 05 10


Volu

me a

dsor

bed

(cm

3g

STP

)

(d)


and (d) HLB = 40)

00

02

04


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(a)

00

02

04


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(b)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(c)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(d)



10nm

(a)

10nm

(b)

(c)

20nm

(d)







2-TPR The









2O3to Cu and Fe

3O4 and the second








000

020

040

060Re

lativ

e fre

quen

cy

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(a)

000

020

040

060

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(b)

000

020

040

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(c)

Size range (nm)

000

020

040

Rela

tive f

requ

ency

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(d)






2consumption [molH



2O3to Cu and Fe

3O4 respectively




3O4+H2O

(

molH2


(3)


2O

(

molH2


(4)



Fe3O4+ 4H2997888rarr 3Fe + 4H

2O

(

mol H2


(5)


2consumptions which




450 550 650 750 850 950 1050 1150Temperature (K)

H2

upta

ke

(a)

(b)

(c)

(d)


0

05

1

15

2

25

3

35

4

45

0 2 4 6 8 10 12 14 16 18

OlP

a rat

io

Carbon number

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 and


(c) HLB = 312 and (d) HLB = 40)















00

05

10

15

20

25

30

35

40


HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)





139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106




HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


0

100

50

150


Volu

me a

dsor

bed

(cm

3g

STP

)

(a)

0

100

50

00 05 10


Volu

me a

dsor

bed

(cm

3g

STP

)

(b)

0

100

50

150


Volu

me a

dsor

bed

(cm

3g

STP

)

(c)

0

100

50

00 05 10


Volu

me a

dsor

bed

(cm

3g

STP

)

(d)


and (d) HLB = 40)

00

02

04


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(a)

00

02

04


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(b)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(c)

00

02


(cm

3n

mg

STP

)Ad

sorp

tiondV

dlo

g(D

)

(d)



10nm

(a)

10nm

(b)

(c)

20nm

(d)







2-TPR The









2O3to Cu and Fe

3O4 and the second








000

020

040

060Re

lativ

e fre

quen

cy

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(a)

000

020

040

060

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(b)

000

020

040

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(c)

Size range (nm)

000

020

040

Rela

tive f

requ

ency

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(d)






2consumption [molH



2O3to Cu and Fe

3O4 respectively




3O4+H2O

(

molH2


(3)


2O

(

molH2


(4)



Fe3O4+ 4H2997888rarr 3Fe + 4H

2O

(

mol H2


(5)


2consumptions which




450 550 650 750 850 950 1050 1150Temperature (K)

H2

upta

ke

(a)

(b)

(c)

(d)


0

05

1

15

2

25

3

35

4

45

0 2 4 6 8 10 12 14 16 18

OlP

a rat

io

Carbon number

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 and


(c) HLB = 312 and (d) HLB = 40)















00

05

10

15

20

25

30

35

40


HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)





139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106




HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


10nm

(a)

10nm

(b)

(c)

20nm

(d)







2-TPR The









2O3to Cu and Fe

3O4 and the second








000

020

040

060Re

lativ

e fre

quen

cy

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(a)

000

020

040

060

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(b)

000

020

040

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(c)

Size range (nm)

000

020

040

Rela

tive f

requ

ency

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(d)






2consumption [molH



2O3to Cu and Fe

3O4 respectively




3O4+H2O

(

molH2


(3)


2O

(

molH2


(4)



Fe3O4+ 4H2997888rarr 3Fe + 4H

2O

(

mol H2


(5)


2consumptions which




450 550 650 750 850 950 1050 1150Temperature (K)

H2

upta

ke

(a)

(b)

(c)

(d)


0

05

1

15

2

25

3

35

4

45

0 2 4 6 8 10 12 14 16 18

OlP

a rat

io

Carbon number

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 and


(c) HLB = 312 and (d) HLB = 40)















00

05

10

15

20

25

30

35

40


HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)





139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106




HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


000

020

040

060Re

lativ

e fre

quen

cy

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(a)

000

020

040

060

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(b)

000

020

040

Rela

tive f

requ

ency

Size range (nm)

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(c)

Size range (nm)

000

020

040

Rela

tive f

requ

ency

5ndash10

10ndash1

5

15ndash2

0

20ndash2

5

25ndash3

0

lt30

(d)






2consumption [molH



2O3to Cu and Fe

3O4 respectively




3O4+H2O

(

molH2


(3)


2O

(

molH2


(4)



Fe3O4+ 4H2997888rarr 3Fe + 4H

2O

(

mol H2


(5)


2consumptions which




450 550 650 750 850 950 1050 1150Temperature (K)

H2

upta

ke

(a)

(b)

(c)

(d)


0

05

1

15

2

25

3

35

4

45

0 2 4 6 8 10 12 14 16 18

OlP

a rat

io

Carbon number

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 and


(c) HLB = 312 and (d) HLB = 40)















00

05

10

15

20

25

30

35

40


HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)





139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106




HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


450 550 650 750 850 950 1050 1150Temperature (K)

H2

upta

ke

(a)

(b)

(c)

(d)


0

05

1

15

2

25

3

35

4

45

0 2 4 6 8 10 12 14 16 18

OlP

a rat

io

Carbon number

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 and


(c) HLB = 312 and (d) HLB = 40)















00

05

10

15

20

25

30

35

40


HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)





139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106




HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

05

10

15

20

25

30

35

40


HLB = 139

(mm

ole

(gca

tmiddoth))

(a)

00

05

10

15

20

25

30

35

0 4 8 12 16

Carbon number

HLB = 237

(mm

ole

(gca

tmiddoth))

(b)

00

05

10

15

20

25

30

0 4 8 12 16

Carbon number

Para

Ol

HLB = 312

(mm

ole

(gca

tmiddoth))

(c)

00

05

10

15

20

25


Para

Ol

HLB = 40(m

mol

e(g

catmiddoth

))

(d)





139 533 0171 93850 124

237 558 0163 87851 116

312 608 0154 84842 112

40 640 0142 79852 106




HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



HLB XCOa HCb OPc






0

00

5 10 15 20 25 30 35

Carbon number

minus120

minus100

minus80

minus60

minus40

minus20

lnX

i

HLB = 139HLB = 237

HLB = 312HLB = 40


2CO)feed = 1 space


HLB = 312 and (d) HLB = 40)








2




1monomers with




4 Conclusion





Acknowledgment


References













2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










2






















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

research article size control of iron oxide nanoparticles...

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