0
Fischer-TropschFischer-Tropsch
CatalystsCatalysts
Preparation, Thermal PretreatmentPreparation, Thermal Pretreatment
and B...
Fischer-Tropsch ProcessFischer-Tropsch Process
 Reaction of carbon monoxide and hydrogen toReaction of carbon monoxide an...
ThemesThemes
 Dissociative adsorption of methane and carbon monoxideDissociative adsorption of methane and carbon monoxid...
Competitive DissociativeCompetitive Dissociative
AdsorptionAdsorption
CH4
H C H H H
2H2
CO O
CO
O O O O O O O O O O O O O ...
Competitive DissociativeCompetitive Dissociative
AdsorptionAdsorption
CO
C O H H
H2O
O
C
O C C C
CO2
C H C C H C H C H C
C...
Reducibility of Metal OxidesReducibility of Metal Oxides
O O O O O O O O O O O O O O
O O O O O O O O O O O O O O O O O O O...
Feed Stock ofFeed Stock of
the Fischer-Tropsch Processthe Fischer-Tropsch Process
 Feed stock : Initially coalFeed stock ...
(Catalytic) Partial Oxidation(Catalytic) Partial Oxidation
 Pure oxygen required to performPure oxygen required to perfor...
Heats of ReactionHeats of Reaction
 Reaction of methane to COReaction of methane to CO22 and Hand H22O very exothermicO v...
Heats of ReactionHeats of Reaction
 Reaction of methane with carbon dioxide and ofReaction of methane with carbon dioxide...
(Catalytic) Partial Oxidation(Catalytic) Partial Oxidation
 Initial highly exothermic reactionInitial highly exothermic r...
CO + H2O CO2 + H2
Reaction PathsReaction Paths
Catalytic Partial OxidationCatalytic Partial Oxidation
CH4 + O2 CO2 + H2O
C...
Direct vs Indirect Catalytic PartialDirect vs Indirect Catalytic Partial
OxidationOxidation
CH4
CO+ H2CO2 + H2O
Direct
Ind...
Methane activationMethane activation
Problem : CH4 activation calls for high
temperature at which the reactivity of CO and...
Methane ActivationMethane Activation
METALS (precious)
Low oxygen coverage
Pd,Pt,Ru,(Ni)
OXIDES
Strongly bound oxygen
Smal...
Precious metal systemsPrecious metal systems
Pt, Pd, Ru, (Ni) T<700°C Indirect CPO
Formation highly active phase for compl...
Precious metals : PdPrecious metals : Pd
0
0.5
1
1.5
2
50 150 250 350 450 550 650
T (°C)
pX(%)
CO
H2
CH4
O2
CO2
300 mg 0.5...
Influence of Oxidizing /Influence of Oxidizing /
Reducing ConditionsReducing Conditions
Highly active but unstable reduced...
Catalytic Partial Oxidation ofCatalytic Partial Oxidation of
MethaneMethane
1 vol% CH4 0.5 vol% O2 in argon 100 ml(stp)/mi...
Catalytic Partial Oxidation onCatalytic Partial Oxidation on
Precious Metals (Nickel)Precious Metals (Nickel)
 Oxidation ...
Trade Time for TemperatureTrade Time for Temperature
 Catalytic partial oxidation at temperaturesCatalytic partial oxidat...
Catalytic Partial Oxidation onCatalytic Partial Oxidation on
OxidesOxides
OXIDES
Strongly bound oxygen
Small amount of ads...
Catalytic Partial Oxidation onCatalytic Partial Oxidation on
ZrOZrO22
0
20
40
60
80
100
450 550 650 750 850
T (°C)
%
XCH
S...
Effect of Residence TimeEffect of Residence Time
0
20
40
60
80
100
0 2 4 6 8 10
Methane conversion (%)
selectivity(%)
2% C...
Oxidation of HOxidation of H22 and CO on ZrOand CO on ZrO22
0
20
40
60
80
100
300 400 500 600 700
T (°C)
Conversion(%)
500...
Experimental Results on ZrOExperimental Results on ZrO22
ZrO2
Inactive reforming catalyst
Low activity CO-shift
Low act...
Survey Different Metal OxidesSurvey Different Metal Oxides
0
20
40
60
80
100
%
X CH
S CO
S H
S C
2% CH4 1% O2 100 ml
/min ...
Orders of the Reaction withOrders of the Reaction with
respect to Oxygen and Methanerespect to Oxygen and Methane
 Reacti...
Orders of the Reaction withOrders of the Reaction with
Respect to Oxygen of Metal OxidesRespect to Oxygen of Metal Oxides
...
DiscussionDiscussion
OxidesOxides
TiOTiO22 ,, ZrOZrO22 ,Y,Y22 OO33 ,La,La22 OO33
Low activity
High selectivity
High reacti...
Catalytic Partial OxidationCatalytic Partial Oxidation
on Metalson Metals
Precious metals Pd, Pt, Ru, (Ni) steady state
co...
Catalytic Partial OxidationCatalytic Partial Oxidation
on Oxideson Oxides
ZrO2, TiO2 : CO , H2 (H2O) primary
products
Y2O3...
Fischer-Tropsch SynthesisFischer-Tropsch Synthesis
 Reaction : CO + 2HReaction : CO + 2H22 →→ ‘CH‘CH22’ + H’ + H22OO
 Un...
Carbon Fibers Grown in CatalystCarbon Fibers Grown in Catalyst
BedBed
Scanning
electron-
micrograph
GBH Enterprises Ltd.
Carbon FibersCarbon Fibers
Transmission electron
micrograph
Thick and thin carbon fibers
have grown from this catalyst
GBH...
Nickel Particle at End ofNickel Particle at End of
Carbon FiberCarbon Fiber
Transmission
electron micrograph
Carbon fibers...
Catalysts forCatalysts for
Fischer-Tropsch SynthesisFischer-Tropsch Synthesis
 Required :Required :
• Dissociation of car...
Catalysts forCatalysts for
Fischer-Tropsch SynthesisFischer-Tropsch Synthesis
 Iron, cobalt and nickel able to react to m...
Catalysts forCatalysts for
Fischer-Tropsch SynthesisFischer-Tropsch Synthesis
 Dissociation of carbon monoxide not on mos...
Promoted Nickel CatalystsPromoted Nickel Catalysts
 Assisted dissociation of carbon monoxide atAssisted dissociation of c...
Preparation of SupportedPreparation of Supported
Nickel CatalystsNickel Catalysts
 Injection of nickel nitrate into suspe...
Mean Size of Nickel OxideMean Size of Nickel Oxide
ParticlesParticles
 Assessment of mean size of nickel oxide particles ...
Temperature-Programmed Reduction ofTemperature-Programmed Reduction of
Silica-Supported Nickel CatalystsSilica-Supported N...
Temperature-Programmed Reduction ofTemperature-Programmed Reduction of
Titania-Supported Nickel CatalystsTitania-Supported...
Infra-Red Spectra of Carbon MonoxideInfra-Red Spectra of Carbon Monoxide
Adsorbed on Nickel CatalystsAdsorbed on Nickel Ca...
CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on
Silica-Supported Nickel CatalystsSilica-Supported Nickel Catalyst...
Selectivities of Fischer-TropschSelectivities of Fischer-Tropsch
Synthesis on Ni/SiOSynthesis on Ni/SiO22 CatalystsCatalys...
CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on
Titania-Supported Nickel CatalystsTitania-Supported Nickel Cataly...
Comparison T.P.R. and Activity at 525 KComparison T.P.R. and Activity at 525 K
of Ni/TiOof Ni/TiO22 CatalystsCatalysts
20 ...
Comparison T.P.R. and Activity atComparison T.P.R. and Activity at
525 K of Ni/TiO525 K of Ni/TiO22 CatalystsCatalysts
20 ...
CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on
Titania-Supported Nickel CatalystsTitania-Supported Nickel Cataly...
CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on
Titania-Supported Nickel CatalystsTitania-Supported Nickel Cataly...
Magnetization ofMagnetization of
Titania-Supported Nickel CatalystsTitania-Supported Nickel Catalysts
Measured after reduc...
Temperature-ProgrammedTemperature-Programmed
Hydrogenation of Nickel CarbidesHydrogenation of Nickel Carbides
20 wt.% Ni/T...
Nickel (Surface) CarbideNickel (Surface) Carbide
C
C
C C C
C
CC
CC C
C
CC C
C C
C C C
C
Surface carbide leading to methane...
Schematic Description of Silica-Schematic Description of Silica-
Supported Nickel CatalystsSupported Nickel Catalysts
GBH ...
Schematic Description of Titania-Schematic Description of Titania-
Supported Nickel CatalystsSupported Nickel Catalysts
GB...
Conclusions about Fischer-Conclusions about Fischer-
Tropsch on NickelTropsch on Nickel
 Promotion of dissociative adsorp...
Preparation of Supported CobaltPreparation of Supported Cobalt
Catalysts by Impregnation and DryingCatalysts by Impregnati...
Shape of Drop dried onShape of Drop dried on
GlassGlass
Drop of solution of copper(II) nitrate dried on microscope glass s...
Shape of Drop dried onShape of Drop dried on
GlassGlass
Drop of solution of copper(II) citrate dried on microscope glass s...
Mean Particle Size of SupportedMean Particle Size of Supported
Cobalt Oxide by XPSCobalt Oxide by XPS
 CatalystCatalyst M...
Estimation of Reducibility byEstimation of Reducibility by
Measurement of the MagnetizationMeasurement of the Magnetizatio...
Estimation of Reducibility byEstimation of Reducibility by
Measurement of the MagnetizationMeasurement of the Magnetizatio...
Fischer-Tropsch Synthesis onFischer-Tropsch Synthesis on
Supported Co catalysts at 525 KSupported Co catalysts at 525 K
Co...
Selectivities of Alumina-SupportedSelectivities of Alumina-Supported
Cobalt Catalysts at 525 KCobalt Catalysts at 525 K
Ca...
Conclusions about SupportedConclusions about Supported
Cobalt CatalystsCobalt Catalysts
 Reduction of alumina-supported c...
Supported Iron CatalystsSupported Iron Catalysts
 Supported iron catalysts very difficult to reduceSupported iron catalys...
Supported Iron CatalystsSupported Iron Catalysts
 Our invention : Initial calcination of supported complexOur invention :...
Supported Iron Alloy CatalystsSupported Iron Alloy Catalysts
 Precipitation of complex cyanides with metal ions toPrecipi...
Supported Iron Alloy CatalystsSupported Iron Alloy Catalysts
 Reaction with potassium iron cyanide complexes leadsReactio...
Supported Iron Alloy CatalystsSupported Iron Alloy Catalysts
 Preparation of potassium-free iron and nickel-ironPreparati...
Comparison of Potassium-Free andComparison of Potassium-Free and
Potassium Containing IronPotassium Containing Iron
Cataly...
Comparison of Potassium-Free andComparison of Potassium-Free and
Potassium Containing NiFe CatalystsPotassium Containing N...
Comparison of Potassium-Free FeComparison of Potassium-Free Fe
and Ni-Fe Catalystsand Ni-Fe Catalysts
NiFe4/TiO2
NiFe/TiO2...
Selectivities of Titania-SupportedSelectivities of Titania-Supported
Fe and Fe-Ni CatalystsFe and Fe-Ni Catalysts
GBH Ente...
Magnetization of K-Free andMagnetization of K-Free and
K Containing Fe/TiOK Containing Fe/TiO22 CatalystsCatalysts
Both po...
Magnetization of Spent Catalysts as aMagnetization of Spent Catalysts as a
Function of Temperature in Flow of HFunction of...
Magnetization of Iron-Nickel CatalystsMagnetization of Iron-Nickel Catalysts
during Fischer-Tropsch Synthesisduring Fische...
Magnetization of Spent CatalystsMagnetization of Spent Catalysts
as a Function of Temperature inas a Function of Temperatu...
Temperature-Programmed Reduction ofTemperature-Programmed Reduction of
Spent Fe and Fe-Ni CatalystsSpent Fe and Fe-Ni Cata...
Temperature-Programmed Reduction ofTemperature-Programmed Reduction of
Spent Fe and Fe-Ni CatalystsSpent Fe and Fe-Ni Cata...
Infra-Red Spectra of Adsorbed CarbonInfra-Red Spectra of Adsorbed Carbon
MonoxideMonoxide
Infra-red spectra of carbon mono...
Conclusions about Effect ofConclusions about Effect of
PotassiumPotassium
 Potassium does not prevent reaction of iron or...
Zirconia-Supported Iron CatalystsZirconia-Supported Iron Catalysts
 Zirconia as a support to limit reaction of iron(II) w...
Fischer-Tropsch Synthesis onFischer-Tropsch Synthesis on
Zirconia-Supported Iron CatalystZirconia-Supported Iron Catalyst
...
Selectivity of Zirconia-Selectivity of Zirconia-
Supported Iron CatalystSupported Iron Catalyst
Synthesis at 24 bar,
623 K...
Fischer-Tropsch Synthesis on Zirconia-Fischer-Tropsch Synthesis on Zirconia-
Supported Iron CatalystSupported Iron Catalys...
Selectivity of Zirconia-SupportedSelectivity of Zirconia-Supported
Iron CatalystIron Catalyst
Synthesis at 24 bar,
623 K, ...
Production of OlefinsProduction of Olefins
 Measurements in nanoflow apparatusMeasurements in nanoflow apparatus
 Relati...
Conclusions (1)Conclusions (1)
 Preparation of supported iron, cobalt, nickel, and iron-Preparation of supported iron, co...
Conclusions (2)Conclusions (2)
 Deposition-precipitation, impregnation withDeposition-precipitation, impregnation with
ba...
Fischer-Tropsch Catalysts: Preparation, Thermal Pretreatment and Behavior During Catalytic Reaction
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Fischer-Tropsch Catalysts: Preparation, Thermal Pretreatment and Behavior During Catalytic Reaction

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Fischer-Tropsch Process
Themes
Competitive Dissociative Adsorption
Reducibility of Metal Oxides
Feed Stock of the Fischer-Tropsch Process
Catalytic Partial Oxidation
Heats of Reaction
Direct vs Indirect Catalytic Partial Oxida.....

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Transcript of "Fischer-Tropsch Catalysts: Preparation, Thermal Pretreatment and Behavior During Catalytic Reaction"

  1. 1. Fischer-TropschFischer-Tropsch CatalystsCatalysts Preparation, Thermal PretreatmentPreparation, Thermal Pretreatment and Behavior during Catalytic Reactionand Behavior during Catalytic Reaction Gerard B. HawkinsGerard B. Hawkins Managing DirectorManaging Director GBH Enterprises Ltd.
  2. 2. Fischer-Tropsch ProcessFischer-Tropsch Process  Reaction of carbon monoxide and hydrogen toReaction of carbon monoxide and hydrogen to mainly liquid hydrocarbonsmainly liquid hydrocarbons  Invented in Germany during the twenties of theInvented in Germany during the twenties of the former centuryformer century  Cobalt and iron as catalystsCobalt and iron as catalysts  Objective : Producing transport fuels out of coalObjective : Producing transport fuels out of coal  Competitor : Bergius coal hydrogenation by I.G.Competitor : Bergius coal hydrogenation by I.G. FarbenFarben GBH Enterprises Ltd.
  3. 3. ThemesThemes  Dissociative adsorption of methane and carbon monoxideDissociative adsorption of methane and carbon monoxide in competition with surface oxidation (catalytic partialin competition with surface oxidation (catalytic partial oxidation) or hydrogenation (Fischer-Tropsch synthesis)oxidation) or hydrogenation (Fischer-Tropsch synthesis)  Reducibility of metal oxides to metal oxides of lowerReducibility of metal oxides to metal oxides of lower valencyvalency  Different special procedures for producing supportedDifferent special procedures for producing supported catalystscatalysts GBH Enterprises Ltd.
  4. 4. Competitive DissociativeCompetitive Dissociative AdsorptionAdsorption CH4 H C H H H 2H2 CO O CO O O O O O O O O O O O O O O CH4 CH4 CO2 H2O CH4 CH4 CO2 H2O Dissociative adsorption of oxygen usually more rapid than dissociative adsorption of methane at temperatures below about 700o C GBH Enterprises Ltd.
  5. 5. Competitive DissociativeCompetitive Dissociative AdsorptionAdsorption CO C O H H H2O O C O C C C CO2 C H C C H C H C H C CnH2n(+2) Relatively low hydrogen coverage Fischer-Tropsch Relatively high hydrogen coverage methanation C H H H C H H H H C H H CH4 GBH Enterprises Ltd.
  6. 6. Reducibility of Metal OxidesReducibility of Metal Oxides O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O Formation of reduced oxide phase Formation of isolated oxygen vacancies CO C(ads) + O(ads)→← CH4 → CO + 2H2 GBH Enterprises Ltd.
  7. 7. Feed Stock ofFeed Stock of the Fischer-Tropsch Processthe Fischer-Tropsch Process  Feed stock : Initially coalFeed stock : Initially coal C + HC + H22O = CO + HO = CO + H22  Desired HDesired H22/CO ratio 2/CO ratio 2  Carbon monoxide shift conversionCarbon monoxide shift conversion CO + HCO + H22O = COO = CO22 + H+ H22  Presently : Natural gasPresently : Natural gas Steam-reforming involvesSteam-reforming involves CHCH44 + H+ H22O = CO + 3 HO = CO + 3 H22 HH22/CO ratio too elevated/CO ratio too elevated  Therefore (Catalytic) Partial OxidationTherefore (Catalytic) Partial Oxidation also Autothermal reformingalso Autothermal reforming GBH Enterprises Ltd.
  8. 8. (Catalytic) Partial Oxidation(Catalytic) Partial Oxidation  Pure oxygen required to performPure oxygen required to perform 2CH2CH44 + O+ O22 = 2CO + 4H= 2CO + 4H22 Desired HDesired H22/CO ratio/CO ratio  Extremely good mixing of natural gas and oxygenExtremely good mixing of natural gas and oxygen required to prevent formation of sootrequired to prevent formation of soot  Formation of explosive mixtures to be preventedFormation of explosive mixtures to be prevented  Initial highly exothermic reaction to carbon dioxideInitial highly exothermic reaction to carbon dioxide and water; subsequent reaction of carbon dioxide andand water; subsequent reaction of carbon dioxide and water with methane to carbon monoxide and hydrogenwater with methane to carbon monoxide and hydrogen GBH Enterprises Ltd.
  9. 9. Heats of ReactionHeats of Reaction  Reaction of methane to COReaction of methane to CO22 and Hand H22O very exothermicO very exothermic  Reaction of methane to CO and HReaction of methane to CO and H22 strongly endothermicstrongly endothermic  Proceeding of homogeneous reaction of methane withProceeding of homogeneous reaction of methane with carbon dioxide and water limits temperature increasecarbon dioxide and water limits temperature increase  High temperatures implies high constraints on materialsHigh temperatures implies high constraints on materials 2CH4+4O2 = 2CO2 + 4H2O -385.5 -385 -384.5 -384 -383.5 -383 -382.5 -382 0 200 400 600 800 1000 1200 1400 1600 Temperature °C HeatofReaction(kcal) 2CH4 + O2 = 2CO + 4H2 -20 -15 -10 -5 0 0 200 400 600 800 1000 1200 1400 1600 Temperature °C Heatofreaction(kcal) GBH Enterprises Ltd.
  10. 10. Heats of ReactionHeats of Reaction  Reaction of methane with carbon dioxide and ofReaction of methane with carbon dioxide and of methane with steam highly endothermicmethane with steam highly endothermic CH4 + H2O = CO + 3H2 48 49 50 51 52 53 54 55 0 200 400 600 800 1000 1200 1400 Temperature °C HeatofReaction (kcal) CH4 + CO2 = 2CO + 2H2 58 59 60 61 62 63 0 200 400 600 800 1000 1200 1400 Temperature °C Heatofreaction (kcal) GBH Enterprises Ltd.
  11. 11. (Catalytic) Partial Oxidation(Catalytic) Partial Oxidation  Initial highly exothermic reactionInitial highly exothermic reaction 2CH2CH44 + 4O+ 4O22 = 2CO= 2CO22 + 4H+ 4H22OO  Subsequent endothermic reactionsSubsequent endothermic reactions COCO22 + CH+ CH44 = 2CO + 2H= 2CO + 2H22 HH22O + CHO + CH44 = CO + 3H= CO + 3H22  Autothermal reforming : Adding steam and oxygen toAutothermal reforming : Adding steam and oxygen to methanemethane  Catalytic partial oxidation aims at achieving reaction ofCatalytic partial oxidation aims at achieving reaction of CHCH44 to CO and Hto CO and H22 at lower temperature levels byat lower temperature levels by promoting the reactionpromoting the reaction 2CH2CH44 + O+ O22 = 2CO + 4H= 2CO + 4H22 GBH Enterprises Ltd.
  12. 12. CO + H2O CO2 + H2 Reaction PathsReaction Paths Catalytic Partial OxidationCatalytic Partial Oxidation CH4 + O2 CO2 + H2O CO + H2 CH4 CO + H2 Direct Indirect CO shift Reforming GBH Enterprises Ltd.
  13. 13. Direct vs Indirect Catalytic PartialDirect vs Indirect Catalytic Partial OxidationOxidation CH4 CO+ H2CO2 + H2O Direct Indirect T cat Axial position 2a 2b 1 1 2b 2a kJ/mol 1 - 40 2a - 800 2b + 200 CH4 CO+ H2 GBH Enterprises Ltd.
  14. 14. Methane activationMethane activation Problem : CH4 activation calls for high temperature at which the reactivity of CO and H2 is relatively high RT 100 350 roxidation H2 CO CH4 T (°C) GBH Enterprises Ltd.
  15. 15. Methane ActivationMethane Activation METALS (precious) Low oxygen coverage Pd,Pt,Ru,(Ni) OXIDES Strongly bound oxygen Small amount of adsorbed oxygen Small number of (isolated) sites Y2O3, La2O3, ZrO2, TiO2 CH4 O CO H2 CHx H CH4 CO H2 O H GBH Enterprises Ltd.
  16. 16. Precious metal systemsPrecious metal systems Pt, Pd, Ru, (Ni) T<700°C Indirect CPO Formation highly active phase for complete oxidation under steady state conditions CH4 + O2 CO2 + H2O CO + H2 Oxidation Reforming ”Oxidic” phase Metallic phase GBH Enterprises Ltd.
  17. 17. Precious metals : PdPrecious metals : Pd 0 0.5 1 1.5 2 50 150 250 350 450 550 650 T (°C) pX(%) CO H2 CH4 O2 CO2 300 mg 0.5 wt% Pd/SiO2 CH4/O2/Ar 1 / 0.5 / 98.5 ml/min GBH Enterprises Ltd.
  18. 18. Influence of Oxidizing /Influence of Oxidizing / Reducing ConditionsReducing Conditions Highly active but unstable reduced system 0 0.4 0.8 1.2 1.6 2 Time pX(%) CH4 O2 CO CO2 O2 H2 pulse 0.5% Ru/TiO2 diluted with quartz 2% CH4 1% O2 in Ar GBH Enterprises Ltd.
  19. 19. Catalytic Partial Oxidation ofCatalytic Partial Oxidation of MethaneMethane 1 vol% CH4 0.5 vol% O2 in argon 100 ml(stp)/min Mn oxide on alumina 850 K GBH Enterprises Ltd.
  20. 20. Catalytic Partial Oxidation onCatalytic Partial Oxidation on Precious Metals (Nickel)Precious Metals (Nickel)  Oxidation to carbon dioxide and waterOxidation to carbon dioxide and water  Subsequent reaction of remaining methaneSubsequent reaction of remaining methane with carbon dioxide and water to carbonwith carbon dioxide and water to carbon monoxide and hydrogenmonoxide and hydrogen  Catalyst bed not uniform being oxidized atCatalyst bed not uniform being oxidized at entrance and reduced at exitentrance and reduced at exit  Catalyst system not stable against deactivationCatalyst system not stable against deactivation by oxidationby oxidation GBH Enterprises Ltd.
  21. 21. Trade Time for TemperatureTrade Time for Temperature  Catalytic partial oxidation at temperaturesCatalytic partial oxidation at temperatures above 1100above 1100oo CC  High rate of reaction; no problem in keepingHigh rate of reaction; no problem in keeping the surface of the precious metal reducedthe surface of the precious metal reduced  Also reaction of methane with carbon dioxideAlso reaction of methane with carbon dioxide and water proceeding rapidlyand water proceeding rapidly  Problem to prevent deposition of carbon onProblem to prevent deposition of carbon on precious metal particlesprecious metal particles  Demands on materials at such elevatedDemands on materials at such elevated temperaturestemperatures GBH Enterprises Ltd.
  22. 22. Catalytic Partial Oxidation onCatalytic Partial Oxidation on OxidesOxides OXIDES Strongly bound oxygen Small amount of adsorbed oxygen Small number of (isolated) sites TiO2, ZrOZrO22, Y2O3, La2O3 GBH Enterprises Ltd.
  23. 23. Catalytic Partial Oxidation onCatalytic Partial Oxidation on ZrOZrO22 0 20 40 60 80 100 450 550 650 750 850 T (°C) % XCH S H S CO ZrO2 1% CH4 0.5% O2 100 ml /min 500 mg 4 2 Conversion CH4 Selectivity to H2 Selectivity to CO GBH Enterprises Ltd.
  24. 24. Effect of Residence TimeEffect of Residence Time 0 20 40 60 80 100 0 2 4 6 8 10 Methane conversion (%) selectivity(%) 2% CH4, 1 % O2 in Ar T=550°C 30000 < GHSV < 150000 (Nl/l)hr-1 ZrO2 Gimex ZrO2 Daiichi CO H2 GBH Enterprises Ltd.
  25. 25. Oxidation of HOxidation of H22 and CO on ZrOand CO on ZrO22 0 20 40 60 80 100 300 400 500 600 700 T (°C) Conversion(%) 500 mg catalyst 1% CO / H2 , 1% O2 in He CO oxidation CH4 oxidation H2 oxidation GBH Enterprises Ltd.
  26. 26. Experimental Results on ZrOExperimental Results on ZrO22 ZrO2 Inactive reforming catalyst Low activity CO-shift Low activity H2 and CO oxidation Primary reaction: CH4 CO + H2 + H2O GBH Enterprises Ltd.
  27. 27. Survey Different Metal OxidesSurvey Different Metal Oxides 0 20 40 60 80 100 % X CH S CO S H S C 2% CH4 1% O2 100 ml /min T=600°C TiO2 ZrO2 Y2O3 La2O3 4 2 2 GBH Enterprises Ltd.
  28. 28. Orders of the Reaction withOrders of the Reaction with respect to Oxygen and Methanerespect to Oxygen and Methane  Reaction orders : PdReaction orders : Pd OO22 0.1 - 0.20.1 - 0.2 CHCH44 0.8 - 1.10.8 - 1.1 • Reduction of surface rate-determiningReduction of surface rate-determining  Oxides : High orders of reaction withOxides : High orders of reaction with respect to oxygenrespect to oxygen • Re-oxidation of surface rate-determiningRe-oxidation of surface rate-determining GBH Enterprises Ltd.
  29. 29. Orders of the Reaction withOrders of the Reaction with Respect to Oxygen of Metal OxidesRespect to Oxygen of Metal Oxides 0 0.2 0.4 0.6 0.8 1 TiO2 ZrO2 Y2O3 La2O3 CH4 O2 GBH Enterprises Ltd.
  30. 30. DiscussionDiscussion OxidesOxides TiOTiO22 ,, ZrOZrO22 ,Y,Y22 OO33 ,La,La22 OO33 Low activity High selectivity High reaction order O2 Low number of (isolated) sites GBH Enterprises Ltd.
  31. 31. Catalytic Partial OxidationCatalytic Partial Oxidation on Metalson Metals Precious metals Pd, Pt, Ru, (Ni) steady state conditions T<700°C “Oxidic” phase highly active in complete combustion Indirect formation of Syngas CH4 CO 2 + H2O CO + H2 GBH Enterprises Ltd.
  32. 32. Catalytic Partial OxidationCatalytic Partial Oxidation on Oxideson Oxides ZrO2, TiO2 : CO , H2 (H2O) primary products Y2O3, La2O3 : CO , H2 (H2O) primary products C2 - products : formation of CH3-species CH4 CO + H2 + H2O C2H6 + H2O CHx CH3 Direct formation of Syngas GBH Enterprises Ltd.
  33. 33. Fischer-Tropsch SynthesisFischer-Tropsch Synthesis  Reaction : CO + 2HReaction : CO + 2H22 →→ ‘CH‘CH22’ + H’ + H22OO  Undesired reactions CO + 3HUndesired reactions CO + 3H22 →→ CHCH44 + H+ H22O, carbonO, carbon deposition on supported metal particles, and carbondeposition on supported metal particles, and carbon monoxide shift conversionmonoxide shift conversion • Higher hydrogen pressure promotes formation ofHigher hydrogen pressure promotes formation of methanemethane  Highly undesired : Growth of carbon nanofibersHighly undesired : Growth of carbon nanofibers • Mechanically very strong carbon fibers plug reactorMechanically very strong carbon fibers plug reactor and can even pierce reactor walland can even pierce reactor wall • With bubble column reactor and suspended catalystWith bubble column reactor and suspended catalyst bodies growth of carbon nanofibers less disastrousbodies growth of carbon nanofibers less disastrous GBH Enterprises Ltd.
  34. 34. Carbon Fibers Grown in CatalystCarbon Fibers Grown in Catalyst BedBed Scanning electron- micrograph GBH Enterprises Ltd.
  35. 35. Carbon FibersCarbon Fibers Transmission electron micrograph Thick and thin carbon fibers have grown from this catalyst GBH Enterprises Ltd.
  36. 36. Nickel Particle at End ofNickel Particle at End of Carbon FiberCarbon Fiber Transmission electron micrograph Carbon fibers grown from silica- supported nickel particles Nickel particle present at end of carbon fiber 90 nm GBH Enterprises Ltd.
  37. 37. Catalysts forCatalysts for Fischer-Tropsch SynthesisFischer-Tropsch Synthesis  Required :Required : • Dissociation of carbon monoxideDissociation of carbon monoxide  Ability to react to metal carbide(s)Ability to react to metal carbide(s) • Removal of adsorbed oxygen by reaction to either carbonRemoval of adsorbed oxygen by reaction to either carbon dioxide or waterdioxide or water • Limited availability of adsorbed hydrogenLimited availability of adsorbed hydrogen  Considerable extent of reduction of supported precursor toConsiderable extent of reduction of supported precursor to metal particlesmetal particles  Oxidation by water resulting from the Fischer-Tropsch reactionOxidation by water resulting from the Fischer-Tropsch reaction to be consideredto be considered GBH Enterprises Ltd.
  38. 38. Catalysts forCatalysts for Fischer-Tropsch SynthesisFischer-Tropsch Synthesis  Iron, cobalt and nickel able to react to metal carbidesIron, cobalt and nickel able to react to metal carbides  Dissociation of carbon monoxide on iron and cobalt notDissociation of carbon monoxide on iron and cobalt not strongly surface-sensitivestrongly surface-sensitive  Dissociation of carbon monoxide on nickel surface-Dissociation of carbon monoxide on nickel surface- sensitivesensitive  Selectivity to methane therefore on iron and cobalt lowerSelectivity to methane therefore on iron and cobalt lower than on nickelthan on nickel  Supported iron and cobalt precursor difficult to reduceSupported iron and cobalt precursor difficult to reduce GBH Enterprises Ltd.
  39. 39. Catalysts forCatalysts for Fischer-Tropsch SynthesisFischer-Tropsch Synthesis  Dissociation of carbon monoxide not on most stableDissociation of carbon monoxide not on most stable Ni(111) surfaceNi(111) surface • Hydrogen from Ni(111) surface migrates towardHydrogen from Ni(111) surface migrates toward carbon atoms resulting from dissociation of carboncarbon atoms resulting from dissociation of carbon monoxide on other crystallographic surfacesmonoxide on other crystallographic surfaces • Abundance of hydrogen leads to undesiredAbundance of hydrogen leads to undesired reaction to methanereaction to methane • Nickel therefore high selectivity to methaneNickel therefore high selectivity to methane H H H H H H H H H H C C C C C C C C C C C C GBH Enterprises Ltd.
  40. 40. Promoted Nickel CatalystsPromoted Nickel Catalysts  Assisted dissociation of carbon monoxide atAssisted dissociation of carbon monoxide at edge of nickel particles by supportedge of nickel particles by support  Comparison of silica-supported nickel andComparison of silica-supported nickel and titania-supported nickeltitania-supported nickel  Titania support reducible to lower valentTitania support reducible to lower valent metal oxidemetal oxide  Application of nickel on support byApplication of nickel on support by deposition-precipitationdeposition-precipitation Titania COOC GBH Enterprises Ltd.
  41. 41. Preparation of SupportedPreparation of Supported Nickel CatalystsNickel Catalysts  Injection of nickel nitrate into suspension ofInjection of nickel nitrate into suspension of silica or titania supportsilica or titania support  Maintaining pH at constant level of 9 byMaintaining pH at constant level of 9 by simultaneous injection of ammoniasimultaneous injection of ammonia  Suspension of finely divided supports inSuspension of finely divided supports in waterwater  After separation from the liquid, washed andAfter separation from the liquid, washed and dried in vacuum at room temperaturedried in vacuum at room temperature  Shaped and subsequently calcined at 573 KShaped and subsequently calcined at 573 K for 3 hoursfor 3 hours GBH Enterprises Ltd.
  42. 42. Mean Size of Nickel OxideMean Size of Nickel Oxide ParticlesParticles  Assessment of mean size of nickel oxide particles inAssessment of mean size of nickel oxide particles in calcined catalysts by evaluation of XPS resultscalcined catalysts by evaluation of XPS results Catalyst Mean Particle Size nm 2Ni/TiO2 1.2 5Ni/TiO2 1.8 10Ni/TiO2 1.9 20Ni/TiO2 4.9 2Ni/SiO2 2.5 10Ni/SiO2 5.7 20Ni/SiO2 10.6 GBH Enterprises Ltd.
  43. 43. Temperature-Programmed Reduction ofTemperature-Programmed Reduction of Silica-Supported Nickel CatalystsSilica-Supported Nickel Catalysts Initial peak due to reduction of non-stoichiometric oxygen NiO1+x 20 wt.% Ni 10 wt.% Ni 2 wt.% Ni Second peak : Reduction of NiO Third peak : Reduction nickel containing clay mineral GBH Enterprises Ltd.
  44. 44. Temperature-Programmed Reduction ofTemperature-Programmed Reduction of Titania-Supported Nickel CatalystsTitania-Supported Nickel Catalysts Initial peak due to reduction of non-stoichiometric oxygen NiO1+x Reduction of NiO second peak Reduction of nickel titanate final peak Extent of reduction of nickel 110 % indicating reduction of titania 5 wt.% 20 wt.% Ni/TiO2 10 wt.% Ni/TiO2 2 wt.% 50 mg samples 5 K/min from 300 to 1123 K GBH Enterprises Ltd.
  45. 45. Infra-Red Spectra of Carbon MonoxideInfra-Red Spectra of Carbon Monoxide Adsorbed on Nickel CatalystsAdsorbed on Nickel Catalysts Catalysts reduced at 673 K Adsorption of CO on reduced sites on TiO2 absorption band around 2180 cm-1 Note higher absorption with 2 wt.% Ni/TiO2 which indicates induced reduction at the edge of nickel particles GBH Enterprises Ltd.
  46. 46. CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on Silica-Supported Nickel CatalystsSilica-Supported Nickel Catalysts Catalysts reduced at 673 K 20 wt.% Ni/SiO2 reduced at temperatures indicated GBH Enterprises Ltd.
  47. 47. Selectivities of Fischer-TropschSelectivities of Fischer-Tropsch Synthesis on Ni/SiOSynthesis on Ni/SiO22 CatalystsCatalysts Catalyst Reduction CO2(%) CH4(%) C2(%) C3 + (%) Temperature °C 2Ni/SiO2 673 0 87 4 9 10Ni/SiO2 673 2 90 5 3 20Ni/SiO2 673 2 90 5 3 20Ni/SiO2 573 7 85 5 3 20Ni/SiO2 673 2 90 5 3 20Ni/SiO2 773 3 90 5 2 GBH Enterprises Ltd.
  48. 48. CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on Titania-Supported Nickel CatalystsTitania-Supported Nickel Catalysts H2/CO = 2 for reaction to CH4 required H2/CO = 3 Catalyst Reduction CO2(%) CH4(%) C2(%) C3 + (%) Temperature °C 20Ni/TiO2 573 21 78 1 0 20Ni/TiO2 673 20 80 0 0 20Ni/TiO2 773 3 54 13 30 GBH Enterprises Ltd.
  49. 49. Comparison T.P.R. and Activity at 525 KComparison T.P.R. and Activity at 525 K of Ni/TiOof Ni/TiO22 CatalystsCatalysts 20 wt.% Ni/SiO2 reduced at temperatures indicated Temperature-Programmed Reduction (T.P.R.) of Ni/SiO2 catalysts. Ni content (wt.%) indicated at T.P.R. curves 50 mg samples 5 K/min from 300 to 1123 K GBH Enterprises Ltd.
  50. 50. Comparison T.P.R. and Activity atComparison T.P.R. and Activity at 525 K of Ni/TiO525 K of Ni/TiO22 CatalystsCatalysts 20 wt.% Ni/TiO2 reduced at temperatures indicated Temperature-Programmed Reduction (T.P.R.) of Ni/TiO2 catalysts. Ni content (wt.%) indicated at T.P.R. curves 50 mg samples 5 K/min from 300 to 1123 K GBH Enterprises Ltd.
  51. 51. CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on Titania-Supported Nickel CatalystsTitania-Supported Nickel Catalysts CO conversion at 525 K of Ni/TiO2 catalysts of different nickel loadings reduced at 673 K Reaction to C3 + at 525 K of Ni/TiO2 catalysts of different nickel loadings reduced at 673 K CO conversion at 525 K of 2 wt.% Ni/TiO2 catalyst reduced at the different temperatures indicated in the figure GBH Enterprises Ltd.
  52. 52. CO Hydrogenation at 525 K onCO Hydrogenation at 525 K on Titania-Supported Nickel CatalystsTitania-Supported Nickel Catalysts Catalyst Reduction CO2(%) CH4(%) C2(%) C3 + (%) Temperature °C 2Ni/TiO2 673 5 37 16 42 5Ni/TiO2 673 6 53 13 28 10Ni/TiO2 673 6 59 12 23 20Ni/TiO2 673 20 80 0 0 2Ni/TiO2 573 4 35 14 47 2Ni/TiO2 673 5 37 16 42 2Ni/TiO2 773 5 34 14 47 GBH Enterprises Ltd.
  53. 53. Magnetization ofMagnetization of Titania-Supported Nickel CatalystsTitania-Supported Nickel Catalysts Measured after reduction at 673 K during exposure to H2/CO = 2 at 525 K Drop in magnetization 31 % with 20Ni/TiO2 and no less than 70 % with 2Ni/TiO2 Measured after reduction at 673 K and Fischer-Tropsch synthesis at 525 K during temperature- programmed hydrogenation in 2 % hydrogen in helium Heating rate 2 K/min GBH Enterprises Ltd.
  54. 54. Temperature-ProgrammedTemperature-Programmed Hydrogenation of Nickel CarbidesHydrogenation of Nickel Carbides 20 wt.% Ni/TiO2 catalyst reduced at 673 and 773 K Measured after Fischer-Tropsch synthesis at 525 K Heating rate 5 K/min Surface carbide is hydrogenated at relatively low temperatures Transport of carbon to the metal surface calls for elevated temperatures GBH Enterprises Ltd.
  55. 55. Nickel (Surface) CarbideNickel (Surface) Carbide C C C C C C CC CC C C CC C C C C C C C Surface carbide leading to methane Magnetization only slightly decreased Hydrogenation of surface carbon at relatively low temperatures Bulk carbide leading to higher hydrocarbons. Magnetization strongly decreased. Hydrogenation of carbon at more elevated temperatures due to transport of carbon through metal GBH Enterprises Ltd.
  56. 56. Schematic Description of Silica-Schematic Description of Silica- Supported Nickel CatalystsSupported Nickel Catalysts GBH Enterprises Ltd.
  57. 57. Schematic Description of Titania-Schematic Description of Titania- Supported Nickel CatalystsSupported Nickel Catalysts GBH Enterprises Ltd.
  58. 58. Conclusions about Fischer-Conclusions about Fischer- Tropsch on NickelTropsch on Nickel  Promotion of dissociative adsorption ofPromotion of dissociative adsorption of carbon monoxide required for synthesis ofcarbon monoxide required for synthesis of higher hydrocarbonshigher hydrocarbons  Promotion by reducible support, which is notPromotion by reducible support, which is not reduced to metal, but to oxygen acceptorreduced to metal, but to oxygen acceptor  Reaction to bulk carbide goes together withReaction to bulk carbide goes together with Fischer-Tropsch synthesis to higherFischer-Tropsch synthesis to higher hydrocarbonshydrocarbons GBH Enterprises Ltd.
  59. 59. Preparation of Supported CobaltPreparation of Supported Cobalt Catalysts by Impregnation and DryingCatalysts by Impregnation and Drying  AluminaAlumina AA22 STST g-aluminag-alumina pore volume 0.48 ml/g, surface area 110 mpore volume 0.48 ml/g, surface area 110 m22 /g/g employed as supportemployed as support  Impregnation withImpregnation with • Solution of cobalt nitrateSolution of cobalt nitrate • Solution of cobalt EDTA complexSolution of cobalt EDTA complex • Solution of cobalt ammonium citrateSolution of cobalt ammonium citrate  Catalyst according to Exxon patent as referenceCatalyst according to Exxon patent as reference catalyst 10Co1Ce/TiOcatalyst 10Co1Ce/TiO22 GBH Enterprises Ltd.
  60. 60. Shape of Drop dried onShape of Drop dried on GlassGlass Drop of solution of copper(II) nitrate dried on microscope glass slide Note preferential build up of crystallites at the rim of the drop GBH Enterprises Ltd.
  61. 61. Shape of Drop dried onShape of Drop dried on GlassGlass Drop of solution of copper(II) citrate dried on microscope glass slide Note absence of large crystallites GBH Enterprises Ltd.
  62. 62. Mean Particle Size of SupportedMean Particle Size of Supported Cobalt Oxide by XPSCobalt Oxide by XPS  CatalystCatalyst Mean particle size (nm)Mean particle size (nm) 2.5Co/Al2.5Co/Al22OO33 nitratenitrate 7.37.3 2.5Co/Al2.5Co/Al22OO33 citratecitrate 1.71.7 2.5 Co/Al2.5 Co/Al22OO33 EDTAEDTA 0.70.7 5 Co/Al5 Co/Al22OO33 nitratenitrate 15.515.5 5 Co/Al5 Co/Al22OO33 citratecitrate 3.93.9 GBH Enterprises Ltd.
  63. 63. Estimation of Reducibility byEstimation of Reducibility by Measurement of the MagnetizationMeasurement of the Magnetization Reducibility depends on size of cobalt oxide particles Small oxide particles react to CoAl2O4, which only reduces at very elevated temperatures GBH Enterprises Ltd.
  64. 64. Estimation of Reducibility byEstimation of Reducibility by Measurement of the MagnetizationMeasurement of the Magnetization Reducibility depends on size of cobalt oxide particles Small oxide particles react to CoAl2O4, which only reduces at very elevated temperatures GBH Enterprises Ltd.
  65. 65. Fischer-Tropsch Synthesis onFischer-Tropsch Synthesis on Supported Co catalysts at 525 KSupported Co catalysts at 525 K Conversion of carbon monoxide roughly parallel with amount of metallic cobalt Catalysts reduced at 673 K Measurements at atmospheric pressure; at higher pressures better selectivities and conversions Measurement of 10Co1Ce/TiO2 at 26 bar and 493 K for 135 h at H2/CO = 2 led to C5 + 87% and CH4 = 7% GBH Enterprises Ltd.
  66. 66. Selectivities of Alumina-SupportedSelectivities of Alumina-Supported Cobalt Catalysts at 525 KCobalt Catalysts at 525 K Catalyst Reduction CO2(%) CH4(%) C2(%) C3 + (%) Temperature °C 20Ni/TiO2 573 21 78 1 0 20Ni/TiO2 673 20 80 0 0 20Ni/TiO2 773 3 54 13 30 Catalyst Reduction CO2(%) CH4(%) C2(%) C3 + (%) Temperature Measurements at atmospheric pressure; at higher pressures better selectivities and conversions. Measurement of 10Co1Ce/TiO2 at 26 bar and 493 K for 135 h at H2/CO = 2 led to C5 + 87% and CH4 = 7% GBH Enterprises Ltd.
  67. 67. Conclusions about SupportedConclusions about Supported Cobalt CatalystsCobalt Catalysts  Reduction of alumina-supported cobalt catalysts difficultReduction of alumina-supported cobalt catalysts difficult  Reaction to cobalt aluminate difficult to preventReaction to cobalt aluminate difficult to prevent  Sasol is therefore coating alumina with siliciumSasol is therefore coating alumina with silicium compoundcompound  Performance of cobalt catalysts in Fischer-TropschPerformance of cobalt catalysts in Fischer-Tropsch synthesis difficult to evaluate from measurement atsynthesis difficult to evaluate from measurement at atmospheric pressureatmospheric pressure  With reduction of nickel and cobalt catalysts in technicalWith reduction of nickel and cobalt catalysts in technical reactors dew point of recirculating hydrogen highlyreactors dew point of recirculating hydrogen highly importantimportant GBH Enterprises Ltd.
  68. 68. Supported Iron CatalystsSupported Iron Catalysts  Supported iron catalysts very difficult to reduceSupported iron catalysts very difficult to reduce  Low water vapor pressure within pores of hydrophilicLow water vapor pressure within pores of hydrophilic supports very difficult to achievesupports very difficult to achieve  New procedure to produce supported metallic iron and ironNew procedure to produce supported metallic iron and iron alloy particlesalloy particles • Application of complex insoluble cyanides on supportApplication of complex insoluble cyanides on support • Very rapid reduction to metals and alloys in hydrogenVery rapid reduction to metals and alloys in hydrogen flowflow • German patent describing catalyst preparation fromGerman patent describing catalyst preparation from complex cyanidescomplex cyanides • Very large metal or alloy particles resulting due to lowVery large metal or alloy particles resulting due to low interaction of metal or alloy with surface of supportinteraction of metal or alloy with surface of support GBH Enterprises Ltd.
  69. 69. Supported Iron CatalystsSupported Iron Catalysts  Our invention : Initial calcination of supported complexOur invention : Initial calcination of supported complex cyanide precursor to oxidecyanide precursor to oxide  Subsequent reduction leads to oxidic layer at interfaceSubsequent reduction leads to oxidic layer at interface between metal or alloy particles and supportbetween metal or alloy particles and support  Oxidic layer anchors metal or alloy particles to surfaceOxidic layer anchors metal or alloy particles to surface of support and provides stable catalystsof support and provides stable catalysts GBH Enterprises Ltd.
  70. 70. Supported Iron Alloy CatalystsSupported Iron Alloy Catalysts  Precipitation of complex cyanides with metal ions toPrecipitation of complex cyanides with metal ions to be present in alloybe present in alloy  Atomic mixing of components of alloyAtomic mixing of components of alloy  Examples for iron-nickel alloy catalystsExamples for iron-nickel alloy catalysts • FeFe2+2+ + K+ K44Fe(CN)Fe(CN)66 ® Fe® Fe22Fe(CN)Fe(CN)66 + K+ K22FeFe(CN)FeFe(CN)66 • FeFe2+2+ + K+ K33Fe(CN)Fe(CN)66 ® Fe® Fe33Fe(CN)Fe(CN)66 + K+ K22FeFe(CN)FeFe(CN)66 • FeFe2+2+ + Na+ Na22Fe(CN)Fe(CN)55NO ® FeFe(CN)NO ® FeFe(CN)55 NONO • NiNi2+2+ + K+ K44Fe(CN)Fe(CN)66 ® Ni® Ni22Fe(CN)Fe(CN)66 + K+ K22NiFe(CN)NiFe(CN)66 • NiNi2+2+ + K+ K33Fe(CN)Fe(CN)66 ® Ni® Ni22Fe(CN)Fe(CN)66 + K+ K22NiFe(CN)NiFe(CN)66 • NiNi2+2+ + Na+ Na22Fe(CN)Fe(CN)55NO® NiFe(CN)NO® NiFe(CN)55NONO GBH Enterprises Ltd.
  71. 71. Supported Iron Alloy CatalystsSupported Iron Alloy Catalysts  Reaction with potassium iron cyanide complexes leadsReaction with potassium iron cyanide complexes leads to catalysts containing potassiumto catalysts containing potassium  Since potassium is very well and homogeneouslySince potassium is very well and homogeneously distributed within the iron containing moieties,distributed within the iron containing moieties, catalysts very well suited to investigate effect ofcatalysts very well suited to investigate effect of potassium on Fischer-Tropsch activitypotassium on Fischer-Tropsch activity  For preparation of potassium-free catalysts startingFor preparation of potassium-free catalysts starting from Hfrom H44Fe(CN)Fe(CN)66 attractiveattractive GBH Enterprises Ltd.
  72. 72. Supported Iron Alloy CatalystsSupported Iron Alloy Catalysts  Preparation of potassium-free iron and nickel-ironPreparation of potassium-free iron and nickel-iron catalystscatalysts • NiNi2+2+ + H+ H44Fe(CN)Fe(CN)66 ® Ni® Ni22Fe(CN)Fe(CN)66 • 0.4Ni0.4Ni2+2+ + 0.6Fe+ 0.6Fe2+2+ + NaFe(CN)+ NaFe(CN)55NO ®NO ® ® (Ni® (Ni0.40.4FeFe0.60.6)Fe(CN))Fe(CN)55NONO  Comparison potassium-free and potassiumComparison potassium-free and potassium containing catalystscontaining catalysts  Titania as the support; Degussa P 25 50 mTitania as the support; Degussa P 25 50 m22 /g/g GBH Enterprises Ltd.
  73. 73. Comparison of Potassium-Free andComparison of Potassium-Free and Potassium Containing IronPotassium Containing Iron CatalystsCatalysts Important conclusion : Potassium containing iron catalysts no significant activity GBH Enterprises Ltd.
  74. 74. Comparison of Potassium-Free andComparison of Potassium-Free and Potassium Containing NiFe CatalystsPotassium Containing NiFe Catalysts Important conclusion : Potassium containing nickel-iron catalysts no significant activity Ni2Fe/TiO2 GBH Enterprises Ltd.
  75. 75. Comparison of Potassium-Free FeComparison of Potassium-Free Fe and Ni-Fe Catalystsand Ni-Fe Catalysts NiFe4/TiO2 NiFe/TiO2 Ni3Fe2/TiO2 Fe/TiO2 GBH Enterprises Ltd.
  76. 76. Selectivities of Titania-SupportedSelectivities of Titania-Supported Fe and Fe-Ni CatalystsFe and Fe-Ni Catalysts GBH Enterprises Ltd.
  77. 77. Magnetization of K-Free andMagnetization of K-Free and K Containing Fe/TiOK Containing Fe/TiO22 CatalystsCatalysts Both potassium containing and potassium-free catalysts react to iron carbides upon exposure to carbon monoxide-hydrogen at 525 K GBH Enterprises Ltd.
  78. 78. Magnetization of Spent Catalysts as aMagnetization of Spent Catalysts as a Function of Temperature in Flow of HFunction of Temperature in Flow of H22 Initial drop in magnetization at rising temperature due to Curie temperature of iron carbide (523 or 530 K) Hydrogenation of carbon in iron carbide only above 700 K GBH Enterprises Ltd.
  79. 79. Magnetization of Iron-Nickel CatalystsMagnetization of Iron-Nickel Catalysts during Fischer-Tropsch Synthesisduring Fischer-Tropsch Synthesis GBH Enterprises Ltd.
  80. 80. Magnetization of Spent CatalystsMagnetization of Spent Catalysts as a Function of Temperature inas a Function of Temperature in Flow of HFlow of H22 GBH Enterprises Ltd.
  81. 81. Temperature-Programmed Reduction ofTemperature-Programmed Reduction of Spent Fe and Fe-Ni CatalystsSpent Fe and Fe-Ni Catalysts Potassium-containing catalyst no reaction to CH4; release of carbon monoxide likely to be due to decomposition of potassium carbonate. The potassium-free catalyst exhibits reaction to methane above about 750 K. GBH Enterprises Ltd.
  82. 82. Temperature-Programmed Reduction ofTemperature-Programmed Reduction of Spent Fe and Fe-Ni CatalystsSpent Fe and Fe-Ni Catalysts NiFe50_C Catalyst NiFe33_A(K) Catalyst Measured after 6 hours Fischer-Tropsch synthesis at 525 K GBH Enterprises Ltd.
  83. 83. Infra-Red Spectra of Adsorbed CarbonInfra-Red Spectra of Adsorbed Carbon MonoxideMonoxide Infra-red spectra of carbon monoxide adsorbed on reduced catalyst NiFe33_A(K) spectrum (a) and NiFe40_B spectrum (b) No molecular adsorption of carbon monoxide on potassium-containing catalyst NiFe33_A(K) GBH Enterprises Ltd.
  84. 84. Conclusions about Effect ofConclusions about Effect of PotassiumPotassium  Potassium does not prevent reaction of iron or nickel-Potassium does not prevent reaction of iron or nickel- iron alloy to carbideiron alloy to carbide  Potassium completely suppresses adsorption ofPotassium completely suppresses adsorption of molecular carbon monoxidemolecular carbon monoxide  Potassium suppresses hydrogenation of carbidicPotassium suppresses hydrogenation of carbidic carbon to hydrocarbonscarbon to hydrocarbons  Potassium segregated on the surface of iron or nickel-Potassium segregated on the surface of iron or nickel- iron particles and suppresses adsorption of carboniron particles and suppresses adsorption of carbon monoxide and hydrogenmonoxide and hydrogen GBH Enterprises Ltd.
  85. 85. Zirconia-Supported Iron CatalystsZirconia-Supported Iron Catalysts  Zirconia as a support to limit reaction of iron(II) withZirconia as a support to limit reaction of iron(II) with the support, which impedes reduction to metallic ironthe support, which impedes reduction to metallic iron  Zirconia of AZirconia of A22 ST, surface area 49 mST, surface area 49 m22 /g; pore volume/g; pore volume 0.28 ml/g0.28 ml/g  Impregnation with ammonium iron citrateImpregnation with ammonium iron citrate  Loading only 2.5 wt.% iron; small iron particles toLoading only 2.5 wt.% iron; small iron particles to suppress encapsulation by graphite layers andsuppress encapsulation by graphite layers and growth of nanofibersgrowth of nanofibers  Activity measurements at elevated pressuresActivity measurements at elevated pressures GBH Enterprises Ltd.
  86. 86. Fischer-Tropsch Synthesis onFischer-Tropsch Synthesis on Zirconia-Supported Iron CatalystZirconia-Supported Iron Catalyst Space velocity does not affect level of conversion ! Oxidation by water formed in the reaction Synthesis at 24 bar, 623 K, H2/CO = 1.0 Note much more elevated conversion at higher pressure GBH Enterprises Ltd.
  87. 87. Selectivity of Zirconia-Selectivity of Zirconia- Supported Iron CatalystSupported Iron Catalyst Synthesis at 24 bar, 623 K, H2/CO = 1.0 Note much more elevated conversion at higher pressure GBH Enterprises Ltd.
  88. 88. Fischer-Tropsch Synthesis on Zirconia-Fischer-Tropsch Synthesis on Zirconia- Supported Iron CatalystSupported Iron Catalyst Synthesis at 24 bar, 623 K, H2/CO = 1.7 1880 h-1 Note much more elevated conversion at higher pressure GBH Enterprises Ltd.
  89. 89. Selectivity of Zirconia-SupportedSelectivity of Zirconia-Supported Iron CatalystIron Catalyst Synthesis at 24 bar, 623 K, H2/CO = 1.7 1880 h-1 Note much more elevated conversion at higher pressure GBH Enterprises Ltd.
  90. 90. Production of OlefinsProduction of Olefins  Measurements in nanoflow apparatusMeasurements in nanoflow apparatus  Relatively large production of olefinsRelatively large production of olefins • C1 C2 C3C1 C2 C3 C2=/C2+C2= C3=/C3+C3= CC2=/C2+C2= C3=/C3+C3= C • 573 K 4.1 7.3 12.6 76.6 91.3 3.4573 K 4.1 7.3 12.6 76.6 91.3 3.4 • 623 K 9.9 13.9 19.7 59.7 88.8623 K 9.9 13.9 19.7 59.7 88.8 10.910.9  Production of olefins promising as well as stability ofProduction of olefins promising as well as stability of catalystcatalyst GBH Enterprises Ltd.
  91. 91. Conclusions (1)Conclusions (1)  Preparation of supported iron, cobalt, nickel, and iron-Preparation of supported iron, cobalt, nickel, and iron- nickel catalysts well developednickel catalysts well developed  Complementing range of analytical techniques forComplementing range of analytical techniques for characterizing catalysts before, during and after Fischer-characterizing catalysts before, during and after Fischer- Tropsch synthesisTropsch synthesis • Mossbauer experiments and results not dealt withMossbauer experiments and results not dealt with  Earlier mentioned items, competitive dissociativeEarlier mentioned items, competitive dissociative adsorption and effect not completely reducible metaladsorption and effect not completely reducible metal oxides well identifiedoxides well identified  Reduction of cobalt catalysts prepared by impregnationReduction of cobalt catalysts prepared by impregnation extensively investigatedextensively investigated GBH Enterprises Ltd.
  92. 92. Conclusions (2)Conclusions (2)  Deposition-precipitation, impregnation withDeposition-precipitation, impregnation with badly crystallizing compounds (citrates, EDTAbadly crystallizing compounds (citrates, EDTA complexes) successfully appliedcomplexes) successfully applied  Complex cyanides very interesting precursorsComplex cyanides very interesting precursors for metals and alloys difficult to reduce or tofor metals and alloys difficult to reduce or to prepare with uniform chemical compositionprepare with uniform chemical composition  Reliable and significant investigation of activityReliable and significant investigation of activity and selectivity of Fischer-Tropsch catalysts canand selectivity of Fischer-Tropsch catalysts can only be performed at elevated pressuresonly be performed at elevated pressures GBH Enterprises Ltd.
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