Electrochemical Technology Program Argonne ... - Energy.gov · DOE/EE/HFCIT Program of Energy Even...
Transcript of Electrochemical Technology Program Argonne ... - Energy.gov · DOE/EE/HFCIT Program of Energy Even...
Hydrogen, Fuel Cells, and Infrastructure TechnologiesOffice of Energy Efficiency and Renewable EnergyU.S. Department of Energy
Water gas shift catalysis
Theodore Krause, Razima Souleimanova,John Krebs, and Mario Castagnola
Electrochemical Technology Program
Argonne National Laboratory
May 24-27, 2004
This presentation does not contain any proprietary or confidential information
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Objectives
• To develop advanced water-gas shift (WGS) catalyststo meet the DOE performance requirements
Compared to Cu-Zn and Fe-Cr WGS catalysts, these newcatalysts will be
more active (higher turnover rates)
less prone to deactivation due to temperature excursions
more structurally stable (able to withstand frequent cycles ofvaporizing and condensing water)
more resistant to sulfur poisoning
Improve our understanding of reaction mechanisms, catalystdeactivation, and sulfur poisoning
Define operating parameters (e.g. steam:carbon ratios,temperature, gas hourly space velocities (GHSV), catalystgeometry) to optimize catalyst performance and lifetime
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Budget, technical barriers and targets• FY04 Funding: $600K
• Technical barriers
A. Fuel Processor Capital Costs
G. Efficiency of Gasification, Pyrolysis, and Reforming Technologies
Z. Catalysts
AB. Hydrogen Separation and Purification
• Technical targets for water gas shift catalysts
gas-hourly space velocity (GHSV) 30,000 h-1
CO conversion 90% and selectivity 99%
lifetime > 5000 h
cost <$1/kWe
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Approach• Identify metal(s) and oxide combinations which promote
one or more elementary reaction steps (e.g. CO oxidation,H2O dissociation, formate/formyl decomposition) involvedin the water-gas shift reaction
• Evaluate the water-gas shift activity of these materials in amicroreactor system
• Use characterization techniques (e.g. X-ray spectroscopy,temperature-program reduction (TPR), and electronmicroscopy) to identify factors needed to improve WGSactivity or to minimize catalyst deactivation
• Develop kinetic model to predict catalyst performance forreformer operating parameters
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Project safety
• Internal safety reviews are performed for all aspects ofthis project to address ESH issues
Catalyst synthesis
• Synthesis procedures are performed in fumehoods toexhaust vapors of powders and solvents
• Waste chemicals are collected and disposed of throughthe Laboratory’s Waste Management Operations
Microreactor systems
Located in fumehoods
Equipped with safety interlocks that shut the systemdown if excessive temperature or pressure is sensed orthe fumehood ventilation fails
• Safety reviews are updated and renewed annually
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Project timeline
Oct 1997: Initiatedwork on Pt shiftcatalyst
May 1999: Began work onnon-precious metalcatalysts
Mar 2003:Demonstrated Pt-Re with higheractivity and betterstability than Pt
Oct 2000: Optimized Cu-mixedmetal oxide formulation Oct 2002: Began
work on Pt bimetallicformulation
May 2002: Demonstrated90% conv., <0.1 kg/kWe,$0.9/kWe with Cu catalyst
June 2003: Begin testingof catalysts supported onmonoliths and foams
Aug 1999: DemonstratedPt catalyst with 0.14 wt%loading
May 2001:Demonstrated Co andRu promoted catalyst
May 2000:Demonstrated Cu-mixed metal oxidecatalyst
Jan-Mar 2004:Completed kineticstudy of Pt-Re andreactor modelinganalysis
Apr 2004: Demonstratedimproved base metalcatalyst
Oct 2003: Determinedoptimal compositionfor Pt-Re
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Addition of Re improves performance of Pt-ceria catalyst
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Temperature, °C
0.91 wt%Pt - 0.95 wt%Re
0.92 wt%Pt - 1.79 wt%Re
1.81 wt%Pt - 1.77 wt%Re
0.87 wt%Pt
1.51 wt% Pt
2.86 wt% Pt
-0.5-10.5011Pt*
-0.17-0.580.40016Pt-Re
dcba Ea(kcal/mol)
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Temperature, °C
cat*s
1.81%Pt - 1.77%Re
0.87%Pt
0.91%Pt - 0.95%Re
2.86%Pt
0.92%Pt - 1.79%Re
Rate Equation: exp(-Ea/RT)*COa*H2Ob*H2
c*CO2d
*Ref: T. Bunluesin et al. Appl. Catal. B, 15 (1998) 107-114.
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TPR and extended X-ray absorption fine structure(EXAFS) analysis suggests that Re stabilizes Pt
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R, Å
FT
((
(k)*
k3)
Pt-Re - as prepared
Pt-Re - 300oC
Pt - 300oC
Pt-Re - 400oC
Pt - 400oC
Pt - as prepared
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Temperature, oC
TC
D R
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on
se, arb
itra
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Pt-Re - 1st TPR
Pt - 1st TPR
Pt - 2nd TPR
Pt-Re - 2nd TPR
• For Pt, shift in reductionpeak to lower temperature isindicative of particle growth
• For Pt-Re, no change inreduction profile
• More Pt-Pt bond formation inPt than Pt-Re after 100+ h onstream at 400°C
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Even with deactivation, Pt-Re catalyst should beable to meet GHSV target
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280 300 320 340 360 380 400 420 440
Inlet temperature, oC
S/C
- s
tea
m-t
o-c
arb
on
ra
tio
20,000 h-1
20,000 h-1
w/deact
30,000 h-1 30,000 h
-1
w/deact
40,000 h-1
w/deact40,000 h
-1
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Time on stream, h
cat*s
ec
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5 ppm H2S
25 ppm H2S
50 ppm H2S
• Pt-Re lost about 50% of itsinitial activity during the first250 hours, but the activitythen stabilized
• Modeling study shows that 1%CO can be achieved even withdeactivation if the temperatureand S/C ratio are increased
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Optimal geometric support for WGS catalyst -foam or monolith?
• Both modeling and experimental studies show that theremay be a slight benefit to using a foam as a support
• However, the monolith is the preferred support based oncost and production capacity
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Exit Temperature, oC
CO
co
nvers
ion
, %
600-cpi Monolith
- 30,000 h-1
Equilibrium
600-cpi Monolith -
45,000 h-1
Foam - 30,000 h-1
Foam - 45,000 h-1
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Exit temperature, °C
CO
co
nvers
ion
, %
Foam - 5% relative density
400-cpi Monolith
600-cpi Monolith
Equilibrium
GHSV = 30, 000 h-1
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Even with the higher activity of the Pt-Re, stillhigher activity is needed to meet the cost targets
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Catalyst loading, g/L
CO
co
nvers
ion
, %
S/C=1.4 Tin=400oC
S/C=3 Tin=400oC
S/C=1.4 Tin=350oC
S/C=3 Tin=350oC
• Modeling studies suggestthat the optimal catalystloading on the structuredsupport is 50-150 g/L
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400-cpi
monolith
600-cpi
monolith
Ceramic
Foam
Metal
Foam
Structured Support
$/k
We
Support
Support + CeO2
Support + CeO2 + 1 wt%Pt - 50g/L
Support + CeO2 + 1 wt% Pt - 150g/L
Target of $1/kWe
Pt price of $893/oz (4/5/04)
• The $1/kWe target is toughto achieve
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We are investigating less-costly precious metalbimetallic catalysts
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Temperature, oC
CO
co
nvers
ion
, %
600-cpi monolith
1200-cpi monolith
equilibrium
GHSV = 30,000 h-1
• A combination of a preciousmetal (PM)-base metal (BM) hasbeen identified that exhibitshigher WGS activity than eitherthe PM or BM
• The equilibrium-predictedCO conversion isachieved at a GHSV of30,000 h-1 at >340oC
• Long-term stability is yetto be verified
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Temperature, oC
cat*
se
c)
1x PM + 3x BM
2.5x PM + 3x BM
7.5x PM + 3x BM
2.5x PM + 1x BM
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Base metal WGS catalysts may also bepossible
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Temperature, °C
cat*
s)
1X - Precursor A
2X - Precursor A
1X - Precursor B
2X - Precursor B
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Temperature, °C
cat*
s)
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CO
to C
O2 s
ele
ctiv
ity, %
Support B
Support A
• The choice of precursor and oxide support were critical factorsfor optimizing activity
• The catalyst promotes methanation; however,
• The selectivity of CO to CO2 does not depend on the precursor orsupport
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A critical factor for the base metal catalyst is to preventformation of the oxide and surface interactions
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Temperature, °C
cat*
s)
Precursor A
Pretreatment 1
Precursor B
Pretreatment 1
Precursor A
Pretreatment 2
Precursor B
Pretreatment 2
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Temperature, °C
no
rmalized
TC
D s
ign
al, a
rbit
rary
Precursor B - Pretreatment 1
Precursor B - Pretreatment 2
Bulk Oxide
• Pretreatment has a significantinfluence on catalyst activity
• The most active catalysts havea reduction peak at ~200°C
• The reduction peak at ~700oC isindicative of metal-supportinteraction
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Comparing the three types of WGS catalysts
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Temperature, °C
cat*
s)
Base Metal
PM + Base Metal
Pt+Re
• Pt-Re
Very active shift catalyst
Good stability
High Cost
• PM + Base Metal
Good shift activity
Less costly than Pt-Re
Stability not yet established
• Base Metal
Less active than both Pt-Reand PM + Base metalcatalysts
Methanation and stabilityare yet to be addressed
Lowest cost
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Can we avoid low temperature shift foron-board reforming?
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Inlet temperature, oC
S/C
- s
tea
m-t
o-c
arb
on
ra
tio
40,000 h-1
isothermal
20,000 h-1
adiabatic
20,000 h-1
isothermal
30,000 h-1
isotherma
30,000 h-1
adiabatic
40,000 h-1
adiabatic
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adiabatic
60,000 h-1
isothermal
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Inlet Temperature, oC
CO
co
nvers
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Pt-Re
12 wt% Cu
8 wt% Cu
Equilibrium
GHSV = 30,000 h-1
Cu kinetics - N. A. Koryabkina et al., J.
Catal. , 217 (2003) 233-239.
• Modeling studies showthat the activity of Pt andCu catalysts decreasessignificantly below 300°C
• Pt-Re can achieve 1% CO at>300°C at GHSV 30,000 h-1
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Interactions and collaborations
• University of Alabama (Prof. Ramana Reddy) tocharacterize shift catalysts using SEM, TEM, andXPS
• Non-disclosure agreement (NDA) with CatalyticaEnergy Systems to evaluate new shift catalysts
• Provided samples for evaluation
Toyota
Nissan
Süd-Chemie, Inc.
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Response to reviewers’ comments from FY03
• Monolith work should be given priority
• Improve durability (longer-term endurancetesting is needed)
• Better performance from non-precious metalcatalysts
• Are low temperature catalysts feasible foron-board fuel processing?
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Milestones
05/04Complete the assessment of the feasibilityof a low temperature non-precious metalcatalyst to meet the DOE targets
09/04Demonstrate <1% CO out using structuredcatalyst(s) for >500 h
05/04Determine the optimal bimetallicformulation for the Pt-based shift catalyst
01/04Determine the optimal operatingconditions for the water-gas shift reactor
DateMilestone
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Future work
• For bimetallic precious metal-base metal and base metalcatalysts
Optimize formulation to increase activity and minimize methanation
Improve our understanding of reaction mechanisms
• To improve catalyst durability and minimize deactivation
Conduct characterization studies of spent catalysts to furtherunderstand deactivation mechanisms
Conduct long-term tests of improved catalyst formulations
• Address catalyst issues identified in “FASTER” Program
Catalyst deactivation and structural stability issues (i.e., effect offrequent and rapid startup)
Obtain performance data as a function of operating parameters todevelop kinetic models