NETL Fuel Processing R&D
2006 SECA Peer Review Meeting
September 13, 2006
David A. Berry Dushyant Shekhawat, Todd Gardner, Maria Salazar National Energy Technology Laboratory
Diesel Fuel Processing Roadmap
Future Plan – 5 year
2008 2008 2006 2007 2009 2010 2010
SECA Gen. 1 Diesel Reformer
SECA Cost-Reduction program ends in 2010 with Phase III Industrial Team Demonstrations. APU for truck transport, generators, and other synergistic applications (IE. Military) are important to fuel cell commercialization and are being considered. Goal is to develop adequate reforming technology to support the demonstrations in 2008 & 2010. Catalyst Development – Oxide-based OxideNETL – Hexaaluminate ANL – Perovskites Eltron – Perovskites U of Mich – Bi-metalics BiAlternative Reforming – Eval & Dev NETL/Other – RV GlideArc Plasma, RF, thermal… Reactor Design – Goodrich / Delevan – Fuel/Air nozzles TBD / SBIR 07 – Alt. Tech/Plasma TBD / Other– Non-SECA Developers Other– OTHER – Test/Eval. Other Test/Eval. Developer Fuel Processors NETL FPU Test Stand Industry II System Demo
THG/OSER Merit Review – 5/2/2006
Select Technology
Subsystem Demo
Industry III System Demo
Fuel Reaction Chemistry Studies Fuel Reaction Chemistry Studies
• Effect of Sulfur • Effect of Recycle
THG/OSER Merit Review – 5/2/2006
Effects of Sulfur on Catalytic Fuel Effects of Sulfur on Catalytic Fuel Reforming Reforming
OBJECTIVE: OBJECTIVE:
•• Evaluate the effects of sulfur impurities on liquid Evaluate the effects of sulfur impurities on liquid
fuel catalytic reforming. fuel catalytic reforming.
THG/OSER Merit Review – 5/2/2006
Sulfur Effects
•• Hard to avoid the Hard to avoid the • Organic sulfur reduction
organosulfur present in organosulfur present in liquid hydrocarbons liquid hydrocarbons
− R2S + 2H2 = H2S + 2R-H
• Dissociative sulfur adsorption
•• Varying range of sulfur Varying range of sulfur
found in liquid HC fuels found in liquid HC fuels
•• Sulfur can be Sulfur can be
− M + H2S (g) = M-S (a) + H2 (g) − M + R2S (g) = M-S (a) + R-R (g) − MO + H2S (g) = M-S (a) + H2O (g)
detrimental to catalyst detrimental to catalyst activity activity
THG/OSER Merit Review – 5/2/2006
Experimental Setup
Vent MFC = Mass Flow Controller PI = Pressure Indicator Insulated Zone Thermocouple PI Product Analysis
Vent PI N2 Liquid Fuel Air H2 MFC HPLC Pump MFC MFC Convection Heater Furnace Fixed-Bed
THG/OSER Merit Review – 5/2/2006
Laboratory Reactor
Online Mass Spectrometer Preheat zone Multiple sample and calibration ports
Reactor
Online GCs
Twin Microreactors
THG/OSER Merit Review – 5/2/2006
Some Definitions
• Yield of product A (H2, CO, or CO2)
Yield of A (%) =
Moles of A produced x 100 N x moles of hydrocarbon fed to the reactor
• Yield of hydrocarbons (olefins, paraffins, and benzene)
Hydrocarbon Yield (%) =
m x moles of hydrocarbon produced x 100 N x moles of diesel fed to the reactor
• Conversion of hydrocarbons
(CO + CO2 + Conv (%) =
i =1- 7 i
∑ iC H ) x 100
i r
N x moles of hydrocarbon fed to the reactor
Where, N is the number of moles of H2/mole of HC for H2 yields and the number of carbons in hydrocarbon fuel for Cox; m is the number of carbons in the hydrocarbon product
THG/OSER Merit Review – 5/2/2006
Experimental Conditions
•• Catalysts: Catalysts: − Hexicat (in-house hexaaluminate catalyst) − Hexicat (in-house hexaaluminate catalyst) − Rh/Zirconia-doped Ceria (ZDC, oxygen-ion − Rh/Zirconia-doped Ceria (ZDC, oxygen-ion conducting support) conducting support) − Pt/g-alumina (Baseline catalyst) − Pt/g-alumina (Baseline catalyst) •• Operating Conditions: Operating Conditions: − Temperature: 850 C − Temperature: 850 C − GHSV: 50,000 h-1 − GHSV: 50,000 h-1 − O/C: 1.2 − O/C: 1.2 − Fuel: Tetradecane − Fuel: Tetradecane
THG/OSER Merit Review – 5/2/2006
Sulfur Effects (50 ppm S in fuel)
(CPOX, T = 850 °C, O/C =1.2, GHSV = 50,000 h-1)
25
•• 50 ppm of S as dibenzothiophene 50 ppm of S as dibenzothiophene •• ••
S added
20
S removed
•• ••
was introduced after 1 h TD only run was introduced after 1 h TD only run Sulfur effects catalyst sensitive Sulfur effects catalyst sensitive H2 & CO yields decreased upon S H2 & CO yields decreased upon S introduction introduction •• Less significant drop from Less significant drop from Rh/ZDC and Hexicat Rh/ZDC and Hexicat Catalyst activity restored after S Catalyst activity restored after S removal from the feed removal from the feed Rate of carbon formation increased Rate of carbon formation increased with S in feed with S in feed − 0.18 g to 0.31 g for Hexicat − 0.18 g to 0.31 g for Hexicat − 0.21 g to 0.57 g for ZDC − 0.21 g to 0.57 g for ZDC − 0.69 g to 0.92 g for Pt/alumina − 0.69 g to 0.92 g for Pt/alumina
Hexicat Rh/ZDC Pt/Al2O3
H2 (%)
15
10
5
0 0 1 2 3 Time on stream (Hrs) 4 5 6
25
S added
20
S removed
Hexicat Rh/ZDC Pt/Al2O3
CO (%)
15
10
5
0 0 1 2 3 Time on stream (hrs)
THG/OSER Merit Review – 5/2/2006
4
5
6
Sulfur Effects (1000 ppm S in fuel)
(CPOX, T = 850 °C, O/C =1.2, GHSV = 50,000 h-1)
25
•• Considerable drop in H2 Considerable drop in H2
S added 20 Rh/ZDC H2 (%) 15 Hexicat 10 Pt/Al2O3 5
S removed
•• •• ••
concentrations compared to CO concentrations compared to CO concentrations concentrations − CO concentrations dropped to − CO concentrations dropped to stationary levels stationary levels − H2 concentration dropped to − H2 concentration dropped to stationary levels only for Rh/ZDC stationary levels only for Rh/ZDC − Catalyst activity recovered after S − Catalyst activity recovered after S removal from the feedow for Pt removal from the feedow for Pt H2/CO ratio >1 before S introduction H2/CO ratio >1 before S introduction H2/CO ratio <1 after S introduction H2/CO ratio <1 after S introduction − <0.5 for Pt − <0.5 for Pt Water produced more easily on Pt Water produced more easily on Pt catalyst compared to Rh catalyst compared to Rh
0 0 1 2 3 4 Time on stream (hrs) 5 6
25
S added S removed
20
Rh/ZDC
CO (%)
15 10 5 0 0
Hexicat Pt/Al2O3
1
2
3
4
5
6
Time on stream (hrs)
THG/OSER Merit Review – 5/2/2006
Conclusions
•• Sulfur effects are very catalyst sensitive Sulfur effects are very catalyst sensitive •• Rate of carbon formation increased with S in feed Rate of carbon formation increased with S in feed •• Catalyst activity recovered after S removal for the Catalyst activity recovered after S removal for the
Rh/ZDC and hexaaluminate catalyst and to lesser Rh/ZDC and hexaaluminate catalyst and to lesser extent for the Pt system extent for the Pt system
THG/OSER Merit Review – 5/2/2006
Effects of Recycle on Catalytic Fuel Effects of Recycle on Catalytic Fuel Reforming Reforming
OBJECTIVE: OBJECTIVE:
•• Evaluate the effects of recycle on catalytic fuel reforming Evaluate the effects of recycle on catalytic fuel reforming
THG/OSER Merit Review – 5/2/2006
Recycle Study Benefits
•• Recycle provides benefits to “dry” reforming Recycle provides benefits to “dry” reforming
systems targeted for commercialization of systems targeted for commercialization of APU and other like applications APU and other like applications
− Water inhibits the carbon formation − Water inhibits the carbon formation − Better heat integration − Better heat integration − Higher efficiency − Higher efficiency − Higher RRs lower the catalyst temperatures and − Higher RRs lower the catalyst temperatures and checks the catalyst sintering checks the catalyst sintering
THG/OSER Merit Review – 5/2/2006
Recycle Study
Configuration
Anode Recycle
CO2, H2O, H2, CO, N2
Diesel Air
Reformer H2, CO, N2, CO2, H2O
Fuel cell
H2, CO, N2, CO2, H2O
Reformer Recycle
H2, CO, H2O, CO2, N2
Fuel Air
Reformer H2, CO, N2, CO2, H2O
Fuel cell
H2, CO, N2, CO2, H2O
THG/OSER Merit Review – 5/2/2006
Recycle Study
Runs Conditions
•• Surrogate diesel fuel was used Surrogate diesel fuel was used
− 40 wt% tetradecane, 20 wt% t-butylbenzene, 18 − 40 wt% tetradecane, 20 wt% t-butylbenzene, 18 wt% t-butylcyclohexane, and 22 wt% decalin wt% t-butylcyclohexane, and 22 wt% decalin − Anode recycle compositions − Anode recycle compositions
•• Estimated equilibrium recycle stream compositions Estimated equilibrium recycle stream compositions
•• 80% conversion of syngas in fuel cell assumed 80% conversion of syngas in fuel cell assumed •• 24% CO2, ,18% H2O, 3% H2, ,3% CO 24% CO2 18% H2O, 3% H2 3% CO •• 24% CO, 22%H2, ,5% H2O, 1% CO2, ,48% N2 24% CO, 22%H2 5% H2O, 1% CO2 48% N2
− Reformer Recycle composition − Reformer Recycle composition
•• ••
Catalyst: Rh/Al2O3 from Alfa Catalyst: Rh/Al2O3 from Alfa Recycle Ratio from 0 to 0.5 studied Recycle Ratio from 0 to 0.5 studied •• O/C: 1.0, T: 850 °C, SV: 50,000 h-1,,preheat: 325 °C O/C: 1.0, T: 850 °C, SV: 50,000 h-1 preheat: 325 °C
THG/OSER Merit Review – 5/2/2006
Effect of Anode Recycle on Product Distribution
120 100 80 Yield (%) 60 40 20 0 H2 -20 CO CO2 Para Unsaturates 0 0.2 0.3 0.4 0.5
•• •• ••
Anode recycle: 24% CO2,,18% H2O, 3% H2,,3% CO Anode recycle: 24% CO2 18% H2O, 3% H2 3% CO H2 and CO yields increase with increasing RR H2 and CO yields increase with increasing RR Negative CO2 yields at higher RRs Negative CO2 yields at higher RRs − CO2 + H2 = CO + H2O − CO2 + H2 = CO + H2O − Dry reforming − Dry reforming •• HC conversion increases HC conversion increases
THG/OSER Merit Review – 5/2/2006
Effect of Reformer Recycle on Product Distribution
120 100 80 60 40 20 0 H2 CO CO2 Para Ole Conv
Yield or Conv (%)
0 0.2 0.3 0.4 0.5
•• Reformer recycle: 24% CO, 22% H2,,5% H2O, 1% CO2,, Reformer recycle: 24% CO, 22% H2 5% H2O, 1% CO2 •• •• ••
48% N2 48% N2 H2 and CO yields decrease with increasing RR H2 and CO yields decrease with increasing RR Lower HC conversion in presence of reformer recycle Lower HC conversion in presence of reformer recycle More conversion to paraffins and unsaturates More conversion to paraffins and unsaturates − More carbon formed − More carbon formed
THG/OSER Merit Review – 5/2/2006
Effect of Recycle on carbon Formation
600 500 Carbon formed (mg) 400 300 200 100 0 0 0.05 0.1 0.15 0.2 0.25 Recycle Ratio 0.3 0.35 0.4 0.45 0.5 Anode Reformer
•• Carbon formation decreases with increasing RR for Carbon formation decreases with increasing RR for
anode recycle anode recycle •• More carbon formed from reformer recycle stream More carbon formed from reformer recycle stream
THG/OSER Merit Review – 5/2/2006
Effect of Individual Recycle Components on carbon Formation
800 600 Carbon formed (g)
400
200
0 CO2 H2O N2 H2 CO
•• CO2 and H2O have similar effects (positive) CO2 and H2O have similar effects (positive)
•• ••
− C + CO2 = 2CO; C + H2O = CO + H2 − C + CO2 = 2CO; C + H2O = CO + H2 − Dry reforming; steam reforming − Dry reforming; steam reforming H2 no effects H2 no effects CO in recycle stream enhance the carbon formation CO in recycle stream enhance the carbon formation
THG/OSER Merit Review – 5/2/2006
Effect of Recycle on Carbon Formation Type Anode Recycle
2 1.6 CO2 evolved (%)
0 0.1 0.2 0.3 0.5 0.4
1.2
0.8
0.4
0 200
300
400
500 600 700 Tempertaure (C)
800
900
1000
•• Mainly two peaks were observed in the TPO Mainly two peaks were observed in the TPO
− Low temperature peaks (~600 °C) can be assigned to carbon − Low temperature peaks (~600 °C) can be assigned to carbon deposition on Rh metal sites55 deposition on Rh metal sites − High temperature peaks (>800 °C) can be attributed to carbon − High temperature peaks5(>800 °C) can be attributed to carbon deposited on the support 5 deposited on the support •• High temperature peak reduces as RR increases High temperature peak reduces as RR increases
5A. Shamsi, J.P. Baltrus, J.J. Spievy, Appl. Catal. A 293 (2005) 145. 5A. Shamsi, J.P. Baltrus, J.J. Spievy, Appl. Catal. A 293 (2005) 145.
THG/OSER Merit Review – 5/2/2006
Conclusions
•• H2 and CO yields increase while carbon H2 and CO yields increase while carbon
formation decreases with increasing ANODE formation decreases with increasing ANODE recycle ratio recycle ratio
•• REFORMER recycle produced more carbon on REFORMER recycle produced more carbon on
the catalyst and, hence, lower hydrocarbon the catalyst and, hence, lower hydrocarbon conversion and product yields conversion and product yields
THG/OSER Merit Review – 5/2/2006
Technology Transfer
•• D. Shekhawat, T. H. Gardner, D. A. Berry, J. J. Spivey, Catalytic Reforming of D. Shekhawat, T. H. Gardner, D. A. Berry, J. J. Spivey, Catalytic Reforming of •• ••
••
•• ••
Liquid Hydrocarbon Fuels for Fuel Cell Applications, Catalysis, Royal Society of Liquid Hydrocarbon Fuels for Fuel Cell Applications, Catalysis, Royal Society of Chemistry, London, 2006, Vol. 19, Chapter 6, pp. 184-253. Chemistry, London, 2006, Vol. 19, Chapter 6, pp. 184-253. D. Shekhawat, T. H. Gardner, D. A. Berry, Fuel Constituent Effects on Fuel D. Shekhawat, T. H. Gardner, D. A. Berry, Fuel Constituent Effects on Fuel Reforming Properties for Fuel Cell Applications, 231ststACS National Meeting, Mar Reforming Properties for Fuel Cell Applications, 231 ACS National Meeting, Mar 26-30, 2006, Atlanta, GA. 26-30, 2006, Atlanta, GA. D. Shekhawat, D. A. Berry, T. H. Gardner, D. J. Haynes, J. J. Spivey, T. Xiao, M. D. Shekhawat, D. A. Berry, T. H. Gardner, D. J. Haynes, J. J. Spivey, T. Xiao, M. L. H. Green, Partial Oxidation Reforming of n-Tetradecane over Pt and Carbide L. H. Green, Partial Oxidation Reforming of n-Tetradecane over Pt and Carbide Catalysts: A Comparative Study, 231ststACS National Meeting, Mar 26-30, 2006, Catalysts: A Comparative Study, 231 ACS National Meeting, Mar 26-30, 2006, Atlanta, GA. Atlanta, GA. D. A. Berry, D. Shekhawat, T. H. Gardner, M. Salazar, D. J. Haynes, J. J. Spivey, D. A. Berry, D. Shekhawat, T. H. Gardner, M. Salazar, D. J. Haynes, J. J. Spivey, Support Effects for Pt and Rh-Based Catalysts for Partial Oxidation of nSupport Effects for Pt and Rh-Based Catalysts for Partial Oxidation of nTetradecane, The Fourth International Conference on Fuel Cell Science, Tetradecane, The Fourth International Conference on Fuel Cell Science, Engineering and Technology, Jun 18-21, 2006, Irvine, CA. Engineering and Technology, Jun 18-21, 2006, Irvine, CA. D. Shekhawat, D. A. Berry, T. H. Gardner, M. Salazar, D. J. Haynes, J. J. Spivey, D. Shekhawat, D. A. Berry, T. H. Gardner, M. Salazar, D. J. Haynes, J. J. Spivey, Support Effects for Pt and Rh-Based Catalysts for Partial Oxidation of nSupport Effects for Pt and Rh-Based Catalysts for Partial Oxidation of nTetradecane, Applied Catalysis A: General, 2006, 311, 8-16 Tetradecane, Applied Catalysis A: General, 2006, 311, 8-16 D. Shekhawat, T. H. Gardner, D. A. Berry, Fuel Constituent Effects On Fuel D. Shekhawat, T. H. Gardner, D. A. Berry, Fuel Constituent Effects On Fuel Reforming Properties For Fuel Cell Applications, Preparing for Int. J. H2 Energy. Reforming Properties For Fuel Cell Applications, Preparing for Int. J. H2 Energy.
THG/OSER Merit Review – 5/2/2006
Oxygen Conducting Catalyst Supports
Role of O2 ion Conducting Role of O2 ion Conducting Supports on Catalytic Fuel Supports on Catalytic Fuel Reforming Reforming
THG/OSER Merit Review – 5/2/2006
Oxygen Conducting Catalyst Supports
Objective To have aafundamental understanding of the role of oxygen Objective To have fundamental understanding of the role of oxygen
conducting supports in reforming of diesel fuel compounds and their role in conducting supports in reforming of diesel fuel compounds and their role in decreasing carbon deposition. decreasing carbon deposition.
CH4 2H2 C*
O2 CO O C
O
There is an empirical knowledge: oxygen ion conducting supports mitigate carbon formation. Reaction mechanism is still not clear. Further fundamental research is necessary O O O O2-
Metal
Oxygen ion conducting support Study is performed during cPOX of CH4. However, results can be extrapolated to higher hydrocarbons.
Fundamental research will allow to use findings for catalysts synthesis and operation conditions in fuel reformers
THG/OSER Merit Review – 5/2/2006
Current & Prior Studies at NETL
Performance Studies Performance Studies
Effect of ionic conductivity on carbon formation Effect of ionic conductivity on carbon formation Effect of catalyst reducibility in catalyst performance Effect of catalyst reducibility in catalyst performance
Characterization Studies Characterization Studies
Effect of Temp. & time on stream on methane conversion Effect of Temp. & time on stream on methane conversion Effect of dopant type in catalyst characteristics Effect of dopant type in catalyst characteristics
*Mechanistic Studies *Mechanistic Studies
Partial Oxidation of methane in the absence of gaseous O22 Partial Oxidation of methane in the absence of gaseous O Catalyst labeling Catalyst labeling Isotopic oxygen uptake & exchange Isotopic oxygen uptake & exchange POM Reactions POM Reactions
THG/OSER Merit Review – 5/2/2006
NETL Fuel Processing R&D Performance and Characterization studies
Catalysts were tested to elucidate effects of: Support type •Oxygen ion conducting support: ceria based oxides •Non-Oxygen ion conducting supports: alumina Catalyst type (Rh, Pt, Ni) Dopant type (Zr, La, Gd) Dopant concentration GDC10 & GDC30
100 experiments have been performed Operation variables during experimental tests included
Reaction Temperature O/C ratio Time on stream Space velocity
Parameters measured during catalytic tests and characterization
Catalytic activity and selectivity Amount of carbon deposition Characterization: Effect of dopant and metal addition on support reducibility. Effect of dopant addition on ionic conductivity and crystal phases Effect of Catalyst Reduction Temperature on catalytic activity and selectivity
THG/OSER Merit Review – 5/2/2006
Isotopic tests/Cat. Labeling/Rh/ZDC50 and Rh/alumina
M ass Spect signal (a.u.)
Oxygen Conducting Catalyst Supports
was dosed to the catalyst until saturation
18O 2 18O 2
O-16 O-16
O-16 O-18
O-18 O-18
Oxygen consumption seems to be due to surface and bulk oxidation of Rh/ZDC50
11:42
isotopic exchange occurred between 16O in the solid catalyst and gaseous 18O from the dose
11:45
11:48
Ms S e t. s n l (ab ayu its a s p c ig a r itr r n )
8 7 6 5 4 3 2 1
Rh/Alumina Catalyst labeling 11:51 11:54
11:57
O-16 O-16
Rh/ZDC50 has a significantly higher OSC and ionic conductivity than Rh/Alumina. Thus, it shows higher Isotopic
O-16 O-18
O-18 O-18
0 10:39
THG/OSER Merit Review – 5/2/2006
10:40
10:42
10:43
Isothermal Isotopic Exchange or catalyst labeling
Suggested mechanism have been proposed for Oxygen Isotopic Exchange 1- Dissociative adsorption of 18O on metal particles 2.-Transfer of 18O species from the metal to oxide surface (spillover) 3.- Surface migration of 18O atomic species on the oxide surface to the sites of exchange 4.-An exchange between 18O species and 16O species of the oxide
18O2 18O16O
J. Phys. Chem. 1996, 100, 9429
5.-Direct exchange between gas phase and oxide 6.-Bulk oxygen diffusion to the oxide surface
(1)
16O 16O
18o
18O
(2)
18 O
(3)
18
18O16O O
Metal
(4)
16
O
18
18O 2
O
(5)
16O
-2
18O
Oxide Support
THG/OSER Merit Review – 5/2/2006
(6)
Oxygen Conducting Catalyst Supports
Isotopic Oxygen Exchange vs. Temperature
O xyg en Exch an g e, 18O 16O ato m s/g s
7.E+19 6.E+19 5.E+19 4.E+19 3.E+19 2.E+19 1.E+19 0.E+00 0 100 200 300 400 500 600 700 800 900 Temperature, C ( aDirectso. x l s ) l l gr a phi exchange between gas
Rh/GDC10 Rh/ZDC50 Pt/GDC10 Pt/ZDC50 ZDC50
phase and ZDC above 400C
Rh and Pt enhance isotopic exchange because they accelerate the rate of O2 dissociation. Rh>Pt
Isotopic Oxygen Exchange trends Rh/ZDC>ZDC (metal red. effect) Rh/GDC10>Rh/ZDC50 (conductivity) Rh >Pt (oxygen binding energy)
THG/OSER Merit Review – 5/2/2006
Isotopic Oxygen Exchange vs. Temperature
4.E+18
Oxygen Exchange, 18O16O atoms/g s
3.E+18 3.E+18 2.E+18 2.E+18 1.E+18 5.E+17 0.E+00 0
Rh/alumina
Alumina
The presence of Rh enhances the isotopic exchange because it increases the rate of dissociation of oxygen
200
400
600
800
1000
Due to lower oxygen mobility (OM) for Alumina, two peaks are detected. Higher (OM) for ceria based catalyst shows a single peak for O2 exchange at metal and support.
Temperature, C (allgraphsISo.xls )
Lower temp. peak : oxygen exchange on metal surface Second peak: exchange on alumina surface
THG/OSER Merit Review – 5/2/2006
NETL 2006 MERIT REVIEW Results/Metal reducibility
Temperature Programmed Reduction Profiles H2 (5%)/Ar, Temp. Ramp. 10C/min
-2 0 T Ds n l (a .) C ig a .u -2.5 -3 -3.5 -4 Temp. C
Pt/ZDC
Rh/ZDC
100
200
300
400
500
600
Binding energy for neutral defects formed between oxygen ion vacancies of Ceria and Rh is lower than for Ceria-Pt, which limits its participation in further reactions
THG/OSER Merit Review – 5/2/2006
J. Phys. Chem. 1994,98, 13625
NETL 2006 MERIT REVIEW Results/Isotopic tests/labeled catalysts
Partial Oxidation of Methane over Labeled Rh/ZDC
3 CO distribution (mol%) 2.5 2 1.5 1 0.5 0 14:34
CO 12 16
This is a strong evidence for the participation of oxygen originating from the catalyst in the POM. CO1216 does not form at the beginning of the reaction, which excludes the possibility of CO formation in the gas phase.
CO 12 18
14:48
15:02 15:17 Time (min)
15:31
15:46
Significant concentration of CO1218 is observed for 1h, which proves that lattice oxygen reacts with methane to generate CO
NETL 2006 MERIT REVIEW Results/18O profiles /Nuclear Reaction Analysis-PNNL
Powder samples were pelletized and loaded into the analysis chamber. Samples were bombarded with 0.74 MeV H+ ions. The alpha particles produced during the reaction (with 3.25 MeV energy) were measured to determine the total uptake of oxygen-18 in samples
THG/OSER Merit Review – 5/2/2006
NETL 2006 MERIT REVIEW Results/18O concentration /Nuclear Reaction Analysis
Concentration profiles of 18O prior & post POM over 18O2 labeled catalysts at 700C
Concent. 18O atoms%
Total no. of atoms 5
4 3 2 1 0
4.5*10E18 3*10E18 2*10E19
5*10E17
Surface catalyst
1*10E21
Prior POM Post POM
0
397
3175
6191
22064
Catalyst Depth (nm)
THG/OSER Merit Review – 5/2/2006
NETL Fuel Processing R&D
O2 Conducting Supports – Rxn Network for CH4
•Decomposition of methane occurs on reduced rhodium resulting on the formation of carbon and H2 atoms
CH 2H
4
CO Surface Migration C C
2 H
H
Metal
(5)
•Formation of O-C bonds is largely 2- (4) 22- (3) 18O 18O 18O controlled by a redox mechanism involving lattice oxygen ions on the surface, which Oxygen Ion O2are not fully conducting support coordinated. Lattice oxygen on the surface is replenished by bulk oxygen (fully coordinated lattice oxygen) This step is faster than O2 dissociation
THG/OSER Merit Review – 5/2/2006
NETL 2006 MERIT REVIEW Summary – From All Studies
•
Metal catalysts dispersed on ionically conductive supports showed significantly lower carbon formation than non-conducting supports. The GDC support material showed the highest ionic conductivity because the similar atomic size between Gd and ceria cation. This resulted in lower carbon formation. Higher metal reducibility resulted in higher H2 production and lower light off temperature Dopant and metal addition to ceria enhanced its reducibility. Especially wrt Rh as compared to Pt due to oxygen binding energies. Labeled catalyst POM studies and Nuclear reaction analysis showed a strong evidence for the participation of oxygen originating from the catalyst in the CO formation. Specifically lattice oxygen. GDC10 has been incorporated in the synthesis of hexaluminates. GDC10 pellets will be evaluated as packing material in the catalytic reactor for projects in this research group.
•
• • •
• •
THG/OSER Merit Review – 5/2/2006
NETL 2006 MERIT REVIEW Technology Transfer
Peer reviewed papers: • Salazar Maria, Berry David A., Todd H. Gardner, Shekhawat Dushyant, Floyd Donald. Catalytic Partial Oxidation of Methane on Pt/Ceria Based Catalysts. Effect of Ionic conductivity. Applied Catalysis 310(206) 54-60
•
Salazar Maria, Berry David A., Todd H. Gardner, Shekhawat Dushyant, Floyd Donald. Synthesis gas by partial oxidation and the role of oxygen-conducting supports: A review. Fuel Cell Science, Engineering and Technology, New York USA, FUEL CELL 2004 p 681-690. Salazar Maria; Berry , David A., Todd H. Gardner, Shekhawat Dushyant, Role of lattice oxygen in the Partial Oxidation of Methane over Rh & Pt/zirconiuim-doped ceria. Mechanistic aspects Preparing draft
•
Presentations: • Salazar Maria; Berry , David A., Todd H. Gardner, Shekhawat Dushyant, Role of lattice oxygen in the Partial Oxidation of Methane over Rh & Pt/zirconia-doped ceria. Mechanistic aspects. Submitted for presentation at the ACS Fall meeting 2006 • Salazar Maria; Berry , David A., Todd H. Gardner, Shekhawat Dushyant, Floyd Donald. Catalytic Partial Oxidation of Methane on Pt-Ceria Based Catalysts. AICHE Fall meeting, 2005 • Presentation project merit review at Spring 2004 SECA Core Meeting • Presentation project merit review at Spring 2005 SECA Core Meeting • FY04 Oxygen Conducting Catalyst Supports Report for SECA • FY05 Oxygen Conducting Catalyst Supports Report for SECA
THG/OSER Merit Review – 5/2/2006
Hexaaluminate Catalysts Development Hexaaluminate Catalysts Development
OBJECTIVE: OBJECTIVE: •• Evaluate & develop a catalyst to reform Evaluate & develop a catalyst to reform ‘extreme’ hydrocarbon fuels (IE. Diesel) ‘extreme’ hydrocarbon fuels (IE. Diesel)
THG/OSER Merit Review – 5/2/2006
Technical Challenges
Fuel: • A wide distribution of constituents in middle distillate with…
− discrete physico-chemical properties − discrete reactivities and adsorption properties • Aromatics, napthenes and paraffins • Organo-sulfur compounds • Olefin formation
Catalyst: • Strongly adsorbing feed constituents result in…
− Active site blocking and coking of catalyst surface • A high temperature reducing environment results in… − Vaporization and sintering of active metals
Process: • Integration with SOFC
THG/OSER Merit Review – 5/2/2006
Catalyst/Reactor Development
Diesel Air Recyc. Exhaust
Vaporizing
S poisoning Agglomeration S S S S
C-deposit
Support Collapse Catalyst Deactivation
Reformate (H2, CO, CH4...)
THG/OSER Merit Review – 5/2/2006
Toward a Middle Distillate Reforming Catalyst…
Target Goals: • A catalyst system capable of continuous long term reforming of middle distillate type fuels
− >1,000 h
•
Low catalyst degradation rate
− − − −
>850°C Carbon deposition resistance (Aromatic <25 wt%) Sulfur tolerance (<50 ppm w/w S) ‘Dry’ feed
THG/OSER Merit Review – 5/2/2006
Technical Approach
To minimize carbon deposition and site blocking… • Disperse catalytically active metals with elements or compounds which do not form strong chemisorption complexes
− Hydrocarbon adsorption affected by geometric and electronic effects
•
Achieve desired effects by doping the lattice of a structural oxide
To reduce metal sulfide formation… • Utilize catalytically active metals which possess unstable metal sulfides • Disperse active sites in low coordination to reduce H2S dissociation
THG/OSER Merit Review – 5/2/2006
Reforming Catalyst Development
Consider dispersing catalytically active metals into the lattice of hexaalumina - a structural oxide…
•Al sites are exchangeable with active transition metals •Active transition metal introduction into the lattice results in strong NNN interactions •Defect sites4 in the mirror plane region are the catalytically active site
Hexaalumina MO·6Al2O3 Structure
4
THG/OSER Merit Review – 5/2/2006
Masato et al., J. Solid State Chem., 95 (1991) 220
Advantages
• Simplicity: An atomically dispersed active site embedded in
a refractory solid oxide
− ‘Tunable’ catalyst activity − Ensemble control • Cost: An inexpensive catalyst system with low transition
metal loading
• Durability: Embedded transition metal cations are less
prone to sintering, vaporization and carbon deposition
THG/OSER Merit Review – 5/2/2006
Productivity and Results
•• Reactor setup and test conditions Reactor setup and test conditions •• Catalyst characterization Catalyst characterization •• Effect of mirror cation on catalyst stability Effect of mirror cation on catalyst stability − Carbon deposition − Carbon deposition − Sulfur poisoning − Sulfur poisoning •• The application of CeO2-based surface The application of CeO -based surface
treatments to the catalyst treatments to the catalyst •• Effect of aromatic compounds in the feed Effect of aromatic compounds in the feed •• Performance assessment on diesel Performance assessment on diesel
− Stability − Stability − Effect of WHSV − Effect of WHSV
2
THG/OSER Merit Review – 5/2/2006
NETL Laboratory Reactor Capability
Online Mass Spectrometer Preheat zone Multiple sample and calibration ports
Reactor
Online GCs
Twin Microreactors
THG/OSER Merit Review – 5/2/2006
Test Apparatus/Reaction Conditions
Test Fuels
Vent
MFC = Mass Flow Controller PI = Pressure Indicator Insulated Zone
Thermocouple
PI
Product Analysis
− − − −
Vent
n-Tetradecane (TD) 50 ppm w/w S as DBT/TD 5 wt% 1-methylnaphthalene/TD DF-2 (C-T)
PI
Fixed-Bed
Catalysts
− MNiyAl12-yAl19-δ (M = Ba, La, Sr) − HEXM catalyst series
N2 Liquid Fuel Air H2
MFC
HPLC Pump
Furnace
MFC
MFC
Convection Heater
Test Conditions
− − − − CPOX: O/C = 1.2 Temp = 850-900°C Preheat temp = 350°C GHSV = 6,250 to 50,000 cm3h-1g-1
THG/OSER Merit Review – 5/2/2006
Productivity and Results
•• Reactor setup and test conditions Reactor setup and test conditions •• Catalyst characterization Catalyst characterization •• Effect of mirror cation on catalyst stability Effect of mirror cation on catalyst stability − Carbon deposition − Carbon deposition − Sulfur poisoning − Sulfur poisoning •• The application of CeO2-based surface The application of CeO -based surface
treatments to the catalyst treatments to the catalyst •• Effect of aromatic compounds in the feed Effect of aromatic compounds in the feed •• Performance assessment on diesel Performance assessment on diesel
− Stability − Stability − Effect of WHSV − Effect of WHSV
2
THG/OSER Merit Review – 5/2/2006
XRD Study on M-site: MNiyAl12-yO19-δ
Calcined at T = 1250°C, 2 h
SrNi0.4Al11.6O19-δ
Series1
Intensity (a.u.)
Series2 Series3
BaNi0.4Al11.6O19-δ
Magnetoplumbite Ba- beta alumina Sr-beta alumina BaAl2O4 SrAl2O4 Unidentified
LaNi0.4Al11.6O19-δ
5
15
25
35
45
55
65
75
2θ, Degree
Substitution of Sr and Ba mirror cations resulted in β-alumina phase formation. La substitution resulted in a magnetoplumbite phase
THG/OSER Merit Review – 5/2/2006
Temperature Programmed Reduction of MNiyAl12-yO19-δ Catalysts
5.15 vol% H2/Ar, Ramp Rate = 10 K/min
H2 Consumed (a.u.)
LaNi1.0Al11O19-δ LaNi0.8Al11.2O19-δ BaNi0.4Al11.6O19-δ SrNi0.4Al11.6O19-δ LaNi0.4Al11.6O19-δ LaNi0.2Al11.8O19-δ 0 200 400 600 800 1000 1200
Ni-O bond in hexaalumina Ni-O bond in hexaalumina lattice was influenced by the lattice was influenced by the mirror cation mirror cation Mirror cation effect suggests Mirror cation effect suggests that Ni in the region near the that Ni in the region near the mirror plane is where mirror plane is where catalytically active defect Ni catalytically active defect Ni sites had formed sites had formed
Temperature, °C
THG/OSER Merit Review – 5/2/2006
Productivity and Results
•• Reactor setup and test conditions Reactor setup and test conditions •• Catalyst characterization Catalyst characterization •• Effect of mirror cation on catalyst stability Effect of mirror cation on catalyst stability − Carbon deposition − Carbon deposition − Sulfur poisoning − Sulfur poisoning •• The application of CeO2-based surface The application of CeO -based surface
treatments to the catalyst treatments to the catalyst •• Effect of aromatic compounds in the feed Effect of aromatic compounds in the feed •• Performance assessment on diesel Performance assessment on diesel
− Stability − Stability − Effect of WHSV − Effect of WHSV
2
THG/OSER Merit Review – 5/2/2006
CPOX: n-C14H30, O/C = 1.2, T = 850°C, P = 2 atm, WHSV = 50,000 cm3h-1g-1
NETL developed hexaaluminate catalysts are very active for the partial oxidation of large hydrocarbons…
20
20
Effect of Mirror Cation on Catalytic Stability
SrNi0.4Al11.6O19-δ
Concentration, vol%
15 H2 CO CO2 HC
10
LaNi0.4Al11.6O19-δ
5
Concentration, vol%
15 H2 CO CO2 HC
0 0 1 2 3 Time, h 4 5 6
10
5
0 0 1 2 3 Time, h 4 5 6
The structural effect induced by the The structural effect induced by the mirror cation influences catalyst mirror cation influences catalyst stability stability High coordination Ni sites result in High coordination Ni sites result in excessively strong HC adsorption excessively strong HC adsorption
THG/OSER Merit Review – 5/2/2006
Effect of Mirror Cation on Sulfur Poisoning
CPOX: n-C14H30, O/C = 1.2, T = 850°C, P = 2 atm, WHSV = 50,000 cm3h-1g-1, Step response to 50 ppm w/w S as DBT/ n-C14H30
Dibenzothiophene (DBT) and its derivatives are difficult to remove from diesel through hydrodesulfurization… LaNi0.4Al11.6O19-δ
20
SrNi0.4Al11.6O19-δ
Concentration, vol%
15 H2 CO CO2 HC
20
10
Concentration, vol%
15 H2 CO CO2 HC
5
10
0 0 1 2 3 Time, h 4 5 6
5
0 0 1 2 3 Time, h 4 5 6
The mirror cation produces a The mirror cation produces a structural effect on the Ni ensemble structural effect on the Ni ensemble High coordination Ni sites result in High coordination Ni sites result in excessively strong S adsorption excessively strong S adsorption
THG/OSER Merit Review – 5/2/2006
CPOX: n-C14H30, O/C = 1.2, T = 850°C, P = 2 atm, WHSV = 50,000 cm3h-1g-1
30 25 Concentration (vol%) 20 15 10 5 0 0 20 40 Time (h) 60 80 100 Hydrogen Carbon Monoxide 30 System upset-N2 purge 25 Concentration (vol%) 20 15 10 5 0 0 20 40 60 Time (h) 80 100 System upset-N2 purge C14H30 feed problems-pump reset
Hexaaluminate Catalyst Stability: 100 hr Aging Tests
Hydrogen Carbon Monoxide
Catalyst: BaNi0.4Al11.6O19-δ Fuel: n-tetradecane
Catalyst: 0.1 wt% Rh/SrNi0.4Al11.6O19-δ Fuel: n-tetradecane/dibenzothiophene (50 ppm w/w S)
Hexaaluminate catalysts showed good stability over 100 hr
THG/OSER Merit Review – 5/2/2006
Hexaaluminate Catalyst / Reactor
Quartz chips used to disperse the catalyst
Laboratory Reactor (Incoloy 800HT, 950°C, 80 psig)
BaNi0.4Al11.6O19-δ catalyst after 100 h CPOX on 50 ppm w/w DBT/ntetradecane. The catalyst remained relatively carbon free.
THG/OSER Merit Review – 5/2/2006
Summary Points
•• Active sites are defective Ni sites in the mirror Active sites are defective Ni sites in the mirror
plane region (coordinatively unsaturated Ni) plane region (coordinatively unsaturated Ni)
•• Geometric distribution of Ni dispersed within Geometric distribution of Ni dispersed within
the mirror plane was affected by the mirror the mirror plane was affected by the mirror cation cation
•• The excellent stability observed with nickel The excellent stability observed with nickel
substituted hexaaluminate catalysts resulted substituted hexaaluminate catalysts resulted from an atomically dispersed active site from an atomically dispersed active site present in low coordination present in low coordination
THG/OSER Merit Review – 5/2/2006
Productivity and Results
•• Reactor setup and test conditions Reactor setup and test conditions •• Catalyst characterization Catalyst characterization •• Effect of mirror cation on catalyst stability Effect of mirror cation on catalyst stability − Carbon deposition − Carbon deposition − Sulfur poisoning − Sulfur poisoning •• The application of CeO2-based surface The application of CeO -based surface
treatments to the catalyst treatments to the catalyst •• Effect of aromatic compounds in the feed Effect of aromatic compounds in the feed •• Performance assessment on diesel Performance assessment on diesel
− Stability − Stability − Effect of WHSV − Effect of WHSV
2
THG/OSER Merit Review – 5/2/2006
Minimization of Carbon Deposition with CeO2Based Surface Treatments
Catalysts exposed to n-C14H30 CPOX, O/C = 1.2 for 5 h at 850°C
Consider the application of a thin film of CeO2 to the surface of the catalyst as a method of minimizing carbon deposition…
TPO experiment TPO experiment reveals that carbon reveals that carbon deposited onto the deposited onto the hexaaluminate catalyst hexaaluminate catalyst surface correlates with surface correlates with the concentration of the the concentration of the CeO2 treatment CeO treatment
2
5
3.5
BaNi0.4Al11.6O19-δ
3 CO2 Conc./Mass Cat., vol%/g 2.5 2 1.5 1
1 wt% GDC10/BaNi0.4Al11.6O19-δ 2 wt% GDC10/BaNi0.4Al11.6O19-δ 3 wt% GDC10/BaNi0.4Al11.6O19-δ
Peak associated with metal burn-off5
0.5 0 0 200 400 600 Temperature, °C 800 1000
A. Shamsi, J.P. Baltrus, J.J. Spievy, Appl. Catal. A 293 (2005) 145.
THG/OSER Merit Review – 5/2/2006
Productivity and Results
•• Reactor setup and test conditions Reactor setup and test conditions •• Catalyst characterization Catalyst characterization •• Effect of mirror cation on catalyst stability Effect of mirror cation on catalyst stability − Carbon deposition − Carbon deposition − Sulfur poisoning − Sulfur poisoning •• The application of CeO2-based surface The application of CeO -based surface
treatments to the catalyst treatments to the catalyst •• Effect of aromatic compounds in the feed Effect of aromatic compounds in the feed •• Performance assessment on diesel Performance assessment on diesel
− Stability − Stability − Effect of WHSV − Effect of WHSV
2
THG/OSER Merit Review – 5/2/2006
CPOX: O/C = 1.2, T = 900°C, P = 2 atm, WHSV = 25,000 cm3h-1g-1
25
Catalyst Step Response Methods
Switch to 1-MN
Concentration, vol%
How do hexaaluminate catalysts respond to the step addition of aromatic compounds (1MN)? Strong Strong adsorption adsorption tendencies have tendencies have been minimized been minimized HEXM series HEXM series catalyst exhibited catalyst exhibited excellent recovery excellent recovery
Switch back to n-TD
20 15 10 5 0 0 1 2 3 4 Time, h 5 6 7
n-TD
H2 CO CO2 CH4
Catalyst: HEXM-1 Step response: n-C14H30 to 5 wt% 1-MN/nC14H30 and back to n-C14H30
THG/OSER Merit Review – 5/2/2006
Productivity and Results
•• Reactor setup and test conditions Reactor setup and test conditions •• Catalyst characterization Catalyst characterization •• Effect of mirror cation on catalyst stability Effect of mirror cation on catalyst stability − Carbon deposition − Carbon deposition − Sulfur poisoning − Sulfur poisoning •• The application of CeO2-based surface The application of CeO -based surface
treatments to the catalyst treatments to the catalyst •• Effect of aromatic compounds in the feed Effect of aromatic compounds in the feed •• Performance assessment on diesel Performance assessment on diesel
− Stability − Stability − Effect of WHSV − Effect of WHSV
2
THG/OSER Merit Review – 5/2/2006
Hexaaluminate Catalyst Stability
CPOX: DF-2 (9 ppm w/w S), O/C = 1.2, T = 900°C, P = 2 atm, WHSV = 25,000 cm3h-1g-1
25 DF-2 20 Concentration, vol%
Catalyst: HEXM-1
15 TD 10 H2 CO CO2 HCs
5
0 0 5 10 15 Time, h 20 25 30 35
NETL Hexaaluminate catalysts show excellent stability over 30 h on DF-2
THG/OSER Merit Review – 5/2/2006
Effect of Residence Time
CPOX: DF-2 (9 ppm w/w S), O/C = 1.2, T = 900°C, P = 2 atm
25 20 Concentration, vol%
15 H2 CO CO2
H2/CO selectivity remained the same H2/CO selectivity remained the same over all residence times. As WHSV was over all residence times. As WHSV was increased, gas phase chemistry became increased, gas phase chemistry became more significant… more significant…
10
Concentration of gas phase hydrocarbons, vol%
5
2.5
2
0 0 20,000 40,000 60,000
3 -1 -1
80,000
100,000
WHSV, cm g h
1.5
Catalyst: HEXM-1 Data collected after 2 h online
-1 -1 As WHSV > 12,500 cm33g-1h-1olefin As WHSV > 12,500 cmg h olefin formation becomes significant. At formation becomes significant. At -1 -1 WHSV < 12,500 cm33g-1h-1only CH4 is WHSV < 12,500 cmg h only CH4 is present… present…
1
Methane Ethane Ethylene Propylene 1-Butene 1-Hexene Benzene
0.5
0 0 20,000 40,000 60,000
3 -1 -1
80,000
100,000
WHSV, cm g h
THG/OSER Merit Review – 5/2/2006
Effect of Residence Time on Carbon Deposition
CPOX: DF-2 (9 ppm w/w S), O/C = 1.2, T = 900°C, P = 2 atm
2 WHSV, cm h g 6,250 12,500 25,000 50,000 100,000
3 -1 -1
CO2 Conc./Mass Cat., vol%/g
1.5
What is the influence of WHSV on carbon deposition?
Carbon deposition Carbon deposition increases with increases with increasing WHSV increasing WHSV
1
0.5
0 0 200 400 600 Temperature, °C 800 1000
THG/OSER Merit Review – 5/2/2006
Proposed Future Work
Catalyst Development: • Continue on series with Hexaalumina & HEXM
− Address selectivity issues − Demonstrate long-term diesel fuel operation − Test engineered catalyst forms with commercial catalysts companies
THG/OSER Merit Review – 5/2/2006
Relevant Literature
Patents Gardner, T., Berry, D., Shekhawat, D., “Hexaaluminate-type catalysts for the reforming of hydrocarbon fuels to hydrogen and carbon monoxide and method for making the same,” U. S. patent pending Book Chapter Shekhawat, D., Berry, D., Gardner, T. and Spivey, J., “Catalytic Reforming of Liquid Hydrocarbon Fuels for Fuel Cell Applications,” Catalysis, Vol. 19, 2006, pp. 214-220 Refereed Journal Papers Gardner, T., Shekhawat, D., Berry, D., Smith, M., Salazar, M. and Kugler, E., “Effect of Nickel Hexaaluminate Mirror Cation on Structure Sensitive Reactions During n-Tetradecane Partial Oxidation,” Accepted Applied Catalysis: A Conference Papers Gardner, T., Shekawhat, D. and Berry, D. “Hexaaluminate Catalysts for the Partial Oxidation of Middle Distillate Fuels,” Proceedings of the 2006 ACS Spring Conference, Atlanta, GA, March 2006. Gardner, T., Shekawhat, D. and Berry, D. “Partial Oxidation of n-Tetradecane over Lanthanum Ni-Hexaaaluminate Catalysts,” Proceedings of the 2004 AIChE Fall Conference, Austin, TX, Nov. 2004. Project Reports Gardner, T., Shekawhat D. and Berry, D., “Development of Hexaaluminate Catalysts,” Solid State Energy Conversion Alliance FY 2005 Progress Report Gardner, T., Shekhawat D. and Berry, D., “Development of Hexaaluminate Catalysts,” Solid State Energy Conversion Alliance FY 2004 Progress Report, pp. 1-6.
THG/OSER Merit Review – 5/2/2006