Hydrogen Production via Reforming of Hydrogen Production via Reforming of Bio Bio - - derived Liquids derived Liquids Yong Wang and David King Yong Wang and David King U.S. Department of Energy Bio-Derived Liquids to Hydrogen Distributed Reforming Working Group Kick-Off Meeting October 24, 2006, Baltimore, Maryland
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Hydrogen Production via Reforming of Bio-Derived Liquids · Hydrogen Production via Reforming of Bio-derived Liquids Yong Wang and David King U.S. Department of Energy Bio-Derived
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Hydrogen Production via Reforming ofHydrogen Production via Reforming ofBioBio--derived Liquidsderived Liquids
Yong Wang and David KingYong Wang and David King
U.S. Department of Energy Bio-Derived Liquids to Hydrogen Distributed Reforming Working Group
Kick-Off Meeting October 24, 2006, Baltimore, Maryland
Production of Hydrogen in the BioProduction of Hydrogen in the Bio--refineryrefinery
hν CO2
Lignocellulosic Biomass
Sugar Production
Fermentation Distillation Ethanol
Hydrolysis
Hydrogenation
HydrogenAqueous Phase Reforming
Aqueous Phase Reforming
Vapor Phase Reforming
Gasification Pyrolysis
Syngas Bio-oil
Chemical Products
Polyols Sorbitol, Xylitol
Longer term target
Hydrogen Potential from Different FeedstocksHydrogen Potential from Different Feedstocks
MW moles H2/ g H2/ kg g H2/kg feed Feedstock Formula feedstock moles/kg mol feed feed w/wgs
Kinetic Control of Reaction Pathways* isKinetic Control of Reaction Pathways* isEssential For Good Hydrogen ProductionEssential For Good Hydrogen Production
Effect of Feed Rate on Sorbitol ProductsEffect of Feed Rate on Sorbitol Products(Microchannel Reactor, Virent Catalyst)(Microchannel Reactor, Virent Catalyst)
¾ Liquid products at incomplete conversion of sorbitol may provide information on reaction pathways and intermediates
¾ Higher space velocities result in greater production of liquid products with only modest changes in gas phase product composition
Effect of Feed Rate on Sorbitol ProductsEffect of Feed Rate on Sorbitol Products(Microchannel Reactor, Virent Catalyst)(Microchannel Reactor, Virent Catalyst)
¾ Glycerol and propylene glycol are most predominant products ¾ C4 and C2 polyols are in approximate balance ¾ Oxygenated products are more consistent with random C-C cleavage than sequential C1 cleavage
¾ No need to vaporize the excess water in bio-ethanol (8-12wt% ethanol), pressurized reformate readily for membrane separation
¾ Stable catalyst life (>300 hrs) ¾ Excellent CO2 selectivity (nearly 100% efficiency in WGS) ¾ H2 productivity approximately doubled when ethanol feed
concentration increases from 10 to 20%
¾ Relatively low productivity 3000 l/l/hr at 235ºC vs 48,000 l/l/hr at 350ºC (vapor phase reforming)
¾ Equal molar of CH4 and CO2 formation ¾ Acetic acid is primary product observed in
liquid phase effluent
Vapor Phase Reforming of Ethanol
Ethanol Vapor Phase ReformingEthanol Vapor Phase Reforming¾ Low temperature SR (<500ºC)
• Potentially less energy intensive • More directly matches with H2 membrane separation • Catalyst deactivation poses challenges
¾ High temperature SR (>500ºC) • High temperatures facilitates subsequent conversion of parallel
product methane • Need CO clean up unless for SOFC • Catalyst deactivation could be masked by excess activity
¾ Oxidative SR (e.g., work at U of Minnesota and Penn State) • Stable catalyst life • Dilution of N2 in reformate • Not amenable to membrane separations
Possible Pathways for SR of Ethanol Theoretical yield: 6 mol H2 / mol EtOH
+ H2O
H2 + CO2
-H2 CH3CHO CH4 + CO + H2C2H5OH CH4
-H2O H2C=CH2 Coke
¾ Dehydrogenation is a preferred pathway to minimize coke formation
¾ Low methanation activity is desired ¾ At low temperatures, methane is more difficult to activate –
likely forming a 50% CO+CO2 and 50% CH4 product mixture via acetaldehyde decomposition
Concept: Increase Hydrogen Selectivity Through CH3CHO Intermediate
C-C bond cleavage
X
3H2O
CH4 + CO facilitated by Rh
CH3-CHO 2CO2 + 5H2 Net: 6 H2
Steam oxidation with CeO2-ZrO2 to produce CO/CO2 + H2 Steam reforming pathway can lead to higher hydrogen yield
Roh et al, Catal.LettCatal.Lett.,., 108(1&2) (2006) 15-19
Previous work with 2wt%Rh on CeO2-ZrO2
Catalyst XEtOH
(%)
H2/EtOH
(m/m)
SCH4
(%)
SCO
(%)
SCO2
(%)
2%Rh/Ce0.8Zr0.2O2 100 4.3 25 11 64
2%Rh/Ce0.6Zr0.4O2 100 4.0 26 18 56
2%Rh/Ce0.4Zr0.6O2 100 4.0 27 20 53
2%Rh/Ce0.2Zr0.8O2 95 3.6 28 21 50
2%Rh/CeO2 53 1.9 22 32 39
450ºC, SV: 133,000 ml/g-h; H2O/EtOH/N2 = 8/1/10.6, Data obtained at 10 h TOS
Roh et al, Topics in CatalysisTopics in Catalysis (in press)
Catalyst Deactivation IssuesCatalyst Deactivation IssuesConversion CO sel CO2 sel CH4 sel H2 yield
0 200 400 600 800 1000 1200 0 100 200 300 400 500 Time on stream (min) TOS, min
¾ At lower SV (133,000 cc/g/hr), deactivation was observed at TOS > 600 min ¾ At higher SV (2,000,000 cc/g/hr), a continuous deactivation was observed
although selectivities to CO, CO2, CH4 were unchanged
Causes of deactivation?
Other Products Can Be Monitored DuringOther Products Can Be Monitored DuringReaction and DeactivationReaction and Deactivation
T=350°C; H2O:EtOH:N2:H2=8:1:9:0.0; SV=483K scc/hr/gcat Se
lect
ivity
, % m
ol
Acetaldehyde Acetone Acetic acid Ethylene
0%
20%
40% Ethane Propane Butane
0.3%
0.2%
0.1%
0.0% 0 100 200 300 400
TOS (min) ¾ Major byproducts/intermediates are the oxygenates acetaldehyde, acetone, and
acetic acid, and they increase as catalyst deactivates
¾ Hydrocarbon byproducts decrease as catalyst deactivates
Examination of Catalyst DeactivationExamination of Catalyst Deactivation
¾ Two major causes considered � Metal sintering or loss of surface area � Fouling by carbonaceous residues
¾ Investigation methods included � HRTEM – look for carbonaceous material, textural damage � FTIR – examine surface species � Dispersion and surface area – count available Rh sites � TPO and in-situ regeneration of spent catalyst – evidence
for, and amount of, carbonaceous deposits
735
735
735
760
760
760
815
815
815
865
865
865
7007508008509009501000
Wavenumber (cm-1)
DRIFTunderETOH SR
Aromatic C-H bending out of plane
Catalyst Surface ChangesCatalyst Surface Changes
¾ TEM indicates no major clusterof carbon; no major texturalchange ¾ In situ FTIR indicates some
carbonaceous deposit present – Need to quantify amount
1380
13
8013
80
1465
14
6514
65
100012001400160018002000
Wavenumber (cm-1)
DRIFT under ETOH SR
C-H bending in methyl grps
C-H bending
Fresh SpentFresh Spent
Amount of Surface Carbonaceous DepositionAmount of Surface Carbonaceous Deposition
CO+CO2, sccm C out mmol/g cat TPO of spent catalyst in 1% O2 in N2