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Title: Fluidizable Reforming Catalyst Development for Conditioning Biomass-Derived Syngas

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
901958
DOE Contract Number:
AC36-99-GO10337
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Catalysis A: General; Journal Volume: 318; Journal Issue: 2007
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; Alternative Fuels

Citation Formats

Magrini-Bair, K. A., Czernik, S., French, R., Parent, Y. O., Chornet, E., Dayton, D. C., Feik, C., and Bain, R. Fluidizable Reforming Catalyst Development for Conditioning Biomass-Derived Syngas. United States: N. p., 2007. Web. doi:10.1016/j.apcata.2006.11.005.
Magrini-Bair, K. A., Czernik, S., French, R., Parent, Y. O., Chornet, E., Dayton, D. C., Feik, C., & Bain, R. Fluidizable Reforming Catalyst Development for Conditioning Biomass-Derived Syngas. United States. doi:10.1016/j.apcata.2006.11.005.
Magrini-Bair, K. A., Czernik, S., French, R., Parent, Y. O., Chornet, E., Dayton, D. C., Feik, C., and Bain, R. Mon . "Fluidizable Reforming Catalyst Development for Conditioning Biomass-Derived Syngas". United States. doi:10.1016/j.apcata.2006.11.005.
@article{osti_901958,
title = {Fluidizable Reforming Catalyst Development for Conditioning Biomass-Derived Syngas},
author = {Magrini-Bair, K. A. and Czernik, S. and French, R. and Parent, Y. O. and Chornet, E. and Dayton, D. C. and Feik, C. and Bain, R.},
abstractNote = {},
doi = {10.1016/j.apcata.2006.11.005},
journal = {Applied Catalysis A: General},
number = 2007,
volume = 318,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Biomass gasification is being investigated to produce clean syngas from biomass or biorefinery residues as an intermediate that can be used directly as a fuel for integrated heat and power production or further refined and upgraded by various processing technologies. Conditioning of biomass-derived syngas, with an emphasis on tar reforming, to make it a suitable feed for high temperature, pressurized liquid fuels synthesis is the goal of current research efforts.
  • Mitigation of tars produced during biomass gasification continues to be a technical barrier to developing systems. This effort combined the measurement of tar-reforming catalyst deactivation kinetics and the production of syngas in a pilot-scale biomass gasification system at a single steady-state condition with mixed woods, producing a gas with an H{sub 2}-to-CO ratio of 2 and 13% methane. A slipstream from this process was introduced into a bench-scale 5.25 cm diameter fluidized-bed catalyst reactor charged with an alkali-promoted Ni-based/Al{sub 2}O{sub 3} catalyst. Catalyst conversion tests were performed at a constant space time and five temperatures from 775 to 875 C.more » The initial catalyst-reforming activity for all measured components (benzene, toluene, naphthalene, and total tars) except light hydrocarbons was 100%. The residual steady-state conversion of tar ranged from 96.6% at 875 C to 70.5% at 775 C. Residual steady-state conversions at 875 C for benzene and methane were 81% and 32%, respectively. Catalytic deactivation models with residual activity were developed and evaluated based on experimentally measured changes in conversion efficiencies as a function of time on stream for the catalytic reforming of tars, benzene, methane, and ethane. Both first- and second-order models were evaluated for the reforming reaction and for catalyst deactivation. Comparison of experimental and modeling results showed that the reforming reactions were adequately modeled by either first-order or second-order global kinetic expressions. However, second-order kinetics resulted in negative activation energies for deactivation. Activation energies were determined for first-order reforming reactions and catalyst deactivation. For reforming, the representative activation energies were 32 kJ/g{center_dot}mol for ethane, 19 kJ/g{center_dot}mol for tars, 45 kJ/g{center_dot}mol for tars plus benzene, and 8-9 kJ/g{center_dot}mol for benzene and toluene. For catalyst deactivation, representative activation energies were 146 kJ/g{center_dot}mol for ethane, 121 kJ/g{center_dot}mol for tars plus benzene, 74 kJ/g{center_dot}mol for benzene, and 19 kJ/g{center_dot}mol for total tars. Methane was also modeled by a second-order reaction, with an activation energy of 18.6 kJ/g{center_dot}mol and a catalyst deactivation energy of 5.8 kJ/g{center_dot}mol.« less
  • Cited by 10
  • The National Renewable Energy Laboratory (NREL) is collaborating with both industrial and academic partners to develop technologies to help enable commercialization of biofuels produced from lignocellulosic biomass feedstocks. The focus of this paper is to report how various operating processes, utilized in-house and by collaborators, influence the catalytic activity during conditioning of biomass-derived syngas. Efficient cleaning and conditioning of biomass-derived syngas for use in fuel synthesis continues to be a significant technical barrier to commercialization. Multifunctional, fluidizable catalysts are being developed to reform undesired tars and light hydrocarbons, especially methane, to additional syngas, which can improve utilization of biomass carbon.more » This approach also eliminates both the need for downstream methane reforming and the production of an aqueous waste stream from tar scrubbing. This work was conducted with NiMgK/Al{sub 2}O{sub 3} catalysts. These catalysts were assessed for methane reforming performance in (i) fixed-bed, bench-scale tests with model syngas simulating that produced by oak gasification, and in pilot-scale, (ii) fluidized tests with actual oak-derived syngas, and (iii) recirculating/regenerating tests using model syngas. Bench-scale tests showed that the catalyst could be completely regenerated over several reforming reaction cycles. Pilot-scale tests using raw syngas showed that the catalyst lost activity from cycle to cycle when it was regenerated, though it was shown that bench-scale regeneration by steam oxidation and H{sub 2} reduction did not cause this deactivation. Characterization by TPR indicates that the loss of a low temperature nickel oxide reduction feature is related to the catalyst deactivation, which is ascribed to nickel being incorporated into a spinel nickel aluminate that is not reduced with the given activation protocol. Results for 100 h time-on-stream using a recirculating/regenerating reactor suggest that this type of process could be employed to keep a high level of steady-state reforming activity, without permanent deactivation of the catalyst. Additionally, the differences in catalyst performance using a simulated and real, biomass-derived syngas stream indicate that there are components present in the real stream that are not adequately modeled in the syngas stream. Heavy tars and polycyclic aromatics are known to be present in real syngas, and the use of benzene and naphthalene as surrogates may be insufficient. In addition, some inorganics found in biomass, which become concentrated in the ash following biomass gasification, may be transported to the reforming reactor where they can interact with catalysts. Therefore, in order to gain more representative results for how a catalyst would perform on an industrially-relevant scale, with real contaminants, appropriate small-scale biomass solids feeders or slip-streams of real process gas should be employed.« less