Evaluation of Catalyst Deactivation during Catalytic Steam Reforming of Biomass-Derived Syngas
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- 作者：Richard L. Bain ; David C. Dayton ; Daniel L. Carpenter ; Stefan R. Czernik ; Calvin J. Feik ; Richard J. French ; Kimberly A. Magrini-Bair ; and Steven D. Phillips
- 刊名：Industrial & Engineering Chemistry Research
- 出版年：2005
- 出版时间：October 12, 2005
- 年：2005
- 卷：44
- 期：21
- 页码：7945 - 7956
- 全文大小：346K
- 年卷期：v.44,no.21(October 12, 2005)
- ISSN：1520-5045
文摘
Mitigation of tars produced during biomass gasification continues to be a technical barrier todeveloping systems. This effort combined the measurement of tar-reforming catalyst deactivationkinetics and the production of syngas in a pilot-scale biomass gasification system at a singlesteady-state condition with mixed woods, producing a gas with an H2-to-CO ratio of 2 and 13%methane. A slipstream from this process was introduced into a bench-scale 5.25 cm diameterfluidized-bed catalyst reactor charged with an alkali-promoted Ni-based/Al2O3 catalyst. Catalystconversion tests were performed at a constant space time and five temperatures from 775 to875 
C. The initial catalyst-reforming activity for all measured components (benzene, toluene,naphthalene, and total tars) except light hydrocarbons was 100%. The residual steady-stateconversion of tar ranged from 96.6% at 875 C to 70.5% at 775 C. Residual steady-stateconversions at 875 C for benzene and methane were 81% and 32%, respectively. Catalyticdeactivation models with residual activity were developed and evaluated based on experimentallymeasured changes in conversion efficiencies as a function of time on stream for the catalyticreforming of tars, benzene, methane, and ethane. Both first- and second-order models wereevaluated for the reforming reaction and for catalyst deactivation. Comparison of experimentaland modeling results showed that the reforming reactions were adequately modeled by eitherfirst-order or second-order global kinetic expressions. However, second-order kinetics resultedin negative activation energies for deactivation. Activation energies were determined for first-order reforming reactions and catalyst deactivation. For reforming, the representative activationenergies were 32 kJ/g·mol for ethane, 19 kJ/g·mol for tars, 45 kJ/g·mol for tars plus benzene,and 8-9 kJ/g·mol for benzene and toluene. For catalyst deactivation, representative activationenergies were 146 kJ/g·mol for ethane, 121 kJ/g·mol for tars plus benzene, 74 kJ/g·mol forbenzene, and 19 kJ/g·mol for total tars. Methane was also modeled by a second-order reaction,with an activation energy of 18.6 kJ/g·mol and a catalyst deactivation energy of 5.8 kJ/g·mol.
C. The initial catalyst-reforming activity for all measured components (benzene, toluene,naphthalene, and total tars) except light hydrocarbons was 100%. The residual steady-stateconversion of tar ranged from 96.6% at 875 C to 70.5% at 775 C. Residual steady-stateconversions at 875 C for benzene and methane were 81% and 32%, respectively. Catalyticdeactivation models with residual activity were developed and evaluated based on experimentallymeasured changes in conversion efficiencies as a function of time on stream for the catalyticreforming of tars, benzene, methane, and ethane. Both first- and second-order models wereevaluated for the reforming reaction and for catalyst deactivation. Comparison of experimentaland modeling results showed that the reforming reactions were adequately modeled by eitherfirst-order or second-order global kinetic expressions. However, second-order kinetics resultedin negative activation energies for deactivation. Activation energies were determined for first-order reforming reactions and catalyst deactivation. For reforming, the representative activationenergies were 32 kJ/g·mol for ethane, 19 kJ/g·mol for tars, 45 kJ/g·mol for tars plus benzene,and 8-9 kJ/g·mol for benzene and toluene. For catalyst deactivation, representative activationenergies were 146 kJ/g·mol for ethane, 121 kJ/g·mol for tars plus benzene, 74 kJ/g·mol forbenzene, and 19 kJ/g·mol for total tars. Methane was also modeled by a second-order reaction,with an activation energy of 18.6 kJ/g·mol and a catalyst deactivation energy of 5.8 kJ/g·mol.