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Poster Presentation 3-12
Heterogeneous Aspects of Dilute-Acid Hydrolysis of a-Cellulose
Qian Xiang1, Y. Y. Lee1, Pär O. Pettersson2 and Robert W. Torget3
1 Department of Chemical Engineering 230 Ross Hall Auburn University, AL 36849
2 Mid Sweden University, 891 18 Örnsköldsvik, Sweden
3 National Renewable Energy Laboratory, Golden, CO, USA
Telephone: (334) 844-2019; Fax: (334) 844-2063; E-mail: yylee@eng.auburn.edu
In recent years, a significant advancement has been made in the treatment of lignocellulosic biomass with dilute sulfuric acid. The focus of the new development is the emergence of a shrinking-bed flow-through (SBFT) reactor and newly explored reaction conditions, i.e., extremely low acid (0.05-0.2 wt%) and high temperature (200-240 oC). Some of the experimental results obtained under these conditions contradict existing kinetic models. We have made further investigation on the fundamental aspects of the reaction kinetics and mechanism involving cellulose hydrolysis, paying special attention to the fact that the reaction is heterogeneous. In this paper, we report experimental kinetic data obtained from batch and BSFT reactors. Use of the BSFT reactor allows prompt removal of the released glucose from the reaction zone, minimizing degradation of sugar products. The hydrolysis reaction can thus be isolated from other reactions. Our experiments confirm that cellulose oligomers are detected in the hydrolyzate liquor. Under the conditions applied in this work, the temperature effect on the hydrolysis does not conform to the Arrhenius Equation. Above certain temperature, the hydrolysis rate rises much more rapidly than what the Arrhenius Equation predicts. Additional experimental data pertaining to the reaction mechanism and kinetics of the dilute-acid hydrolysis process are presented.
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