Sunday, May 4, 2008
4-54

Kinetics Study on High-diversity Grassland Perennials Liquefaction

Hua-Jiang Huang, Bo Zhang, and Shri Ramaswamy. Department of Bioproducts and Biosystems Engineering, University of Minnesota, Kaufert Lab., 2004 Folwell Ave., St. Paul, MN 55108

The hydrothermal liquefaction of low-input high-diversity mixtures of native grassland perennials [1] was studied using the following treatment variables: heating rate, cooling rate, reaction temperature, reaction time, and catalysts. The liquefaction yields were found to be dependent on the final liquefaction temperature, the length of liquefaction time and the heating rate. The highest liquid yield of 82.1% was achieved within short residence time of 1 minute at 374°C. A modified version of the previous model [2] is presented, which assumes that biomass first decomposes to gaseous products, tars, and chars via three competitive reactions and then tars go through a second cracking reaction to produce gases. Through the proposed model, the calculated data fit well with the experimental data obtained from liquefaction of prairie grasses. The dependence of the calculated kinetic coefficients on temperature was established using Arrhenius-type equations.

 [1] Tilman, D., Hill, J., Lehman, C., (2006) Carbon-negative biofuels from low-input high-diversity grassland biomass. Science, 314:1598-600.
[2] Zhang, B., Huang, H. and Ramaswamy, S. (2008) Reaction kinetics of the hydrothermal treatment of lignin, Applied Biochemistry and Biotechnology, (in press).


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