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Oral
Presentation 1-07 A Depolymerization Kinetics Model For the Degradation of
Hemicellulose
Todd
Lloyd, Charles E. Wyman
Thayer School
of Engineering
Dartmouth
College
8000 Cummings
Hall
Hanover, New
Hampshire 03755
Telephone: (603) 646-3193; Fax: (603) 646-2277; E-mail: Todd.Lloyd@Dartmouth.edu Pretreatment has been shown to be the single most
expensive processing step in the conversion of lignocellulosic biomass to fuels
and chemicals. Although the importance
of pretreatment processing is universally acknowledged, a fundamental
understanding of pretreatment mechanisms has been elusive. For over 50 years the most commonly used
models have been based on first order homogenous kinetics, or some variation. In the case of hemicellulose degradation and
solubilization during pretreatment, these models provide a useful fit of
experimental data but suffer from some inconsistencies. This paper describes an alternative kinetic
model based on a depolymerization mechanism that assumes hemicellulose linkages
are broken (and subsequently hydrolyzed) at random. This creates oligomers with a distribution of chain lengths, with
their concentrations at any time determined in a statistical manner. The model is compared to pretreatment data
from various researchers and other models.
The prediction of oligomers that may be solubilized during hydrolysis is
emphasized.
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