Cellulosic biomass materials have three principal
components: cellulose, hemicellulose, and lignin. Under
mild acid conditions and high temperature, the first two
components yield a variety of sugars: hexoses and pentoses,
which are subject to decomposition on continued exposure to
hot dilute acid. In the process hexoses yield
hydroxymethylfurfural (HMF) which, on continued heating,
yields levulinic acid and formic acid and some
uncharacterized solid products. Biomass hydrolysis research
has now progressed to the point where process analysis and
optimization requires a generalized kinetic correlation for
hexose degradation. The kinetics for the reaction of
glucose to HMF has been studied previously. However, not
all of the rate constants for the dehydration of glucose and
HMF had been modeled to fit the experimental data.
This research had two parts. The first was to model
the kinetics for the formation of HMF from glucose in the
aqueous phase using the three-constant model suggested by S.
W. McKibbins et al. (1962). The other was to study the
aqueous-phase reaction carried in the presence of an organic
solvent, o-nitrotoluene (ONT), for the purpose of
extracting HMF as it is produced; thereby minimizing
subsequent degradation of HMF to levulinic acid, formic
acid, and solid materials.
The HMF distribution coefficient for o-nitrotoluene was
measured at different temperatures and modeled as the
integrated Van't Hoff equation.
Predicted glucose, HMF, and organic acids concentration
profiles were compared to the experimentally determined
values. The predicted concentration profiles are in good
agreement with the experimental data, indicating that the
proposal three-constant model is consistent with the true
reaction system. In the two-phase system case study, the
process was diffusion limiting due to lack of agitation of
the mixture
