Modeling the conversion of glucose to hydroxymethylfurfural

Graduation date: 1989Cellulosic biomass materials have three principal\ud components: cellulose, hemicellulose, and lignin. Under\ud mild acid conditions and high temperature, the first two\ud components yield a variety of sugars: hexoses and pentoses,\ud which are subject to decomposition on continued exposure to\ud hot dilute acid. In the process hexoses yield\ud hydroxymethylfurfural (HMF) which, on continued heating,\ud yields levulinic acid and formic acid and some\ud uncharacterized solid products. Biomass hydrolysis research\ud has now progressed to the point where process analysis and\ud optimization requires a generalized kinetic correlation for\ud hexose degradation. The kinetics for the reaction of\ud glucose to HMF has been studied previously. However, not\ud all of the rate constants for the dehydration of glucose and\ud HMF had been modeled to fit the experimental data.\ud This research had two parts. The first was to model\ud the kinetics for the formation of HMF from glucose in the\ud aqueous phase using the three-constant model suggested by S.\ud W. McKibbins et al. (1962). The other was to study the\ud aqueous-phase reaction carried in the presence of an organic\ud solvent, o-nitrotoluene (ONT), for the purpose of\ud extracting HMF as it is produced; thereby minimizing\ud subsequent degradation of HMF to levulinic acid, formic\ud acid, and solid materials.\ud The HMF distribution coefficient for o-nitrotoluene was\ud measured at different temperatures and modeled as the\ud integrated Van't Hoff equation.\ud Predicted glucose, HMF, and organic acids concentration\ud profiles were compared to the experimentally determined\ud values. The predicted concentration profiles are in good\ud agreement with the experimental data, indicating that the\ud proposal three-constant model is consistent with the true\ud reaction system. In the two-phase system case study, the\ud process was diffusion limiting due to lack of agitation of\ud the mixture