The Selective Production of Biomass Derived Chemicals using Heterogeneous Catalysts.

摘要

The development of heterogeneous catalytic technologies for the selective conversion of lignocellulosic biomass to platform molecules such as 5-hydroxymethylfurfural (HMF) and 2,5-dihydroxymethylfurfural (DHMTHF) has been studied. Supported metal catalysts were used for the selective hydrogenation of HMF to DHMTHF. Small trace amounts of acid in the aqueous solution with HMF feed was found to play an important role in determining the selectivity for the hydrogenation of HMF to DHMTHF.;DHMTHF, tetrahydrofuran (THF), gamma valerolactone (GVL), and other aprotic miscible organic solvents were mixed with water to form a monophasic co-solvent. These co solvents systems were found to be separation friendly solvents compared to dimethyl sulfoxide (DMSO) and other higher boiling organic solvents that are selective for HMF production. The monophasic co-solvents investigated were also selective for the production of HMF from fructose using Bronsted acid catalysts; additionally, an increase in the rate of reaction, compared to water, was observed. Fructose tautomerization favors the furanose form in the mixed solvent, relative to water alone, explaining at least part of the rate enhancement.;The use of co-solvents and acid-functionalized ordered mesoporous silica catalysts show high selectivity for HMF from fructose. The synthesis to intercalate PVP on the catalyst surface was developed to achieve high selectivities previously achieved only with ionic liquids. The high concentration of pyrrolidone in the confined space of the pores favors the furanose tautomers which can be easily dehydrated to HMF. Thus, the reaction environment within the catalyst has been designed to favor the desired product.;Solvent reactivity studies for homogenous base, homogenous Lewis acid, solid bases, and solid Lewis acids for glucose isomerization to fructose were conducted. The small addition of miscible organic solvent led to a drop of reactivity compared to that of pure water. However, with increasing GVL concentration, the reactivity increased as well. Benzene-bridged PMOs doped with Lewis acidic Sn sites were readily and rapidly synthesized. These thermally robust, hydrophobic materials catalyze the selective isomerization of glucose to fructose in co-solvent systems. Bronsted acid sites were incorporated and a bifunctional PMO was synthesized for tandem conversion of glucose to fructose and its dehydration to HMF.