Cascade conversion of glucose to 5-hydroxymethylfurfural over Bronsted-Lewis bi-acidic SiO2-ZrO2 catalysts

Abstract

The control of acidic properties of a heterogeneous catalyst is one of the key features of biomass utilization technology for the production of chemical feedstock. In this study, Bronsted (B) and Lewis (L) acidic silica-zirconia (SZ) catalysts with controllable acidity were prepared using a simple hydrothermal method with a Si/(Si + Zr) molar ratio of 0.0-1.0, characterized by IR spectroscopy with adsorbed pyridine, and subsequently applied for the cascade conversion of glucose to 5-hydroxymethylfurfural (5-HMF). The Bronsted acidity of the SZ catalysts increased proportionally with the concentration of silica in the catalyst. The optimum ratio of B/(B + L) was investigated to maximize the yield of 5-HMF, which is converted from the glucose via fructose by a cascade reaction. Both the glucose conversion and selectivity to 5-HMF reached their maxima at a B/(B + L) ratio of 0.4, which showed a typical volcano relationship.