(511d) Heterogeneous Catalysts for Conversion of Carbohydrates

Conversion of carbohydrates to valuable fuels and chemicals is an important step toward shifting to a biomass-based platform for chemicals and fuels. Carbohydrates represent 75% of the annual renewable biomass. Most of the processes for conversion of carbohydrates to valuable chemical intermediates involve homogeneous catalysts. Although these processes yield high conversions and selectivities, separation of the homogeneous catalysts from products becomes a challenge. Recently, it has been shown that a tin containing zeolite beta catalyst is a very active and selective heterogeneous catalyst for isomerization of carbohydrates in aqueous media and epimerization of carbohydrates in methanol. Here, we will discuss our efforts in determining the feasibility of another class of solid acid catalysts as active heterogeneous catalysts for epimerization of carbohydrates in aqueous media. We have developed composition/performance relationships for these acid catalysts that allow us to identify the factors that impact their performance. Well-controlled kinetic isotope-labeling experiments were employed to probe the mechanism of carbohydrate conversion on these acid catalysts.