Lactic Acid Production from Glucose over Y2O3-based Catalysts under Base-free Conditions

Methods to catalytic conversion of glucose into lactic acid (LA), which is a versatile platform chemical, have been widely investigated. Herein, various kinds of metal oxide catalysts were used for lactic acid (LA) production from glucose under strong homogeneous base-free conditions. Among the metal oxides tested, Y2O3 afforded LA in moderate yield (33 %) together with trioses (dihydroxyacetone and glyceraldehyde) and fructose. It was found that the Y2O3/SiO2 catalyst can effectively catalyze the transformation of glucose into LA. Compared to Y2O3, the LA yield was remarkably improved (45 %). The characterization results showed that Y(OH)(3) was highly dispersed on the Y2O3/SiO2 catalyst, acting as a Bronsted base and promoting LA formation from pyruvaldehyde (PA). Bronsted acid sites (hydroxyl groups) located at the interface between Y(OH)(3) and SiO2 promoted the dehydration of trioses to form PA. The acid and base sites on the Y2O3/SiO2 catalyst functioned in concert to ensure that the overall reaction proceeded efficiently.