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

Abstract

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 Brønsted base and promoting LA formation from pyruvaldehyde (PA). Brønsted 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.