Coproduction of Lactic Acid and Glycolic Acid from Xylose Via Bifunctional Co 3 O 4 Leveraging Lattice Oxygen and Lewis Acid Sites

To achieve atom-economic conversion of xylose into high-value-added chemicals, a green and novel process route for the coproduction of lactic acid (LA) and glycolic acid (GA) has been proposed. However, the realization of this route faces three major challenges. Here, Co 3 O 4 with bifunctional active sites was prepared, which for the first time achieved the efficient coproduction of LA (42.39%) and GA (32.57%) from xylose under an air atmosphere. The yields of LA and GA can be adjusted by modifying the reaction atmosphere. The reaction mechanism of dual-path parallel reactions promoted by dual active sites was clarified through multiscale experiments, kinetic studies, and DFT calculations. The Lewis acid site and lattice oxygen oxidation mechanisms mediated by Co 3+ drive the formation pathways of LA and GA, respectively. Lewis acid sites exhibit excellent stability in an air atmosphere, and oxidative activity is also retained after 5 cycles under an O 2 atmosphere. The activity of used catalysts can be fully restored through calcination treatment. This work provides new insights for enhancing atom economy in biomass refining.