Synergistic catalysis of tandem Li/S-1 and Sn-Beta catalysts for the conversion of glucose to fructose and lactic acid at 90 °C in water

Abstract

Efficient simultaneous lactic acid production with fructose isomerization from glucose at 90 °C under atmospheric pressure was demonstrated using a physically mixed Li/S-1 and Sn-Beta catalyst, resulting in a lactic acid yield of 33.1% and a fructose yield of 56.0% for 1 h in water. In situ FTIR and ¹³C NMR spectroscopy and the control experiment results revealed the formation of enol intermediates over the Li/S-1 catalyst through a typical alkali-catalyzed reaction in glucose isomerization. In the subsequent tandem catalysis over the Sn-Beta catalyst, strong adsorption between Sn sites and the enol structure efficiently promotes C–C breaking during the retro-aldol reaction process, which was proved by the detailed EXAFS results and DFT calculations.