Continuous production of glyceric acid and lactic acid by catalytic oxidation of glycerol over an Au–Pt/Al2O3 bimetallic catalyst using a liquid-phase flow reactor

Abstract

In this study, we investigated an Au–Pt/Al2O3 bimetallic catalyst prepared by a conventional deposition–precipitation method for the production of the high-value carboxylic acids glyceric acid and lactic acid from glycerol using liquid-phase flow reactor. Also, the distribution of the products was significantly different from the previously reported Au monometallic catalyst. A long-term (>1000 min) catalytic activity test at 358 K using a liquid-phase flow reactor, which is a common type of reactor used in large-scale commercial catalytic processes, revealed that the catalyst provided a glycerol conversion greater than 90 % and yields of lactic acid and glyceric acid of approximately 40 % and 20 %–25 %, respectively; however, an induction period was observed at the beginning of the test, and deactivation of the catalyst was observed at the end. Scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy characterization of fresh catalyst revealed that nanosized Au and Pt species were highly dispersed on the Al2O3 support.