Efficient and selective glycerol electrolysis for the co-production of lactic acid and hydrogen with multi-component Pt/C-zeolite catalyst

Abstract

Among various electrochemical reactions to produce fuels and chemicals, glycerol electrolysis to co-produce hydrogen and lactic acid has received great attention. However, studies have shown the benchmark Pt based catalysts are insufficient in selectively catalysing the glycerol to lactic acid transformation, resulting in a low yield of lactic acid. Here we report a study on glycerol electrolysis with anion-exchange membrane electrode assembly electrolyser. The reaction conditions including mass transport, temperature, current density and KOH concentration were optimised, among which temperature played a significant role in facilitating the reaction rate and thermodynamics. With the optimised condition a multicomponent Pt/C-zeolite electrocatalyst system (Pt/C-CBV600) was developed and tested, which is capable to increase the lactic acid selectivity to 57.3% from the 33.8% with standalone Pt/C. Although the detailed mechanism required further investigation, it is hypothesised that the CBV600 zeolite with abundant Lewis acid surface sites can effectively bind the dihydroxyacetone intermediate, and drive the reaction towards pyruvaldehyde heterogeneously, the key step to form lactic acid.