Recent progress in glycerol oxidation to lactic acid and pyruvic acid with heterogeneous metal catalysts

Abstract

The production of biodiesel generates a significant amount of glycerol by-products. One way to utilize glycerol is converting it into lactic acid, which can then be further transformed into pyruvic acid. In this review, we examine existing reaction pathways and propose a new approach for the indirect synthesis of pyruvic acid using glycerol and lactic acid as intermediates. Noble metals and transition metals are suitable for the oxidation of glycerol and lactic acid, and the combination of different metal sites may exhibit synergy effect and promote the process. It should be noted that the dehydration and isomerization of 1,3-dehydroxyacetone to lactic acid can be catalyzed by Lewis acids, which can be utilized in the base-free system that simplifies the postprocess procedure. Excepting noble metals, synergistic effect between iron and molybdenum also shows promising performance in catalyzed oxidation of lactic acid. Furthermore, many research results also suggest that mass transfer plays a critical role in this cascade reaction, which shed light on the catalysts modification for the similar reactions.

Keywords

• Glycerol
• Lactic acid
• Pyruvic acid
• Mechanism
• Two-step reaction route