Recent Advances in Selective Oxidation of Glycerol to Lactic Acid over Noble Metal Catalysts

The problem of excess glycerol as a by-product of biodiesel production has become more and more prominent, and the catalytic conversion of glycerol to high-value-added chemicals is of great significance. In recent years, noble metal catalysts (Au, Pt, Pd, etc.) are often used to catalyze the conversion of glycerol to lactic acid, in which the improvement of lactic acid selectivity and catalyst stability are the key challenges for the catalysts. Here, we summarized the reaction mechanism of selective oxidation of glycerol to lactic acid over supported noble metal catalysts, revealing the role of different metal active sites. At the same time, the effects of metal particle size, support, and pH of the reaction system on the reaction performance are discussed based on the structure and electronic properties of noble metal active sites. Also, the role of metal in the promotion and support of strong interaction on the activation of the hydroxyl groups of glycerol was clarified. Finally, the main challenges and prospects for the selective oxidation of glycerol to lactic acid were clarified.