Comparative study of WCx-based catalysts for aqueous phase hydrogenolysis of glycerol into bioadditives

Abstract

Hydrogenolysis of glycerol has been a subject of intensive research in recent decades. Great efforts have been made investigating the mechanism of bond cleavage using metal or metallic oxide catalysts. In this work, effects of a series of WC_x-based catalysts, including WC_x, Cu/WC_x, Pt/WC_x, Ru/WC_x, CuRu/WC_x and CuPt/WC_x, were studied on hydrogenolysis of glycerol to investigate the role of each active phase. WO₃-Based catalysts were employed as a comparison with the WC_x-based catalysts. Hydrogenolysis of model compounds (1,2-PDO and EG) of glycerol was also studied using these catalysts, in attempts to determine the mechanism of the whole reaction. The presence of metal elements on WC_x or WO₃ can significantly improve the conversion of reactant. In addition, the ability of WC_x to promote cleavage of C–C was verified. Ru is more beneficial for formation of EG than Pt, whereas Pt is favorable for formation of 1,2-PDO. It had been supposed that hydrogenolysis of glycerol by WC_x-based catalysts occurred via two different but overlapping routes: WC_x-related reactions caused by C–C cleavage and metal-related reactions caused by C–O cleavage, which happen simultaneously in the reaction. The current study not only demonstrates that the catalytic performance of WC_x can be manipulated by varying metal loading, but also offers a possible mechanism for C–C and C–O cleavage in hydrogenolysis of glycerol, which could be beneficial when focusing on the target product.