A green process for glycerol valorization to glycerol carbonate over heterogeneous hydrotalcite catalyst

Abstract

Biodiesel production is accompanied by 10% w/w glycerol which needs to be valorized to into bulk and specialty chemicals in order to make the biodiesel economics favorable. Glycerol carbonate is one such product from glycerol which has many potential applications. A green process using calcined hydrotalcite supported on hexagonal silica (CHT-HMS) catalyst was developed for the conversion of glycerol to glycerol carbonate using dimethyl carbonate. Effects of various Al:Mg composition and loading on hexagonal mesoporous silica (HMS) were studied. Al:Mg composition of 1:2 with 15% w/w loading on HMS was the best catalyst. . CHT-HMS catalyst was fully characterized by various techniques such as FT-IR, EDAX, SEM, TPD, XRD, etc. The effects of various parameters such as speed of agitation, catalyst concentration, mole ratio, and temperature were studied. The catalyst is robust and recyclable. The reaction follows Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism with weak adsoption of all species. Thus, a second order rate equation for the reaction was developed and the activation energy estimated.