Enviro-benign synthesis of glycerol carbonate utilizing bio-waste glycerol over Na-Ti based heterogeneous catalyst: Kinetics and E- metrics studies

Abstract

Glycerol carbonate (GlyC) is valuable chemical and found many applications in pharmaceuticals, cosmetics, food, and chemical industries. However, the high production cost of GlyC restricts its practical applications. Thus, its facile and economical production is needed. The production of GlyC from biodiesel derived glycerol has recently emerged as an economical and sustainable process. A robust heterogeneous catalyst Na/TiO2, has been synthesized through a template free cleaner process (wet impregnation method) and utilized for transesterification of glycerol (Gly) with dimethyl carbonate (DMC) to produce GlyC. The synthesized catalyst has been studied via different analytical techniques, including XRD, TG-DSC, FTIR, XPS, BET, Raman and HR-TEM analysis. Easily available and versatile acceptable spectroscopic techniques (H-1 and C-13 NMR) were utilized to study the conversion of the glycerol-to-glycerol carbonate. The various reaction parameters viz. time, molar ratio, temperature, catalytic loading, etc., were optimized using OVAT (i.e., one variable at a time) method and found that efficient conversion was obtained at 3 wt% of catalyst loading, 1:2 molar ratio of Gly: DMC, 90 ? reaction temperature, and 90 min reaction time. The selectivity of synthesized catalysts for glycerol carbonate was found 96.4% with 94.5% yield and 98.5% conversion percentage of glycerol-to-glycerol carbonate. The synthesized catalyst is non-toxic, environment compatible and based on low-cost precursors. The high thermal stability and recyclability make it an efficient heterogeneous catalyst for its wide applications.