Glycerol Carbonate Synthesis: Critical Analysis of Prospects and Challenges with Special Emphasis on Influencing Parameters for Catalytic Transesterification

Due to the global depletion of natural resources, developing economically and environmentally sustainable energy sources is critical. Biodiesel can substitute for diesel without significant modification of existing engines. Biodiesel production has accelerated in recent years, because of aggressive government policies and incentives to meet energy demand and environmental concerns. A surplus amount of glycerol (Gly) is generated during biodiesel production as a byproduct. Thus, developing viable routes for the valorization of Glyl is crucial for the sustainability of the biodiesel industry. Valorization of Gly-to-glycerol carbonate (Glc) is considered an attractive route due to its wide industrial applicability. This paper discusses the potential synthesis routes including glycerolysis of urea, direct carbonation of Gly with CO2, enzymatic transesterification of Gly, and catalytic transesterification of Gly with alkyl carbonate to produce Glc. This paper addresses the performance of various homogeneous and heterogeneous catalysts used in Glc synthesis. Among various synthesis routes, catalytic transesterification of Gly with dimethyl carbonate (DMC) is considered as green and environmentally friendly, operates under mild reaction conditions, and is an industrially feasible process with high selectivity and yield. In order to achieve high yield and selectivity of Glc, key influencing process parameters such as catalyst dose, molar ratio of DMC/Gly, reaction temperature, reaction time, and basic sites of the catalyst are discussed. Repurposing of surplus glycerol for Glc production enhances biodiesel economics. Finally, this paper suggests future prospects for various pathways for the sustainable production of Glc.