Process optimization of the production of glycerol carbonate from glycerol

As a consequence of the prosperity of the biodiesel industry in the past decades, glycerol, as a major byproduct of biodiesel production, has been oversaturated in the market. As such, how to effectively exploit and valorize glycerol becomes an important problem. Converting glycerol (GL) to glycerol carbonate (GC) via its reaction with dimethyl carbonate (DMC) is one of the attractive options due to the high economic value of glycerol carbonate. In this study, we designed and assessed the process of converting glycerol into glycerol carbonate via its reaction with dimethyl carbonate. We first integrated the reaction between GL and DMC and the distillation process in reactive distillation, given the reaction reversibility and the azeotrope formed between the DMC and the byproduct methanol. The reactive distillation is then followed by an extractive distillation process and a heat integration system to make the process energy-saving.

As a result, at a molar ratio of glycerol to dimethyl carbonate of 1:4, the process reached 99 mol% of conversion, yielding glycerol carbonate at a rate of 1169 kg/hr, which was highly profitable given 8000 working hours per year. In addition, to make the process economics favorable, we optimized every unit in the process based on the minimization of total annual cost (TAC) and conducted the economic assessment. At last, we designed the control system and evaluated the whole process comprehensively.

This work was representative of National Taiwan University in the 2017 Collegiate Process Design Competition and was awarded the 3rd prize.