Synthesis and Optimization of Glycerol Carbonate from Crude Glycerol Using Sodium Carbonate (Na2CO3) as a Heterogeneous Catalyst

The essential need for sustainable energy sources to replace fossil fuels has fueled interest in renewable energy and biorefinery processes. Biodiesel production generates a considerable amount of crude glycerol (CG), which poses a challenge for the industry. This study aims to address this challenge by purifying CG through acidification. The acidification process successfully purified crude glycerol (PCG), resulting in a purity of 98.4 wt %. Subsequently, synthesizing glycerol carbonate (GC) from PCG and dimethyl carbonate (DMC) was undertaken by using heterogeneous catalysts. Sodium carbonate (Na2CO3) emerges as the most promising catalyst, considering its suitability in the presence of impurities such as 0.72 wt % of water and 0.57 wt % of matter organic nonglycerol (MONG) in PCG. The optimum catalyst dosage of Na2CO3 was determined as 2.1% mol of PCG. The experiments were carried out using a central composite design (CCD) methodology. By employing the response surface method (RSM), the optimal reaction conditions were determined to be a PCG/DMC molar ratio of 1:2.37 and a reaction time of 1.83 h. Under these conditions, an observed GC yield of 72.13% and PCG conversion of 78.39% were achieved. Despite the purification process, PCG still contains residual water, making Na2CO3 a suitable catalyst capable of tolerating a water content up to 3 wt %. This study not only enhances the effective utilization of CG within the biodiesel industry but also offers valuable insights for further exploration of sustainable chemical processes in future research.