Efficient and simultaneous cleaner production of biodiesel and glycerol carbonate in solvent-free system via statistical optimization

A solvent-free co-production process for biodiesel and glycerol carbonate (GC) was developed based on enzyme (Novozyme 435). Glycerol obtained from transesterification reactions could be directly converted to GC. The reactions were optimized using the response surface methodology (RSM) separately. The optimal factors, which are enzyme loading, molar ratio of dimethyl carbonate to soybean oil, water content, and reaction temperature, were derived from the response optimizer. The results of optimization for biodiesel and GC production were re-analyzed by overlapping the contour plots of the factors. The following were the optima obtained: enzyme loading of 25 g/L, molar ratio of 15:1, water content of 0.082% (v/v), and reaction temperature of 59.65 °C. When the co-production of biodiesel and GC was conducted using the optima, biodiesel and GC production were achieved with conversions of 97.6% and 95.5%, respectively.