Valorization of glycerol to mono- and di-glycerides: Feedstocks, intensified reactors, challenges and perspectives

The surplus of crude glycerol from biodiesel production can be valorized by the glycerolysis of various feedstocks such as triglycerides, free fatty acids, and fatty acid methyl esters to higher-value monoglycerides (MGs) and diglycerides (DGs). These products are widely used in the food and pharmaceutical industries as emulsifying, stabilizing, and nutritional agents. High purity of MGs and DGs production necessitates high energy consumption to maintain a high reaction temperature and to operate a high vacuum or molecular distillation. This perspective discusses various potential feedstocks that involve different reaction routes and by-products, the effects of operating parameters on glycerol conversion, MGs and DGs selectivities, and various intensified reactors to enhance the reaction performance. In addition, key challenges and perspectives for the success of glycerol valorization for MGs and DGs are highlighted.