Glycerol Esters from Real Waste Cooking Oil Using a Robust Solid Acid Catalyst

Notwithstanding the food-​for-​fuel debate, turning waste cooking oil and fat (WCO) into a valuable product is a classic example of green chem. We demonstrate that sulfated zirconia and lanthanum-​supported sulfated zirconia are good catalysts for the esterification of WCO free fatty acids (FFAs) with glycerol, giving high-​value monoglycerides. Various catalysts were first screened using palmitic acid as a model FFA. Subsequently, six 10-​kg batches of actual WCO were collected from com. cookeries over a period of 28 wk, pre-​treated in a purpose-​built decanter and esterified with industrial grade glycerol using heterogeneous catalysis. Good yield and turnovers were obtained. The pre-​treatment stage and the catalytic esterification expts. are described and discussed.