Esterification of an Agro-Industrial Waste on Kaolinite-Derived Catalyst Prepared via Microwave Irradiation

Fatty Acid Ethyl Esters (FAEEs) were obtained via single-step esterification of non-edible raw materials, namely a distillate from the deodorization of palm oil (DDPO), an agro-industrial by-product of high concentration of free fatty acids (FFAs approximately 84%) with Ethanol (EtOH) over a solid acid catalyst MF4W15 prepared from Amazon flint kaolin (FK). This material exhibited a catalytic activity reaching 94% conversion of DDPO using a molar ratio of DDPO to EtOH of 1:30 in 2.5 h at 140 °C with a 5% catalyst content. The stability of the catalytic activity of the catalyst was examined through recovery and reuse after washing and drying through five consecutive use cycles, maintaining its activity (60% conversion) with higher values than those of autocatalysis (28%). The results presented prove the efficiency of the MF4W15 catalyst as a promising low-cost and reusable material with adequate catalytic properties to promote esterification reactions involving residual FFAs for sustainable biofuels production. The utilization of waste for catalyst synthesis and FAEEs production can minimize the overall production costs of biofuels. Graphical Abstract