Production of fatty acid methyl esters and hydrogen from waste Jatropha oil catalyzed by magnetic nanolayered particles

A series of solid catalysts was synthesized through the alkalization of NiCuZnAl/O precursors enhanced by ultrasonic radiation (UR) or mechanical agitation (MA), respectively. Relative to the conventional auxiliary method of MA, UR promotes the formation of catalyst with a reduced pore size but larger pore volume and specific surface area. Following an intensive UR treatment for 90 min, the synthesized U90-NiCuZnAl/O particles exhibit a nanolayered structure on which the elements of Ni, Cu and Zn are distributed uniformly. Attributed to a large number of active sites on the catalyst surface, U90-NiCuZnAl/O can catalyze both esterification and transesterification simultaneously during the fatty acid methyl esters production from waste Jatropha oil with a high acid value of 46.0 mg KOH/g. Compared with the reported Na2SiO3@Ni/C catalyst, a higher average yield of fatty acid methyl esters and catalyst recovery rate can be achieved over 5 cycles of catalyst use. Additionally, the U90-NiCuZnAl/O also catalyzed the hydrothermal gasification of crude glycerol at 350 °C for 5 min with 81.8 % gasification rate and a high H2 purity of 91.6 %. It was revealed that Ni on the surface of the nanolayered particles acted as strong binding intermediates, thus reducing the apparent activation energy.