Catalytic production of Jatropha biodiesel and hydrogen with magnetic carbonaceous acid and base synthesized from Jatropha hulls

Abstract

Magnetic carbonaceous solid acid (C-SO3H@Fe/JHC) and base (Na2SiO3@Ni/JRC) catalysts were synthesized by loading active groups on the carbonaceous supporters derived from Jatropha-hull hydrolysate and hydrolysis residue. Characterization of their morphology, magnetic saturation, functional groups and total acid/base contents were performed by various techniques. Additional acidic functional groups that formed with Jatropha-hull hydrolysate contributed to the high acidity of C-SO3H@Fe/JHC catalyst for the pretreatment (esterification) of crude Jatropha oil with high acid values (AV). The AV of esterified Jatropha oil dropped down from 17.2 to 1.3mg KOH/g, achieving a high biodiesel yield of 96.7% after subsequent transesterification reaction with Na2SiO3@Ni/JRC base that was cycled at least 3 times with little loss of catalysis activity. Both solid acid and base catalysts were easily recovered by magnetic force with average recovery yields of 90.3wt% and 86.7%, respectively. After washed by ethanol, the catalysts were cycled for 10 times. The AV of esterified oil and biodiesel yield using the recycled catalysts remained below 2.0mg KOH/g and above 85%, respectively. The existence of catalyst ions and residual methanol contributed to high H2 yield (81.0%) and high purity (81.7%) in the hydrothermal gasification of glycerol by-product using the deactivated solid base.