Synthesis of magnetic carbonaceous acids derived from hydrolysates of Jatropha hulls for catalytic biodiesel production

A series of magnetic carbonaceous acids (JHC-T-1-T-2-SO3H@Fe/Fe3O4) were synthesized by the assembly of nano-Fe3O4 magnetic cores (particle size < 20 nm) and carbon coatings derived fromhydrolysates of Jatropha hulls. A magnetic JHC-12-600-SO3H@Fe/Fe3O4 catalyst with a total acid content of 2.69 mmol g(-1) and a magnetic saturation of 40.3 A m(2) kg(-1) was successfully prepared via a sequence of hydrothermal precipitation, pyrolytic carbonization, and finally sulfonation with H2SO4. The catalyst was directly used for the production of biodiesel from Jatropha crude oil with an acid value (AV) of 17.2 mg KOH per g, and the optimized conditions (180 degrees C for 7.5 h with a molar ratio of methanol/oil of 18/1 and a catalyst loading of 7.5 wt%) were determined by single-factor tests. An average biodiesel yield of 95.9% was achieved with a recovery rate of 94.3% after 5 reaction cycles in a 5 L batch reactor for testing the feasibility of the catalyst for large-scale use. This study demonstrates an alternative green approach to fully utilizing waste biomass from energy plants in the catalytic synthesis of Jatropha biodiesel with high efficiency.