Liquid hydrocarbon fuels from jatropha oil through catalytic cracking technology using AlMCM-41/ZSM-5 composite catalysts Original Research Article

Biofuels, the hydrocarbons less than C18, produced by catalytic cracking of nonedible vegetable oils are the potential source to battle energy demand and pollution. Among the non edible oils, jatropha is the apt candidate for the production of biofuel. Jatropha oil can be cracked catalytically over solid acid catalysts to yield liquid fuels with superior characteristics. We present here the hydrothermal syntheses of a microporous solid acid catalyst (HZSM-5 with Si/Al = 14), mesoporous materials (AlMCM-41) with varying Si/Al ratios (Si/Al = 18, 41, 72 and 95) and composite catalyst comprising HZSM-5 (as core) and varying coating percentages (5, 10 and 20%) of AlMCM-41 (as shell). All the synthesized catalysts were characterized by using XRD, BET N2 sorption studies, ICP, TPD and SEM techniques. Herein we report the catalytic activities of all the synthesized catalysts towards the cracking of jatropha oil obtained at the optimized conditions of temperature – 400 °C, WHSV – 4.6 h−1 and reaction time – 1 h. Of all the mesoporous catalysts with varying Si/Al ratios, AlMCM-41 (Si/Al = 18) was found to be the most active catalyst as it converted 65% of jatropha oil yielding 39% of bioliquid fuel with 47% and 36% selectivities towards green diesel and green gasoline respectively. In the core–shell architecture of the composite catalyst, different % coatings of the best active mesoporous material (AlMCM-41, Si/Al = 18) over the best active microporous material (ZSM-5, Si/Al = 14) were done. AlMCM-41/ZSM-5 (25, 15, 10) showed remarkable performance in the conversion of jatropha oil (99%) yielding 70% of bioliquid fuel with very high selectivity (61%) towards green gasoline.