Synthesize of iso-paraffin fuels from palm oil over heterogeneous acid and base catalysts

Abstract

This study focused on the synthesis of hydrocarbon fuel containing a high iso-paraffin and very low oxygen content from palm oil using a mixed acid-base catalyst. The catalysts were characterized by nitrogen adsorption-desorption, X-ray diffraction, hydrogen-temperature programmed reduction, carbon dioxide- and ammonia-temperature programmed desorption as well as thermogravimetric analysis. Solid base (MgO, CaO, SiO2 and Na2SiO3) and solid acid (HY, H-beta, HZSM5 and Al2O3) catalysts were individually evaluated for their catalytic activity in a semi-batch reactor in terms of the deoxygenation level of palm oil. The best acid and alkali catalyst were then selected for mixing at different volume ratios for catalytic deoxygenation of palm oil. Finally, the reaction temperature (400–460 oC), residence time were optimized. The main components in the liquid product obtained were normal paraffins, iso-paraffins, olefins and aromatics. For the single base catalysts, a liquid yield of higher than 65 wt.% was obtained at a 460 oC using MgO catalyst, which also realized an excellent decarboxylation and decarbonylation. For the single acid catalysts, the zeolite beta catalysts reached a liquid yield of around 55 wt.% with a high iso-paraffin content. The optimal MgO: beta zeolite ratio for the acid-base hybrid catalyst was 3:1, which resulted the products with a high iso-paraffin content (25% and 35% in nitrogen and hydrogen atmosphere, respectively).