Influence of NiMoP phase on hydrodeoxygenation pathways of jatropha oil

Abstract

This work investigates the conversion pathway of jatropha oil to C16 + C18 by a one-pot method regulated by different moles of phosphorus and supports. Preferential direct deoxygenation is of interest for the carbon atom economy. Herein, SAPO-11, ZSM-5, and Zr-SBA-15 as supports, a series of nickel molybdenum phosphide catalysts were prepared, characterized, and used to hydrodeoxygenation (HDO) of jatropha oil in an autoclave. Our results showed that different supports affect the formation of the active phase of nickel molybdenum phosphide and its acid sites, thus affecting the catalytic performance, resulting in different HDO pathway ratios. The HDO pathway ratios of different n(Ni–Mo)/n(P) catalysts on the same support differed. Compared with the NiMo catalysts, the NiMoP2/Zr-SBA-15 catalyst showed the most remarkable HDO performance, with C15 + C17/C16 + C18 decreasing from 6.95 to 2.24. The presence of P in the catalyst promotes direct deoxygenation, while inhibiting decarboxylation and decarbonylation. In addition, the NiMoP phase exhibited excellent catalytic activity, with more than 90% deoxidization. Refined oil contains high levels of jet fuel components, with C8–C16 alkanes account for more than 50% and naphthenes reaching more than 20%. The catalysts were tested at 360 °C, 30 bar, and 4 h, and results showed that the NiMoP phase plays an important role in inhibiting coke deposition on the catalyst.