Enhanced Isomerization Performance of Unsupported Ni–Nb–O Catalyst for One-Step Hydrogenation of Jatropha Oil to Alkanes

Abstract

Biolipids and oil hydrogenation are prominent alternatives to petroleum-based fuels. Currently, the catalysts used are limited to deoxidation activity, resulting in the reaction products with a high content of n-alkanes and waxes, necessitating secondary treatment to increase iso-alkane content. Herein, an unsupported Ni–Nb–O catalyst with trifunctional capabilities (i.e., hydrodeoxygenation, hydrocracking, and isomerization) was developed for the efficient conversion of methyl stearate and jatropha oil into small molecular alkanes. The metal ratio significantly affects the catalytic performance, in which Ni/Nb = 2:0.6 exhibited the highest isomerization activity. Moreover, 84% of the deoxidized products are C₈–C₁₇ hydrocarbons, with 53.4% being isomeric hydrocarbons. The catalyst also demonstrated excellent stability, maintaining 54% selectivity for C₈–C₁₇ iso-alkanes in jatropha oil feedstock during 240 h of operation.