Highly selective Co<inf>3</inf>O<inf>4</inf>/silica-alumina catalytic system for deoxygenation of triglyceride-based feedstock

The catalytic deoxygenation of biomass to produce renewable carbon energy addresses major concerns of limited energy sources. In particular, the second-generation biodiesel by selective deoxygenation possesses a higher cetane number, lower cloud point, and higher oxidation stability compared to the fatty acid ester-based biodiesel, and therefore, can be fed directly to the current diesel engines. In present work, we address the significant concerns of cost-effectiveness, high hydrodeoxygenation (HDO) selectivity, modest hydrogen environments, and solvent-free condition using high surface area silica-alumina-supported cobalt oxide nanoparticles as a catalyst to produce fuel-grade hydrocarbons from fatty acid-based feeds that are palm oil and jatropha oil. The catalytic performance is tested for methyl stearate to achieve the best conversion efficiency with remarkable deoxygenation selectivity. The HDO selectivity was as high as 87% at 250 °C and 30 bar H2 pressure, whereas moderate HDO selectivity with relatively higher cracking was observed at 300 °C and 2 bar H2 pressure. Remarkably, the HDO selectivity was comparable in the absence of solvent. The catalyst is recyclable with low metal leaching during the deoxygenation. The use of non-noble metal catalysts under solvent-free conditions offers facile production of fuel-grade hydrocarbons.