Hydrodeoxygenation of Oleic Acid on Supported and Unsupported MoS2 and NiMoS2 Catalysts for the Production of Green Diesel Fuel

Abstract

MoS₂/Al₂O₃ and NiMoS₂/Al₂O₃ catalysts were prepared by incipient wetness impregnation of alumina using aqueous solutions of 12-molybdophosphoric heteropolyacid and nickel citrate. Unsupported catalysts were prepared by etching a support made from MoS₂/Al₂O₃ using hydrofluoric acid (Et-MoS₂) and thermal decomposition of aluminum tetrathiomolybdate (Ref-MoS₂). The activity of the catalysts in hydrodeoxygenation decreases in the series NiMoS₂/Al₂O₃ = Et-MoS₂ > MoS₂/Al₂O₃ > Ref-NiS₂. On the other hand, the selectivity relative hydrogenation of oleic acid has a different order: Et-MoS₂ > MoS₂/Al₂O₃ > Ref-MoS₂ > NiMoS₂/Al₂O₃. The unsupported Et-MoS₂ catalyst has similar activity to NiMoS₂/Al₂O₃ in hydrodeoxygenation and the highest selectivity, which indicates virtually completion of the hydrodeoxygenation reaction through a hydrogenation pathway without the formation of CO or CO₂. These gases display strong inhibiting properties and have a detrimental eject on the environment.