Deoxygenation of Methyl Oleate and Commercial Biodiesel Over W and Ni-W Catalysts

Abstract

The enhancement of biodiesel fuel properties by modifying/optimizing fatty ester composition is an area of ongoing research. Chemical upgrading methods include catalytic hydrodeoxygenation process (HDO), hydrothermal liquefaction, Fischer–Tropsch synthesis (F–T synthesis), and super-critical modification. Catalytic hydrodeoxygenation process for converting biodiesel into renewable petrodiesel-like fuels substitutes is gaining considerable importance. The biodiesel upon hydrotreatment produces green diesel that has a cetane number higher than commercial petroleum diesel. In this paper, we report the findings of using tungsten as a deoxygenation catalyst supported over γ–Al2O3 to convert methyl oleate and biodiesel to green diesel. The catalysts were characterized by XPS analysis and N2 adsorption–desorption. The effect of reduction temperature, hydrogen flowrate, Ni promoter and anion (oxide vs sulfide catalyst) on the hydrodeoxygenation activity of the catalyst were examined. It was found that catalyst reduced at 300/350 °C was optimal from a selectivity point of view. Moreover, increasing the hydrogen flowrate favored hydrodeoxygenation over decarbonylation/decarboxylation. It was further deduced that Ni promoted the activity and that the oxide catalyst was superior in this respect to the sulfide catalyst.