LAUSR

Bimetallic Mo–W carbides supported on biochar were synthesized and used in the catalytic hydrotreatment of canola oil at 250 °C to produce diesel-range hydrocarbons. The effects of carburization temperature and metal content on the nature of active sites were investigated by using X-ray diffraction (XRD), N2 physisorption, X-ray photoelectron spectroscopy (XPS), and CO and H2 chemisorption. Varying temperature over the range of 550–700 °C did not have any effect on the formation of the Mo2C phase in the bimetallic carbide. As for the tungsten component in the mixed carbide, formation of the WC phase at a high temperature of 700 °C was dominant and increased the density of hydrogen activating sites, whereas at lower temperatures (≤600 °C), W2C and metallic W phases were formed and showed more CO adsorption sites. Increasing metal loading enhanced the particle size resulting in a lower density of catalytically active sites. The addition of W into the molybdenum carbide system strongly increased the catalytic performance with >95% conversion and >76% hydrocarbon yield over all mixed metal carbides at a mild temperature of 250 °C. These values were both higher than those obtained using Mo2C/C and Ru/Al2O3 (48 and 35% hydrocarbon yield, respectively) under identical conditions. All carbide catalysts favor hydrodeoxygenation (HDO) products over decarboxylation/decarbonylation (DCO) products; however, W addition into mixed metal carbides increases the DCO selectivity in comparison with Mo2C/C due to higher ratios of H2/CO adsorption sites. The bimetallic carbides still retained a high catalyst activity after regeneration.