Elucidating the Role of Ni(Pd) in Ni(Pd)-Mo2C/Carbon Catalysts for the Hydrodeoxygenation of Dibenzofuran and Bio-Oil

Abstract

Mo2C catalysts (10 wt %) promoted with Ni or Pd (1 wt %) and supported on activated biochar were synthesized by carbothermal hydrogen reduction and assessed for the hydrodeoxygenation (HDO) of dibenzofuran (DBF) as a model bio-oil reactant. Ni and Pd improved the activity of the Mo2C/ABC catalyst and shifted selectivity from direct deoxygenation products to hydrogenated products. The results correlated with an increased hydrogenation of O species adsorbed on the passivated catalysts at low temperature, indicative of a decrease in oxidation of the Mo2C and confirmed by X-ray photoelectron spectroscopy and temperature programmed oxidation-reduction analysis. Density functional theory calculations showed the increased horizontal adsorption of DBF and a reduced energy barrier for dissociative H2 adsorption on the Ni(Pd)-promoted Mo2C surface. The high hydrogenation activity of the Ni-and Pd-Mo2C catalysts was also apparent during the HDO of an esterified bio-oil, significantly decreasing coke yield together with the phenol and ester content and the O/C ratio of the hydrotreated bio-oil.