Influence of bimetallic characteristics on the performance of MoCoP and MoFeP catalysts for methyl laurate hydrodeoxygenation

Abstract To study the influence of bimetallic characteristics on activity and selectivity, SiO2-supported CoP, FeP, monometallic MoP and bimetallic MoCoP/MoFeP phosphides (MoxCo1-xP and MoxFe1-xP (x = 0.5)) were investigated for the deoxygenation of methyl laurate to C11-C12 hydrocarbons. Here, we aimed to modulate the catalytic properties using different metal compositions with equimolar amounts of total metal phosphide. The catalysts were characterized by X-ray diffraction, N2 adsorption-desorption at -196 °C, transmission electron microscopy, CO chemisorption, NH3 temperature-programmed desorption and X-ray photoelectron spectroscopy; the conversion of methyl laurate, selectivity for hydrocarbons and C11/C12 ratio were related to the composition and physicochemical properties of the catalysts. The conversion (maximum of 85% for MoP and minimum of 8% for FeP) is mainly influenced by phosphide dispersion, which, in turn, is associated with acidity, and the same trend was found for both parameters (MoP > MoCoP > MoFeP > FeP > CoP). The yield of hydrocarbon formation follows the trend MoP > MoCoP > CoP > MoFeP > FeP, with synergy between Mo and Co in the MoCoP catalyst. The C11/C12 ratio is influenced by the metal phosphide nature; the results indicate that Mo-based catalysts favor a hydrogenation (dehydration) pathway (C12 selectivity, 91% in MoP/SiO2) and that Co-based catalysts favor oxygen elimination by decarbonylation/decarboxylation (C11 selectivity 75% in CoP/SiO2). The activity results show synergy between Mo and Co in bimetallic phosphides by a kind of interaction that yields an enhancement in the catalytic activity of the MoCoP/SiO2 catalyst with respect to the sum of contributions from individual MoP/SiO2 and CoP/SiO2.