Efficient hydrogenation performance improvement of MoP and Ni2P catalysts by adjusting the electron distribution around Mo and Ni atoms

Abstract

MoP and Ni₂P catalysts were modified by elements with different electronegativities. Based on this method, two series of catalysts were designed and synthesized: Mo based phosphide catalysts (MoP, Mo₈WP₉, Mo₈CuP₉) and Ni based phosphide catalysts (Ni₂P, Ni₃₈W₂P₂₀). The consistency between synthetized and designed materials was mainly verified by XRD, SEM-EDS, TEM, EXAFS. Then, relative catalyst parameters were further characterized using BET, and CO chemisorption. The hydrogenation properties of verified synthesized catalysts are evaluated by hydrodeoxygenation of methyl palmitate. The activity of the catalysts followed the order: Mo₈WP₉ > MoP > Mo₈CuP₉, Ni₃₈W₂P₂₀ > Ni₂P. In particular, the W modified catalysts (Mo₈WP₉ and Ni₃₈W₂P₂₀) exhibited hydrogenation activities 2.83 and 3.68 times that of MoP and Ni₂P, respectively. Further, the product selectivities of different catalysts were analysed detailedly. The C16/C15 molar ratio was increased with the incorporation of W, which represented that the selectivity of the HDO pathway increased. While the C16/C15 molar ratio was decreased with the introduction of Cu, and this suggested that the selectivity of decarbonylation increased. These results indicate that the adjustment of the electron distribution around Mo and Ni atoms could successfully control the hydrogenation properties of catalysts.