Tuning crystal phase of molybdenum carbide catalyst to induce the different selective hydrogenation performance

α-MoC, β-Mo₂C, and MoC-Mo₂C were synthesized and investigated in the selective hydrogenation of 1,3-butadiene to understand the effect of crystal phases. The catalysts were characterized by XRD, N₂-physisorption, SEM, TEM, XPS and chemisorptions. The adsorption properties and electronic properties over MoC(001) and Mo₂C(001) were investigated by DFT calculations. The catalysts were evaluated at low and high temperatures in a fixed-bed reactor. β-Mo₂C exhibits high activity and low butenes selectivity, due to the high concentration of hydrogen at each active site as well as the stronger adsorption and higher capacity of alkene; MoC-Mo₂C shows better stability due to synergetic effect. At high temperature, the reaction rate is more dependent on the P_H2 than P_C4H6. Increasing P_H2 could promote the activity and reduce oligomers formation. β-Mo₂C exhibits the best performance at high temperatures concerning its high activity and the inhibition of oligomerization. This work is valuable for the non-precious metal catalyst development.