Elucidating the Promoting Role of Mo2C in Methane Activation Using Ni-xMo2C/FAU to Catalyze Methane Steam Reforming

We report the synthesis and characterization, reaction kinetics, and deactivation mechanism of a series of catalysts with metallic nickel (Ni) and molybdenum carbide (Mo 2 C) particles supported on zeolite Y (Ni-Mo 2 C/FAU) in methane steam reforming (MSR) reaction at 850 °C. Despite a low Ni loading of 2.4 wt%, MSR on Ni-Mo 2 C/FAU exhibits high activity and stability, yet deactivation of Ni-FAU is significant. Further investigations elucidate that the catalyst deactivation is caused by Ni particle sintering via Ostwald ripening instead of coking, and steam induces hydroxylated Ni surface that accelerates sintering. Moreover, Mo 2 C boosts the activity and stability of Ni on zeolite Y by enhancing CH 4 activation rather than activating H 2 O. The interplays among Mo 2 C and Ni particles dynamically balance the carbon formation and consumption rates, and inhibit Ni sintering. This study demonstrates that high MSR activity and stability can be achieved on transition metal carbide – Ni catalysts with systematically tuned compositional, structural, and interfacial factors. • Sintering and coking are the deactivation mechanisms of Ni- and Mo 2 C-FAU in MSR. • The synergy between Ni and Mo 2 C increased both activity and stability in MSR. • Mo 2 C enhanced CH 4 activation, shown by its 4 times higher CH 4 decomposition rate. • Mo 2 C has excellent thermal stability and is still highly dispersed after reaction. • The real active sites are Mo 2 C decorated Ni species as shown in TEM-EDX.