Effect of additives on the properties of nickel molybdenum carbides for the tri-reforming of methane

A series of NiMo carbides modified with different additives were prepared with the temperature programmed reduction method. Characterization and catalytic properties for the tri-reforming of methane were performed. It was found that the presence of nickel species in NiMo series carbides stimulated the dissociation of methane and supplied the active carbon for the carburization process. La-promoted NiMo carbide could prevent the aggregation of small particles, facilitate the topotactic transformation of Mo2C species and inhibit the carbon deposition, which were benefit for the excellent catalytic performance. Ce and Co additives deteriorated the activities of NiMo carbides to some extent due to the larger particle size. Mg favored the coke generation and decreased the surface area and pore volume of NiMoCMg carbide. The addition of K suppressed the carburization process of molybdemum oxide species and caused the phase transformation of active γ-Al2O3 to less active θ-Al2O3. Mg and K modified NiMo carbides, especially the latter, showed a dramatic decrease in the redox ability for the tri-reforming of methane. The oxidation of carbidic species, the agglomeration of small particles and the carbon deposition decreased the catalytic activities of NiMo series carbides for the tri-reforming of methane.