The methane activation and methane dry reforming resections were studied and compared over 4 wt% Ni/CeO2 and 4 wt% Ni/CeZrO2 (containing 20 wt% Zr) catalysts. Upon the incorporation of Zr into the ceria support, the catalyst exhibited a significantly improved activity, H2 selectivity and stability. To understand the effects of doping zirconia into the ceria support and reveal the structure-reactivity relationship underlying the enhanced catalytic performance of the Ni/CeZrO2 catalyst, both Ni/CeO2 and Ni/CeZrO2 catalysts were characterized and compared via in-situ Time-Resolved X-ray diffraction (TR-XRD), X-ray absorption fine structure (XAFS) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) for methane activation process and methane dry reforming reaction. The TR-XRD and AP-XPS indicate a higher reducible ceria-zirconia support in the Ni/CeZrO2 catalyst than the ceria support in the Ni/CeO2 catalyst upon the reaction with pure methane or with the methane and carbon dioxide gas mixture for the methane dry reforming reaction. The particle size of both nickel and ceria or ceria-zirconia support under the reaction condition were analyzed by Rietveld refinement and XAFS fittings, showing that the existence of Zr in the ceria support mitigates the particle sintering and maintains the small particle size for both metallic nickel and the oxide support under reaction condition. The in-situ characterization showed small and well dispersed metallic Ni particles cooperating with the highly reduced and structurally stable ceria-zirconia support in the Ni/CeZrO2 catalysts, which leads to its enhanced reaction activity, H2 selectivity and stability for the dry reforming reaction than the Ni/CeO2 catalyst.

Effects of doping Zr into the ceria support for the methane dry reforming reaction on Ni/CeO2 catalyst

2019 Fall National Meeting

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