Improving the anti-coking ability in the Ni-M(M = Ce, Zr, Co)@SiO2 yolk-shell catalysts for dry reforming of methane

Abstract

Dry methane reforming (DRM) represents a highly promising approach to greenhouse gas conversion (CO2 and CH4) to valuable byproducts. However, severe carbon deposition and catalyst deactivation inhibit large-scale applications. The work designed new catalysts with a yolk-shell structure using the water-in-oil microemulsion method. The catalysts were composed of a yolk-shell structure, with Ni-M as the active point and silica as the shell. The catalytic performance evaluation indicates that the Ni-M @SiO2 catalysts show higher CH4 and CO2 conversion compared with the Ni@SiO2 and conventional catalysts at 750 ℃, suggesting the yolk-shell structure and added M species enhance the DRM activity. The XRD, HRTEM, XPS, BET, H2-TPR, and CO2-TPD analysis confirmed the existence of yolk-shell configuration and evident electronic effect among Ni, M species, and SiO2. The long term measurements indicate that the added M species also bring higher carbon deposition tolerance for DRM, where Ni-Ce@SiO2 and Ni-Zr@SiO2 exhibit good structural and catalytic stability for DRM over 100 h. Through XRD, TEM, and TGA characterizations of the exhausted catalysts, it is determined that the coke deposition resistance of the catalyst is improved as a result of increased oxygen mobility and enhanced Ni dispersion on the catalytic surface, both of which are enhanced by the added Ce species. The structural analysis of the spent catalysts indicates that the tolerance of carbon deposition is improved by the yolk-shell samples. This study can offer valuable insights for the development of Ni-based catalysts with exceptional carbon deposition capability for DRM.