Synergistic Effect of Cerium Promoter and Dendritic Mesoporous Silica Support on Ni-Catalyzed CO2 Methanation

Abstract

Enhancing the dispersion of active metals and tuning their interaction with a suitable support are crucial for improving catalytic performance. Here, we utilize Ce-promoted dendritic mesoporous silica (Ce-DMS) as a support that offers abundant oxygen vacancies (O-v) and a high surface area to boost the performance of Ni-catalysed CO2 methanation by enriching the Ni-O-v-Ce interface and enhancing Ni dispersion. The optimized Ni/5Ce-DMS catalyst exhibits a high turnover frequency of 1.6 s(-1) at 300 degrees C, which outperformed Ni/DMS and Ni/CeO2 reference catalysts, as well as other Ni-based CO2 methanation catalysts reported in the literature. Combined in situ and ex situ analyses reveal that the superior activity of the Ni/5Ce-DMS originates from the large specific surface area of the Ce-DMS support and formation of abundant Ni-O-v-Ce interfaces. The oxygen vacancies provided by highly dispersed cerium on the catalyst surface facilitate CO2 activation, thereby promoting the formation of CH4 even at low temperatures. Moreover, the numerous silica layers in DMS enhance Ni dispersion and prevent Ni aggregation, thereby achieving enhanced catalytic activity as well as stability.