Enhanced performance and selectivity of CO2 methanation over phyllosilicate structure derived Ni-Mg/SBA-15 catalysts

Abstract

Ni and Ni-Mg phyllosilicate mesoporous SBA-15 catalysts were successfully prepared via ammonia evaporation (AE) method as evidenced by XRD, H2-TPR, TEM, FTIR and EXAFS fitting results. The catalysts derived from phyllosilicate structure exhibit superior catalytic performance in CO2 methanation as compared to catalyst prepared via wetness impregnation (WI) method due to enhanced metal-support interaction and the presence of weakly basic sites provided by surface hydroxyl groups. Incorporation of Mg into phyllosilicate structure with optimum 5 wt% is also found to increase medium basic sites, which can promote monodentate formate formation as identified by DRIFTS analysis and improve CO2 methanation activity at lower temperatures. Additionally, the turnover frequency of CO2 conversion can be well correlated with the concentration of basic sites. The strong metal-support interaction derived from phyllosilicate structure along with confinement effect of SBA-15 can suppress metal sintering, resulting in good stability.