The difference of roles of alkaline-earth metal oxides on silica-supported nickel catalysts for CO2 methanation

The roles of alkaline-earth metal oxides on CO2 methanation over modified Ni/SiO2 catalysts were investigated. Ni/MO/SiO2 catalysts with variable elements (M = Mg, Ca, Sr and Ba) were prepared by the sequential impregnation method. The results indicated that the presence of SrO promoted the catalytic activity and enhanced the catalyst stability. In addition, BaO addition enhanced the reaction activity, but the Ni/BaO/SiO2 catalyst deactivated significantly after 50 h of time-on-stream due to the sintering of metallic Ni. Moreover, CaO addition affected negligibly the performance of the Ni/CaO/SiO2 catalyst, and MgO addition inhibited significantly the methanation performance because of the low reducibility of Ni species.