CO 2 Methanation Using Multimodal Ni/SiO 2 Catalysts: Effect of Support Modification by MgO, CeO 2 , and La 2 O 3

: Ni/oxide-SiO 2 (oxide: MgO, CeO 2 , La 2 O 3 , 10 wt.% target concentration) catalyst samples were prepared by successive impregnation of silica matrix, first with supplementary oxide, and then with Ni (10 wt.% target concentration). The silica matrix with multimodal pore structure was prepared by solvothermal method. The catalyst samples were structurally characterized by N 2 adsorption-desorption, XRD, SEM/TEM, and functionally evaluated by temperature programmed reduction (TPR), and temperature programmed desorption of hydrogen (H 2 -TPD), or carbon dioxide (CO 2 -TPD). The addition of MgO and La 2 O 3 leads to a better dispersion of Ni on the catalytic surface. Ni/LaSi and Ni/CeSi present a higher proportion of moderate strength basic sites for CO 2 activation compared to Ni/Si, while Ni/MgSi lower. CO 2 methanation was performed in the temperature range of 150–350 ◦ C and at atmospheric pressure, all silica supported Ni catalysts showing good CO 2 conversion and CH 4 selectivity. The best catalytic activity was obtained for Ni/LaSi: CO 2 conversion of 83% and methane selectivity of 98%, at temperatures as low as 250 ◦ C. The used catalysts preserved the multimodal pore structure with approximately the same pore size for the low and medium mesopores. Except for Ni/CeSi, no particle sintering occurs, and no carbon deposition was observed for any of the tested catalysts.