Enhancement of CO2 Methanation over La-Modified Ni/SBA-15 Catalysts Prepared by Different Doping Methods

A new, highly active Ni-La2O3/SBA-15(C) catalyst for CO2 methanation was prepared using a citrate complex method, where the formed LaNiO3 with perovskite structure was a key precursor. The physicochemical properties of the catalyst, as-prepared and spent, and its catalytic performance were analyzed in detail and compared with catalysts prepared through a typical wet impregnation method. 10 wt % nickel with lanthanum in the molar ratio of 1:1 was used to prepare the La-modified catalysts. It was found that the La2O3 doping methods had a noticeable effect on the structures of the catalysts and their catalytic performances. Ni-La2O3/SBA-15(C) showed a high dispersion of Ni with a small particle size less than 5 nm, which is one-third of the particle size of that prepared by impregnation. Decent catalytic performance was achieved with a CO2 conversion of 90.7% and CH4 selectivity of 99.5% at 320 degrees C. Due to the specific perovskite structure of LaNiO3, the interaction between La and Ni was intensified, thus enhancing the synergistic effect of La2O3 and Ni, which contributed to the high dispersion of Ni nanoparticles as well as the good antisintering and anticarbon deposition properties. Density functional theory calculations also suggested that the catalyst derived from LaNiO3 favored the adsorption and activation of CO2 and facilitated further hydrogenation. This work provides an effective strategy to develop highly active and stable catalysts for CO2 methanation.