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

Wang, Xiaoliu, Zhu, Lingjun, Zhuo, Yexin, Zhu, Yanqun, Wang, Shurong
ACS sustainable chemistry & engineering 2019 v.7 no.17 pp. 14647-14660
adsorption, carbon dioxide, catalysts, catalytic activity, citrates, density functional theory, hydrogenation, lanthanum, methane, methane production, nanoparticles, nickel, particle size, physicochemical properties, synergism
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 °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.