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The process of the reaction among elemental mercury (Hg 0 ) and reactive flue gas components across the selective catalytic reduction (SCR) catalyst was studied in a laboratory-scale reactor. Prepared vanadia-based SCR catalysts were characterized and analyzed to understand the potential reaction pathways. Mercury oxidation was observed when pro-exposure of the SCR catalyst to HCl, followed by passing through Hg 0 /N 2 in the absence of gas-phase HCl. At testing conditions, Hg 0 was found to desorb from the catalyst surface by adding HCl to the gas steam, which implies that HCl adsorption onto the SCR catalyst is strong relative to the mercury. Surface analysis verified the absorption of HCl onto the SCR catalysts, and the potential reaction pathways were proposed. Indeed, the monomeric vanadyl sites on the catalyst surface were found to be responsible for the adsorption of both Hg 0 and HCl, which means they are active for mercury oxidation. Furthermore, the detailed Langmuir-Hinshelwood mechanism was proposed to explain the mercury oxidation on the SCR catalyst, where reactive Cl generated from adsorbed HCl reacts with adjacent Hg 0 .

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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.