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.
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