Preparation and properties of Ni/KIT-6 catalysts modified with different metals for methanation of CO₂

Ni/KIT-6 catalysts modified by Mg, Ce, V and La for CO₂ methanation were prepared by co-impregnation method.The catalysts were characterized by N₂ absorption-desorption, XRD, H₂-TPD and TEM.The effects of different promoters on structure and properties of Ni/KIT-6 catalysts were investigated. The results show that the dispersity of Ni and promoters are very high. The dispersion of Ni particles depends primarily on the confinement effect of the well-ordered mesoporous structure of KIT-6, and is not affected by the addition of metal promoters. The addition of promoters does not affect the surface morphology of Ni/KIT-6 catalyst, but has effects on the difficulty and reduction degree of Ni reduction. Among the metal promoters studied, V addition makes the reduction of NiO in the catalyst easily and results in a high reduction degree. The oxide of V can change the reaction mechanism of CO₂ methanation, resulting in the best methanation performance. Compared with the unmodified catalyst, the catalyst modified by V makes the conversion of CO₂ and the selectivity of CH₄ increase by 3.7% and 11.6% respectively. The selectivity of CH₄ is 100%.