CO Methanation over Ni/SiO₂ Catalyst Prepared by Ammonia Impregnation and Plasma Decomposition

Supported Ni catalysts are prepared by water impregnation, ammonia impregnation and ammonia impregnation combined with dielectric-barrier discharge (DBD) method. The catalyst prepared by the third method shows superior activity, excellent aiti-sintering and anti-coking performances at high temperature in CO methanation. For this catalyst X-ray powder diffraction and transmission electron microscopy reveal the high dispersion of Ni particles. High-resolution transmission electron microscopy shows special surface with more Ni(111). Temperature programmed reduction uncovers the strong metal–support interaction between Ni and SiO₂. This is mainly caused by the formation of nickel-containing phyllosilicate during ammonia impregnation and the controlled growth at lower temperature in subsequent process of DBD treatment. High dispersion of Ni particles leads to improved activity. Strong metal–support interaction suppresses the mobility of Ni particles, which further improves the anti-sintering performance of Ni/SiO₂. Small Ni particles with more Ni(111) facets inhibit carbon deposition. Hence, DBD method combined with ammonia impregnation is an effective way to enhance the activity and high temperature stability of Ni/SiO₂ catalyst.