CO2 reforming of methane over Mg-promoted Ni/SiO2 catalysts: the influence of Mg precursors and impregnation sequences

Mg-promoted Ni/SiO2 catalysts with different Mg precursors were prepared by different impregnation sequences and used in CO2 reforming of methane. The catalysts were characterized by XRD, TPR-H-2, TPD-CO2, TG-DTA and SEM techniques. The use of Mg(CH3COO)(2) as Mg precursor favored the performance of the catalyst. The impregnation of Mg(CH3COO)(2) prior to Ni led to stronger interaction of nickel species with the support and the formation of stable Ni2SiO4 and Mg2SiO4 species, which inhibited the sintering of metallic Ni and then made the catalyst show better activity and stability. The catalyst thus prepared also exhibited enhanced capacity of CO2 adsorption, which accelerated the CO2 activation and the elimination of deposited carbon. No significant carbon deposition was observed on the surface of the catalysts, keeping the catalyst stable.