Nanoparticle modified Ni-based bimodal pore catalysts for enhanced CO2 methanation

Abstract

Nanoparticle promoted Ni-based bimodal pore catalysts (20Ni/SiO₂–Si, 20Ni/SiO₂–Al, 20Ni/SiO₂–Zr) were developed by the impregnation of nickel over SiO₂, Al₂O₃ and ZrO₂ nanoparticle modified SiO₂ supports. The effects of nanoparticle type on the structures and performances of the catalysts for CO₂ methanation were systemically studied. Catalyst characterizations indicated that bimodal pore structures were formed by the introduction of nanoparticles into the SiO₂ support, which increased the surface areas of the catalysts and improved the dispersion of nickel. The activity for CO₂ methanation was also enhanced significantly by the promotion of nanoparticles. The CO₂ conversion increased in the order of 20Ni/SiO₂ (unmodified catalyst) < 20Ni/SiO₂–Si < 20Ni/SiO₂–Al < 20Ni/SiO₂–Zr, corresponding to the increasing order of their surface areas. It is found that the modification of ZrO₂ and Al₂O₃ nanoparticles improved the CO₂ chemisorption and dissociation, and thus resulted in extremely high CH₄ selectivity (about 100%) at low reaction temperatures (<450 °C). A strong metal–support/promoter interaction was also observed in ZrO₂ and Al₂O₃ nanoparticle promoted catalysts, which inhibited the sintering of nickel and contributed to the high stabilities of these two catalysts in CO₂ methanation. Due to their excellent activity, selectivity and stability, ZrO₂ nanoparticle modified Ni-based catalysts exhibited high potential for application in CO₂ methanation in the future.