Catalytic methanation in a slurry-bed reactor over Ni/SiO2 catalysts: improvement by ZrO2 and β-cyclodextrin addition

Mesoporous silica (SiO 2 ) supported highly dispersed Ni catalysts with ZrO 2 and surfactant β-cyclodextrin (CD) were prepared by the impregnation method, and their catalytic performance for three-phase methanation of CO were evaluated. It is shown that ZrO 2 promotes the dispersion of Ni species on mesoporous SiO 2 , leading to the increase in Ni dispersion and methanation activity. For the ZrO 2 content, the optimum is 5 wt%. Moreover, when adding CD in the preparation of Ni5Zr/SiO 2 catalyst, CD was found effectively enhanced the dispersion of Ni species and interaction between Ni species and support, leading to a smaller size of NiO particles and more exposed active surfaces, which promotes the CO adsorption capacity. As the molar ratio of CD/Ni rises, the crystallite size of metallic Ni decreased. Ni5Zr/SiO 2 (1:5) catalyst prepared with 5 wt% ZrO 2 and 1:5 molar ratio of CD/Ni shows the optimal catalytic activity for the three-phase CO methanation reaction. This is because of the highest dispersion of metallic Ni and smallest size of NiO particles.