Influence of the pore structure of alumina support on the dispersed nickel particle size and CO2-methanation activity.

Three kinds of γ-aluminas offered by Catalysis Society of Japan were calcined at 910, 1, 060 and 1, 130°C for 30min. Changes with calcination temperature in support properties such as BET-surface area (S) and effective diffusivity (De) were observed. Using these calcined aluminas as supports, Ni-La2O3 catalysts were prepared by use of the impregnation method, and the correlation between the pore structure of the support and the activity of CO2-methanation was examined. With increasing calcination temperature, S decreased and De increased for all of these alumina supports. However, the maximum methanation activity was observed in every case for the catalyst using the support calcined at 1, 060°C. The particle size of the supported nickel depended not only on S of the support but also on De which would affect the drying stage of the impregnation solution. Thus, it was concluded that the activity of the catalyst should be determined by the proper balance between De and nickel particle size.