Effect of nickel content of catalyst on carbon dioxide reforming of methane

Carbon dioxide reforming of methane and carbonaceous deposition were investigated with Al2O3-supported nickel catalysts of different nickel content, Turnover frequency, based on the surface nickel atom, decreased with an increase in the nickel content of the catalyst. The relationship between the turnover frequency and nickel particle size revealed that the reforming reaction mainly took place at the nickel-support boundary. Thermogravimetric analysis was carried out in order to observe carbonaceous deposition which would decrease the catalytic activity. The amount of carbonaceous deposit became smaller in a catalyst of lower nickel content, in other words, a catalyst with smaller nickel particles. This would be due to the suppression of formation of carbon whiskers. The relationship between the catalytic activity and the amount of carbonaceous deposit was discussed. Catalytic activity was not damaged seriously by the carbonaceous deposition which was enough to cover the nickel surface. These results suggested that the reforming reaction and carbonaceous deposition took place at different nickel sites.