Carbon dioxide reforming of methane over MgO-promoted Ni/SiO2 catalysts with tunable Ni particle size

摘要

Design and preparation of coke resistant nickel-based (Ni-based) catalyst is the key point for the industrial application of carbon dioxide reforming of methane. In this work, MgO-promoted Ni/SiO2 catalysts with tunable particle size were prepared by the multiple-impregnation method and were employed to catalyze carbon dioxide reforming of methane. Results showed that the additive MgO was an electron donor, and its providing electron capacity to Ni became stronger as the Ni particle size was smaller. Catalytic activity evaluation presented that the Ni-en-0.4 %MgO catalyst possessed superior catalytic activity (CH4 and CO2 conversions maintained at 83.6 % and 89.9 %) at 750 degrees C. Its carbon deposition amount was only 0.16 wt.% after 100 h runs. The higher activity and the stronger coke resistance of the Ni-en-0.4 %MgO catalyst were due to the smaller Ni particle size (8.4 nm) and higher Ni electron density, which could promote CO2 activation and dissociation, and finally balance the formation rates of C species and O species over the MgO-promoted Ni/SiO2 catalysts.