The effect of temperature and initial methane concentration on carbon dioxide methanation on Ni based catalysts

摘要

A series of Ni based catalysts prepared by incipient wetness method were characterized by chemisorption and studied for CO2 methanation. Ru had apparently a positive effect on the active metal surface area, and thus the catalytic activity. The CO2 conversion was greatly affected by temperature where the conversion ranged from 12%-85% at temperatures of 300 to 400 oC on the 12% Ni/Al2O3 catalyst. At 350 oC, higher Ni loading resulted in increased activity. The incorporation of 0.5% Ru lead to a drastic increase in catalytic activity, which can be explained by increased reducibility and a synergetic effect between Ni and Ru, and was further enhanced by increased Ni loading. Addition of CH4 at twice the initial concentration of CO2 to the feed gas mixture was found to decrease the conversion from 52% to 48% at 350 oC on the 20% Ni/Al2O3 catalyst, whereas only a slight reduction in selectivity was observed. The results preliminary demonstrate that high methane purity can be achieved from a biogas feed stream over Ni based catalysts.