Study On CO₂ Methanation Performance Of Plasma-treated And Promoter Modified Ni-basesd Catalyst

Currently, under the situation of shortage of natural gas and global warming becoming more serious, the synthesis of natural gas based on CO₂ methanation is of great importance in energy and environment protection. The development of catalysts is the key of CO₂ methanation techology. Ni-based catalyst is one of most promising catalysts due to its excellent performance for CO₂ methanation reaction.In this paper, we prepared Ni/Al OOH and Ni/Al₂O₃ catalyst by the wet incipent impregnation method, and the last third catalyst Ni/Al₂O₃ was prepared by coprecipitation method. It was found that Ni/Al₂O₃ prepared by impregnation method showed the best catalytic performance. Furthermore, we compared the Ni/Al₂O₃ catalyst prepared by impregnation method and treated by different methods, calcinations, DBD plasma, first DBD plasma then calcinations, respectively. The characterization showed that the plasma-treated method can decrease the interaction of Ni-Al, increased the dispersion and reduction of Ni O and CO₂ adsorption sites.Based on the impregnation and plasma method, we added Ce to improve the low temperature CO₂ methanation activity. It was found that 2 wt.% Ce was the best choice when co-impregnating Ce with different contents and Ni into Al₂O₃. Besides, the CeO₂-Al₂O₃ composite supports with different Ce/Al ratio were prepared and it was the best choice when the Ce/Al ratio is 4/6. Furthermore, we added 2 wt.% Ce by the two ways, and it was found that both of the two ways can enhance the catalytic activity while co-impregnating Ce and Ni was the best method.The effect of Fe on CO₂ methanation was aslo investigated on the catalyst prepared by impregnation method and DBD plasma. Compared to a series of bimetallic Ni–Fe with different Ni/Fe ratio, the monometallic Ni-based and Fe-based supported on Al₂O₃ catalysts, it was found that Fe was not the active metal but improve the catalytic activity. Besides, adding large amounts of Fe to the catalyst with high loadings of Ni can decrease the catalytic activity. It was found that two roles of Fe were giving appropriate electric surroundings to Ni and wrapping Ni to the supports. The main role of Fe was different with the Ni loadings.