载体效应与镍晶粒尺寸对CO_(2)甲烷化低温催化性能的影响

Effect of support and nickel crystal size on low temperature catalytic performance of carbon dioxide methanation

采用等体积浸渍法制备MgO和CeO_(2)负载的一系列不同镍含量催化剂,对其进行了二氧化碳甲烷化催化性能评价。研究结果表明NiO/CeO_(2)基催化剂具有优异的低温催化活性,其中80%NiO/CeO_(2)催化剂,在18 L/(g·h)、H_(2)/CO_(2)=4和350℃反应条件下甲烷产率为67%。探究了镍含量对NiO/MgO和NiO/CeO_(2)催化剂活性的影响,结果表明,随着镍含量增加,二氧化碳转化率、甲烷产率升高,在镍负载量为50%~80%时催化性能最佳。通过X射线衍射(XRD)、氢气程序升温还原(H_(2)-TPR)、拉曼(Raman)、CO_(2)-TPD表征探究不同载体和Ni晶粒大小对NiO/MgO,NiO/CeO_(2)催化剂催化活性的影响。本研究可为设计具有优异低温催化性能的二氧化碳甲烷化催化剂提供参考。

A series of catalysts with different nickel contents supported by MgO and CeO_(2) were prepared by the equal volume impregnation method and evaluated for their methanation catalytic reaction.The research results show that the NiO/CeO_(2)-based catalyst has better low-temperature reaction performance,and the 80%NiO/CeO_(2) catalyst has a methane yield of 67%under the reaction conditions of 18 L/(g•h),H_(2)/CO_(2)=4,and 350℃.The effect of nickel content on the catalytic activity of NiO/MgO and NiO/CeO_(2) catalysts was also explored.The results show that with the increase of nickel content,the carbon dioxide conversion rate and the methane yield increase,and when the nickel loading is 50%-80%the catalytic performance is optimal.By X-ray diffraction(XRD),hydrogen temperature programmed reduction(H_(2)-TPR),Raman and CO_(2)-TPD characterization,it is found that Ni crystal size and content are the key factors that affecting the catalytic activity of NiO/MgO and NiO/CeO_(2) catalysts.This study can provide guidance for the design of carbon dioxide methanation catalysts with excellent catalytic performance at low temperature.