Preparation, Characterization And Catalytic Activity Of New Ni-based Catalysts For CO₂Methanation

Ni-based catalysts are the most popular catalysts for CO2methanation, as Ni has a lot of advantages such as wide variety of sources, cheap, high hydrogenation ability and high selectivty for CH4. But there is still one problem. Ni based catalysts are prone to sintering and deactivating during the process of reaction.Our work aimed at designing Ni based catlysts with high dispersion and stability, which can exhibit high catalytic activity at low temperature. The main works are introduced as follows:(1)The NixMgyO nanoparticles (NPs) with different Ni/Mg ratios were prepared by chemical co-coprecipitation. And then the NixMgyO NPs were encapsulated by porous silica shell using modified Stober method for CO2methanation reaction. The structure and surface property of the catalysts were investigated by XRD、XPS、TEM、N2-physisorption and H2-TPR characterization. The effects of Ni/Mg ratios in core-shell structured catalysts, GHSV and reduction temperature on CO2conversion and CH4selectivity were examined. Results showed that the NixMgyO@SiO2catalyst with Ni/Mg ratio of4/1exhibited the highest catalytic activity (87%of conversion for CO2and99%of selectivity for CH4) at low temperature and excellent stability. Thus it can be concluded that the high catalytic activity and stability of this catalyst Ni0.8Mgo.20@Si02could be attributed to the isolated highly dispersed Ni NPs, which were obtained through the reduction of NiO-MgO solid solution protected by silica shell.(2) Ni-based catalysts Ni/SBA-15and Ce promoted Ni-Ce/SBA-15were prepared by ultrasonication impregnation method. The structure and surface property of the catalysts were investigated by XRD、XPS、TEM、N2-physisorption and H2-TPR characterization. The effects of promoter Ce of Ni/SBA-15on CO2conversion and CH4selectivity of CO2methanation were examined. The result showed that Ni-Ce/SBA-15exhibited higher catalytic activity than Ni/SBA-15under the whole reaction temperature.