Design Of Graphene-Supported Nickel-Based Catalysts And Their Catalytic Performance For The CO₂ Methanation Reaction

The CO₂ emission has led to a series of environmental problems.The CO₂methanation technology can not only reduce CO₂ emissions,but also realize the recycling of CO₂ resources,and is considered to be one of the most effective methods to solve CO₂ emission problems.Compared with noble metal?Ru and Rh?catalysts,metal N i is relatively inexpensive and has good catalytic activity.Graphene has characteristics such as large specific surface area,good electrical and thermal conductivity,good thermal stability,and large mechanical strength,and is a good catalyst carrier material.At present,there are few reports on the use of supported N i-based catalysts prepared from graphene as a carrier for methanation of CO₂.In this paper,graphene is used as carrier,metal N i is supported on graphene by impregnation method,and supported N i-based catalyst is prepared by adjusting the loading of N i and the added amount of rare-earth additive Ce,and the catalytic performance of CO₂ methanation is explored.Specifically,we will study from the following three aspects.1.Different reduction methods and reducing agents were used to prepare reduced graphene oxide,and the supported N i-based catalyst was prepared as a carrier to study its catalytic hydrogenation performance.Through a series of characterizations,it was found that the reduction degree of reduced graphene oxide prepared from hydrazine hydrate as a reducing agent is the highest,and the loaded Ni-based catalyst shows the best performance.2.The RGO,AC and?-Al₂O₃ were used as the nickle based catalyst supports,the CO₂ methanation were used to test the catalysts ability.Though the XRD,TEM,H₂-TPR and N₂-BET characterization,we found that the RGO supported nickel base catalyst shows the highest nickel dispersion,small nickel size,best catalyst ability and low reaction temperature.3.The ceria can improve the catalysts ability of N i/RGO,Ni/AC and N i/?-Al₂O₃.The XRD,TEM,H₂-TPR and N₂-BET characterization shows that the addition of ceria favors the formation of small nickel particles.The 5wt%ceria loaded on the catalysts show the highest CO₂ convension and CH₄ selectivity.The reaction temperature decrease 50?,compare with the catalysts with no ceria.