Study On The Catalyst For Carbon Dioxide Hydrogenation

At present,carbon dioxide hydrogenation reaction has attracted significant attention from industrial and academic community as an effective way to solve the problem of global CO2 excess.Among all hydrogenation reactions,CO2 methanation has become a hot topic due to its advantages of low reaction conditions and high conversion efficiency.However,the common catalysts have the problems of poor reaction stability,which restricts the development of industrialization.Therefore,inspired by the core-shell structure materials,we prepared a highly active and highly stable embedded Ni-based catalyst through hydrothermal synthesis.And on this basis,we have further fabricated a Ni-Mo bimetallic catalyst of embedment structure,and the catalyst was used to couple CO2 methanation and methane anaerobic aromatization reaction to achieve the direct production of aromatics products by CO2 hydrogenation.First of all,a highly active and stable Ni@HZSM-5 catalyst was synthesized by hydrothermal method using conventional Ni/SiO2 catalyst as unique silicone source.Then we explored the synthesis conditions,types and proportions of materials.The Ni@HZSM-5 showed high activity and excellent stability during 40 h CO2 methanation reaction,comparing to the conventional Ni/SiO2 and Ni/HZSM-5 catalysts prepared by impregnation method.Draw conclusions through a series of characterizations,after a prolonged reaction,the Ni@HZSM-5 still maintain similar nickel content and the structure of active nickel to fresh catalyst,due to the special embedment structure.Meanwhile,it is found that the nickel active phase of the Ni@HZSM-5 catalyst donates more electrons to zeolite,resulting in higher BE values,lower wavenumber and weak intensity of CO bands.Hence,the Ni@HZSM-5 catalyst can prevent the formation of volatile metal-molecule intermediates(gaseous Ni(CO)x),which resulted in serious sintering and loss of the supported nickel in conventional Ni catalysts.Finally,on the research results of the synthesis of Ni@HZSM-5,we produced a dual-function catalyst named Ni-Mo@HZSM-5.Ensure that the methane continuously produced in the system can generate aromatic hydrocarbon products with the action of active Mo,and realize the coupling of the CO2 methanation and MDA reactions.And we continue to improve the selectivity of aromatics in the product by improving the metal ratio,catalyst synthesis conditions and other factors.At the reaction temperature of 400?,the catalyst can ensure 20.68%aromatic selectivity and 44.60% CO2 conversion.