Preparation Of CuO/ZnO Hybrid Nanoparticle Catalysts And Study On Performance Of Water Gas Shift Reaction

Energy has always been a prerequisite for human civilization,and all human activities are inseparable from energy.People have been using fossil fuels to meet their energy needs for a long time.However,these sources of energy are limited in quantity,non-renewable,and seriously pollute the environment in the burning process,prompting the focus on renewable and cleaner alternatives.Hydrogen is such a promising choice.It has many advantages,such as wide source,high energy,green and pollution-free,and good safety performance.It can be used as an alternative to traditional fossil fuels.However,hydrogen is a secondary energy source.At present,the method of large-scale industrial hydrogen production in China is the conversion of fossil energy to hydrogen production,in which the important process is water gas shift reaction（WGSR）.As is known to all,water gas shift reaction is the reaction of upgrading carbon monoxide to hydrogen.Under the appropriate catalyst,it can not only effectively reduce the CO concentration,but also generate the same volume of H₂.The traditional water gas conversion catalysts have some disadvantages and can not meet the needs of fuel cells and small hydrogen production equipment.Although precious metal catalysts have been proved to have superior catalytic activity for water gas shift reaction,their application is greatly limited due to their high price and scarcity.Therefore,the development of new and efficient non-noble metal water gas shift catalyst is of great research significance.In this paper,a novel strategy of p/n heterojunction was proposed by combining p type CuO and n type ZnO,the CuO/ZnO hybrid nanoparticle catalyst was prepared,.and its modification was studied by adding promoter.It was investigated systematically that the effects of preparation methods,pretreatment conditions,load,vapor/gas ratio,calcination temperature and calcination time on the activity of water gas shift reaction.The catalyst was characterized by XRD,SEM,TEM,XPS,N₂-physical adsorption and TGA.Combined with experimental data and characterization analysis,the following conclusions were drawn:（1）A series of CuO-ZnO catalysts were prepared by different methods（co-precipitation method,deposition precipitation method and step-by-step precipitation method）,and their water gas shift reaction performance was studied.Experimental data and results show that the CuO-ZnO hybrid nanoparticle catalyst prepared by step-by-step precipitation method showed the best catalytic activity.When the reaction temperature is 180oC,the conversion of the catalyst is 100%.（2）A series of CuO/ZnO-ZrO₂ hybrid nanoparticle catalysts were prepared by a step-by-step precipitation method.The reaction results and XPS and H₂-TPR characterization confirmed the synergistic effect between CuO and ZnO.The addition of ZrO₂ promoter promoted the dissociation adsorption of H₂O and the activation oxidation of CO.The prepared CuO/ZnO-ZrO₂ hybrid nano-particle catalyst has high WGSR activity at low temperature,high stability and high selectivity.When the reaction temperature is as low as 160oC,the CO conversion rate can reach 100%,and it can run stably for more than 24 h.（3）A series of CuO/ZnO-TiO₂ hybrid nanoparticle catalysts were prepared by step-by-step precipitation method.The results showed that CuO/ZnO-TiO₂hybrid nanoparticle catalyst had excellent activity and stability of water gas shift reaction.When the load of CuO is 20%and n（CuO）:n（ZnO）=1:1,the catalytic activity is the highest.When the reaction temperature is 160oC,the catalyst can maintain a high conversion rate of 100%within 24 hours.