Construction Of A New Supported Cu/MnO_X Catalyst And Its Catalytic Performance For Ethanil Dehydrogenation

In recent years,energy and environmental problems have become increasingly serious,the development and utilization of sustainable renewable energy has become an important problem to be solved in human development.At the same time,the proposal of the goals of"carbon neutralization"and"carbon compliance"also highlights the urgent need for renewable energy to replace traditional fossil energy in today’s society.As an important biomass derivative,ethanol has the characteristics of wide sources,easy access and rich reserves.It can be transformed into many high value-added chemicals through series reactions such as dehydrogenation,so as to alleviate the fossil energy crisis.Among them,the anaerobic dehydrogenation of ethanol to acetaldehyde has the advantages of high atomic economy and easy separation of products.At the same time,acetaldehyde is the key intermediate of ethanol catalytic conversion,which is of great practical significance to realize the high-value conversion of ethanol.Copper based catalysts are widely used in ethanol dehydrogenation because of their high catalytic activity and low price.However,copper nanoparticles are easy to agglomerate and inactivate at high temperature.Therefore,the construction of catalyst structure is very important to improve the dispersion and stability of catalyst active components.Based on the above research status,this paper constructs a new supported Cu/MnO_x catalyst with MnO_x as the carrier,studies its ethanol dehydrogenation performance,and puts forward a new idea of constructing multicomponent composite metal oxides and metal based nano materials based on nucleation/crystallization isolation method based on micro liquid membrane reactor.The contents are as follows:（1）Cu/MnO_x catalyst was prepared by nucleation/crystallization isolation method based on micro liquid membrane reactor.Compared with traditional coprecipitation method and impregnation method,the effects of different preparation methods on the performance of catalyst for ethanol dehydrogenation were investigated.A series of characterization results show that there are a large number of Mn²⁺-Ov-Mn²⁺oxygen vacancies in the catalyst sample,which is conducive to the adsorption and activation of ethanol,breaking the O-H bond and forming ethoxy intermediates;moreover,this method significantly enhances the interaction between Cu-Mn,is conducive to the formation of a large number of Cu⁺-O-Mninterface structures,prevents the agglomeration of Cu nanoparticles,effectively stabilizes ethoxy intermediates,and is conducive to the formation of acetaldehyde.Moreover,the nucleation/crystallization isolation method based on micro liquid membrane reactor solves the shortcomings of uneven mixing,wide particle size distribution and weak interaction between components in the traditional coprecipitation and impregnation method,which is conducive to the high dispersion of Cu nanoparticles,showing high acetaldehyde yield and stability for a long time.（2）The effects of different copper manganese ratios on the dehydrogenation of ethanol to acetaldehyde were investigated.The results show that different copper manganese ratio changes the reduction performance of the catalyst.At the same time,the increase of Mncontent is conducive to the formation of higher content of Mn²⁺-Ov-Mn²⁺oxygen vacancies and a large number of Cu⁺-O-Mninterface structures.The reaction mechanism is further verified,the abundant oxygen vacancies on the surface are conducive to the adsorption and activation of ethanol.The strong interaction between Cu-Mncan induce the formation of a stable Cu⁺-O-Mninterface structure at the interface between Cu and MnO_x,which can effectively stabilize the intermediates,and finally improve the performance of Cu/MnO_x catalytic dehydrogenation of ethanol to acetaldehyde.