Application Of Loaded Composite Fiber Constructed By Epitaxial Growth Strategy In Ozone Decomposition

Ozone is gradually becoming the primary "killer" of air pollution in China.Research on catalyst materials for efficient ozone decomposition is an important part of solving ozone pollution.Manganese based layer double hydroxide(Mn-LDH)has abundant active hydroxyl groups,which provides a large number of active sites for ozone decomposition.Therefore,Mn-LDH has a good application prospect in ozone decomposition.However,the disadvantages of easy loss and difficult recovery of powder catalyst material make the application of catalyst encounter great obstacles.As a novel catalyst,LDH supported fiber membrane has an open pore structure and a large specific surface area,which can fully expose the reaction site of the catalyst,improve the interphase mass transfer behavior and solve a series of problems in the application of powder catalyst.In this thesis,a convenient method of preparing ozone-degrading fiber membrane catalyst based on epitaxial growth strategy was proposed,and its ozone decomposition performance was studied in fixed bed reactor and simulated under different working conditions.The major research contents and results are listed below:1.Herein,a series of LDHs were in-situ growth on the polyacrylonitrile(PAN)fiber in constant shock by the method of coprecipitation and Epitaxial growth strategy,and a series of PAN@LDH nanofiber composite membrane was prepared,which can achieve the decomposition of ozone at 60 ppm concentration of 100% for more than12 h.In order to understand the process of ozone decomposition,we recognized the intermediates in the degradation process by in-situ technology,combined with DFT calculation confirmed that PAN@NiMn-LDH has high activity Mn-OH,as the preferentially adsorbed site in the degradation process,and realized the efficient decomposition of ozone.At the same time,it is proved that oxygen vacancy can decreases the adsorption energy of its adjacent hydroxyl group to oxygen,accelerate the process of oxygen desorption,which is beneficial to maintain the stability of ozone decomposition.2.On the basis of the previous chapter,PAN@NiMn-LDH with different morphologies was prepared by regulating the types of metal salt solutions.At the same time,it was found that the proportion of metal cations on the laminate was different.The presence of nickel increases the electron cloud density of manganese and reduces the valence state of manganese.The effect of nickel element on Mn-O stress on laminates was studied.The content of nickel element on laminates affects the degree of cell distortion and the stability of lattice elements,thus changing the strength of Mn-O bond.The results provide new insights for the design and preparation of LDH ozonation catalysts.