Mechanism Of Microwave Thermal Catalysis And Antibacterial Of CuMnCeO_x Based On Surface Defect Regulation

The threat of volatile organic compounds（VOCs）and bioaerosols in indoor environment to human health cannot be ignored.At present,air purification technologies such as filter interception,plasma purification and catalytic oxidation have been developed.In the actual operation process,the secondary pollution problem,efficiency problem and cost problem caused by air purification technology should be considered.Therefore,air purification technology based on catalytic oxidation of non-noble metal composite oxides has become a promising research route.In this paper,high-efficiency catalysts for air purification devices were obtained by preparing and optimizing supported copper-manganese-cerium oxide（CuMnCeO_x）catalysts.Mainly relying on the type and concentration regulation of active sites on the surface of the material,the causal relationship between the physical and chemical structure changes of CuMnCeO_xcatalyst and its mechanism of action was analyzed.This study aims to promote the deep development of catalytic materials based on surface defect structure regulation in the purification of VOCs and bioaerosol pollution,and explore the potential application value of catalytic oxidation in the field of air purification.The main research results of this paper are as follows:（1）CuMnCeO_x catalysts based on commercial Al₂O₃materials were prepared by impregnation and calcination methods.By characterizing the surface morphology,element distribution,specific surface area,pore size distribution,element chemical state and defect structure,Cu O_x,Mn O_xand Ce O_xhad synergistic effects on improving the physical and chemical properties of the catalyst.The redox cycle between Cu⁺,Cu²⁺,Mn²⁺,Mn³⁺,Mn⁴⁺,Ce³⁺and Ce⁴⁺in the active components of the catalyst increased the atomic ratio of O_ads/O_latt,which could promote the uniform distribution of the active components on the catalyst surface and the generation of crystal structure defects.（2）The degradation performance of CuMnCeO_xcatalyst for VOCs under different microwave thermocatalytic conditions was investigated by using toluene,ethyl acetate,acetone and their mixture as experimental objects.The intermediate products and active species in the degradation process were detected.Results showed that the removal ratio of toluene,ethyl acetate and acetone with a concentration of about 500 ppm could be stabilized at 99%under 250 W microwave power.In order to reveal the bactericidal performance of CuMnCeO_x,three basic sterilization experiments were designed,including air standing mode,liquid oscillation mode and microwave thermal catalysis mode.Hanseniaspora uvarum was screened from the laboratory air environment as the treatment target of sterilization experiment.The initial bacterial concentration was 3.6×10⁴CFU/m L.The action time of 99%antibacterial ratio in the three modes was 2 h,20h and 60 s,respectively.（3）The active component layout and defect structure of CuMnCeO_xcatalyst were regulated by organic acid reduction and heat treatment.Results showed that the modified CuMnCeO_xcatalyst could achieve 99%antibacterial efficiency within 4 h in gas and liquid systems with higher initial bacterial concentration（3.5×10⁵CFU/m L）.The removal efficiency of 200～500 ppm VOCs by CuMnCeO_xcould be stabilized at99%after 1 h of reaction under 200 W microwave thermocatalysis.L（+）-ascorbic acid partially converted the highly oxidized metal ions in the CuMnCeO_xcatalyst into low valence states and adjusted the ratio of surface oxygen,forming the expected surface defects during the conversion process.Secondary calcination at 500°C in N₂atmosphere could adjust the properties of the acid sites on the surface of the catalyst after L（+）-ascorbic acid treatment.The modified CuMnCeO_xcatalyst involved the synergistic antibacterial mechanism of metal ions dissolution and free radical generation.