Preparation And Performance Study Of Catalytic Denitrification Functional Polyphenylene Sulfide(PPS) Needle Filtration Material

In the following table of the dual role of industrialization and urbanization,more and more environmental pollution phenomena have appeared,affecting human health and survival.In recent years,the rapid increase in energy consumption has directly contributed to increased emissions of various pollutants during the combustion of solid fuels.Dust fine particles are one of the key pollutant components in exhaust emissions.In order to solve the pollution problems caused by fine particles,bag-type dust removal technology has been widely adopted by the industry and used in the field of high temperature and high concentration flue gas treatment.In addition to dust particles,another important pollutant in flue gas is harmful nitrogen oxides?NO_x?,which can cause various respiratory diseases,such as pneumonia and bronchitis.At present,the most effective method to achieve NO_x removal in fuel exhaust gas is ammonia selective catalytic reduction?NH₃-SCR?technology,which has become a hotspot of extensive research in recent years because of its low cost,high efficiency,and ease of promotion.This subject aims to develop a new type of filter material to replace the high-cost flue gas purification technology,while removing smoke and nitrogen oxides?NO_x?,to achieve the integration of dust removal and denitrification.The polyphenylene sulfide?PPS?needle-punched filter material is selected as the carrier,which supports Mn and Ce oxides as the catalyst for the NH₃-SCR reaction.The preliminary experiment of the research group preliminarily discussed the process flow of the catalyst supported by in-situ deposition,focusing on the NH₃-SCR catalytic principle and mechanism,as well as the construction and use of the laboratory-made denitration platform.On the basis of previous experiments,this thesis subdivides the process flow of the traditional impregnated catalyst loading into two steps-catalyst loading and heat treatment process.A single factor experiment was adopted to optimize the process parameters systematically.It was concluded that the molar concentration of Ce was 0.07mol/L,the molar ratio of Mn/Ce was 6/1,the immersion time was 60min,the heat treatment temperature was 200°C,and the heat treatment time was 60min.In order to achieve better load efficiency and load fastness,two different pretreatment methods—sodium alginate?SA?deposition and plasma pretreatment were used to perform preliminary functional finishing of the PPS needle-punched filter material.The optimal parameters for sodium alginate deposition are obtained:SA mass fraction is0.8%,the immersion time is 60min;the optimal parameters for plasma treatment of supported catalyst:voltage 280V,duty cycle 60%,nozzle moving speed 8m/min,frequency 19KHz.The basic performance evaluation of PPS needle-punched filter materials treated with different load methods proved that the load rate of the unpretreated sample PPS NPFF/Mn/Ce-C was 8.96%,and the sample load after pretreatment by two methods The rate has been greatly improved,of which the plasma-treated PPS NPFF/Mn/Ce-P has the highest loading rate,reaching 23.03%;the three samples have a load fastness of more than 99.7%;the plasma-treated samples PPS NPFF/Mn/Ce-P has the highest Mn and Ce contents,20.2%and 7.9%,respectively,and is loaded on the fiber surface,showing good uniformity and dispersion;catalyst loading can significantly reduce the pore size distribution range and significantly reduce the average pore size;Three kinds of catalyst-supported PPS needle filter materials still have good mechanical properties and gas permeability,which can meet the requirements of dust removal and denitrification applications.The filtration and denitration performance evaluation of PPS needle-punched filter media loaded with catalysts in different ways,the results prove that the filter media loaded with catalyst has a more excellent filtration efficiency than the original sample PPS NPFF,arranged from high to low:PPS NPFF/Mn/Ce-P>PPS NPFF/Mn/Ce-D>PPS NPFF/Mn/Ce-C>PPS NPFF.The filtration efficiency of the three samples after catalyst loading is greater than 80%when the particle size is 2.5?m,and the filtration efficiency is close to 100%when the particle size is greater than 4?m;the three filter materials have good denitrification performance,and the denitration rate is from high to low.It is:PPS NPFF/Mn/Ce-P>PPS NPFF/Mn/Ce-D>PPS NPFF/Mn/Ce-C.Among them,the highest denitration rate of PPS NPFF/Mn/Ce-P reached 92.99%.By changing the ratio of temperature to ammonia-nitrogen,the optimal parameters of the denitration experiment are obtained:the temperature is 200?and the NH₃/NO flow ratio is 1.The above research shows that the manganese/cerium oxide-loaded PPS needle-punched filter material we prepared has the advantages of stable structure,convenient operation,high filtration efficiency,and good denitration performance.It has great application potential in the field of gas purification.In addition,in order to achieve enhanced filtration efficiency,we have prepared a new type of composite needle-punched filter material.Selecting sulfone sulfonate?PSA?as the raw material,changing the solvent system and the solid content of PSA respectively,preparing an electrospinning membrane and characterizing its performance,the results prove that:dichloromethane?DCM?and N,N-dimethyl The electrospinning membrane prepared by the mixed solvent system of acetamide?DMAc?has better performance,its fibers and webs have a uniform shape and good mechanical properties,and the highest filtration efficiency is as high as 97.3%at a particle size of 0.225?m.The above electrospun membrane was combined with PPS needle-punched filter material to prepare PSA/PPS composite needle-punched filter material,and its basic performance was tested and evaluated.The results show that PSA/PPS composite needle-punched filter material has high temperature resistance and good Mechanical properties and excellent filtration performance,when the particle size is less than 0.5?m,the filtration efficiency of the composite filter material is about 4-5 times that of the PPS needle-punched filter material,which achieves the purpose of enhancing the filtration efficiency.The above research shows that the composite filter material we prepared has ultra-high filtration efficiency,which greatly improves the filtration performance of the single PPS needle-punched filter material and prolongs the service life of the material.