过滤复合等离子体催化降解萘的研究
发布时间：2018-07-24 16:27
【摘要】：多环芳烃(PAHs)由于其具有三致(致癌、致畸、致突变)作用,在近年来受到越来越多的关注。其作为一类大气污染物,会引发环境产生的一系列负面问题,同时会对生物产生毒害作用。同时伴随近年来雾霾天气,大气中气溶胶颗粒物增多,PAHs能吸附在气溶胶颗粒物微孔结构中而较为长久的停留在大气中,产生更为严重的污染。因此,对PAHs排放控制问题已迫在眉睫。过滤复合等离子体催化技术能在去除萘的同时,对萘的降解产物和臭氧也能达到良好地去除效果。该方法处理效率高,能耗低以及副产物少的优点。本研究以去除大气中有机污染作为首要目标,为了方便研究,选取了一种最具代表性的物质采用介质阻挡放电(DBD)研究了萘在不同反应器(过滤式反应器和非过滤式反应器)条件下的去除特性,并结合催化技术对其降解进行探究。重点研究了萘在过滤式反应器内的去除效果及影响因素(初始浓度和能量密度),同时分析了颗粒物生成特点和萘降解机理;本实验中比较三种催化剂与作为催化剂载体γ-A1203的作为主要催化剂,实验温度和银负载量等对萘去除效果的影响,研究结果表明:(1)在两种不同的反应器条件下,能量密度的提升会使萘的去除率和COx的选择率均增大,而萘初始浓度的提升会致使萘的去除率和COx选择减小。对比两种反应器在介质阻挡放电条件下萘去除率和COx选择,得知过滤式反应器对萘的降解效果要优于非过滤式反应器。而对比气溶胶颗粒物浓度数据可知,非过滤反应器内颗粒物单粒径下数量浓度峰值和总数量浓度为5.45E+06#/cm3和5.04 E+07#/cm3,而相同条件下过滤式反应器仅为8.43E+02#/cm3和2.0E+04#/cm3。由此可见,过滤式反应器对萘具有更好的降解效果,同时能非常有效地去除萘降解过程中产生的颗粒物,避免了传统等离子技术降解有机废气导致大量气溶胶颗粒物生成的缺点。(2)过滤式反应器中萘的去除率和COx选择性会受到温度、初始浓度以及氧气含量的影响。可以看出,氧气含量的和温度提升都会对萘的去除率和COx选择性产生积极影响,而萘的初始浓度的增加则会导致两者不同程度的减小。初始浓度为25 ppm时放电生成的颗粒物主要集中于10-24 nm粒径段;当浓度为100 ppm时,会出现10-19 nm和62-91 nm两个粒径段;当浓度为100 ppm时,颗粒物历经范围落在了 68-217 nm之间。由此可以看出,增加萘的初始浓度会使放电生成的颗粒物粒径段发生改变,产生向大粒径段迁移的趋势。(3)BET数据显示了负载催化剂后γ-A1203小球结构的变化情况,可以看到比表面积与总孔孔容均出现不同程度下降。而Ag/γ-A1203的XPS表征结果说明通过利用浸渍法并煅烧后,Ag元素被成功负载于γ-A1203小球上。在等离子体区域之后填充不同种类的催化剂能促进萘的降解,提升萘的去除率和COx选择性。其原理主要是利用等离子体对萘进行初步降解后,再将气体通入后置催化剂区域,利用催化剂促使臭氧分解成活性氧原子并且进一步降解萘及其中间产物。填充催化剂后,各催化剂对萘去除率的依次为:Ag/γ-Al2O3Mn/γ-Al2O3≈Co/γ-Al2O3γ-Al2O3,而对于COx选择性的影响也呈现相似趋势,同时可以添加催化剂对臭氧和颗粒物都有良好的去除效果。温度的升高会提升Ag/γ-A1203催化氧化萘及其降解中间产物的效果,同时对COx选择性具有促进作用。而5%银负载量是最佳值,对COx选择性最好。
[Abstract]:Polycyclic aromatic hydrocarbons (PAHs) have attracted more and more attention in recent years because of their three (carcinogenic, teratogenic and mutagenic) effects. As a class of atmospheric pollutants, they will cause a series of negative environmental problems and toxic effects on the organisms. At the same time, with the haze weather in recent years, the aerosol particles in the atmosphere increase, PAHs It can be adsorbed in the microporous structure of aerosol particles and stay in the atmosphere for a long time and produce more serious pollution. Therefore, the control of PAHs emission is imminent. The filtration compound plasma catalysis technology can remove naphthalene and the degradation products of naphthalene and ozone can also be well removed. This method is treated by this method. With the advantages of high efficiency, low energy consumption and less by-products, this study aims to remove the organic pollution in the atmosphere as the primary goal. In order to facilitate the study, a most representative material is selected by dielectric barrier discharge (DBD) to study the removal characteristics of naphthalene under the conditions of different reactors (filter reactor and non filter reactor). The removal efficiency and the influence factors (initial concentration and energy density) of naphthalene in the filter reactor were studied, and the formation and degradation mechanism of the particles were analyzed. In this experiment, the three catalysts were compared with the catalyst carrier gamma -A1203 as the main catalyst and the experimental temperature. The effect of the amount of silver loading on the removal of naphthalene was found. The results showed: (1) the removal rate of naphthalene and the selection rate of COx increased with the increase of the energy density under the two different reactor conditions, while the enhancement of the initial naphthalene concentration would lead to the reduction of naphthalene and the reduction of the COx selection. The comparison of two kinds of reactors under the condition of dielectric barrier discharge The removal efficiency and COx selection showed that the degradation effect of naphthalene was better than that of non filter reactor. Compared with the aerosol particle concentration data, the concentration peak and total number concentration under the single particle size of the non filter reactor were 5.45E+06#/cm3 and 5.04 E+07# /cm3, while the filter reactor under the same condition was only 8. .43E+02#/cm3 and 2.0E+04#/cm3. show that the filter reactor has a better degradation effect on naphthalene, and can effectively remove the particles produced in the naphthalene degradation process, and avoid the disadvantages of the traditional plasma technology for the formation of large amount of aerosol particles resulting from the degradation of organic waste gases by plasma technology. (2) the removal rate of naphthalene and COx in the filter reactor. Selectivity is affected by temperature, initial concentration and oxygen content. It can be seen that both the oxygen content and the temperature increase have a positive effect on the removal rate of naphthalene and the selectivity of COx, while the increase of the initial concentration of naphthalene will lead to the decrease of the two degrees. The particles generated by the initial concentration of 25 ppm are mainly concentrated on the particles. 10-24 nm particle size section; when the concentration is 100 ppm, there will be 10-19 nm and 62-91 nm segments. When the concentration is 100 ppm, the range of particles falls between 68-217 nm. Thus, it can be seen that the increase of the initial concentration of naphthalene will change the particle size of the particles generated by the discharge, and produce the trend to migrate to the large size segment. (3) BET data. The changes in the structure of the gamma -A1203 ball after the loading of the supported catalyst showed that the specific surface area and the pore volume of the total pore decreased in varying degrees. The XPS characterization results of the Ag/ gamma -A1203 showed that the Ag element was successfully loaded on the gamma -A1203 pellets by impregnation and calcined. After the plasma region, different kinds of urges were filled. The chemical agent can promote the degradation of naphthalene and enhance the removal rate of naphthalene and the selectivity of COx. The principle is to use the plasma to degrade naphthalene, and then pass the gas into the post catalyst area, use the catalyst to decompose the ozone into the living oxygen atom and further degrade the naphthalene and the inter product. The removal rate of naphthalene is as follows: Ag/ gamma -Al2O3Mn/ gamma -Al2O3 Co/ gamma -Al2O3 gamma -Al2O3, which also has a similar tendency to the effect of COx selectivity. At the same time, the catalyst can have good removal effect on both ozone and particles. The increase of temperature will enhance the effect of Ag/ gamma -A1203 catalytic oxidation naphthalene and the degradation of intermediate products. Meanwhile, COx is selected for COx. Selectivity has a promoting effect, while the 5% silver load is the best value and the best selectivity for COx.
【学位授予单位】：浙江工商大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X51
本文编号：2141963
[Abstract]:Polycyclic aromatic hydrocarbons (PAHs) have attracted more and more attention in recent years because of their three (carcinogenic, teratogenic and mutagenic) effects. As a class of atmospheric pollutants, they will cause a series of negative environmental problems and toxic effects on the organisms. At the same time, with the haze weather in recent years, the aerosol particles in the atmosphere increase, PAHs It can be adsorbed in the microporous structure of aerosol particles and stay in the atmosphere for a long time and produce more serious pollution. Therefore, the control of PAHs emission is imminent. The filtration compound plasma catalysis technology can remove naphthalene and the degradation products of naphthalene and ozone can also be well removed. This method is treated by this method. With the advantages of high efficiency, low energy consumption and less by-products, this study aims to remove the organic pollution in the atmosphere as the primary goal. In order to facilitate the study, a most representative material is selected by dielectric barrier discharge (DBD) to study the removal characteristics of naphthalene under the conditions of different reactors (filter reactor and non filter reactor). The removal efficiency and the influence factors (initial concentration and energy density) of naphthalene in the filter reactor were studied, and the formation and degradation mechanism of the particles were analyzed. In this experiment, the three catalysts were compared with the catalyst carrier gamma -A1203 as the main catalyst and the experimental temperature. The effect of the amount of silver loading on the removal of naphthalene was found. The results showed: (1) the removal rate of naphthalene and the selection rate of COx increased with the increase of the energy density under the two different reactor conditions, while the enhancement of the initial naphthalene concentration would lead to the reduction of naphthalene and the reduction of the COx selection. The comparison of two kinds of reactors under the condition of dielectric barrier discharge The removal efficiency and COx selection showed that the degradation effect of naphthalene was better than that of non filter reactor. Compared with the aerosol particle concentration data, the concentration peak and total number concentration under the single particle size of the non filter reactor were 5.45E+06#/cm3 and 5.04 E+07# /cm3, while the filter reactor under the same condition was only 8. .43E+02#/cm3 and 2.0E+04#/cm3. show that the filter reactor has a better degradation effect on naphthalene, and can effectively remove the particles produced in the naphthalene degradation process, and avoid the disadvantages of the traditional plasma technology for the formation of large amount of aerosol particles resulting from the degradation of organic waste gases by plasma technology. (2) the removal rate of naphthalene and COx in the filter reactor. Selectivity is affected by temperature, initial concentration and oxygen content. It can be seen that both the oxygen content and the temperature increase have a positive effect on the removal rate of naphthalene and the selectivity of COx, while the increase of the initial concentration of naphthalene will lead to the decrease of the two degrees. The particles generated by the initial concentration of 25 ppm are mainly concentrated on the particles. 10-24 nm particle size section; when the concentration is 100 ppm, there will be 10-19 nm and 62-91 nm segments. When the concentration is 100 ppm, the range of particles falls between 68-217 nm. Thus, it can be seen that the increase of the initial concentration of naphthalene will change the particle size of the particles generated by the discharge, and produce the trend to migrate to the large size segment. (3) BET data. The changes in the structure of the gamma -A1203 ball after the loading of the supported catalyst showed that the specific surface area and the pore volume of the total pore decreased in varying degrees. The XPS characterization results of the Ag/ gamma -A1203 showed that the Ag element was successfully loaded on the gamma -A1203 pellets by impregnation and calcined. After the plasma region, different kinds of urges were filled. The chemical agent can promote the degradation of naphthalene and enhance the removal rate of naphthalene and the selectivity of COx. The principle is to use the plasma to degrade naphthalene, and then pass the gas into the post catalyst area, use the catalyst to decompose the ozone into the living oxygen atom and further degrade the naphthalene and the inter product. The removal rate of naphthalene is as follows: Ag/ gamma -Al2O3Mn/ gamma -Al2O3 Co/ gamma -Al2O3 gamma -Al2O3, which also has a similar tendency to the effect of COx selectivity. At the same time, the catalyst can have good removal effect on both ozone and particles. The increase of temperature will enhance the effect of Ag/ gamma -A1203 catalytic oxidation naphthalene and the degradation of intermediate products. Meanwhile, COx is selected for COx. Selectivity has a promoting effect, while the 5% silver load is the best value and the best selectivity for COx.
【学位授予单位】：浙江工商大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X51
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