催化剂成分对低温等离子体降解吸附态甲苯的影响

发布时间：2018-05-07 06:09

本文选题：催化剂 + 低温等离子体　；参考：《西安建筑科技大学》2015年硕士论文

【摘要】：挥发性有机物(VOCs)是大气污染的重要组成部分,对环境和人体健康会造成严重危害。随着工业发展及人类生活水平要求的提高,寻求并使用经济高效的方法来治理VOCs成为当务之急。低温等离子体技术所具有低费用、工艺简单及适用范围广等优点使其成为治理VOCs的重要研究方向,尤其在处理印刷、喷涂等行业具有浓度低、风量大特点的有机废气时展现出较好的优势。针对VOCs治理过程中降解不充分及产生副产物的问题,论文选取常用有机溶剂甲苯作为研究对象,制备了不同成分的催化剂,分别对低温等离子体循环降解系统及催化联合低温等离子体循环降解系统处理吸附态甲苯进行了研究,考察了吸附存储量、施加电压、循环气体流量、循环背景气体等工艺参数及不同催化剂成分对甲苯降解效果的影响,并分析了催化剂的加入对降解程度、O3及N2O副产物的影响规律,为工业应用提供了理论基础及设计依据。论文主要结论如下:(1)低温等离子体循环降解系统处理甲苯的研究表明:COx产率和CO2选择性随着甲苯的吸附存储量的增加而减小,但COx产量会增加;随着施加电压及循环气体流量的增大,COx产率及CO2选择性均会增大;氧气做循环背景气体时比空气时对应的COx产率及CO2选择性均有所增大。(2)催化联合低温等离子体循环降解系统处理甲苯的研究表明:催化剂的加入可显著提高COx产率和CO2选择性,氧气为循环背景气体时,提升幅度更大。相同条件下,不同催化剂成分对应COx产率排序为:CeMnAgCo,对应CO2选择性排序为AgMnCoCe。双组分复合型金属氧化物催化剂Ce/Ag、Mn/Ag可以同时有效提升COx产率和CO2选择性。(3)吸附态甲苯降解产物FT-IR图谱分析表明,主要产物为CO2、H2O及少量的CO,副产物主要为O3;无催化剂时产物中残留极微量甲苯,催化剂的加入可使甲苯全部被去除,同时减少CO和O3的排放;循环背景气体为空气时有N2O生成。(4)空气为循环背景气体时,催化剂的加入可抑制N2O的生成(Ce除外),对应N2O抑制性能大小为:CoMnAg无催化剂Ce;三组分复合型催化剂Ce/Ag/Co、Mn/Ag/Co在提高COx产率和CO2选择性的同时能有效抑制N2O。催化剂的加入可以减少O3,催化剂对提升甲苯降解效果的能力与分解O3的能力没有相关性。
[Abstract]:Volatile organic compounds (VOCs) are important components of air pollution, which can cause serious harm to environment and human health. With the development of industry and the improvement of human standard of living, it is urgent to seek and use economic and efficient methods to control VOCs. The low temperature plasma technology has the advantages of low cost, simple process and wide application scope, which makes it an important research direction in the treatment of VOCs, especially in the treatment of printing, spraying and other industries with low concentration. The organic waste gas with large air volume features shows a good advantage. In order to solve the problem of inadequate degradation and by-product production in the process of VOCs treatment, toluene, a common organic solvent, was selected as the research object, and catalysts with different compositions were prepared. The treatment of adsorbed toluene by low temperature plasma cycle degradation system and catalytic combined low temperature plasma body cycle degradation system was studied respectively. The adsorption storage capacity, applied voltage and circulating gas flow rate were investigated. The effects of process parameters such as cyclic background gas and different catalyst compositions on the degradation of toluene were analyzed. The effects of catalyst addition on the degradation degree of O _ 3 and N _ 2O by-products were analyzed, which provided the theoretical basis and design basis for industrial application. The main conclusions are as follows: (1) the study on the treatment of toluene by low temperature plasma system showed that the yield and selectivity of CO2 decreased with the increase of the amount of toluene adsorption and storage, but the yield of COx increased. With the increase of the applied voltage and the flow rate of the circulating gas, the yield of COx and the selectivity of CO2 will increase. When oxygen was used as the background gas, the corresponding COx yield and the selectivity of CO2 were increased. The results showed that the COx yield and CO2 selectivity could be significantly improved by the addition of the catalyst in combination with the low temperature plasma system for degradation of toluene. When oxygen is the background gas, the lift is greater. Under the same conditions, the order of COx yield and CO2 selectivity for different catalysts were: 1 CeMnAgCoand and AgMnCoCe respectively. The two-component composite metal oxide catalyst ce / AgM / Ag can effectively improve the yield of COx and the selectivity of CO2 at the same time. The FT-IR spectra of toluene degradation products in adsorbed state are analyzed. The main product is CO _ 2H _ 2O and a small amount of CO, and the by-product is mainly O _ 3. When there is no catalyst, the residual trace toluene in the product can be removed completely and the emission of CO and O _ 3 can be reduced by the addition of catalyst. When the circulating background gas is air, N2O is produced. 4) when the air is the circulating background gas, The addition of catalyst can inhibit the formation of N2O with the exception of ce, corresponding to the N2O inhibition performance of 1: CoMnAg without catalyst Ce.The three-component composite catalyst CeR / CoMN / Ag- / Co can effectively suppress N _ 2O while increasing the yield of COx and the selectivity of CO2. The addition of catalyst can reduce O _ 3, and the ability of the catalyst to improve the degradation of toluene is not related to the ability to decompose O _ 3.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X701;O643.36

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