低温等离子体场内复合不同晶型氧化锰催化降解甲苯性能和机理（英文）

发布时间：2018-03-12 18:41

本文选题：甲苯　切入点：催化氧化　出处：《催化学报》2017年05期 　论文类型：期刊论文

【摘要】：作为典型的挥发性有机化合物,甲苯通常来源于建筑涂料、交通运输和各种工业生产过程,是PM2.5、臭氧和光化学烟雾的重要前驱体,对环境和人类健康造成巨大影响.近年来,低温等离子体技术因具有在常温常压下就能通过高能电子、活性氧物种和羟基等活性粒子有效降解挥发性有机物的优点而受到广泛关注.然而,高能耗和大量副产物的产生是等离子体技术工业化应用的巨大障碍.当前最有效的策略之一是将等离体技术与催化技术结合,从而加快反应速率,提高产品的选择性和能源利用率.在所应用的催化剂中,MnO_2因具有较好的O3分解效率而成为最有潜力的催化剂之一.但是MnO_2具有不同的晶型结构、隧道结构和形貌,这些均会显著影响MnO_2的催化活性.本文通过一步水热法制备了α-,β-,γ-和δ-MnO_2四种MnO_2催化剂,并将其用于等离子体催化降解甲苯研究,在此基础上系统考察了等离子体催化降解性能和MnO_2不同晶型之间的关系.结果表明,当能量密度为160 J/L时,等离子体单独降解甲苯去除效率为32.5%.引入催化剂能够显著提高甲苯的降解效率,其中α-MnO_2效果最显著,甲苯降解效率能够提升至78.1%,β-,γ-和δ-MnO_2能够相应提升至47.4%,66.1%和50.0%.采用X射线衍射、拉曼光谱、扫面电子显微镜、透射电子显微镜、比表面积-孔结构分析、氢气程序升温还原和X射线光电子能谱等手段研究了催化剂的理化特性.结果表明,隧道结构、催化剂在等离子体中的稳定性、Mn O键能和催化剂表面吸附氧均在等离子体催化降解甲苯中发挥了重要作用.在此基础上,通过GC-MS分析降解产生的气相副产物推断甲苯在等离子体和等离子体催化体系中的降解机理.在等离子体催化体系中,通过Mn4+,Mn3+和Mn2+价态的变化,等离子体产生的O3,O2*和其他活性自由基会被吸附到催化剂表面,随后与催化剂吸附的甲苯或中间副产物发生氧化还原反应,将甲苯氧化为CO2等小分子物质.此外,MnO_2作为分解O3最有效的催化剂,可以吸附O3并将其分解为O?或者与H2O生成?OH参与到反应中,从而提高甲苯的降解效率.
[Abstract]:As a typical volatile organic compound, toluene is usually derived from architectural coatings, transportation and various industrial processes. It is an important precursor of PM2.5, ozone and photochemical smog, and has a great impact on the environment and human health in recent years. Low temperature plasma technology has attracted wide attention for its advantages of effectively degrading volatile organic compounds through active particles such as high energy electrons, active oxygen species and hydroxyl groups at room temperature and atmospheric pressure. The production of high energy consumption and large amount of by-products is a great obstacle to the industrial application of plasma technology. One of the most effective strategies is to combine in vitro technology with catalytic technology to accelerate the reaction rate. In order to improve the selectivity and energy efficiency of the product, MNO _ 2 has become one of the most promising catalysts because of its better decomposition efficiency of O _ 3. However, MnO_2 has different crystal structure, tunnel structure and morphology. In this paper, four kinds of MnO_2 catalysts, 伪 -, 尾 -, 纬-and 未 -MnO _ 2, were prepared by one step hydrothermal method and used in plasma catalytic degradation of toluene. On this basis, the relationship between plasma catalytic degradation and different crystal forms of MnO_2 was systematically investigated. The results show that when the energy density is 160J / L, The removal efficiency of toluene by plasma alone is 32.5%. The degradation efficiency of toluene can be significantly improved by introducing catalyst, among which 伪 -MnO2 is the most effective, toluene degradation efficiency can be raised to 78.1%, 尾 -, 纬-and 未 -MnO 2 can be raised to 47.4% 66.1% and 50.0B. X-ray diffraction is used. The physical and chemical properties of the catalyst were studied by Raman spectroscopy, scanning electron microscope, transmission electron microscope, specific surface area pore structure analysis, hydrogen temperature-programmed reduction and X-ray photoelectron spectroscopy. The stability of the catalyst in plasma and the adsorption of oxygen on the surface of the catalyst both play an important role in the degradation of toluene by plasma. The degradation mechanism of toluene in plasma and plasma catalytic system was inferred by GC-MS analysis of gas phase by-products produced by degradation. In plasma catalytic system, the changes of valence states of Mn4 mn 3 and Mn2 were obtained by means of Mn4 mn 3 and Mn2. O _ 3O _ 2 * produced by plasma and other active free radicals are adsorbed to the surface of the catalyst and then redox with toluene or intermediate by-products adsorbed by the catalyst. Toluene was oxidized to small molecular substances such as CO2. In addition, MNO _ 2 was used as the most effective catalyst for the decomposition of O _ 3, which could be adsorbed and decomposed into O _ (3)? Or with H2O? OH takes part in the reaction to improve the degradation efficiency of toluene.
【作者单位】：浙江大学环境与资源学院污染环境修复与生态健康教育部重点实验室;浙江省工业锅炉炉窑烟气污染控制工程技术研究中心;浙江大学化学工程与生物工程学院工业生态与环境研究所;
【基金】：supported by the National Key Research and Development Plan of China(2016YFC0204700) Zhejiang Provincial“151”Talents Program(2013) Key Project of Zhejiang Provincial Science and Technology Program,the Program for Zhejiang Leading Team of S&T Innovation(2013TD07) Special Program for Social Development of Key Science and Technology Project of Zhejiang Province(2014C03025) Changjiang Scholar Incentive Program(2009)~~
【分类号】：O621.251;O643.36

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