Knowledge Management System Of Institute of process engineering,CAS
|关键词||钌 钒 挥发性有机物 催化氧化 机理|
目前，大气污染是我国最为突出的环境问题之一，其中挥发性有机物（volatile organic compounds, VOCs）是大气污染物的重要来源。通过催化氧化过程将VOCs分解为CO2和H2O等小分子物质可以彻底消除其污染，是控制VOCs排放的重要技术手段。然而，如果废气中存在较多氯代VOCs（chlorinated VOCs, Cl-VOCs），目前的催化体系通常表现出较差的催化效果，并且容易发生永久失活。因此，开发能够有效降解Cl-VOCs的催化剂体系是十分重要的研究方向。 本文采用价格远低于Pt、Pd等常见贵金属的Ru作为活性组分，详细研究了Ru催化剂对苯、氯苯和三氯乙烯的催化氧化反应特征，揭示了Ru物种与不同模型VOCs污染物作用时的活性结构，并考察了不同活性结构的稳定性。最后，鉴于Ru催化剂在氯苯的催化氧化过程中出现了多氯代苯副产物，详细研究了不存在此问题的V2O5/P25-TiO2催化剂对多种氯代苯的催化氧化过程，通过对比两种催化体系得到的结果提出了多氯代苯的生成机理。 论文取得的主要成果如下： 1) 研究了Ru催化剂在苯的催化氧化过程中活性物种构成以及活性位点和反应物（苯和O2）的作用机制，分析了RuO2的颗粒尺寸效应产生的原因，以及催化剂表面的惰性RuO2结构对催化剂的影响； 2) 通过Ru催化剂对氯苯和三氯乙烯的催化氧化研究，发现RuOxCly结构能够在含有外加H2O的VOCs催化氧化条件下保持稳定，并且Ru催化剂对氯苯和三氯乙烯的催化氧化活性远高于目前报道的其它催化剂体系； 3) 对比了RuO2在多种不同载体上的热稳定性，发现RuO2/rutile-TiO2结构的热稳定性最高，这种特点使得P25-TiO2或rutile-TiO2更适合作为用于VOCs催化氧化的Ru催化剂载体； 4) 氯苯在V2O5/P25-TiO2催化剂上的催化氧化过程中不会形成多氯代副产物，这主要归因于氯苯与V=O位点作用形成的表面酚盐物种不会脱附。
Nowadays, air pollution is one of the most prominent environmental problems in China, and VOCs (volatile organic compounds) are important components of atmospheric pollutants. Catalytic oxidation process can completely decomposing VOCs into CO2, H2O and other small molecular substances, which makes it become an significant approach for the control of VOCs emission. However, the catalytic systems utilized at present usually show poor activities and tend to occur deactivation permanently, when the exhaust gas contains a considerable amount of chlorinated VOCs (Cl-VOCs). Therefore, developing a catalyst system that effectively applied for the catalytic oxidation of Cl-VOCs is an important research direction. In this thesis, ruthenium was used as active component, and the catalytic properties of supported ruthenium catalysts for the catalytic oxidation of benzene, chlorobenzene and trichloroethylene were studied. The active structures of ruthenium during its interaction with the different reactants were disclosed, and the stabilities of these structures were investigated. Furthermore, in consideration of polychlorinated benzenes were generated during the catalytic oxidation of chlorobenzene over the ruthenium catalysts, the catalytic processes of a variety of chlorobenzene species over V2O5/P25-TiO2 catalysts were investigated in depth, and through comparing the results of these catalytic systems, the formation mechanism of polychlorinated benzenes during the catalytic oxidation of chlorobenzene was proposed. Main results are as follows: 1) The active species and the mechanism of interaction between the reactant and the active sites were studied for the ruthenium catalysts under the condition of benzene oxidation, the causes of size effect of RuO2 particles were investigated, and the cause of inert RuO2 and its influence on catalyst activity were analyzed; 2) Through the study on the ruthenium catalysts for the catalytic oxidation of chlorobenzene, it was found that the catalytic activity of RuOxCly structure could maintain stable during the catalytic oxidation of chlorobenzene and trichloroethylene in the presence of additional H2O, thus blocking the path of inert RuO2 formation, and the activities of ruthenium catalysts for the catalytic oxidation of chlorobenzene and trichloroethylene were much higher than that of former reported systems; 3) The thermal stabilities of RuO2 over different supports were compared, it was suggested that the Ru/rutile-TiO2 structure showed the best performance, which made P25-TiO2 and rutile-TiO2 more suitable as supports for RuO2 in the catalytic oxidation of VOCs; 4) No polychlorinated benzenes was found during the catalytic oxidation of all studied chlorobenzene species over the V2O5/P25-TiO2 catalysts, it was attributed that the surface phenolate species formed throuh the reaction between the reactants and the V=O structure of VOx species could not desorb form the catalyst surface.
|王健. 负载型钌催化剂对VOCs的催化氧化研究[D]. 北京. 中国科学院研究生院,2016.|