甲苯催化氧化研究进展

Current progress on catalytic oxidation of toluene: a review

挥发性有机污染物(VOCs)作为空气污染物的主要成分之一,也是形成细颗粒物和臭氧的重要前体物. VOCs来源广泛,涉及石油化工、汽车制造、纺织等多个行业.甲苯作为一种典型的VOCs,对人体健康造成严重危害;同时,其具有稳定的芳环结构、不易降解,对其治理迫在眉睫.在众多处理技术中,催化氧化技术可以在低温下将其完全转化成二氧化碳和水,该技术的核心是开发出高活性、高稳定性、抗水抗硫性强的催化剂.因此,本文综述了近几年贵金属催化剂、过渡金属氧化物催化剂、尖晶石型复合氧化物催化剂、钙钛矿型复合氧化物催化剂和金属有机骨架基催化剂等催化氧化甲苯的研究进展,并对其反应机理和动力学进行了讨论,以期帮助开发用于将甲苯完全氧化或者选择性氧化的高效催化材料.

Volatile organic compounds(VOCs)have boiling points ranging from 50℃to 260℃at room temperature.These compounds are emitted from complex sources,including automobile manufacturing,fine chemicals,the pharmaceutical industry,interior decoration,and the plastics industry.VOCs serve as important precursors of secondary organic aerosols and ozone.However,some VOCs discharged into the atmosphere undergo photochemical reactions,resulting in the formation of photochemical smog.This byproduct is irritating,teratogenic,and carcinogenic,causing considerable harm to human health and posing a serious threat to the environment.Among VOCs,aromatic hydrocarbons originate from a wide range of sources relevant to human life.These compounds have been a constant hot spot in the field of VOC removal due to their unique aromatic ring structure,highly toxic effects,and challenging treatment.VOC removal mainly comprises source reduction,process management,and end–to–end treatment.End–to–end treatment methods involve adsorption,photocatalytic,plasma decomposition,membrane separation,and catalytic oxidation.Catalytic oxidation can effectively convert VOCs into carbon dioxide and water at relatively low temperatures,making it one of the most effective methods for VOC treatment.Efficient catalyst development is the key point for catalytic oxidation methods.This review highlights progress in catalyst development for the catalytic oxidation of toluene,focusing on the characteristics of noble-metal catalysts,such as noble-metal species,particle size,alloying systems,and support properties.While transition-metal oxide catalysts are abundant and inexpensive,they exhibit low catalytic performance for toluene oxidation.Therefore,discussions on transition-metal oxide catalysts include synthesis or calcination temperature,atomic substitution(isovalent and heterovalent substitutions),surface modification(noble-and transition-metal doping),and in situ surface treatment(chemical etching and surface modification).Although studies on toluene degradation using spinel-and perovskite-type oxide catalysts and metal-organic framework-based catalysts are limited,a brief summary of their characteristics during catalytic oxidation of toluene is provided,focusing on the relationship between the catalyst microstructure and performance.Furthermore,the kinetic model for the catalytic oxidation of toluene was briefly evaluated,and the corresponding reaction mechanism and kinetics were analyzed.This review aims to contribute to the development of efficient catalysts for the complete or selective oxidation of toluene.