气相臭氧分解催化材料的研究进展

Research Progress of Gaseous Ozone Decomposition Catalysts

随着工业化的快速发展,以臭氧为氧化剂的高级氧化技术被广泛应用于水污染处理、空气净化以及杀菌消毒领域。然而,过量未反应的臭氧被排放到空气中,造成严重的空气污染问题,威胁人类生命健康。相比于传统的吸附、热分解、药液吸收等臭氧治理技术,催化臭氧分解技术通过催化材料加速臭氧的分解过程,因其安全高效、绿色环保的优势而备受关注。随着研究的不断深入,臭氧分解催化材料的种类更加丰富,包括非金属碳材料、贵金属、过渡金属氧化物、金属-有机框架材料等,其应用形式也从粉末型催化材料发展到整体式催化材料。然而,在实际应用中,臭氧分解催化材料面临着活性和抗湿性两个主要问题:前期研究表明,过氧物种在催化材料表面活性位点的脱附是反应的速控步;而过氧物种会覆盖臭氧分解催化剂活性位点,导致催化活性降低;除此之外,臭氧往往伴随着大量的水汽,其与臭氧在活性位点的竞争吸附,会导致催化剂活性位点的失活。因此,急需开发高催化活性和高耐湿性的臭氧分解催化材料。对于活性来说,通过提高比表面积、构建氧空位、晶面调控、掺杂和表面修饰等手段可以提高催化材料表面的活性位点数量,促进催化反应过程得失电子循环以增强催化材料的活性。对于抗湿性来说,疏水性处理是提高催化材料抗湿性的有效措施。近几年来,研究学者发现,一些独特的活性位点可以把水当作助催化剂,这一方面提高了催化活性,另一方面避免了水的竞争吸附导致催化材料稳定性的下降。本文归纳了气相臭氧分解催化材料的研究进展,介绍了气相臭氧分解的过程和机理,系统梳理了不同类型催化材料在催化臭氧分解过程中的优势和存在的问题,并在此基础上着重介绍了臭氧分解催化材料活性提升和稳定性提高的策略;以期为制备高效稳定的新型臭氧分解催化材料、推动臭氧氧化技术在化工领域得到更大规模的推广和应用提供参考。

Advanced oxidation technology involving strong oxidizing ozone has been applied in the fields of water treatment,air purification and sterilization.But the excessive discharge of ozone causes substantial air pollution and represents a major hazard to human health.Compared to typical ozone treatment procedures,such as adsorption,thermal decomposition,absorption and so on,catalytic ozone decomposition has garnered a lot of attention since it is very efficient,safe and environmentally benign.Up to now,great progress has been made on catalysts for ozone decomposition.The types of catalysts have become more abundant,including activated carbon,noble metals,transition metal oxides,metal-organic framework materials,etc.,and their application forms have evolved from powder-based materials to monolithic materials.Nevertheless,two major difficulties severely limit the practical application of catalysts:on the one hand,catalyst deactivation is unavoidable due to the accumulation of intermediate oxygen species at surface active sites,which is the rate-limiting phase of the reaction.On the other hand,due to the intense competing adsorption between water molecules and ozone at active sites,catalysts are rapidly poisoned in moist conditions.As a result,catalysts with high catalytic activity and water resistance are highly desirable.To enhance the catalytic property,some effective strategies,including enlarging the surface area,fabricating oxygen vacancy,regulating lattice plane,doping and surface modification,are used to increase the concentration of active sites and accelerate the electron transfer.While hydrophobic treatment is a common approach to improve water resistance.Furthermore,researchers have shown in recent years that water can ope-rate as a promoter at some specific active sites,which not only boosts catalytic activity but also prevents unstable performance caused by water adsorption competition.This overview covers the research progress of catalytic ozone decomposition materials,as well as the gas ozone decomposition reaction process and mechanism.Especially,the advantages and challenges of various catalysts are summarized and the strategies for improving the activity and stability are highlighted.This review serves as a good reference for the preparation of stable and efficient catalytic ozone decomposition materials and the large-scale application of ozone oxidation technology in the chemical industry.