锰基氧化物上甲苯催化氧化的研究进展

Catalytic Removal of Toluene Over Manganese-Based Oxide Catalysts

挥发性有机化合物(VOCs)的控制日益引起学术界和产业界的高度关注,催化燃烧法由于具有高效、低温和低成本的优势,被认为是目前降解VOCs最有前景的方法之一。甲苯作为VOCs中一种典型的污染物,其催化燃烧对VOCs的控制具有重要意义。催化燃烧法中催化剂的选择至关重要,锰氧化物(MnO x)由于具有良好的氧化还原性能、水热稳定性以及价格低廉等优点,国内外研究者对锰基氧化物上甲苯催化氧化进行了深入研究。目前改性锰基氧化物催化剂的种类主要有多相锰氧化物、过渡金属掺杂锰氧化物和负载型锰氧化物。多相锰氧化物(如α@β-MnO 2)不仅使α-MnO 2和β-MnO 2在催化氧化甲苯的过程中发挥各自的优势,而且利用相界面产生更多氧空穴,促进氧流动,从而提高催化效率。过渡金属掺杂锰氧化物有利于不同金属间的电子转移和催化剂表面的氧流动,提高催化剂的氧化还原能力。负载型锰氧化物通过产生金属与载体相互作用来改善锰氧化物的催化性能。除此之外,通过调控MnO x形貌、对锰基氧化物进行酸处理等会影响催化剂的比表面积、活性氧种类和氧化还原能力等,从而改善催化剂的催化活性。甲苯在锰基氧化物催化剂上的氧化可遵循Mars-van Krevelen(MVK)机理与Langmuir-Hinshelwood(L-H)机理,中间产物均为吸附在催化剂表面带芳环的中间体。本文以甲苯的催化氧化为目标反应,综述了锰基氧化物催化剂种类、影响因素及甲苯催化氧化机理,并对锰氧化物的发展趋势进行了展望,以期为设计对甲苯催化氧化具有良好性能的催化剂提供理论指导。

The control of volatile organic compounds(VOCs)has attracted attention in both academic and industrial communities.Catalytic oxidation is considered to be one of the most promising methods for the removal of VOCs due to the high efficiency,low reaction temperature and low cost.The catalytic removal of toluene,which is one of the typical VOCs,is very important for the control of VOCs.Catalyst plays a key role for the catalytic oxidation of toluene.Considering the good redox property,high hydrothermal stability and the low cost of MnO x,many researchers have conducted intensive study on the catalytic oxidation of toluene over MnO x-based catalysts.MnO x-based catalysts can be classified into heterogeneous MnO x,transition metal-doped MnO x and supported MnO x.For the heterogeneous MnO x,such asα@β-MnO 2,the advantages of different MnO x phase can be made full use of.In addition,more oxygen vacancies are generated in the phase interface,promoting the oxygen flow and thereby improving the reaction efficiency.Introduction of transition metals to MnO x would contribute to the electron transfer between metals and enhance the oxygen mobility of the catalyst,thus enhancing the redox property.In the case of supported MnO x the strong metal-support interaction is beneficial for the improvement of the catalytic performance.Morphology control and the acid treatment of MnO x-based catalysts can also lead to improved activity by regulating the specific surface area,the active oxygen species and the redox ability of the catalysts.The oxidation of toluene on the MnO x-based catalyst follows Mars-van Krevelen(MVK)or Langmuir-Hinshelwood(L-H)mechanism.For both mechanisms the intermediate with an aromatic ring is formed.In this review,the types of MnO x catalysts,influencing factors and mechanism of the catalytic oxidation of toluene over manganese-based oxide have been summarized and discussed.And the perspective on MnO x-based catalysts for the catalytic oxidation of toluene has been proposed.