• 关键词：MCM-41  孔径  催化燃烧  挥发性有机物（VOCs）  甲苯  等体积浸渍

• 基金项目：国家自然科学基金（ No.51878338）

• 吴宇昊
• 南京大学环境学院，污染物控制与资源化研究国家重点实验室，南京 210023

• 张健
• 南京大学环境学院，污染物控制与资源化研究国家重点实验室，南京 210023

• 龙超
• 南京大学环境学院，污染物控制与资源化研究国家重点实验室，南京 210023

• 摘要：以3种不同孔径的介孔分子筛MCM-41（2.66、4.24和4.64 nm）为载体，采用等体积浸渍法制备MnO_x/MCM-41，考察了其催化氧化甲苯的活性，并用XRD、TEM、H₂-TPR、O₂-TPD和XPS等手段对催化剂进行表征.结果表明，增大载体孔径改变了锰元素的价态分布，提高了Mn³⁺和 表面吸附氧的含量，使得催化剂的氧化还原性和晶格氧流动性也有所提升.因此，载体孔径从2.66 nm增大至4.64 nm后，MnO_x/MCM-41催化氧化甲苯的T₉₀（体积空速=21200 h^-1）从369 ℃降至335 ℃.此外，还利用FTIR分析了甲苯的降解途径：甲苯先被活化脱氢，形成苯甲基，被吸附于 催化剂表面；然后苯甲基被氧化为苯甲醇、苯甲醛和苯甲酸，随后苯环被破坏，苯甲酸裂解为马来酸、羧酸和甲酸等物质；最后被完全氧化为 水和二氧化碳.

• Abstract：Three kinds of mesoporous molecular sieve MCM-41 with different pore diameters （2.66， 4.24 and 4.64 nm） were used as support to prepare MnO_x/MCM-41 catalysts by incipient wetness impregnation method. The catalytic performance of MnO_x/MCM-41in catalytic combustion of toluene was investigated. The catalysts were characterized by X-ray diffraction （XRD）， transmission electron microscopy （TEM）， hydrogen temperature programmed reduction （H₂-TPR）， oxygen temperature programmed desorption （O₂-TPD）， and X-ray photoelectron spectroscopy （XPS）. The results showed that increasing pore size of MCM-41 increased the content of Mn³⁺ and surface adsorbed oxygen species， correspondingly enhancing the reducibility and mobility of lattice oxygen of catalysts. Hence， T₉₀ （GHSV=21200h^-1） decreased from 369 ℃ to 335 ℃ when the pore diameter of MCM-41 increased from 2.66 nm to 4.64 nm. In addition， Fourier transform infrared spectroscopy was used to analyze the degradation pathway of toluene in MnO_x/MCM-41. FTIR revealed that toluene was first activated and dehydrogenated to form benzyl group， which was adsorbed on the surface of the catalyst. Then it was oxidized to form benzyl alcohol， benzaldehyde and benzoic acid. The benzene ring was destroyed， thus benzoic acid was cracked into maleic acid， acetic acid， formic acid and other substances. Finally， toluene was oxidized into water and carbon dioxide completely.

• Key words：MCM-41  pore diameter  catalytic combustion  volatile organic compounds（VOCs）  toluene  incipient wetness impregnation

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