Mn的氧化价态对Mn／γ-Al2O3催化剂催化臭氧氧化气相低浓度甲苯的影响

采用共沉淀法，以Al2O3为载体制备Mn／γ-Al2O3和Mn—Ce／Mn／γ-Al2O3催化剂，并分别在N2气氛和O2气氛下焙烧。采用固定床连续流动反应器，研究所制备催化剂在室温条件下催化臭氧氧化甲苯的性能。通过XRD、XPS和FTIR等手段对催化剂的结构和组成进行表征。结果表明，Mn／Mn／γ-Al2O3催化剂具有良好的催化臭氧氧化甲苯和催化臭氧自身分解的性能，共沉淀法制备催化剂的最佳Mn负载量为20％。O2气氛焙烧和Ce的加入，可以有效提高催化剂的活性和寿命。原因是O2气氛焙烧和Ce的加入可以提高Mn的氧化价态。催化剂失活的主要原因是有机副产物在催化剂表面吸附堆积，失活催化剂在550℃、空气气氛下焙烧可恢复催化性能。

Effects of Mn valence on catalytic oxidation of gas-phase low-concentration toluene by ozone over Mn/Al2O3 catalyst

By coprecipitation method, using Al2O3 as carrier, Mn/γ-A1203 and Mn-Ce/γ/-Al2O3 catalysts were prepared and calcined in an atmosphere of N2 or O2 ,respectively. The fixed-bed continuous flow reactor was utilized to research performances for catalytic oxidation of toluene by ozone of the above catalysts at room temperature. The structure and composition of these catalysts were characterized by means of XRD,XPS and FTIR. Results show that Mn/γ/-Al2O3 catalysts have good performances for catalytic ozonation of toluene and catalytic ozone decomposition. And,20% is the optimum Mn load. Calcination in an atmosphere of O2 or addition of cocatalyst Ce can effectively improve the activity and life of the catalyst. It can be attributed that calcination in O2 and addition of Ce can increase the oxidation state of Mn. The main reason for deactivation of the catalyst is the accumulation of organic byproducts absorbed on the catalyst surface. However, the catalytic performance of inactivated catalyst can recover after calcining under an atmosphere of air at 550℃.