MO_x/Y催化剂常温催化臭氧氧化甲苯的性能

Catalytic performance of MO_x/Y Catalyst for the Toluene Oxidation with Ozone at Room Temperature

以Y分子筛为载体,采用等体积浸渍法制备了MOx/Y催化剂,并用于常温催化臭氧氧化甲苯反应。采用XRD、BET、H2-TPR、甲苯吸附对催化剂进行表征,以甲苯转化率维持95%以上的时间(t95)为指标对催化性能进行评价。结果表明:10%MnO2/Y催化剂〔m(MnO2)/m(Y)=0.1〕具有较大的比表面积(538.6m2/g)和孔容积(0.440 cm3/g),较好的催化臭氧氧化甲苯活性(t95=210 min);CuO的加入提高了催化活性,5%MnO2-5%CuO/Y〔m(MnO2)/m(Y)=0.05且m(CuO)/m(Y)=0.05〕催化剂上t95=240min,COx选择性为80.6%,CO2与CO摩尔比为4.970。由表征结果可知,较大的比表面积和孔容积有利于甲苯吸附,CuO与Mn O2之间的相互作用促进了氧化还原性能的提高,进而有利于催化活性的提高。GC-MS结果表明:反应副产物堵塞催化剂孔道,占据催化剂表面活性位,导致催化剂失活。5%MnO2-5%CuO/Y催化剂失活-再生4次后t95可达220 min。

A series of MOx/Y catalysts were prepared by incipient-wetness impregnation method with Y zeolite as support for the toluene oxidation with ozone at room temperature. The catalysts were characterized by XRD, BET, H2-TPR and toluene adsorption techniques. The catalytic performance was evaluated by the time(t95) of toluene conversion rate above 95%. The results revealed that 10% MnO2/Y〔m(MnO2)/m(Y)=0.1〕catalyst had a larger specific surface area of 538.6 m2/g and pore volume of 0.440 cm3/g, and exhibited a better catalytic activity for toluene oxidation with ozone at room temperature. The addition of CuO improved the catalytic activity of 5% MnO2-5% CuO/Y〔m(MnO2)/m(Y)=0.05 and m(CuO)/m(Y)=0.05〕catalyst(t95 of 240 min, COx selectivity of 80.6%, and molar ratio of CO2 to CO of 4.970). It was found that larger surface area and pore volume promoted toluene adsorption, the interaction between CuO and MnO2 improved the reduction property of 10% MnO2/Y catalyst. Thus, 5% MnO2-5% CuO/Y catalyst exhibited a high catalytic activity in the toluene oxidation with ozone at room temperature. GC-MS results revealed that the by-products blocked the catalysts pores and occupied active sites on the surface of the catalysts, resulting in the inactivation of the catalysts. The results of regeneration experiment indicated that5% Mn O2-5% CuO/Y〔m(MnO2)/m(Y)=0.05 and m(CuO)/m(Y)=0.05〕catalyst showed good catalytic activity with t95 of 220 min after regeneration for four times.