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以浸渍在不同晶相TiO2(金红石型(R)、锐钛矿型(A)和P25型(P))上的锰基催化剂为对象,研究了TiO2晶相对MnOx/TiO2催化剂催化NO氧化活性的影响.结果表明,MnOx/TiO2(P)催化剂活性最高,NO转化率在300°C及GHSV=20000 h–1条件下可达83%.各催化剂活性顺序为MnOx/TiO2(P)>MnOx/TiO2(A)>MnOx/TiO2(R).采用X射线粉末衍射、场发射扫描电子显微镜、X射线光电子能谱、H2程序升温还原和O2程序升温脱附等手段研究了TiO2晶相影响MnOx/TiO2催化剂催化活性的作用机理.结果表明,相比于A和R型TiO2,P型TiO2能够增加MnOx在其表面的分散度并抑制催化剂颗粒的团聚和粘连,且更有利于Mn2O3的生成,而后者催化NO氧化活性比其它MnOx更高;此外,P型TiO2可以增加MnOx尤其是Mn2O3的还原性,并可促进O2–从M3+–O键的脱附.
The effects of TiO2 crystal on the catalytic activity of MnOx / TiO2 catalyst for NO oxidation were studied with manganese-based catalysts impregnated on different crystalline phases of TiO2 (rutile (R), anatase (A) and P25 (P) The results show that the activity of MnOx / TiO2 (P) catalyst is the highest, the conversion rate of NO is up to 83% at 300 ℃ and GHSV = 20000 h-1.The activity sequence of each catalyst is MnOx / TiO2 (P)> MnOx / TiO_2 (A)> MnOx / TiO_2 (R). The influence of the crystal phase of TiO2 on the MnOx / The results showed that compared with A and R type TiO2, P-type TiO2 can increase the dispersion of MnOx on its surface and inhibit the agglomeration and adhesion of catalyst particles, and is more conducive to the formation of Mn2O3, and then Catalyzed NO oxidation activity higher than other MnOx; In addition, P-type TiO2 can increase the reducibility of MnOx, especially Mn2O3, and can promote the desorption of O2- from the M3 + -O bond.