Key Laboratory of Green Chemistry & Technology of the Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, Sichuan, PR China.
J Hazard Mater. 2009 Dec 30;172(2-3):631-4. doi: 10.1016/j.jhazmat.2009.07.040. Epub 2009 Jul 18.
The catalytic decomposition of ozone was investigated over Pd-Mn/SiO(2)-Al(2)O(3) catalysts in the ground air. The catalysts were prepared by incipient wetness impregnation method and characterized by powder X-ray diffraction (XRD), thermo gravimetric (TG) analysis, and N(2) adsorption/desorption measurements (Brunauer-Emmet-Teller method). The influence of calcination temperature on the catalytic activities, and the lifetime test of the catalyst pretreated at 350 degrees C had been studied. XRD and TG results show that when calcined in the temperature range of 300-450 degrees C, manganese carbonate (MnCO(3)) is partly decomposed to MnOx (x=1.6-2.0) species in the catalysts. However, when calcined at 500 degrees C, MnOx partly turns into Mn(2)O(3) in the catalyst. The catalytic activity test indicates that the catalysts calcined at 300-400 degrees C exhibit the best performance for O(3) decomposition, and the completely conversion temperature of ozone (T(100)) is in the region of 30-35 degrees C, which is lower than surface temperature of water tanks of running automobile. Under gas hour space velocity (GHSV) of 635,000h(-1) and reaction temperature of 40 degrees C, after lifetime test for 80 h, the catalyst calcined at 350 degrees C keeps 90% conversion, which indicates that they have excellent ability to resist deactivation. The catalysts calcined at 300-400 degrees C show great potential to be applied at lower temperature, especially in winter and at the stage of automobile engine cold start.
在地面空气中，研究了 Pd-Mn/SiO(2)-Al(2)O(3)催化剂上臭氧的催化分解。催化剂采用等体积浸渍法制备，并通过粉末 X 射线衍射 (XRD)、热重 (TG) 分析和 N(2)吸附/脱附测量 (BET 法)进行了表征。研究了煅烧温度对催化活性的影响，以及在 350°C 预处理的催化剂的寿命测试。XRD 和 TG 结果表明，当在 300-450°C 的温度范围内煅烧时，催化剂中部分碳酸锰 (MnCO(3)) 分解为 MnOx(x=1.6-2.0)物种。然而，当在 500°C 煅烧时，催化剂中的 MnOx 部分转化为 Mn(2)O(3)。催化活性测试表明，在 300-400°C 煅烧的催化剂对 O(3)分解表现出最佳性能，臭氧的完全转化温度 (T(100)) 在 30-35°C 范围内，低于运行汽车水箱的表面温度。在空速 (GHSV) 为 635,000h(-1)和 40°C 的反应温度下，在 80 h 的寿命测试后，在 350°C 煅烧的催化剂保持 90%的转化率，表明它们具有出色的抗失活能力。在较低温度下，特别是在冬季和汽车发动机冷启动阶段，300-400°C 煅烧的催化剂具有很大的应用潜力。
