煅烧温度对Mn/TiO_2催化剂催化NO氧化活性的影响  

Influence of calcination temperature on the catalytic activity of Mn/TiO_2 for NO oxidation

作　　者：安忠义[1] 禚玉群[1] 陈昌和[1] 

机构地区：[1]清华大学热科学与动力工程教育部重点实验室,北京100084

出　　处：《燃料化学学报》2014年第3期370-376,共7页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(51276034)

摘　　要：以浸渍在二氧化钛上的锰基催化剂为对象,研究了制备过程中煅烧温度对锰基催化剂催化NO氧化活性的影响。结果表明,较低的煅烧温度有利于提高Mn/TiO2催化剂对于NO氧化的催化效率。利用X射线粉末衍射(XRD)、场发射扫描电子显微镜(FESEM)、X射线光电子能谱(XPS)、H2程序升温还原(H2-TPR)和O2程序升温脱附(O2-TPD)等表征手段研究了煅烧温度影响Mn/TiO2催化剂催化活性的作用机理。结果表明,在NO氧化过程中发挥主要作用的是Mn2O3,较低的煅烧温度有利于提高Mn2O3在锰氧化物中所占的比例,同时增加锰氧化物在载体表面的分散度,从而改善催化剂活性;当煅烧温度超过500℃时,催化剂会发生烧结,载体TiO2的晶形开始由锐钛型向金红石型转变,Mn2O3也从非晶相向晶相转变。H2-TPR和O2-TPD测试结果表明,低温煅烧有利于提高催化剂的还原性能和表面化学吸附态O2-的脱附性能,良好的还原性能和脱附性能的相互作用使催化剂表面的氧有较好的移动能力,从而促进催化剂的活性。The influence of calcination temperature on the catalytic activity of Mn-based catalysts impregnated on TiO2 for the oxidation of NO was studied. The results showed that, relatively low calcination temperature was beneficial to promote the catalytic activity of Mn/TiO2 catalysts. The catalysts were characterized by various techniques to study the influence mechanism of calcination temperature, including X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, X-ray photoelectron spectroscopy （XPS）, H2 temperature programmed reduction （H2-TPR） and O2 temperature programmed desorption （O2-TPD）. It could be concluded that Mn2 O3 played a dominant role in the process of NO oxidation, and the relatively lower calcination temperature could enhance the percentage of Mn2 O3 in MnOx, as well as promote the dispersion of MnOx on TiO2, thus raising the catalytic activity of Mn/TiO2. When the calcination temperature was higher than 500℃, the agglomeration began to appear, and the crystalline phase of TiO2 was transformed from anatase to ruffle, Mn2O3 was, as well, transformed from amorphous phase to crystalline phase. The test results of H2-TPR and O2-TPD showed that relatively lower calcination temperature was beneficial to the reduction ability of Mn/ TiO2 catalysts and the desorption of chemisorbed O2- on catalysts surface, the interaction of the two factors resulted in good mobility of chemisorbed O2- on catalysts surface, which was good for the activity of catalysts.

关 键 词：煅烧温度 NO氧化 催化剂 制备 污染控制 

分 类 号：TQ032.4[化学工程]