Mn-Ce-Zr/γ-Al_2O_3催化剂低温选择性催化还原脱硝性能分析  

Performances of Mn-Ce-Zr/γ-Al_2O_3 Catalyst for Low Temperature Selective Catalytic Reduction of NO

作　　者：曹蕃[1] 苏胜[1] 向军[1] 王鹏鹰[1] 胡松[1] 孙路石[1] 陆骑 

机构地区：[1]煤燃烧国家重点实验室(华中科技大学),湖北省武汉市430074

出　　处：《中国电机工程学报》2015年第9期2238-2245,共8页Proceedings of the CSEE

基　　金：国家科技支撑计划(2011BAC05B00);国家高技术研究发展计划项目(2012AA063504);中央高校基本科研业务费资助(HUST:2014QN188)~~

摘　　要：采用溶胶凝胶法制备了低温脱硝活性良好的Mn-Ce-Zr/γ-Al2O3催化剂。催化剂在150℃下达到接近70%的脱硝效率并在250~300℃下升高到95%左右。空速和SO2/H2O性能影响实验表明催化剂具有较好的空速变化适应能力和抗SO2/H2O中毒性能。NH3和NO氧化性能实验在固定床上进行。结果发现NH3在300℃以上会逐渐被氧化为NO;而NO在250~300℃下容易被氧化为NO2,这有利于选择性催化还原反应的进行。利用多种表征手段,如N2吸附脱附、X射线衍射、H2程序升温还原和程序升温脱附,对催化剂进行了表征。结果表明Zr可以掺杂进入Ce O2微晶晶格内并形成了固溶体结构,这可以提高催化剂的比表面积和孔结构参数。程序升温脱附结果表明NH3主要吸附在催化剂的不稳定酸性位上,而NO吸附后可以亚硝酸盐、不稳定和稳定硝酸盐等多种形式存在,这有利于促进低温选择性催化还原反应的进行。The Mn-Ce-Zr/γ-Al2O3 catalyst with high selective catalytic reduction （SCR） activity at low temperature was prepared by the sol-gel method. The NO conversion reaches 70% at 150 ℃ and then increases to 95% at 250- 300℃. The catalyst can also be well-behaved under high space velocity and in the presence of SO2 and H2O. NH3 and NO oxidation performance was tested on the fixed bed. It shows that NH3 can be oxidized to NO at high temperature, while NO is easy to be oxidized to NO2 at 250-300 ℃, which is beneficial for the proceeding of SCR reactions. Several characterization methods, such as N2 adsorption-desorption, X-ray diffraction （XRD）, H2-temperature programmed reduction （H2-TPR） and temperature programmed desorption （TPD） were adopted. It shows that Zr can be incorporated into the CeO2 crystal lattice and form the solid solution, resulting that the BET surface area and pore volume of this catalyst increases obviously. The results of TPD indicate that NH3 is mainly adsorbed on the weak acid sites, and NO can be adsorbed as the nitrite, unstable and stable nitrate species, which is in favor of the low-temperature SCR reaction proceedings.

关 键 词：脱硝 低温选择性催化还原(SCR) Mn-Ce-Zr 固溶体 氨气 程序升温脱附 

分 类 号：TK228[动力工程及工程热物理—动力机械及工程]