新型铬钴复合氧化物中低温选择性催化NOx还原及原位机理研究  

A novel Cr-Co mixed-oxide catalyst for selective catalytic reduction of NOx with NH_3 at medium-low temperature and in situ DRIFTS research on its reaction mechanism

作　　者：薛隆毅 邓志毅[1] 陈定盛[2] 唐志雄[2] 陈雄波[2] 方平[2] 岑超平[2] 陈志航[2] 

机构地区：[1]湘潭大学环境工程系,湖南湘潭411005 [2]环境保护部华南环境科学研究所,广东广州510655

出　　处：《工业催化》2015年第9期693-697,共5页Industrial Catalysis

基　　金：国家自然科学基金(201206048)资助项目;广州市珠江科技新星专项(2014J2200036)

摘　　要：采用固相法合成系列铬钴复合氧化物催化剂,该催化体系在中低温[（180~300）℃]下具有优异的氨选择性催化氮氧化物还原活性,其中,Cr（0.5）-Cr Ox催化剂在空速50 000 h-1、反应温度200℃和220℃条件下,NOx转化率达100%。采用原位DRIFIS研究催化剂表面吸附物种以及催化机理,在反应温度220℃考察Cr（0.5）-Co Ox催化剂表面NH3与NO的吸附态形式和NH3-SCR反应过程中中间态及其反应机理。结果表明,Cr（0.5）-Cr Ox催化剂上NH3吸附在L酸位,也能吸附在B酸位,但只与气态的NOx反应,生成中间体NH2NO,再进一步反应,最终生成N2与H2O。吸附态的NOx不参与SCR反应,反应遵循Eley-Rideal机理。A series of Cr-Co mixed oxide catalysts was prepared by solid states reaction method,which were used for selective catalytic reduction（ SCR） of NOx with NH3 in the presence of excess oxygen at medium-low temperature [（ 180 ~ 300） ℃]. The experimental results showed that under the condition of space velocity 50 000 h- 1and reaction temperature 200 ℃ and 220 ℃,NOx conversion reached 100% on Cr（ 0. 5）-Co Oxcatalyst. In situ diffuse reflectance infrared transform（ DRIFT） spectroscopy was employed for investigating the adsorption species on Cr（ 0. 5）-Co Oxcatalyst surface and revealing the reaction mechanism under reaction temperature 220 ℃. Based on the in situ DRIFTS results,it was found that NH3 was adsorbed on Lewis and Brnsted acid sites of Cr（ 0. 5）-Cr Oxcatalyst,and then decomposed into-NH2. The gas phase NO could bond with-NH2 and form an intermediate NH2 NO,which could further decompose into N2 and H2O. The adsorbed NOx didn＇t participate in the SCR reaction. NH3-SCR reaction on Cr（ 0. 5）-Co Oxcatalyst mainly followed the Eley-Rideal mechanism.

关 键 词：催化化学 铬钴复合氧化物 中低温选择性催化还原 原位DRIFIS 

分 类 号：O643.36[理学—物理化学] X701.7[理学—化学]