CO为还原剂同时还原SO_2和NO的SnO_2-TiO_2固溶体催化剂 Ⅲ.催化剂的活性位和反应机理  

SnO_2-TiO_2 Solid Solution Catalyst for Simultaneous Reduction of SO_2 and NO by CO Ⅲ. Catalyst Active Sites and Reaction Mechanism

作　　者：刘赵穹[1] 马骏[1] 杨锡尧[1] 

机构地区：[1]北京大学化学与分子工程学院,北京100871

出　　处：《催化学报》2004年第8期624-632,共9页

基　　金：国家重点基础研究发展规划项目 (G19990 2 2 2 );国家自然科学基金资助项目 ( 2 0 0 770 0 2 )

摘　　要：采用显微红外光谱、漫反射红外光谱、瞬变应答反应以及催化剂活性测试等实验手段 ,对SnO2 TiO2 催化剂上SO2 +CO ,NO +CO和SO2 +NO +CO (SRSN)反应的机理及活性位进行了综合研究 .结果表明 ,SO2 +CO和NO +CO反应按典型的Redox机理进行 ,催化剂的表面晶格氧 [O]和氧阴离子空穴 [□ ]([O] [□ ])是Redox反应的活性位 .对于SO2 +CO反应 ,其 [O] [□ ]位于SnO2 TiO2 催化剂中邻近Sn离子和邻近Ti离子的位置 ,邻近Ti离子的 [O] [□ ]的活性比邻近Sn离子的[O] [□ ]的活性高 .NO +CO反应主要在邻近Sn离子的 [O] [□ ]中心上进行 .对于SRSN反应 ,其中的SO2 +CO反应的机理及催化剂的活性位与单纯的SO2 +CO反应相同 ,而其中的NO +CO反应按两种机理进行 :一种和单纯的NO +CO反应相同 ,即按一般的Redox机理进行 ,其活性位为邻近Sn离子的 [O] [□ ]中心 ;另一种按SO2 促Redox反应机理进行 ,其活性位为表面活性硫物种 [SO] .The reaction mechanism of SO 2+CO, NO+CO and SO 2+NO+CO (simultaneous reduction of SO 2 and NO, SRSN) reactions on the SnO 2-TiO 2 catalyst and catalyst active sites were investigated by microscopic infrared spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy, transient response experiments and catalytic reaction test. SO 2+CO and NO+CO reactions are typical redox reactions and both are carried out on the active sites composed of surface crystal oxygen [O] and oxygen anion vacancy [□] ( [O] - [□] ). In the case of the SO 2+CO reaction, the active sites [O] - [□] are near either Ti ions or Sn ions, and the sites near Ti ions are more active than those near Sn ions. For the NO+CO reaction, however, the active sites are mainly near Sn ions. As for the SRSN reaction, SO 2+CO has the same mechanism as the pure SO 2+CO reaction, while NO+CO proceeds along two paths: one is the typical redox reaction with [O] - [□] as the active sites and the other is the SO 2-assisted NO+CO reaction carried out on the active sites which are consisted of surface active sulfur species [SO] *.

关 键 词：二氧化锡 二氧化钛 固溶体 一氧化碳 还原 二氧化硫 一氧化氮 反应机理 活性位 

分 类 号：O643[理学—物理化学] X7[理学—化学]