Cu-Ni/Zn催化剂甲醇裂解机理原位XPS研究  

In-situ XPS Study for Reaction Mechanism of Methanol Decomposition over Cu-Ni/Zn Catalyst

作　　者：席靖宇[1] 王志飞[1] 王卫平[1] 吕功煊[1] 

机构地区：[1]中国科学院兰州化学物理研究所羰基合成与选择氧化国家重点实验室,兰州730000

出　　处：《物理化学学报》2002年第1期82-86,共5页Acta Physico-Chimica Sinica

基　　金：国家重点基础研究发展规划资助项目(G20000264)~~

摘　　要：利用原位XPS和TPD-MS技术研究了Cu-Ni/Zn催化剂在甲醇裂解反应中的机理和活性中心.TPD-M脱附产物中仅检测到CH3OH、H2和CO,而未发现CH4和CH3OCH3、HCOOCH3等其它含氧物种,说明在CH3O裂解过程中仅包括O-H、C-H键的断裂,而不存在C-O键的断裂过程.In-situXPS的研究发现,在反应温度升高到200℃以上时,Cu/Zn催化剂中的Zn明显被还原,反映出Cu/Zn催化剂失活过程的Cu-Zn合金生成过程,而在Cu-Ni/Zn催化剂中未观察到Zn的还原,且表面出现Cu+/Cu0共存的现象.Cu+和Cu0很可能共同构成催化剂表面的活性中心,Cu+应该是在甲醇裂解反应过程中形成的中间态.产物氢从Cu-Ni/Zn催化剂表面脱附为反应的控速步骤.In-situ XPS and TPD-MS techniques were used to study the reaction mechanism and the active center of Cu-Ni/Zn catalyst for methanol decomposition. Significant amount of CH3OH, H-2 and CO were detected during the methanol decomposition with TPD-MS, however no evidences of CH4, CH(3)OCHs and HCOOCH3 formation were obtained. TPD-MS results indicated that O - H and C - H bonds instead of C - O bond were broken in methanol decomposition on Cu/Zn/Ni catalyst. It was found that H-2 desorption from the surface of Cu-Ni/Zn catalyst was the rate control step, In-situ XPS studies confirmed that the Zn species was easily reduced when temperature was higher than 200 degreesC in Cu/Zn catalyst. However, similar reduction of Zn was not observed in Cu/Zn/Ni catalyst. Furthermore, both Cu+ and Cu-0 species were observed in Cu/Zn/Ni catalyst. Our study indicated that active center(s) in Cu/Zn/Ni catalyst may be Cu-0 and/or Cu+ species, in which Cu+ formed during the reaction.

关 键 词：甲醇 裂解 氢气 Cu-Ni/Zn催化剂 原位-XPS 反应机理 活性中心 铜-镍/锌催化剂 

分 类 号：O643.3[理学—物理化学]