预吸附氧对NO在Pt(110)表面吸附和分解的影响  

Effect of Precovered Oxygen on the Adsorption and Decomposition of NO on Pt(110) Surface

作　　者：李金兵[1] 黄伟新[2] 姜志全[2] 包信和[3] 

机构地区：[1]北京燕山石油化工公司研究院,北京102500 [2]中国科学技术大学化学物理系,安徽合肥230026 [3]中国科学院大连化学物理研究所催化基础国家重点实验室,辽宁大连116023

出　　处：《催化学报》2006年第1期65-70,共6页

基　　金：国家自然科学基金资助项目(29525305).

摘　　要：利用程序升温反应谱、X射线光电子能谱和高分辨电子能量损失谱研究了NO在清洁和预吸附氧的Pt(110)表面的吸附和分解.在清洁的Pt(110)表面,室温下低覆盖度时NO以桥式吸附为主,高覆盖度时NO以线式吸附为主.加热过程中部分NO(主要是桥式吸附物种)分解,生成N2和N2O.室温下O2在Pt(110)表面发生解离吸附.Pt(110)表面预吸附氧会抑制桥式吸附NO的生成,并导致其脱附温度降低40K.降低脱附温度有利于桥式吸附NO的分子脱附,从而抑制分解反应.这些结果从表面化学的角度合理地解释了铂催化剂在富氧条件下对NO分解能力的降低.The adsorption and decomposition of NO on clean and oxygen-precovered Pt（110） surfaces were investigated by means of thermal desorption spectroscopy, X-ray photoelectron spectroscopy, and high-resolution electron energy loss spectroscopy. At room temperature, NO molecularly adsorbs on the clean Pt（110） surface. NO adsorbing on the bridge sites dominates at low coverage whereas NO adsorbs on the terminal sites at high coverage. Some NO （mainly the bridge-bound NO） undergoes dissociation upon heating, forming N2 and N2O. Molecular oxygen dissociates on Pt（110） at room temperature. Precovered oxygen adatoms on Pt（110） inhibit the formation of bridge-bound NO, which results in a decrease in the desorption temperature of bridge-bound NO from the surface by 40 K. The decrease in the desorption temperature facilitates the thermal desorption of bridge-bound NO on Pt（110）, and thus inhibits the dissociation reaction of NO. These results provide a reasonable surface science approach to understand the deactivation of Pt catalysts for NO decomposition under the oxygen rich atmosphere.

关 键 词：氧化氮 氧 铂 吸附 分解 表面化学 

分 类 号：O647.3[理学—物理化学]