Pt(110)表面催化CO氧化反应原位研究  

In-situ studies of CO oxidation on Pt(110)

作　　者：李昌 蔡军 杨甜 韩永 董乔 李毅敏 刘志 LI Chang;CAI Jun;YANG Tian;HAN Yong;DONG Qiao;LI Yimin;LIU Zhi(State Key Laboratory of Functional Materials for Informatics,Shanghai Institute of Microsystem and lnformation Technology,Chinese Academy of Sciences,Shanghai 200050,China;School of Physical Science and Technology,ShanghaiTech University,Shanghai 201210,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海微系统与信息技术研究所信息功能材料国家重点实验室,上海200050 [2]上海科技大学物质科学与技术学院,上海201210 [3]中国科学院大学,北京100049

出　　处：《核技术》2018年第12期59-65,共7页Nuclear Techniques

基　　金：国家自然科学基金(No.11227902);上海市科学技术委员会(No.14520722100)资助~~

摘　　要：CO氧化作为最重要的原型反应之一始终受到广泛关注,而Pt系金属表面催化CO氧化反应的机理目前仍存争议。为了研究Pt表面催化CO氧化反应的机理,借助近常压光电子能谱(AmbientPressureX-ray PhotoelectronSpectroscopy,APXPS)结合在线质谱(MassSpectra,MS),原位分析了Pt(110)表面催化CO氧化反应过程中表面物种以及反应产物的变化。实验结果表明:Pt(110)表面催化CO氧化反应过程可以分为三个状态:1)低反应活性状态,Pt(110)表面CO中毒,CO2的产生速率很低;2)高反应活性状态,Pt(110)表面发生点火反应并伴随大量反应热的释放;3)传质速率限制的反应状态,Pt(110)表面O过量,反应速率受到CO扩散速率的限制。保持反应气体总压强为100 Pa,通过改变不同的CO和O2比例,发现Pt(110)表面催化CO氧化反应的点火温度随着CO含量的增加而升高。本工作对于理解Pt(110)表面催化CO氧化反应机理具有重要帮助,同时为进一步弄清催化反应的活性物种提供了基础。[Background] CO oxidation is a very important prototypical reaction in heterogeneous process. The reaction mechanism of Pt-group metals under ultrahigh vacuum (UHV) conditions was studied in detail, and unambiguous evidence of Langmuir-Hinshelwood kinetics was found. However, the reaction mechanism of the Pt(110) surface under high pressure conditions was still controversial.[Purpose] This study aims to clarify the reaction mechanism and active sites of CO oxidation on Pt(110).[Methods] The oxidation of CO on Pt(110) surface was studied under total pressures up to 100 Pa in different CO:O2 reaction mixtures. Surface species and composition of products were analyzed in situ by ambient pressure X-ray photoelectron spectroscopy (APXPS) and online gas analysis by mass spectra (MS).[Results] The process of CO oxidation on Pt(110) fell into three regimes:1) low active regime with CO poisoned Pt(110) surface and low CO2 formation rate; 2) highly active regime with ignition reaction on Pt(110) surface companied by a large amount of heat release; 3) mass transfer rate limited regime, excessive O-rich Pt(110) surface, the CO2 formation rate controlled by CO diffusion rate.[Conclusion] The active sites of CO oxidation reaction on Pt(110) surface are metallic Pt.

关 键 词：CO氧化 Pt(110)表面 催化 近常压光电子能谱 质谱 

分 类 号：O647[理学—物理化学]