气氛环境下Au/CeO2催化剂烧结行为的原位电镜研究

气氛环境下Au/CeO₂催化剂烧结行为的原位电镜研究

陈炳伟，吴哲敏^*，韩仲康，袁文涛，姜  颖^*，杨杭生，王  勇，张  泽

（浙江大学电子显微镜中心，硅材料国家重点实验室，材料科学与工程学院，浙江杭州 310027）

摘  要  气氛环境下原位研究催化剂的烧结行为，能够为理解催化剂在预处理以及反应条件下的烧结机理和高稳定催化剂的设计提供重要的实验依据。本文以Au/CeO₂模型纳米催化剂为研究对象，利用环境透射电子显微镜原位观察其在O₂与CO气氛下的高温动态烧结过程。实验发现，负载在CeO₂上的Au纳米颗粒在O₂与CO气氛环境中表现出不同的烧结行为，其在O₂气氛下具有较高的烧结速度，同时存在颗粒迁移与聚集长大（particle migration and coalescence, PMC）和奥斯特瓦尔德熟化（Ostwald ripening, OR）两种烧结过程；在CO气氛下烧结速度较慢，烧结过程以OR为主。对比不同气氛环境下烧结后催化剂的表面结构可知，CO增加了CeO₂表面台阶的数量以及表面氧空位浓度，增强了载体对Au颗粒的锚定作用，从而提升Au/CeO₂催化剂的稳定性。

关键词   Au/CeO₂模型催化剂; 氧气;一氧化碳; 烧结; 原位透射电镜

中图分类号：O793；O77⁺1；O64   文献标识码:  A      doi:10.3969/j.issn.1000-6281.2024.01.007

In-situTEM study of gas-dependent sintering behavior of Au/CeO₂

CHEN Bing-wei，WU Zhe-min^*，HAN Zhong-kang，YUAN Wen-tao，JIANG Ying^*，

YANG Hang-sheng，WANG Yong，ZHANG Ze

(Center of Electron Microscopy, State Key Laboratory of Silicon Materials, and Department of Materials Science and Engineering, Hangzhou Zhejiang 310027, China)

Abstract     In-situinvestigation of catalyst sintering behavior under atmospheric conditions provides the crucial experimental evidence for understanding the sintering mechanism of catalysts during pretreatments and reactions, and for designing highly stable catalysts. In this study, a model nanocatalyst system composed of Au/CeO₂ was employed to examine the high-temperature dynamic sintering process using an environmental transmission electron microscopy (ETEM). It was observed that the Au nanoparticles supported on CeO₂ exhibited distinct sintering behaviors in O₂ and CO atmospheres. In the O₂ atmosphere, the sintering rate was significantly accelerated by the presence of both particle migration and coalescence (PMC) and Ostwald ripening (OR) processes. In contrast, in the CO atmosphere, the sintering rate was slow and predominantly governed by the OR process. The comparative analysis of the surface structures of sintered catalysts under different atmospheres revealed that the CO gas increased the number of surface steps and the concentration of surface oxygen vacancies in CeO₂, thereby enhancing the anchoring effect of the support on Au particles, and improving the stability of the Au/CeO₂ catalyst.

Keywords  Au/CeO₂ model catalyst; oxygen; carbon monoxide; sintering; in-situ TEM

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