In situ characterization of supported metal catalysts and model surfaces by time-resolved and three-dimensional XAFS techniques
In situ characterization of supported metal catalysts and model surfaces by time-resolved and three-dimensional XAFS techniques
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DOI：
10.1016/s0021-9517(02)00138-0
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发表时间：
2003-05-15
影响因子：
7.3
通讯作者：
Iwasawa, Y
中科院分区：
文献类型：
--
作者：
Iwasawa, Y
本文着重介绍了近5~10年发展起来的用于催化剂和模型表面原位表征的新技术，即用于时间分辨结构分析的能量色散X射线吸收精细结构(DXAFS)和用于三维结构分析的偏振相关全反射荧光X射线吸收精细结构(PTRF-XAFS)。DXAFS是一种用于阐明催化剂表面活性金属中心的动态结构变化的强大技术，它涉及金属-金属、金属-吸附和金属-载体键的形成和断裂序列；它开辟了结构动力学的新领域，揭示了催化反应、催化剂制备、催化剂失活和再生过程中的动力学参数。PTRF-XAFS是另一种用于阐明单晶模型表面活性金属中心的三维结构的强大技术，它以高表面灵敏度独立确定三个不同方向的结构参数，开辟了催化结构化学的新领域，提供了关于不对称和各向异性键排列和转化的信息。本文所讨论的问题涉及到理解新的催化结构和反应机理以及开发新的催化材料的新概念和新策略的重要关键问题，这些问题是其他技术难以解决的。(C)2003年埃尔塞维尔科学公司(美国)。版权所有。
This paper emphasizes novel issues in in situ characterization techniques for catalysts and model surfaces, namely, energy dispersive X-ray absorption fine structure (DXAFS) for time-resolved structure analysis and polarization-dependent total-reflection fluorescence X-ray absorption fine structure (PTRF-XAFS) for 3D structure analysis, which have been developed in the past 5-10 years. DXAFS is a powerful technique for elucidating dynamic structural changes at active metal sites on catalyst surfaces that involve a sequence of formation and breaking of metal-metal, metal-adsorbate, and metal-support bonds; it opens a new area of structure kinetics, revealing kinetic parameters during catalytic reactions, catalyst preparations, and catalyst deactivation and regeneration. PTRF-XAFS is another powerful technique for elucidating 3D structures of active metal sites at single crystal model surfaces, determining structural parameters in three different directions independently with high surface sensitivity, which opens up a new area of catalytic structural chemistry, presenting information on asymmetric and anisotropic bond arrangements and transformations. The issues addressed in this paper are relevant to important key issues in understanding new catalytic structures and reaction mechanisms and to developing new concepts and strategies for novel catalytic materials, which can hardly be addressed by other techniques. (C) 2003 Elsevier Science (USA). All rights reserved.