In Situ EPR Study of the Redox Properties of CuO–CeO2 Catalysts for Preferential CO Oxidation (PROX)
In Situ EPR Study of the Redox Properties of CuO–CeO2 Catalysts for Preferential CO Oxidation (PROX)
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DOI：
10.1021/acscatal.6b00589
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发表时间：
2016-05
期刊：
影响因子：
12.9
通讯作者：
Feng Wang;R. Büchel;A. Savitsky;Michal Zalibera;D. Widmann;S. Pratsinis;W. Lubitz;F. Schüth
中科院分区：
文献类型：
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作者：
Feng Wang;R. Büchel;A. Savitsky;Michal Zalibera;D. Widmann;S. Pratsinis;W. Lubitz;F. Schüth
了解金属氧化物基催化剂的氧化还原性质是催化研究的一个重要课题。原位电子顺磁共振（EPR）光谱能够监测氧化还原反应过程中金属离子价态的变化和活性位点的形成，从而识别正在进行的氧化还原途径。本文利用原位EPR谱结合在线气体分析，结合非原位X射线光电子能谱（XPS）、X射线衍射（XRD）、X射线吸收近边结构（XANES）、产物时间分析（TAP）和质谱（MS）研究，研究了CuO-CeO 2催化剂在PROX条件下（氢气中一氧化碳优先氧化）的氧化还原行为。揭示了两种氧化还原机制：（i）在Cu 0/Cu+物种氧化成Cu 2+期间涉及氧化还原对Ce 4 +/Ce 3+的协同机制和（ii）绕过氧化还原对Ce 4 +/Ce 3+的直接机制。此外，EPR实验与同位素富集17 O2…
Understanding the redox properties of metal oxide based catalysts is a major task in catalysis research. In situ electron paramagnetic resonance (EPR) spectroscopy is capable of monitoring the change of metal ion valences and formation of active sites during redox reactions, allowing for the identification of ongoing redox pathways. Here in situ EPR spectroscopy combined with online gas analysis, supported by ex situ X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), temporal analysis of product (TAP), and mass spectrometry (MS) studies, was utilized to study the redox behavior of CuO–CeO2 catalysts under PROX conditions (preferential oxidation of carbon monoxide in hydrogen). Two redox mechanisms are revealed: (i) a synergetic mechanism that involves the redox pair Ce4+/Ce3+ during oxidation of Cu0/Cu+ species to Cu2+ and (ii) a direct mechanism that bypasses the redox pair Ce4+/Ce3+. In addition, EPR experiments with isotopically enriched 17O2 ...