Silver species reduction upon exposure of Ag/Al₂O₃ catalyst to gaseous ethanol: An in situ Quick-XANES study

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• 作者：Elie Sayah ; Camille La Fontaine ; Val¨¦rie Briois ; Dalil Brouri ; Pascale Massiani
• 关键词：X-ray absorption spectroscopy ; In situ Quick-XANES ; Silver nanoparticles ; Ethanol ; Reduction ; UV&ndash ; visible spectroscopy ; SCR catalysis
• 刊名：Catalysis Today
• 出版年：2012
• 出版时间：30 July, 2012
• 年：2012
• 卷：189
• 期：1
• 页码：55-59
• 全文大小：792 K

文摘

The evolution of supported silver species of a pre-calcined Ag/Al₂O₃ catalyst was monitored upon thermal treatment under an air flow enriched with 3000 ppm of ethanol (EtOH) using transmission electron microscopy and UV-visible and X-ray absorption spectroscopies. A special focus is put on the application of in situ Quick-XAS that permits to acquire high quality spectra at the Ag K-edge with a good time resolution (30 s), thus informing in real time on the transformations of the silver species. While the reduction of silver under Air/EtOH flow is shown to possibly occur at room temperature, the process is strongly accelerated by heating, most of the silver being indeed reduced at ca. 78 ¡ãC, a temperature which corresponds to the ethanol boiling point. The possible impact of this silver sensitivity on the behavior of silver-alumina catalysts in reactions such as the selective catalytic reduction (SCR) of NO_x in presence of ethanol is addressed.