Quasi In Situ 57Fe Mssbauer Spectroscopic Study: Quantitative Correlation between Fe2+ and H2 Concentration for PROX over Ir−Fe/SiO2 Catalyst

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• 作者：Kuo Liu ; Aiqin Wang ; Wansheng Zhang ; Junhu Wang ; Yanqiang Huang ; Jianyi Shen ; Tao Zhang
• 刊名：Journal of Physical Chemistry C
• 出版年：2010
• 出版时间：May 13, 2010
• 年：2010
• 卷：114
• 期：18
• 页码：8533-8541
• 全文大小：293K
• 年卷期：v.114,no.18(May 13, 2010)
• ISSN：1932-7455

文摘

In this study, Ir−Fe/SiO₂ catalyst was prepared by coimpregnation and investigated for preferential oxidation of CO under the presence of H₂. It was found that the presence of H₂, even in a slight excess, led to a large increase in the reaction rate for CO oxidation over the Ir−Fe/SiO₂ catalyst, which was quite different from the case of Ir/SiO₂. To reveal the promotional role of Fe associated with the presence of H₂, quasi in situ Mssbauer spectroscopy, in combination with in situ DRIFTS and microcalorimetry, was employed. The results showed that the relative amount of Fe²⁺ increased with increasing H₂ concentration in the reaction stream, well consistent with the trend of reaction rate for CO conversion, strongly suggesting that Fe²⁺ is the active site for oxygen activation. H₂ promoted CO oxidation mainly via maintaining a substantial amount of Fe existing as Fe²⁺.