Relating Rates of Catalyst Sintering to the Disappearance of Individual Nanoparticles during Ostwald Ripening

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• 作者：Sivakumar R. Challa ; Andrew T. Delariva ; Thomas W. Hansen ; Stig Helveg ; Jens Sehested ; Poul L. Hansen ; Fernando Garzon ; Abhaya K. Datye
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：December 28, 2011
• 年：2011
• 卷：133
• 期：51
• 页码：20672-20675
• 全文大小：753K
• 年卷期：v.133,no.51(December 28, 2011)
• ISSN：1520-5126

文摘

Sintering of nanoparticles (NPs) of Ni supported on MgAl₂O₄ was monitored in situ using transmission electron microscopy (TEM) during exposure to an equimolar mixture of H₂ and H₂O at a pressure of 3.6 mbar at 750 掳C, conditions relevant to methane steam reforming. The TEM images revealed an increase in the mean particle size due to disappearance of smaller, immobile NPs and the resultant growth of the larger NPs. A new approach for predicting the long-term sintering of NPs is presented wherein microscopic observations of the ripening of individual NPs (over a span of a few seconds) are used to extract energetic parameters that allow a description of the collective behavior of the entire population of NPs (over several tens of minutes).