17O Solid-State NMR Study on the Size Dependence of Oxygen Activation over Silver Catalysts

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• 作者：Xuefeng Wang ; Xiuwen Han ; Yining Huang ; Junming Sun ; Suochang Xu ; Xinhe Bao
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：December 13, 2012
• 年：2012
• 卷：116
• 期：49
• 页码：25846-25851
• 全文大小：361K
• 年卷期：v.116,no.49(December 13, 2012)
• ISSN：1932-7455

文摘

The capabilities of silver catalysts with different particle sizes for oxygen activation were systematically studied by ¹⁷O solid-state NMR. The observation of ¹⁷O signal at around 0 ppm for silver catalysts indicates that silver activates ¹⁷O₂ molecules and that subsequent formation of active ¹⁷O species leads to the oxygen exchange with the mesoporous SiO₂ supports. The initial appearances of the ¹⁷O signals at different temperatures for three silver catalysts show that oxygen activation strongly depends on the size of Ag particle. Their ability of activating oxygen molecules is in the order Ag-3/MCM-41 > Ag-5/SBA-15 > Ag-10/SBA-15. Ag-3/MCM-41 is able to activate oxygen molecules and facilitates the oxygen exchange with the support even at room temperature. Although the NMR signal of active ¹⁷O species on silver catalysts is not observed directly, the approach described in this work can be used to indirectly determine the conditions on which the active oxygen species can be produced during catalytic oxidation reactions. The silver catalysts can also be used for ¹⁷O enrichment of the oxide-based materials under mild conditions.