Enhanced Activity and Selectivity in the One-Pot Hydroxylation of Phenol by Pd/SiO2@Fe-Containing Mesoporous Silica Core–Shell Catalyst

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• 作者：Shohei Ikurumi ; Shusuke Okada ; Kazuki Nakatsuka ; Takashi Kamegawa ; Kohsuke Mori ; Hiromi Yamashita
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：January 9, 2014
• 年：2014
• 卷：118
• 期：1
• 页码：575-581
• 全文大小：389K
• ISSN：1932-7455

文摘

A novel approach to enhance the catalytic performances in one-pot hydroxylation of phenol into catechol and hydroquinone was examined using core鈥搒hell type catalysts which consist of Pd nanoparticles (NPs) for direct synthesis of H₂O₂ from H₂ and O₂ and Fe-containing mesoporous silica (Fe-MS) for hydroxylation of phenol using in situ produced H₂O₂. We have newly prepared three types of core鈥搒hell catalysts: (i) Pd/SiO₂ core covered with Fe-MS (Pd/SiO₂@Fe-MS), (ii) SiO₂ core covered by Fe-MS with randomly distributed Pd NPs within the mesoporous silica structure (SiO₂@Pd(R)/Fe-MS), where (R) indicates random, and (iii) SiO₂ core covered by Fe-MS with Pd NPs deposited on the outer surface of the mesopores SiO₂@Pd(S)/Fe-MS, where (S) indicates the surface. The effects of the relative position between the Pd NPs and Fe-MS on the catalytic activity and the selectivity were investigated. As a result, it was clearly demonstrated that the relative position significantly affects not only the reaction rate but also the product selectivity, and the Pd/SiO₂@Fe-MS showed the best performance among them. The applicability of the Pd/SiO₂@Fe-MS is also demonstrated in the one-pot oxidation of adamantine. The present design strategy offers a very simple and efficient methodology to realize a one-pot reaction.