Direct Synthesis of Low-Coordinate Pd Catalysts Supported on SiO2 via Surface Organometallic Chemistry

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• 作者：Shengsi Liu ; J. Miles Tan ; Ahmet Gulec ; Neil M. Schweitzer ; Massimiliano Delferro ; Laurence D. Marks ; Peter C. Stair ; Tobin J. Marks
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：December 2, 2016
• 年：2016
• 卷：6
• 期：12
• 页码：8380-8388
• 全文大小：597K
• ISSN：2155-5435

文摘

Highly dispersed low-coordinate Pd sites on SiO₂ are fabricated by grafting the Pd^II PCP-pincer complex (^tBuPCP)Pd–OH (^tBuPCP = 2,6-C₆H₃(CH₂P^tBu₂)₂) on SiO₂, followed by calcination with ozone (100 °C) and reduction with H₂ (300 °C). The chemisorption process and structure of this organometallic complex on SiO₂ is established by solution-phase ¹H and ³¹P NMR and solid-state ³¹P CPMAS NMR spectroscopy, XPS, DRIFTS, and AC-HAADF-STEM. The CO adsorption properties of the Pd centers reveal a surprisingly high fraction of adsorption sites where CO is bound in a linear fashion, indicative of low-coordinate Pd. Furthermore, enhanced selectivity of these catalyst centers in aerobic alcohol oxidation versus a control catalyst argues that these low-coordinate sites are the catalytically active sites.