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首页> 外文期刊>Chemistry: A European journal >Hydrophobic Modification of Pd/SiO_2@Single-Site Mesoporous Silicas by Triethoxyfluorosilane: Enhanced Catalytic Activity and Selectivity for One-Pot Oxidation
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Hydrophobic Modification of Pd/SiO_2@Single-Site Mesoporous Silicas by Triethoxyfluorosilane: Enhanced Catalytic Activity and Selectivity for One-Pot Oxidation

机译：三乙氧基氟硅烷对Pd / SiO_2 @单孔介孔二氧化硅的疏水改性：增强的催化活性和一锅氧化的选择性

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摘要

To enhance the catalytic activity in a selective onepot oxidation using in-situ generated H_2O_2, a hydrophobically modified core–shell catalyst was synthesized by means of a simple silylation reaction using the fluorine-containing silylation agent triethoxyfluorosilane (TEFS, SiF(OEt)_3). The catalyst consisted of a Pd-supported silica nanosphere and a mesoporous silica shell containing isolated Ti~(IV) and F ions bonded with silicon (Si-F bond). Structural analyses using XRD and N_2 adsorption–desorption suggested that the mesoporous structure and large surface area of the mesoporous shells were retained even after the modification. During the one-pot oxidation of sulfide, catalytic activity was enhanced significantly by increasing the amount of fluorine in the shell. A hydrophobic surface enhanced adsorption of the hydrophobic reactant into the mesopore, while the less hydrophobic oxygenated products efficiently diffused into the outside of the shell, which improved the catalytic activity and selectivity. In addition, the present methodology can be used to enhance the catalytic activity and selectivity in the one-pot oxidation of cyclohexane by using an Fe-based core–shell catalytic system.
机译：为了提高使用原位生成的H_2O_2的选择性一锅氧化的催化活性，使用含氟甲硅烷基化剂三乙氧基氟硅烷（TEFS，SiF（OEt）_3）通过简单的甲硅烷基化反应合成了疏水改性的核壳催化剂。该催化剂由钯负载的二氧化硅纳米球和介孔二氧化硅壳组成，其中含有孤立的Ti〜（IV）和与硅键合的F离子（Si-F键）。使用XRD和N_2吸附-解吸的结构分析表明，即使改性后，介孔结构和大表面积的介孔壳仍然保留了。在硫化物的一锅法氧化过程中，通过增加壳中的氟含量，可显着提高催化活性。疏水性表面增强了疏水性反应物对中孔的吸附，而疏水性较低的氧化产物有效地扩散到了壳的外部，从而提高了催化活性和选择性。此外，通过使用铁基核壳催化体系，本方法可用于增强环己烷的一锅法氧化的催化活性和选择性。

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