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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
Author(s) -
Nakatsuka Kazuki,
Mori Kohsuke,
Okada Shusuke,
Ikurumi Shohei,
Kamegawa Takashi,
Yamashita Hiromi
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201402586
Subject(s) - catalysis , mesoporous material , selectivity , silylation , adsorption , chemistry , mesoporous silica , cyclohexane , desorption , surface modification , chemical engineering , inorganic chemistry , mesoporous organosilica , heterogeneous catalysis , organic chemistry , engineering
To enhance the catalytic activity in a selective one‐pot oxidation using in‐situ generated H 2 O 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 (SiF 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.