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Effect of silanol groups on the acidic and catalytic properties of alkylsulphoacidic silicas and SiO2/narion nanocomposites

Effect of silanol groups on the acidic and catalytic properties of alkylsulphoacidic silicas and SiO2/narion nanocomposites
Effect of silanol groups on the acidic and catalytic properties of alkylsulphoacidic silicas and SiO2/narion nanocomposites
Sets of silicas covalently modified with alkylsulphoacidic groups (SiO2-SO3H) and nanocomposites of silica with superacidic Nafion(R)\ polymer (SiO2/Nafion) were synthesised. End-capping the silanol groups with trimethylsilyl groups was used to obtain surface hydrophobisation. The materials obtained were characterised by nitrogen and water adsorption measurements, MAS NMR spectroscopy and dielectric relaxation spectroscopy (DRS). The acidity of the materials was tested by P-31 MAS NMR spectroscopic examination of samples with adsorbed triethylphosphine oxide (TEPO). It was demonstrated that end-capping excluded part of the surface silanol groups from interaction with acidic groups, thereby causing the sulphonic groups to exhibit an increased acidity. With SiO2-SO3H, end-capping also increased their catalytic activity in the synthesis of ethyl t-butyl ether (ETBE). However, end-capping had a negligible effect on the catalytic properties of SiO2/Nafion, probably because the catalytic reaction occurred inside the Nafion polymer nanoparticles.
solid acids, surface, phase
0263-6174
615-625
Alekseev, Serge A.
8a99bc51-105c-4e8c-9e81-4e74cf5cc556
Zaitsev, V.N.
4d2da248-21d0-47ea-8259-3df679d94ca1
Alekseev, A.N.
04f967ed-d08b-44c1-8246-348a4c840bf4
Kochkin, Yu N.
1d0d54e0-2138-43ca-83b5-7b7ba5bf1bd2
Evans, J.
05890433-0155-49fe-a65d-38c90ea25c69
Alekseev, Serge A.
8a99bc51-105c-4e8c-9e81-4e74cf5cc556
Zaitsev, V.N.
4d2da248-21d0-47ea-8259-3df679d94ca1
Alekseev, A.N.
04f967ed-d08b-44c1-8246-348a4c840bf4
Kochkin, Yu N.
1d0d54e0-2138-43ca-83b5-7b7ba5bf1bd2
Evans, J.
05890433-0155-49fe-a65d-38c90ea25c69

Alekseev, Serge A., Zaitsev, V.N., Alekseev, A.N., Kochkin, Yu N. and Evans, J. (2004) Effect of silanol groups on the acidic and catalytic properties of alkylsulphoacidic silicas and SiO2/narion nanocomposites. Adsorption Science & Technology, 22 (8), 615-625. (doi:10.1260/0263617042844175).

Record type: Article

Abstract

Sets of silicas covalently modified with alkylsulphoacidic groups (SiO2-SO3H) and nanocomposites of silica with superacidic Nafion(R)\ polymer (SiO2/Nafion) were synthesised. End-capping the silanol groups with trimethylsilyl groups was used to obtain surface hydrophobisation. The materials obtained were characterised by nitrogen and water adsorption measurements, MAS NMR spectroscopy and dielectric relaxation spectroscopy (DRS). The acidity of the materials was tested by P-31 MAS NMR spectroscopic examination of samples with adsorbed triethylphosphine oxide (TEPO). It was demonstrated that end-capping excluded part of the surface silanol groups from interaction with acidic groups, thereby causing the sulphonic groups to exhibit an increased acidity. With SiO2-SO3H, end-capping also increased their catalytic activity in the synthesis of ethyl t-butyl ether (ETBE). However, end-capping had a negligible effect on the catalytic properties of SiO2/Nafion, probably because the catalytic reaction occurred inside the Nafion polymer nanoparticles.

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Published date: 2004
Keywords: solid acids, surface, phase

Identifiers

Local EPrints ID: 20113
URI: https://eprints.soton.ac.uk/id/eprint/20113
ISSN: 0263-6174
PURE UUID: 9039e7f1-1bf4-4de7-a42d-0e7441b55f25

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Date deposited: 23 Feb 2006
Last modified: 17 Jul 2017 16:29

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