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Spectroscopic Characterization of Mixed Titania-Silica Xerogel Catalysts

Published online by Cambridge University Press:  10 February 2011

MA Holland ,
DM Pickup ,
G Mountjoy ,
SC Tsang ,
GW Wallidge ,
RJ Newport  and
ME Smith
MA Holland
Affiliation:
contact author: [email protected]
DM Pickup
Affiliation:
School of Physical Sciences, University of Kent at Canterbury, CT2 7NR, UK.
G Mountjoy
Affiliation:
School of Physical Sciences, University of Kent at Canterbury, CT2 7NR, UK.
SC Tsang
Affiliation:
Centre for Catalysis, Department of Chemistry, University of Reading, RG6 6AD, UK.
GW Wallidge
Affiliation:
Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.
RJ Newport
Affiliation:
School of Physical Sciences, University of Kent at Canterbury, CT2 7NR, UK.
ME Smith
Affiliation:
Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.
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Abstract

The synthesis of high surface area (TiO2)0.18(SiO2)0.82xerogels has been achieved using the sol-gel route. Heptane washing was used before the drying stage to minimise capillary pressure and hence preserve pore structure and maximise the surface area. The as-prepared xerogels were tested for their catalytic activity using the epoxidation of cyclohexene with tert-butyl hydrogen peroxide (TBHP) as a test reaction. Surface areas up to 450 m2g-1 were achieved with excellent selectivities and reasonable percent conversions. SAXS data has identified that heptane washing during drying, in general, results in a preservation of the pore structure, and produces more effective catalysts with higher surface areas and larger pore diameters. Fr-IR spectroscopy has revealed that the catalytic activity is dependant upon the number of Si-O-Ti linkages, inferring intimate mixing of the precursors at the atomic level. XANES data reveals the presence of reversible 4/6-fold Ti sites that are thought to be ‘active’ catalytic sites. The most effective catalyst was produced with a calcination temperature of 500°C, and a heating rate of 5 °Cmin-l

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 590: Symposium R – Applications of Synchrotron Radiation Techniques…V , 1999 , 77
Copyright
Copyright © Materials Research Society 2000

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References

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