Abstract
A systematic study was carried out to examine the viable synthesis condition at high acidic condition for the direct incorporation of a high level of vanadium into the 3D cubic arrangement of SBA-16 molecular sieves. The extent of mesopore structural ordering was determined by X-ray diffraction, N-2 physisorption, SEM and TEM analysis. The coordination and nature of the V sites were characterized by FT-Raman, electron spin resonance, Si-29 nuclear magnetic resonance spectroscopy, UV-visible diffuse reflectance spectroscopy and NH3-TPD analysis. The surface area of calcined V-SBA-16 was similar to 1000 m(2)/g, while the mesopore volume of the SBA-16 cage ranged from 0.3 to 0.6 cm(3)g(-1). The pore size distribution was similar to 3.0 nm with a wall thickness of similar to 9.7 nm at the maximum. The Si/V ratios as determined by ICP-OES technique was varied from 438 to 8, respectively. The calcined samples exhibited promising catalytic activity in the oxidation of styrene with tert-butyl hydroperoxide as an oxidant. (c) 2008 Elsevier Inc. All rights reserved.