Abstract
Highly ordered three-dimensional V-SBA-16 materials were prepared at mild acidic condition by tuning the key parameters for metal substitution such as molar ratio of silica to 1-butanol (TEOS/BuOH), water to hydrochloric acid (H
2O/HCl ratio) and hydrothermal aging time in the initial gel containing 0.0035 F127/0.01
V/0.91–2.00 TEOS/2.08–0.76 BuOH/0.70–1.16 HCl/118.6–120.1 H
2O. The extent of mesopore structural ordering was confirmed by small-angle X-ray scattering and nitrogen adsorption isotherms. The presence of incorporated vanadium in a highly dispersed tetrahedral state was confirmed by electron spin resonance (ESR) and Drs-UV spectroscopy. The NH
3-TPD profile showed that the materials tend to posses medium-acidic V–OH sites; strong-acidic sites increased with decreasing Si/V ratios. TEM analysis shows that the cubic phase was stable up to 3.6
wt.% vanadium loading. The activity of V-SBA-16 was tested for the selective oxidation of ethylbenzene to acetophenone by studying the effect of temperatures, time on stream, and the mole ratio of ethylbenzene to TBHP.