Comparison study on molybdena-titania supported on TUD-1 and TUD-C synthesized via sol-gel templating method: Properties and catalytic performance in olefins epoxidation

A direct comparison between nanostructured Technische Universiteit Delft-1 (TUD-1) and Technische Universiteit Delft-Crystalline (TUD-C) as catalyst supports for molybdenum doped titania catalysts was carried out. The characterizations results showed that TUD-1 is a mesoporous amorphous silicate material with high surface area and porosity. Meanwhile, TUD-C is an ordered mesoporous crystalline aluminosilicate matters featured high acidity. In fact, TUD-C was obtained from the modification of TUD-1 with the addition of aluminium isopropoxide as the zeolite precursor. The catalytic testing demonstrated TUD-1 supported 1 mol% molybdena doped titania was inactive for epoxidation of 1,2-epoxyoctane and showed moderate activity (18%-21% conversion yield) and selectivity (approximately 70%) in epoxidation reaction of 1,2-epoxycyclohexane (0.51 mmol) and styrene oxide (1.25 mmol). Meanwhile, TUD-C supported 1 mol% molybdena doped titania achieved remarkably higher conversion yield for 1,2-epoxyoctane (2.7 mmol), 1,2-epoxycyclohexane (4.8 mmol) and styrene oxide (6.2 mmol) respectively with 100% selectivity towards all 3 analytes under ambient condition with constant stirring. The results strongly indicated that high Bronsted and Lewis acidic sites existed within the TUD-C framework is the key factor for the exceptional oxidative capabilities for molybdena-titania catalysts.