Effect of Ti-modified mesoporous materials on the direct epoxidation of propylene by molecular oxygen

Ti- and Al-containing MCM-41 (Al-c-MCM-41 and Al–Ti-c-MCM-41) have been synthesized and tested for direct oxidation of propylene with molecular oxygen. The reaction occurred over Al- and Ti-containing MCM-41 like materials. Al–Ti-c-MCM-41 was found to be more effective than Al-c-MCM-41, while no product was formed for MCM-41 alone. The catalyst performances of Al–Ti-c-MCM-41 at 523 K were dependent on the Si/Al2 and Si/Ti ratios and the highest PO yield was 3% when Si/Al2 of 150 and Si/Ti ratios of 100 were used. A postulated scheme containing Al and Ti species is proposed.