Solvent-free and low template content synthesis of Ti-Beta zeolite via interzeolite transformation for oxidative desulfurization

Solvent-free and low-template synthesis of zeolite materials is the future direction of zeolite production, which meets the requirements of green chemistry. Ti-Beta zeolite with opened channel systems of the 3-dimensional 12 -membered ring is a promising industrial catalyst in the field of selective oxidations. Herein, nanosized Ti-Beta zeolites were successfully synthesized via interzeolite transformation of siliceous MOR zeolite using sample and commercially available tetraethylammonium hydroxide (TEAOH) as organic structure-directing agents under solvent-free and low-template-content (TEAOH/SiO2 = 0.2) conditions within a short crystallization time. The crystallization mechanism and Ti coordinated state were thoroughly investigated by numerous characterization techniques. It was found that the hydrothermal synthesis of Ti-Beta-M zeolites obeyed a liquid crystallization mechanism, during which pre-dissolution of the silicon source MOR zeolite was a critical step in achieving successful crystallization. Ti4+ ions mainly existed in the form of tetrahedrally coordinated states in zeolite framework. Thus Ti-Beta zeolites showed remarkable activity and reusability during the oxidative desulfurization of fuel oil. Moreover, the deactivated mechanism and regenerated method were also studied in detail. This work provides new guidance for solvent-free and low template content synthesis of metallosilicate zeolites.