Postsynthesis of FAU-type stannosilicate as efficient heterogeneous catalyst for Baeyer-Villiger oxidation

Sn-Y zeolite with hierarchical pore system was prepared using the atom-planting method from properly dealuminated USY zeolite and SnCl₄ vapor. Sn ions were tetrahedrally incorporated into the zeolite framework by the reaction between the SnCl₄ molecules and the "silanol nests" generated by steaming and acid treatment. The amount of incorporated Sn depended closely on the dealumination degree, in which the maximum Sn content of 2.6 wt.% was achieved when the parent USY zeolite was treated by precisely controlled acid treatment. Compared with Sn-MFI, Sn-MWW, Sn-MCM-41, hydrothermally synthesized or postsynthesized Sn-Beta, thus prepared Sn-Y zeolite showed excellent catalytic properties in the Baeyer-Villiger oxidation of 2-adamantanone using hydrogen peroxide or tert-butyl hydroperoxide as oxidant, which was mainly attributed to the open pore system contributed by 3-dimensional 12-membered ring channels and dealumination-derived intracrystal mesoporosity.