Dry Gel Conversion Method for the Synthesis of Organic–Inorganic Hybrid MOR Zeolites with Modifiable Catalytic Activities

Abstract

Dry gel conversion (DGC) technique is first applied in the synthesis of organic-inorganic hybrid aluminosilicate zeolites. By using the DGC method, methylene-bridged organic-inorganic hybrid zeolites with an MOR topology are synthesized without organic additive, which are structurally characterized by powder XRD, FTIR, solid-state Si-29, C-13, Al-27 MAS NMR, SEM, elemental analysis, XRF, XPS, and N-2 adsorption techniques. This work first reports that thus-synthesized methylene-bridged hybrid zeolites can be successfully bestowed with excellent catalytic activities through different modification treatments. Co2+-exchanged hybrid zeolites are applied in the epoxidation of alkenes with air to achieve good conversions and selectivities. Especially, methylene-bridged hybrid zeolites can be sulfonated with fuming sulfuric acid to form acidic MOR-SO3H catalyst, which exhibits highly catalytic activity for the acid-catalyzed condensation reaction of cyclohexanone and glycol. This method will be one potential route for the fabrication of organic-inorganic hybrid zeolite or related molecular sieve catalysts.