Ionic Liquid Modification of Hierarchical ZSM-5 for Solvent-Free Insertion of CO2 to Epoxides

Abstract

Hierarchical H-form ZSM-5 (h-ZSM-5) was synthesized and successfully functionalized with imidazolium-based ionic liquids for solvent-free insertion of carbon dioxide to epoxides and synthesis of cyclic carbonate. Tetrapropyl ammonium hydroxide and polyurethane foam were used as soft and hard templates, respectively, to introduce mesoporosity in the structure. The synthesized hierarchical H-form ZSM-5 provided a large surface area for covalent attachment of imidazolium-based ionic liquids to produce h-ZSM-5-IL. The successful synthesis of the new catalyst was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, the Brunauer–Emmett–Teller method, and scanning electron microscopy and utilized for the insertion of carbon dioxide to epoxides and production of cyclic carbonate under solvent-free conditions. High conversion and selectivity for the synthesis of cyclic carbonate and recovery of the catalyst for five consecutive times without loss of catalytic activity are the advantages of this newly synthesized catalyst.