The mechanism of promoter-induced zeolite nanosheet crystallization under hydrothermal and microwave irradiation conditions

Abstract

The mechanism of MFI zeolite nanosheet formation was established under accelerated conditions using perchlorate ions and fresh zeolite seeds as promoters. The results indicated that the particles after pretreatment were initially formed as an ordered amorphous assembly that was stepwise converted into zeolite nanosheets. The MFI nanosheet fabrication occurs through the transformation from an MCM-41-like structure to a KIT-1-like structure, lamellar structure, disordered lamellar structure and MFI nanosheets. The application of uniform microwave heating with the addition of promoters made it possible to obtain the assembly of all types of structures in 6 hours. The MFI nanosheet generation process was analyzed by X-ray powder diffraction, IR spectroscopy, N₂ adsorption isotherm measurements, SEM and TEM. A linear function of selectivity for bulky products in the solid acid alkylation process in proportion to the concentration of Brønsted acid sites has been determined for the materials possessing a mesophase.