Synthesis and structural properties of hierarchically structured aluminosilicates with zeolite Y (FAU) frameworks

Abstract

Hierarchical zeolites have emerged as an important class of materials for applications in adsorption, separation and catalysis. Herein, hierarchical zeolite Y was hydrothermally synthesized using an organosilane surfactant, which was added into the conventional synthesis composition for crystalline microporous aluminosilicates as mesopore-generating agent. X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) (with KBr and pyridine), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), ²⁷Al magic-angle spinning nuclear magnetic resonance (²⁷Al MAS NMR) and N₂ adsorption–desorption isotherms were used to characterize structural and textural features of the hierarchical zeolite Y. In addition, the molecular properties of the organosilane surfactant were investigated by density functional theory calculation. The hierarchical zeolite Y with mesoporous characteristics and the microporous crystalline structure of zeolites exhibited high catalytic activity and resistance to deactivation in the aldol condensation of benzaldehyde with n-butyl alcohol, as compared with conventional zeolite Y. This phenomenon could be attributed to improved mass transport ability of guest species through the interconnected micropore-to-mesopore networks. Such a hierarchical zeolite Y, that combines the advantages of two different pore structures, may find potential applications as advanced materials in various fields such as adsorption, separation and catalysis.