Aluminium-containing mesoporous benzene-silicas with crystal-like pore wall structure

Abstract

Mesoporous benzene-silicas with a high content of tetrahedral aluminium in the framework (Si/Al = 37 and 59) were successfully synthesized, as evidenced by X-ray diffraction, N₂ sorption analyses, transmission electron microscopy and solid state ¹³C CP-MAS, ²⁷Al and ²⁹Si MAS NMR spectroscopy. These materials have well-ordered 2D hexagonal mesostructure with a molecular scale periodicity in the pore walls. The existence of the phenylene groups in the framework greatly enhances the hydrothermal stability of the aluminium-containing mesoporous benzene-silicas. The acidity of the mesoporous benzene-silicas arising from the incorporated aluminium was measured by the FT-IR spectra of pyridine adsorption measurements. The organic groups bridged in the mesoporous framework affect significantly the acidity of the resultant materials although most aluminium atoms are in tetrahedral coordination. These materials are catalytically active for alkylation of 2,4-di-tert-butylphenol with cinnamyl alcohol.