Tertiary butylation of phenol over hexagonal p6mm mesoporous aluminosilicates with enhanced acidity

Through a two-step crystallization procedure and using cetyltrimethylammonium bromide (CTAB) as template, hexagonal p6mm mesoporous aluminosilicates (denoted as MB41) with nSi/nAl ratios from 15 to 50 have been assembled from the preformed zeolite Beta precursors under alkaline conditions. MB41 materials were characterized by powder XRD, N2 adsorption–desorption, 27Al-MAS NMR and pyridine adsorbed FT-IR spectroscopy techniques. Results obtained show that they are highly ordered hexagonal symmetry, and Al atoms are in tetrahedral coordination. Compared with classic Al-MCM-41, MB41 materials have stronger acidity, and also show significantly higher activities in the alkylation reaction of phenol with tert-butanol. At the reaction temperature of 145 °C, phenol conversion of 85.7% and 2,4-DTBP selectivity of 43.1% over MB41(25) are observed, but these over Al-MCM-41(25) are only 61.3% and 13.2%, respectively.

Graphical abstractEnhancedly acidic mesoporous MB41 materials have been prepared by the self-assembly of the preformed zeolite Beta precursors under alkaline conditions. In the IR spectra of pyridine adsorption, MB41(25) displays stronger acidity than amorphous Al-MCM-41(25). In the tert-butylation reaction of phenol, MB41(25) catalyst shows obviously higher catalytic activity than Al-MCM-41(25). Figure optionsDownload full-size imageDownload as PowerPoint slide