Cubic Pm3n mesoporous aluminosilicates assembled from zeolite seeds as strong acidic catalysts

Abstract

Cubic Pm3n mesoporous aluminosilicates isomorphous to SBA-1, with 3D interconnected pore structures, were assembled from Al-incorporating zeolite seeds at around pH 9 using cetyltriethylammonium bromide as a pore-directing agent. The resultant series of materials (termed Al–ZSBA-1) has the advantages of strong acidity from the zeolitic structure and good diffusivity of bulky reactants from the 3D interconnected mesopores. Al–ZSBA-1, with Al loading up to an Al/Si molar ratio of 0.057, still retains a cubic Pm3n structure and high surface area (ca. 600 m² g⁻¹). The acidities were stronger than the counter materials prepared using sodium silicate as the silica source (referred to as Al–SBA-1-alk). Moreover, all the Al(III) ions in Al–ZSBA-1 retained their tetrahedral coordination after calcination at 823 K, while a portion of Al(III) in Al–SBA-1-alk became octahedrally coordinated. When tested for the catalytic alkylation of 2,4-di-tert-butylphenol with cinnamyl alcohol, Al–ZSBA-1 gave higher flavan selectivities and yields in comparison to Al–SBA-1-alk, ZSM-5, and beta zeolites.