Location of Al and acid strength of Brønsted acid in Beta zeolite

Abstract

Density functional theory (DFT) was applied to study the distribution of framework aluminum atoms at nine inequivalent T sites and the acidity of Brønsted acid sites in Beta zeolite. The calculation was carried out at B3LYP/6-31G (d,p) level based on the 8T cluster model. According to the calculated Al/Si substitution energies, (Al, H)/Si substitution energies, proton affinities and the adsorption energies of ammonia (NH3), we propose that the most favorable sites for Al substitution and Brønsted acid sites are at the T5 and T6 sites. The acidity of A15-014-Si9 is the highest among the preferred Brønsted acid sites and the A17-03-Sil site is the lowest. © Editorial office of Acta Physico-Chimica Sinica.