%0 Generic
%A Sastre, German
%A Katada, Naonobu
%A Suzuki, Katsuki
%A Niwa, Miki
%D 2008
%T Computational Study of Brønsted Acidity of Faujasite. Effect of the Al Content on the Infrared OH Stretching Frequencies
%U https://acs.figshare.com/articles/dataset/Computational_Study_of_Br_nsted_Acidity_of_Faujasite_Effect_of_the_Al_Content_on_the_Infrared_OH_Stretching_Frequencies/2893351
%R 10.1021/jp807623m.s004
%2 https://acs.figshare.com/ndownloader/files/4591492
%K results show
%K silica models
%K Al content
%K OxH frequencies
%K neighbor Al centers
%K faujasite unit cell
%K O 4H
%K Si 34Al model
%K Computational Study
%K O 1H O 2H
%K 3H
%K Br ønsted Acidity
%K Infrared OH
%K composition Si 34Al
%K OH population
%X In this study we use the experimental data from a commercial sample of faujasite (Si/Al ∼ 2.5) and we compare the infrared OH stretching bands with periodic density functional calculations of a faujasite unit cell of composition Si34Al14O96H14 (Si/Al = 2.4). Assuming that O4H is not populated, the computational results show the following bands for O1H, O2H, and O3H: 3588−3689, 3555−3588, and 3517−3560 cm−1, respectively, which are in good agreement with the experimental values of 3648, 3571, and 3526 cm−1, respectively. We have studied how the OxH frequencies (x = 1−4) change due to the presence of two neighbor Al centers (Si46Al2O96H2, Si/Al = 23), with respect to the isolated case (Si47Al1O96H1, Si/Al = 47). The experimental infrared bands cannot be explained by the high silica models (Si/Al = 47, 23) and can only be explained when taking into account (i) the experimental Al content, by using a Si34Al14O96H14 model, (ii) the experimental OH population, and (iii) the experimental Si(nAl) (n = 0−4) population.
%I ACS Publications