10.1021/jp807623m.s004
German Sastre
German
Sastre
Naonobu Katada
Naonobu
Katada
Katsuki Suzuki
Katsuki
Suzuki
Miki Niwa
Miki
Niwa
Computational Study of Brønsted Acidity of Faujasite. Effect of the Al Content on the Infrared OH Stretching Frequencies
American Chemical Society
2008
results show
silica models
Al content
OxH frequencies
neighbor Al centers
faujasite unit cell
O 4H
Si 34Al model
Computational Study
O 1H O 2H
3H
Br ønsted Acidity
Infrared OH
composition Si 34Al
OH population
2008-12-11 00:00:00
Dataset
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
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 Si<sub>34</sub>Al<sub>14</sub>O<sub>96</sub>H<sub>14</sub> (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<sup>−1</sup>, respectively, which are in good agreement with the experimental values of 3648, 3571, and 3526 cm<sup>−1</sup>, respectively. We have studied how the OxH frequencies (<i>x</i> = 1−4) change due to the presence of two neighbor Al centers (Si<sub>46</sub>Al<sub>2</sub>O<sub>96</sub>H<sub>2</sub>, Si/Al = 23), with respect to the isolated case (Si<sub>47</sub>Al<sub>1</sub>O<sub>96</sub>H<sub>1</sub>, 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 Si<sub>34</sub>Al<sub>14</sub>O<sub>96</sub>H<sub>14</sub> model, (ii) the experimental OH population, and (iii) the experimental Si(<i>n</i>Al) (<i>n</i> = 0−4) population.