Prediction of pKa of FAU zeolite by DFTB

Abstract

Zeolite is aluminosilicate with a unique pore structure. Adsorbent properties and solid acidity are developed due to the unique pore structure, and it is used for adsorbent and hydrocarbon decomposition catalyst. In this study, the correlation between Si/All ratio of zeolite framework and pKa was investigated. In order to conduct this study, multiple models with different Si/Al ratios were created. H₃O⁺ was placed in the pores of these models, and the reactivity of acid sites was investigated by performing structural optimization calculations. As a result, proton desorption from the zeolite did not occur in the optimized structure of this model, and H₃O⁺ adsorption structure to zeolite was obtained. Therefore, it is a model which is not suitable for the evaluation of pKa, and it was found that other ingenuity is necessary.