A computational study on stabilization trends of the adsorption complexes of C1-C4 primary alcohols on modified acidic zeolites.

Articles in Press

Document Type : Research Article

Authors

1 Department of Materials Science University of Ioannina

2 Department of Chemistry University of Ioannina

3 Department of materials science University of Ioannina

Abstract

The adsorption complexes and the binding energies of a series of aliphatic alcohols on Ti and P modified acidic zeolites have been studied computationally employing combined quantum mechanics/molecular mechanics (QM/MM) methods suit for large-scale calculation. The investigation has been carried out using an extended 84T cluster model with one hydroxyl Brønsted acidic site. This model, has been studied with the help of the two-layered ONIOM2 schemes: B3LYP/6-31+G(d,p):UFF and B3LYP-D3/6-31+G(d,p): UFF approach, to test its ability to reproduce the experimental heats of adsorption available in the literature. The use of the B3LYP-D3 technique has led to a considerable improvement in the B3LYP results, underlining the critical role of the dispersion forces. The calculations show higher deprotonation energies and a decreasing acidic character upon modification. The 84T cluster model appears to offer an attractive alternative to periodic simulations on the entire H-FAU unit cell, resulting in virtually identical final adsorption enthalpies with the latter method, at a moderate cost. The modified clusters show a considerable reduction of the order of 3 to 4 kcal/ mol in adsorption energy for all alcohol molecules, especially emphasized in the Ti-modification in comparison to that of Al- zeolite.

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Iranian Journal of Chemistry and Chemical Engineering

Articles in Press, Accepted Manuscript
Available Online from 04 October 2023

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