Under high temperature and external pressures, up to 6 GPa, the structural changes of two Linde Type A (LTA) zeolites were investigated by Lattice Dynamics and energy minimization techniques. In our simulations classical empirical potentials have been used. The unit cell of ZK4 and Na-A structures were thermodynamically stable in the studied range of temperature (0 ≤ T ≤ 1300 K). The analysis of the unit cell geometry and vibrational spectra at selected pressures suggest the loss of crystallinity of the aluminosilicate structures. We found that a low-density amorphous phase is reached at pressures around 2.5-5.0 GPa. These results are compatible with Raman and X-ray diffraction studies. We obtained the structural properties of the new phase. In addition, we report the simulated elastic constants and the Bulk modulus of ZK4 and Na-A zeolites at ambient pressure. The simulated results are in semi-quantitative agreement with the experiment. Finally, we report a comparison of the results of two potential models in order to evaluate the impact of rigidity of the SiO4and AlO4tetrahedra on the zeolite stability.

Computational studies on the effects of pressure and temperature on zeolite framework structures / Demontis, Pierfranco; Gulín-González, Jorge; Ruiz-Puentes, Andrés; San, Marco; Gabrieli, Andrea; Suffritti, Giuseppe B.. - In: ADVANCED SCIENCE LETTERS. - ISSN 1936-6612. - 23:6(2017), pp. 5824-5827. [10.1166/asl.2017.9040]

Computational studies on the effects of pressure and temperature on zeolite framework structures

Demontis, Pierfranco;Gabrieli, Andrea;
2017

Abstract

Under high temperature and external pressures, up to 6 GPa, the structural changes of two Linde Type A (LTA) zeolites were investigated by Lattice Dynamics and energy minimization techniques. In our simulations classical empirical potentials have been used. The unit cell of ZK4 and Na-A structures were thermodynamically stable in the studied range of temperature (0 ≤ T ≤ 1300 K). The analysis of the unit cell geometry and vibrational spectra at selected pressures suggest the loss of crystallinity of the aluminosilicate structures. We found that a low-density amorphous phase is reached at pressures around 2.5-5.0 GPa. These results are compatible with Raman and X-ray diffraction studies. We obtained the structural properties of the new phase. In addition, we report the simulated elastic constants and the Bulk modulus of ZK4 and Na-A zeolites at ambient pressure. The simulated results are in semi-quantitative agreement with the experiment. Finally, we report a comparison of the results of two potential models in order to evaluate the impact of rigidity of the SiO4and AlO4tetrahedra on the zeolite stability.
Computational studies on the effects of pressure and temperature on zeolite framework structures / Demontis, Pierfranco; Gulín-González, Jorge; Ruiz-Puentes, Andrés; San, Marco; Gabrieli, Andrea; Suffritti, Giuseppe B.. - In: ADVANCED SCIENCE LETTERS. - ISSN 1936-6612. - 23:6(2017), pp. 5824-5827. [10.1166/asl.2017.9040]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/211823
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