2025 AIChE Annual Meeting

(628f) Molecular Simulations Study on the Stiffening of Zeolites Induced By Gas Adsorption

Authors

Alina Emelianova, New Jersey Institute of Technology
Gennady Gor, New Jersey Institute of Technology
Zeolites are widely used for gas adsorption applications thanks to their crystalline porous structure, high surface area, and mechanical stability. Experiments using magnetoelastic sensors showed that gas adsorption can noticeably alter the elastic moduli of zeolites, making the zeolite samples much stiffer [1]. Here, we used molecular simulations to explore this effect in silico. We calculated separately the elastic moduli of dry zeolites, adsorbed fluids, and zeolite-fluid composites. We considered carbon dioxide in two zeolite structures -- 13X and 4A [2]. The moduli of the composite systems were calculated using two alternative approaches: from the moduli of the constituents (unsaturated zeolite and adsorbed fluid) using the Gassmann equation and Monte Carlo [3], and directly, using the Birch-Murnaghan equation of state and molecular dynamics. Figure 1 shows the resulting bulk moduli after following these two approaches. The direct approach showed better agreement with the experimental observations, showing approximately an increase in the bulk modulus of zeolites due to gas adsorption. Our results show that the elasticity of microporous materials can be highly sensitive to gas adsorption, even if the bulk modulus of the adsorbed fluid is one order of magnitude lower than the bulk modulus of the material (bulk modulus of adsorbed CO2 in the zeolites raised to ~2.5 GPa, while the bulk modulus of the composite increased ~20 GPa from the Birch-Murnaghan equation of state), and also suggest that the elasticity of fluids adsorbed in micropores is qualitatively different from the elasticity of the same fluids in mesopores [4].

Acknowledgements

Acknowledgement: This work was supported by the National Science Foundation (grants CBET-1944495 and CBET-2344923).

References

[1] T. Baimpos; I. G. Giannakopoulos; V. Nikolakis, D. Kouzoudis, Effect of Gas Adsorption on the Elastic Properties of Faujasite Films Measured Using Magnetoelastic Sensors. Chem. Mater., 20 (2008) 1470–1475.
[2] A. Emelianova; C. Balzer; G. Reichenauer; G. Y. Gor, Adsorption-Induced Deformation of Zeolites 4A and 13X: Experimental and Molecular Simulation Study, Langmuir, 39 (2023) 11388–11397.
[3] G. Y. Gor; B. Gurevich, Gassmann Theory Applies to Nanoporous Media. Geophys. Res. Lett. 45 (2018) 146–155.
[4] S.A. Flores Roman; A. Emelianova; G. Y. Gor, Molecular Simulation Study of Elasticity of Fluid-Saturated Zeolites, J. Phys. Chem. C. 2025, 129 (3), 1841-1849.