DOI: https://doi.org/10.9767/jcerp.20805

Effect of Si/Al Ratio on Competitive CO₂/H2O Adsorption in FAU Zeolite for Humid Flue Gas Capture: A Computational Study

Directorate General of Maysan Education, Ministry of Education, Iraq

Received: 29 Jul 2026; Revised: 10 Aug 2026; Accepted: 12 Aug 2026; Available online: 16 Aug 2026; Published: 26 Dec 2026.
Editor(s): Istadi Istadi
Open Access Copyright (c) 2026 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group
Creative Commons License This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
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Abstract

Carbon capture from humid flue gas is problematic. Many microporous adsorbents are poisoned by water vapor. This research aims to study the effect of the Si/Al ratio on the competitive adsorption of CO₂ and H₂O in FAU-type zeolites, as well as evaluate their performance in capturing humid flue gases. Grand Canonical Monte Carlo (GCMC) simulations were performed to study the competitive adsorption of equimolar CO₂/H₂O mixtures at 298 K in two FAU zeolites: Zeolite 13X (Na₇₇, Si/Al ≈ 1.5) and Zeolite Y (Na₄₉, Si/Al≈2.92). The results showed that Zeolite 13X shows higher adsorption of CO₂ under low pressures, with the phenomenon of the roll-over occurring in the case of high pressure because of competitive adsorption with H₂O. In turn, the adsorption of CO₂ for Zeolite Y remained stable over the entire pressure range and exhibited lower H₂O uptake. Isosteric heats of CO₂ adsorption on the zeolites are 15.71 kcal/mol for Zeolite 13X and 13.23 kcal/mol for Zeolite Y. The energy of CO₂ binding in the presence of H₂O decreased by 1.14 kcal/mol for Zeolite 13X and for 2.03 kcal/mol for Zeolite Y. These findings indicate that high-silica FAU zeolites, such as Zeolite Y, are efficient CO₂ adsorbents. Copyright © 2026 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Keywords: CO₂ adsorption; Zeolite 13X; Zeolite Y; FAU zeolite; GCMC simulation; carbon capture; competitive adsorption; humidity; water poisoning; isosteric heat

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Section: Original Research Articles
Language : EN
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