Theoretical investigation of Fe and Cu cations hosted within the MOR zeolite framework

• Published in: Materials today communications 2024-12, Vol.41, p.110418, Article 110418
• Main Authors: Antúnez-García, Joel, Ponce-Ruiz, Jesus L.A., Núñez-González, Roberto, Petranovskii, Vitalii, Murrieta-Rico, Fabian N., Serrato, Armando Reyes, Shelyapina, Marina G., Xiao, Mufei, Zamora, Jonathan
• Format: Article
• Language: English
• Subjects: Density functional theory (DFT); Magnetic properties; MOR zeolite; α-Fe
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2024.110418

Periodic Density Functional Theory (DFT) calculations were used to determine the preferred localization sites of Fe2+ and Cu2+ exchangeable cations in mordenite zeolite. The results revealed that a single Fe2+ ion preferred to occupy the main channel, whereas Cu2+ ion chosen to inhabit the secondary channel. When both Fe2+ and Cu2+ ions were simultaneously present in the zeolite (bimetallic material), both cations were maximally separated within the unit cell. Notably, the iron cation was embedded in a six-membered ring (6MR) with an α-Fe configuration (FeIIO4 unit), which is observed experimentally in many zeolites; this structure was formed despite the fact that, unlike many other zeolites, in mordenite the 6MR ring contains only one Al ion. Additionally, to evaluate the stability of α-Fe, a hydroxyl radical was introduced into the system to interact directly with the iron ion. The results show that in the absence of Cu2+, iron ion Fe2+ is oxidized to Fe3+. However, when Cu2+ is present in the zeolite framework, the coordination of iron with 6MR is preserved despite the formation of a bond with the hydroxyl radical. [Display omitted]