Revisit the molecular sieving mechanism in LTA zeolites: does size really matter?

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dc.contributor.authorSun, MZen_AU
dc.contributor.authorHanif, Aen_AU
dc.contributor.authorWang, TQen_AU
dc.contributor.authorTao, ZYen_AU
dc.contributor.authorChen, DSen_AU
dc.contributor.authorLi, Gen_AU
dc.contributor.authorLiu, Zen_AU
dc.contributor.authorGu, QFen_AU
dc.contributor.authorWebley, PAen_AU
dc.contributor.authorShang, Jen_AU
dc.date.accessioned2025-07-03T03:59:02Zen_AU
dc.date.available2025-07-03T03:59:02Zen_AU
dc.date.issued2025-03-13en_AU
dc.date.statistics2025-07-03en_AU
dc.description.abstract“Molecular sieving”-based separation of similar-sized gases (e.g., CO2, N2, and CH4) is both desirable and challenging due to the difficulty of obtaining adsorbents with pore sizes that permit exclusive admission. The “molecular trapdoor effect” offers a promising solution, focusing on the difference in gases’ ability to dynamically open a “door” via interaction with the “door-keeper” in adsorbents, rather than relying on size-sieving. In this study, we studied Na and K-exchanged zeolites with Si/Al ratios ranging from 1 to 2.2 and demonstrate that potassium form zeolite LTA with a Si/Al ratio of 2.2 (referred to as r2KLTA) exhibits the molecular trapdoor mechanism, as evidenced by CO2/N2 separation, gas adsorption, and in situ powder X-ray diffraction experiments. The K+ ion, acting as the door-keeper, is situated at the eight-membered ring (8MR) pore aperture of LTA, enabling the exclusive separation. Notably, this separation mechanism diverges from the traditional static sieving model and suggests that gas molecule admission is regulated by dynamic door-opening. In contrast to previous reports showing negligible CO2 adsorption in r1KLTA (3 A zeolite), our findings reveal a significant CO2 uptake, which points to the trapdoor mechanism as the key factor. This study offers new insights into the classical zeolite molecular sieve (3 A) for gas separation, where gas selectivity is governed by dynamic door-opening rather than static interactions. The demonstrated molecular trapdoor effect in r2LTA zeolites opens new possibilities for designing adsorbents with high selectivity and enhanced kinetics at optimal temperatures. © 2025 Springer Natureen_AU
dc.description.sponsorshipThis work was financially supported by the Science and Technology Innovation Commission of Shenzhen Municipality (Ref: JCYJ20240813153123031), the Research Grants Council of Hong Kong (Ref: CityU 11317722, 11310223), Research Grants from City University of Hong Kong (Ref: CityU 11308420, 6000716, 11307321, 9667217). The authors also would like to acknowledge the research undertaken on the PD beamline at the Australian Synchrotron.en_AU
dc.identifier.articlenumber59en_AU
dc.identifier.citationSun, M., Hanif, A., Wang, T., Tao, Z., Chen, D., Li, G., Liu, Z., Gu, Q., Webley, P. A., & Shang, J. (2025). Revisit the molecular sieving mechanism in LTA zeolites: does size really matter? Adsorption, 31(3), 59. doi:10.1007/s10450-025-00616-5en_AU
dc.identifier.issn0929-5607en_AU
dc.identifier.issn1572-8757en_AU
dc.identifier.issue3en_AU
dc.identifier.journaltitleAdsorptionen_AU
dc.identifier.pagination59en_AU
dc.identifier.urihttps://doi.org/10.1007/s10450-025-00616-5en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/16237en_AU
dc.identifier.volume31en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherSpringer Natureen_AU
dc.subjectMolecular sievesen_AU
dc.subjectZeolitesen_AU
dc.subjectCarbon dioxideen_AU
dc.subjectNitrogenen_AU
dc.subjectGasesen_AU
dc.subjectMethaneen_AU
dc.subjectAdsorbentsen_AU
dc.subjectTemperature rangeen_AU
dc.subjectCatalysisen_AU
dc.subjectSeparation processesen_AU
dc.titleRevisit the molecular sieving mechanism in LTA zeolites: does size really matter?en_AU
dc.typeJournal Articleen_AU
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