{"entity": "publication", "iuid": "8225e98e6c16416bad28e5ef097f8407", "timestamp": "2026-05-19T06:03:58.461Z", "links": {"self": {"href": "https://publications.scilifelab.se/publication/8225e98e6c16416bad28e5ef097f8407.json"}, "display": {"href": "https://publications.scilifelab.se/publication/8225e98e6c16416bad28e5ef097f8407"}}, "title": "Intracrystalline Transport Barriers Affecting the Self-Diffusion of CH4 in Zeolites |Na12|-A and |Na12\u2013K|-A", "authors": [{"family": "Hedin", "given": "Niklas", "initials": "N", "orcid": "0000-0002-7284-2974", "researcher": {"href": "https://publications.scilifelab.se/researcher/36ec1b6fa2654626b17b88e7c9d18412.json"}}, {"family": "Rzepka", "given": "Przemyslaw", "initials": "P", "orcid": "0000-0003-3185-3535", "researcher": {"href": "https://publications.scilifelab.se/researcher/7c11e0ded4eb4ce189f907d4f554b580.json"}}, {"family": "Jasso-Salcedo", "given": "Alma Berenice", "initials": "AB"}, {"family": "Church", "given": "Tamara L", "initials": "TL", "orcid": "0000-0002-0494-9657", "researcher": {"href": "https://publications.scilifelab.se/researcher/72b6f8f1af2d402b904504fcc8ca0686.json"}}, {"family": "Bernin", "given": "Diana", "initials": "D", "orcid": "0000-0002-9611-2263", "researcher": {"href": "https://publications.scilifelab.se/researcher/7ad134b1d8ab41b8a8a3318801d92e10.json"}}], "type": "journal-article", "published": "2019-10-08", "journal": {"title": "Langmuir", "issn": "0743-7463", "volume": "35", "issue": "40", "pages": "12971-12978", "issn-l": null}, "abstract": "Carbon dioxide must be removed from biogas or natural gas to obtain compressed or liquefied methane, and adsorption-driven isolation of CO2 could be improved by developing new adsorbents. Zeolite adsorbents can select CO2 over CH4, and the adsorption of CH4 on zeolite |Na12-Kx|-A is significantly lower for samples with a high Kx+ content, i.e., x > 2. Nevertheless, we show, using 1H NMR experiments, that these zeolites adsorb CH4 after long equilibration times. Pulsed-field gradient NMR experiments indicated that in large crystals of zeolites |Na12-Kx|-A, the long-time diffusion coefficients of CHx4 did not vary with x, and the upper limit of the mean-square displacement was about 1.5 \u03bcm, irrespective of the diffusion time. Also for zeolite |Na12|-A samples of three different particle sizes (\u223c0.44, \u223c2.9, and \u223c10.6 \u03bcm), the upper limit of the mean-square displacement of CH4 was 1.5 \u03bcm and largely independent of the diffusion time. This similarity provided further evidence for an intracrystalline diffusion restriction for CH4 within the medium- and large-sized zeolite A crystals and possibly of clustering and close contact among the small zeolite A crystals. The upper limit of the long-time diffusion coefficient of adsorbed CH4 was (at 1 atm and 298 K) about 10-10 m2/s irrespective of the size of the zeolite particle or the studied content of K+ in zeolites |Na12-Kx|-A and |Nax12|-A. The T1 relaxation time for adsorbed CH4 on zeolites |Na12-Kx|-A with xx > 2 was smaller than for those with x < 2, indicating that the short-time diffusion of CH4 was hindered.", "doi": "10.1021/acs.langmuir.9b02574", "pmid": "31510744", "labels": {"Swedish NMR Centre": "Collaborative"}, "xrefs": [], "notes": [], "created": "2023-05-31T16:48:06.605Z", "modified": "2025-10-17T13:03:57.510Z"}