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dc.contributor.authorLozinska, Magdalena Malgorzata
dc.contributor.authorJamieson, Sophie
dc.contributor.authorVerbraeken, Maarten Christiaan
dc.contributor.authorMiller, David Noel
dc.contributor.authorBode, Bela
dc.contributor.authorMurray, Claire
dc.contributor.authorBrandani, Stefano
dc.contributor.authorWright, Paul Anthony
dc.identifier.citationLozinska , M M , Jamieson , S , Verbraeken , M C , Miller , D N , Bode , B , Murray , C , Brandani , S & Wright , P A 2021 , ' Cation ordering and exsolution in copper-containing forms of the flexible zeolite Rho (Cu,M-Rho; M = H, Na) and their consequences for CO 2 adsorption ' , Chemistry - A European Journal , vol. 27 , no. 51 , 202101664 , pp. 13029-13039 .
dc.identifier.otherPURE: 274892303
dc.identifier.otherPURE UUID: 62183ab7-fa73-4127-994d-58982d332b89
dc.identifier.otherORCID: /0000-0002-4243-9957/work/98487558
dc.identifier.otherORCID: /0000-0002-3384-271X/work/98487865
dc.identifier.otherWOS: 000682401400001
dc.identifier.otherScopus: 85112659064
dc.descriptionFunding: UK Engineering and Physical Sciences Research Council. Grant Numbers: EP/N024613/1, EP/N032942/1, EP/L017008/1.en
dc.description.abstractThe flexibility of the zeolite Rho framework offers great potential for tunable molecular sieving. The fully copper-exchanged form of Rho and mixed Cu,H- and Cu,Na-forms have been prepared. EPR spectroscopy reveals that Cu2+ ions are present in the dehydrated forms and Rietveld refinement shows these prefer S6R sites, away from the d8r windows that control diffusion. Fully exchanged Cu-Rho remains in an open form upon dehydration, the d8r windows remain nearly circular and the occupancy of window sites is low, so that it adsorbs CO2 rapidly at room temperature. Breakthrough tests with 10 % CO2/40 % CH4 mixtures show that Cu4.9-Rho is able to produce pure methane, albeit with a relatively low capacity at this pCO2 due to the weak interaction of CO2 with Cu cations. This is in strong contrast to Na-Rho, where cations in narrow elliptical window sites enable CO2 to be adsorbed with high selectivity and uptake but too slowly to enable the production of pure methane in similar breakthrough experiments. A series of Cu,Na-Rho materials was prepared to improve uptake and selectivity compared to Cu-Rho, and kinetics compared to Na-Rho. Remarkably, Cu,Na-Rho with >2 Cu cations per unit cell exhibited exsolution, due to the preference of Na cations for narrow S8R sites in distorted Rho and of Cu cations for S6R sites in the centric, open form of Rho. The exsolved Cu,Na-Rho showed improved performance in CO2/CH4 breakthrough tests, producing pure CH4 with improved uptake and CO2/CH4 selectivity compared to that of Cu4.9-Rho.
dc.relation.ispartofChemistry - A European Journalen
dc.rightsCopyright © 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.en
dc.subjectCopper zeolitesen
dc.subjectCO2 adsorptionen
dc.subjectCO2 separationen
dc.subjectZeolite Rhoen
dc.subjectQD Chemistryen
dc.titleCation ordering and exsolution in copper-containing forms of the flexible zeolite Rho (Cu,M-Rho; M = H, Na) and their consequences for CO2 adsorptionen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews.School of Chemistryen
dc.contributor.institutionUniversity of St Andrews.EaSTCHEMen
dc.contributor.institutionUniversity of St Andrews.Biomedical Sciences Research Complexen
dc.contributor.institutionUniversity of St Andrews.Centre of Magnetic Resonanceen
dc.description.statusPeer revieweden

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