TY - JOUR

T1 - Ultrahigh selectivity of benzene/cyclohexane separation by ZIF-8 framework: Insights from spin-probe EPR spectroscopy

AU - Poryvaev, Artem S.

AU - Yazikova, Anastasiya A.

AU - Polyukhov, Daniil M.

AU - Fedin, Matvey V.

N1 - Funding Information: This work was supported by RFBR (No. 18-29-04013 ). A.S.P. thanks RFBR and Novosibirsk region (No. 20-43-543038 ). D.M.P. thanks the Ministry of Education and Science of the Russian Federation (state contract no. № 075-15-2021-580 ). Funding Information: This work was supported by RFBR (No. 18-29-04013). A.S.P. thanks RFBR and Novosibirsk region (No. 20-43-543038). D.M.P. thanks the Ministry of Education and Science of the Russian Federation (state contract no. ? 075-15-2021-580). Publisher Copyright: © 2021 Elsevier Inc.

PY - 2022/1

Y1 - 2022/1

N2 - Liquid-phase separation of cyclohexane and benzene is both demanded and challenging, and the use of selective sorbents, such as metal-organic frameworks (MOFs), for extraction of one component from the mixture is the most promising solution. We report new mechanistic insights into diffusion of benzene and cyclohexane in well-known MOF ZIF-8 using recently developed methodology of encapsulated spin probes detected by Electron Paramagnetic Resonance (EPR). We demonstrate unambiguously that only one component of the hydrocarbons mixture, benzene, can penetrate into ZIF-8 particles, and these EPR-based conclusions are confirmed by high values of sorption selectivity measured by gas chromatography. However, systematic analysis of the mixtures containing small fractions of benzene (e.g. ∼1%) shows noticeable decrease in separation efficiency and only partial removal of benzene from diluted benzene/cyclohexane mixtures. This occurs due to the reverse diffusion of benzene from MOF particles into solution in equilibrium. At the same time, our diffusion study clearly points out that the membrane separation of benzene/cyclohexane using ZIF-8 should be highly perspective and pursued in the future.

AB - Liquid-phase separation of cyclohexane and benzene is both demanded and challenging, and the use of selective sorbents, such as metal-organic frameworks (MOFs), for extraction of one component from the mixture is the most promising solution. We report new mechanistic insights into diffusion of benzene and cyclohexane in well-known MOF ZIF-8 using recently developed methodology of encapsulated spin probes detected by Electron Paramagnetic Resonance (EPR). We demonstrate unambiguously that only one component of the hydrocarbons mixture, benzene, can penetrate into ZIF-8 particles, and these EPR-based conclusions are confirmed by high values of sorption selectivity measured by gas chromatography. However, systematic analysis of the mixtures containing small fractions of benzene (e.g. ∼1%) shows noticeable decrease in separation efficiency and only partial removal of benzene from diluted benzene/cyclohexane mixtures. This occurs due to the reverse diffusion of benzene from MOF particles into solution in equilibrium. At the same time, our diffusion study clearly points out that the membrane separation of benzene/cyclohexane using ZIF-8 should be highly perspective and pursued in the future.

KW - Benzene/cyclohexane separation

KW - Diffusion measurements

KW - EPR spectroscopy

KW - Metal-organic framework

KW - Molecular sieving

KW - ZIF-8

UR - http://www.scopus.com/inward/record.url?scp=85119424420&partnerID=8YFLogxK

U2 - 10.1016/j.micromeso.2021.111564

DO - 10.1016/j.micromeso.2021.111564

M3 - Article

AN - SCOPUS:85119424420

VL - 330

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

SN - 1387-1811

M1 - 111564

ER -