TY - JOUR

T1 - Mobility and separation of linear and branched C5 alkanes in UiO-66 (Zr) probed by 2H NMR and MD simulations

AU - Khudozhitkov, Alexander E

AU - Plekhanov, Mikhail S

AU - Arzumanov, Sergei S

AU - Kolokolov, Daniil I

AU - Stepanov, Alexander G

N1 - This work was supported by Ministry of Science and Higher Education of the Russian Federation (project AAAA-A21-121011390053-4 for Boreskov Institute of Catalysis).

PY - 2023/10/18

Y1 - 2023/10/18

N2 - The UiO-66 (Zr) metal-organic framework (MOF) is of notable interest due to its facile synthesis, robustness under a wide range of chemical and physical conditions and its capability to separate industrially relevant hydrocarbons mixtures. However, the knowledge of the molecular mechanisms behind these process remains limited. Here, we present a combined experimental (2H NMR) and computational study of the molecular mobility, transport and adsorption of C5 alkanes isomers in a dehydroxylated UiO-66 (Zr) MOF. We show that the tetrahedral cages of the MOF are the preferred adsorption location for both n-pentane and isopentane. In a binary mixture of the isomers, isopentane interacts more strongly with the material leading it to occupy more of the tetrahedral cages than n-pentane, resulting in an isopentane/n-pentane adsorption selectivity of αads = 2 (at 373 K). At the same time, the microscopic diffusivity for n-pentane, Dn (En = 18 kJ mol-1), is significantly lower than for isopentane, Diso (Eiso = 28 kJ mol-1), which results in a high separation selectivity for a n-pentane/isopentane mixture of α ≈ 13 (at 300 K). This shows that the UiO-66 MOF is indeed a promising active material for use in light hydrocarbon separation processes.

AB - The UiO-66 (Zr) metal-organic framework (MOF) is of notable interest due to its facile synthesis, robustness under a wide range of chemical and physical conditions and its capability to separate industrially relevant hydrocarbons mixtures. However, the knowledge of the molecular mechanisms behind these process remains limited. Here, we present a combined experimental (2H NMR) and computational study of the molecular mobility, transport and adsorption of C5 alkanes isomers in a dehydroxylated UiO-66 (Zr) MOF. We show that the tetrahedral cages of the MOF are the preferred adsorption location for both n-pentane and isopentane. In a binary mixture of the isomers, isopentane interacts more strongly with the material leading it to occupy more of the tetrahedral cages than n-pentane, resulting in an isopentane/n-pentane adsorption selectivity of αads = 2 (at 373 K). At the same time, the microscopic diffusivity for n-pentane, Dn (En = 18 kJ mol-1), is significantly lower than for isopentane, Diso (Eiso = 28 kJ mol-1), which results in a high separation selectivity for a n-pentane/isopentane mixture of α ≈ 13 (at 300 K). This shows that the UiO-66 MOF is indeed a promising active material for use in light hydrocarbon separation processes.

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85174540721&origin=inward&txGid=6b398232ce31bac7afcd63e670834031

U2 - 10.1039/d3cp02601a

DO - 10.1039/d3cp02601a

M3 - Article

C2 - 37800380

VL - 25

SP - 27516

EP - 27523

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 40

ER -