TY - JOUR

T1 - Molecular Insight into the Slow Dynamics of C4Hydrocarbons in the Zeolitic-Imidazole Framework (ZIF-8)

AU - Khudozhitkov, Alexander E.

AU - Zhao, Hengli

AU - Ghoufi, Aziz

AU - Arzumanov, Sergei S.

AU - Kolokolov, Daniil I.

AU - Maurin, Guillaume

AU - Stepanov, Alexander G.

N1 - Funding Information: This work was supported by the Russian Foundation for Basic Research (Grants no. 18-29-04009) and by the Ministry of Science and Higher Education of the Russian Federation (project AAAA-A21-121011390053-4 for Boreskov Institute of Catalysis). The authors thank the French ANR Agency MeaCOPA project for funding. This work was granted access to the HPC resources of CINES under the allocation A0100907613 made by GENCI. Publisher Copyright: © 2021 American Chemical Society.

PY - 2021/7/21

Y1 - 2021/7/21

N2 - The family of zeolitic-imidazole framework (ZIF) materials is currently considered for the challenging separation of C4 hydrocarbons. However, yet, the microscopic diffusion mechanism for these hydrocarbons in these narrow gate porous materials remains elusive by conventional methods due to its very slow nature. Experimental (solid-state 2H nuclear magnetic resonance-NMR) and computational (molecular dynamics-MD) approaches were applied together to derive slow diffusional dynamics of n-butane and 1-butene in ZIF-8. By means of the 2H NMR technique, we evidenced the presence of two adsorption sites for the guests localized inside the cages of ZIF-8 and in the vicinity of the gates. We characterized the molecular mobility at each site and revealed that the translational intercage diffusion is realized by a slow directional motion associated with the gate-crossing. MD simulations provide an in-depth analysis of the diffusion and fully support the proposed dynamics picture for both n-butane and 1-butene. These calculations enable the derivation of the diffusivity and barriers for the long-range diffusion of both hydrocarbons in ZIF-8 and unraveled the microscopic diffusion mechanism implying intracage and intercage motions. We show that this NMR approach combined with modeling is a valuable tool to probe the molecular mobility for slow diffusing species in ordered cagelike porous frameworks.

AB - The family of zeolitic-imidazole framework (ZIF) materials is currently considered for the challenging separation of C4 hydrocarbons. However, yet, the microscopic diffusion mechanism for these hydrocarbons in these narrow gate porous materials remains elusive by conventional methods due to its very slow nature. Experimental (solid-state 2H nuclear magnetic resonance-NMR) and computational (molecular dynamics-MD) approaches were applied together to derive slow diffusional dynamics of n-butane and 1-butene in ZIF-8. By means of the 2H NMR technique, we evidenced the presence of two adsorption sites for the guests localized inside the cages of ZIF-8 and in the vicinity of the gates. We characterized the molecular mobility at each site and revealed that the translational intercage diffusion is realized by a slow directional motion associated with the gate-crossing. MD simulations provide an in-depth analysis of the diffusion and fully support the proposed dynamics picture for both n-butane and 1-butene. These calculations enable the derivation of the diffusivity and barriers for the long-range diffusion of both hydrocarbons in ZIF-8 and unraveled the microscopic diffusion mechanism implying intracage and intercage motions. We show that this NMR approach combined with modeling is a valuable tool to probe the molecular mobility for slow diffusing species in ordered cagelike porous frameworks.

KW - 1-butene

KW - H NMR

KW - butane

KW - diffusion

KW - hydrocarbons

KW - MOF

KW - molecular dynamics

KW - ZIF-8

UR - http://www.scopus.com/inward/record.url?scp=85111225518&partnerID=8YFLogxK

U2 - 10.1021/acsami.1c08529

DO - 10.1021/acsami.1c08529

M3 - Article

C2 - 34241993

AN - SCOPUS:85111225518

VL - 13

SP - 33685

EP - 33692

JO - ACS applied materials & interfaces

JF - ACS applied materials & interfaces

SN - 1944-8244

IS - 28

ER -