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Probing the Dynamics of CO 2 and CH 4 within the Porous Zirconium Terephthalate UiO‐66(Zr): A Synergic Combination of Neutron Scattering Measurements and Molecular Simulations
Author(s) -
Yang Qingyuan,
Jobic Hervé,
Salles Fabrice,
Kolokolov Daniil,
Guillerm Vincent,
Serre Christian,
Maurin Guillaume
Publication year - 2011
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201003596
Subject(s) - thermal diffusivity , molecular dynamics , neutron scattering , diffusion , materials science , zirconium , self diffusion , chemical physics , scattering , analytical chemistry (journal) , chemistry , thermodynamics , computational chemistry , physics , optics , metallurgy , self service , business , chromatography , marketing
Quasi‐elastic neutron scattering (QENS) measurements combined with molecular dynamics (MD) simulations were conducted to deeply understand the concentration dependence of the self‐ and transport diffusivities of CH 4 and CO 2 , respectively, in the humidity‐resistant metal–organic framework UiO‐66(Zr). The QENS measurements show that the self‐diffusivity profile for CH 4 exhibits a maximum, while the transport diffusivity for CO 2 increases continuously at the loadings explored in this study. Our MD simulations can reproduce fairly well both the magnitude and the concentration dependence of each measured diffusivity. The flexibility of the framework implemented by deriving a new forcefield for UiO‐66(Zr) has a significant impact on the diffusivity of the two species. Methane diffuses faster than CO 2 over a broad range of loading, and this is in contrast to zeolites with narrow windows, for which opposite trends were observed. Further analysis of the MD trajectories indicates that the global microscopic diffusion mechanism involves a combination of intracage motions and jump sequences between tetrahedral and octahedral cages.