Hydrocarbon Adsorption in the Flexible Metal Organic Frameworks MIL-53(Al, Cr)

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Hydrocarbon Adsorption in the Flexible Metal Organic Frameworks MIL-53(Al, Cr)
Hydrocarbon Adsorption in the Flexible Metal Organic Frameworks MIL-53(Al, Cr)
 Tạp chí J. Am. Chem. Soc. 2008 November 17, 2008; 130 (50):16926–16932
 Tác giả   Thuy Khuong Trunga, Philippe Trensa, Nathalie Tanchouxa, Sandrine Bourrellyb, Philip L. Llewellynb, Sandra Loera-Sernab, Christian Serrec, Thierry Loiseauc, François Fajulaa and Gérard Féreyc
 Nơi thực hiện   aMACS, Institut Charles Gerhardt, UMR 5253 CNRS/ENSCM/UM2/UM1, 8 rue de l’Ecole Normale, 34296 Montpellier cedex 5, France
 Từ khóa   Adsorption, MIL-53, MOFs
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Abstract

A general study of the adsorption of n-alkanes in the flexible metal organic framework (MOF) MIL-53 is presented. The roles of the length of the alkyl chain (n = 1−9), the nature of the metal (Al, Cr), and temperature were investigated. The shape of the adsorption curves is driven by the alkyl chain length of the n-alkanes. While traditional type-I isotherms are observed for short alkanes (n = 1, 2), adsorbates with longer chains induce clear substeps in the isotherm curves whose positions depend on the chain length. Such substeps are due to a breathing phenomenon, as proven by ex situ X-ray diffraction analysis. They strongly depend on the amount of adsorbate in the pores and on the nature of the metal (Al, Cr), which, for a given alkane, leads to a strong change in the substep positions despite the similar characteristics of the two metals. The adsorption kinetics are highly sensitive to small variations in temperature. Their detailed analysis in different regions of the isotherms shows in some cases the existence of distinct diffusion regimes and/or conformations within the flexible phases.