title: Direct Observation of Xe and Kr Adsorption in a Xe-Selective Microporous Metal-Organic Framework.
abstract: The cryogenic separation of noble gases is energy-intensive and expensive, especially when low concentrations are involved. Metal-organic frameworks (MOFs) containing polarizing groups within their pore spaces are predicted to be efficient Xe/Kr solid-state adsorbents, but no experimental insights into the nature of the Xe-network interaction are available to date. Here we report a new microporous MOF (designated SBMOF-2) that is selective toward Xe over Kr under ambient conditions, with a Xe/Kr selectivity of about 10 and a Xe capacity of 27.07 wt % at 298 K. Single-crystal diffraction results show that the Xe selectivity may be attributed to the specific geometry of the pores, forming cages built with phenyl rings and enriched with polar -OH groups, both of which serve as strong adsorption sites for polarizable Xe gas. The Xe/Kr separation in SBMOF-2 was investigated with experimental and computational breakthrough methods. These experiments showed that Kr broke through the column first, followed by Xe, which confirmed that SBMOF-2 has a real practical potential for separating Xe from Kr. Calculations showed that the capacity and adsorption selectivity of SBMOF-2 are comparable to those of the best-performing unmodified MOFs such as NiMOF-74 or Co formate.
authors.affiliation: †Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.
authors.forename: Xianyin
authors.initials: X
authors.lastname: Chen
authors.affiliation: ‡Department of Geosciences, Stony Brook University, Stony Brook, New York 11794, United States.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Plonka
authors.forename: Debasis
authors.initials: D
authors.lastname: Banerjee
authors.affiliation: ∥Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Rajamani
authors.initials: R
authors.lastname: Krishna
authors.forename: Herbert T
authors.initials: HT
authors.lastname: Schaef
authors.affiliation: ⊥Photon Sciences, Brookhaven National Laboratory, Upton, New York 11973, United States.
authors.forename: Sanjit
authors.initials: S
authors.lastname: Ghose
authors.forename: Praveen K
authors.initials: PK
authors.lastname: Thallapally
authors.affiliation: †Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States.|‡Department of Geosciences, Stony Brook University, Stony Brook, New York 11794, United States.|⊥Photon Sciences, Brookhaven National Laboratory, Upton, New York 11973, United States.
authors.forename: John B
authors.initials: JB
authors.lastname: Parise