Selective O₂ Sorption at Ambient Temperatures via Node Distortions in Sc-MIL-100

Abstract

An open pored metal−organic framework (MOF) with oxygen selectivity at exceptionally high temperatures is confirmed by synthesis, sorption, and synchrotron structural analyses. The large-pore MIL-100 framework with access to the metal center (e.g., Sc and Fe) resulted in preferential O 2 over N 2 gas uptake at temperatures ranging from 77 K to ambient temperatures (258, 298, and 313 K). Most notably, Sc-MIL-100 shows exceptional O 2 sorption; pair distribution function analyses indicate that this is due to distortions in the framework owing to the size of Sc atoms, in particular in the trimer metal cluster. Experimental studies also correlate very well with GCMC simulations, confirming more favorable O 2 -framework interactions at pressures up to 1 bar, due to the close proximity of O 2 to the high density of metal centers in the small tetrahedral cages. Both materials maintain their crystallinity upon gas adsorption cycling, are regenerable, and show exceptional promise for use in energy efficient oxygen purification processes, such as Pressure Swing Adsorption.

Mixed hierarchical local structure in a disordered metal–organic framework

“…2b and Supplementary Fig. 13 ) 23 , 38 . Beyond this, peaks within the PDF arise from multiple overlapping contributions.…”

Co-immobilization of a Rh Catalyst and a Keggin Polyoxometalate in the UiO-67 Zr-Based Metal–Organic Framework: In Depth Structural Characterization and Photocatalytic Properties for CO2 Reduction

“…However, the use of PDF and d-PDF methods is still limited in the field of guest@MOF materials, with only a few reports, most of which concerning the adsorption of small molecules. 30,[23][24][25][26][27][28][29][30][31][32][33][34][35] To the best of our knowledge, the investigation of POM@MOF and (POM,cat)@MOF composites by differential PDF analysis is the first of the kind.…”

Tuning the Redox Activity of Metal−Organic Frameworks for Enhanced, Selective O₂ Binding: Design Rules and Ambient Temperature O₂ Chemisorption in a Cobalt−Triazolate Framework

“…As a result of the large difference in O2 and N2 binding in Co2(OH)2(BBTA), ideal adsorbed solution theory 99,100 predicts an O2/N2 selectivity of 49 at 298 K, 0.21 bar O2, and 0.79 bar N2 (Figure S17), which is particularly high compared to that of most other MOFs reported in the literature for air separation applications. [18][19][20]22,23,[101][102][103] For reference, Co-BTTri has a selectivity of 41 at 195 K, but this greatly decreases to only 13 at 243 K; Co-BDTriP has a selectivity of 40 at 243 K, with a significantly lower selectivity expected at 298 K. 22 The binding energies resulting from the DFT screening procedure describe the thermodynamic favorability of O2 and N2 adsorption, making it possible to gain fundamental insights and identify promising MOF candidates to investigate in greater detail. While the binding strengths of O2 and N2 are perhaps the most important properties to compute, they are not the only factors to consider once MOF promising candidates are identified.…”