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Selective Binding of O2 over N2 in Redox- Active Metal-Organic Framework with Open Iron(II) Coordination Sites



Eric D. Bloch, Leslie J. Murray, Wendy Queen, Sachin Chavan, Sergey N. Maximoff, Julian P. Bigi, Rajamani Krishna, Vanessa Peterson, Fernande Grandjean, Berend Smit, Silvia Bordiga, Craig Brown, Jeffrey R. Long


The air-free reaction of FeCl2 and H4dobdc (dobdc4- = 2,5-dioxido-1,4- benzenedicarboxylate) in a mixture of DMF and methanol affords Fe2(dobdc), a metal-organic framework isostructural to M2(dobdc) (M = Mg2+, Mn2+, Co2+, Ni2+, Zn2+). The desolvated form of this material has a BET surface area of 1360 m2/g and features 1-D hexagonal pores lined with coordinatively unsaturated Fe2+ cations. O2 adsorption isotherms indicate Fe2(dobdc) irreversibly binds oxygen at 298 K at a capacity over 10 mass fraction (wt %), corresponding to the adsorption of one O2 molecule per two framework Fe2+ cations. At reduced temperatures, O2 uptake is doubled to one bound oxygen molecule per iron site. Powder neutron diffraction and IR spectroscopy indicate that in both scenarios O2 is coordinated to iron in an unusual side-on manner as superoxide at low temperatures and peroxide at room temperature. Ideal adsorbed solution theory calculations reveal that Fe2(dobdc) is a promising material for the separation of O2 from air at temperatures well above those currently used in industrial settings.
Journal of the American Chemical Society


Metal-Organic Framework, Oxygen Adsorption, Porous, Oxyfuel Combustion


Bloch, E. , Murray, L. , Queen, W. , Chavan, S. , Maximoff, S. , Bigi, J. , Krishna, R. , Peterson, V. , Grandjean, F. , Smit, B. , Bordiga, S. , Brown, C. and Long, J. (2011), Selective Binding of O<sub>2</sub> over N<sub>2</sub> in Redox- Active Metal-Organic Framework with Open Iron(II) Coordination Sites, Journal of the American Chemical Society, [online], (Accessed June 24, 2024)


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Created August 9, 2011, Updated October 12, 2021