Hydrogen Storage and Carbon Dioxide Capture in an Iron-based Sodalite-type Metal-Organic Framework (Fe-BTT) Discovered via High-throughput Methods

Author

Kenji Sumida
Satoshi Horike
Steven S. Kaye
Zoey R. Herm
Wendy L. Queen
Craig M. Brown
Fernande Grandjean, Missouri University of Science and TechnologyFollow
Gary J. Long, Missouri University of Science and TechnologyFollow
Anne M. Dailly
Jeffrey R. LongFollow

Abstract

Using high-throughput instrumentation to screen conditions, the reaction between FeCl₂ and H₃BTT·2HCl (BTT^3- = 1,3,5-benzenetristetrazolate) in a mixture of DMF and DMSO was found to afford Fe₃[(Fe₄Cl)₃(BTT)₈] ₂·22DMF·32DMSO·11H₂O. This compound adopts a porous three-dimensional framework structure consisting of square [Fe₄Cl]⁷⁺ units linked via triangular BTT^3- bridging ligands to give an anionic 3,8-net. Mössbauer spectroscopy carried out on a DMF-solvated version of the material indicated the framework to contain high-spin Fe²⁺ with a distribution of local environments and confirmed the presence of extra-framework iron cations. Upon soaking the compound in methanol and heating at 135 °C for 24 h under dynamic vacuum, most of the solvent is removed to yield Fe₃[(Fe₄Cl) ₃(BTT)₈(MeOH)₄]₂ (Fe-BTT), a microporous solid with a BET surface area of 2010 m² g^-1 and open Fe²⁺ coordination sites. Hydrogen adsorption data collected at 77 K show a steep rise in the isotherm, associated with an initial isosteric heat of adsorption of 11.9 kJ mol^-1, leading to a total storage capacity of 1.1 wt% and 8.4 g L^-1 at 100 bar and 298 K. Powder neutron diffraction experiments performed at 4 K under various D₂ loadings enabled identification of ten different adsorption sites, with the strongest binding site residing just 2.17(5) Å from the framework Fe ²⁺ cation. Inelastic neutron scattering spectra are consistent with the strong rotational hindering of the H₂ molecules at low loadings, and further reveal the catalytic conversion of ortho-H₂ to para-H₂ by the paramagnetic iron centers. The exposed Fe²⁺ cation sites within Fe-BTT also lead to the selective adsorption of CO ₂ over N₂, with isotherms collected at 298 K indicating uptake ratios of 30.7 and 10.8 by weight at 0.1 and 1.0 bar, respectively.

Recommended Citation

K. Sumida and S. Horike and S. S. Kaye and Z. R. Herm and W. L. Queen and C. M. Brown and F. Grandjean and G. J. Long and A. M. Dailly and J. R. Long, "Hydrogen Storage and Carbon Dioxide Capture in an Iron-based Sodalite-type Metal-Organic Framework (Fe-BTT) Discovered via High-throughput Methods," Chemical Science, vol. 1, no. 2, pp. 184 - 191, Royal Society of Chemistry, Aug 2010.

The definitive version is available at https://doi.org/10.1039/c0sc00179a

Department(s)

Chemistry

Keywords and Phrases

Adsorption Site; BET Surface Area; Bridging Ligands; Carbon Dioxide Capture; Catalytic Conversion; Cation Sites; Coordination Sites; Dynamic Vacuum; Extra-framework Iron; High-throughput; High-throughput Method; Hydrogen Adsorption; Inelastic Neutrons; Iron Centers; Iron-based; Isosteric Heat Of Adsorption; Local Environments; Low Loading; Metal Organic Framework; Microporous Solids; Powder Neutron Diffraction; Selective Adsorption; Ssbauer Spectroscopies; Storage Capacity; Three-dimensional Frameworks; Binding Sites; Carbon Dioxide; Chlorine Compounds; Dyes; Hydrogen; Hydrogen Storage; Iron; Isotherms; Methanol; Molybdenum; Paramagnetism; Positive Ions; Gas Adsorption

International Standard Serial Number (ISSN)

2041-6520

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2010 Royal Society of Chemistry, All rights reserved.

Creative Commons Licensing

This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

Publication Date

01 Aug 2010