Probing the mechanism of CO2 capture in diamine-appended metal–organic frameworks using measured and simulated X-ray spectroscopy
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Univ. Grenoble Alpes, Grenoble (France)
- Univ. of California, Berkeley, CA (United States)
- Univ. of Minnesota, Minneapolis, MN (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
Diamine-appended metal–organic frameworks display great promise for carbon capture applications, due to unusual step-shaped adsorption behavior that was recently attributed to a cooperative mechanism in which the adsorbed CO2 molecules insert into the metal–nitrogen bonds to form ordered ammonium carbamate chains. We present a detailed study of this mechanism by in situ X-ray absorption spectroscopy and density functional theory calculations. Distinct spectral changes at the N and O K-edges are apparent upon CO2 adsorption in both mmen-Mg2(dobpdc) and mmen-Mn2(dobpdc), and these are evaluated based upon computed spectra from three potential adsorption structures. The computations reveal that the observed spectral changes arise from specific electronic states that are signatures of a quasi-trigonal planar carbamate species that is hydrogen bonded to an ammonium cation. This eliminates two of the three structures studied, and confirms the insertion mechanism. Here, we note the particular sensitivity of X-ray absorption spectra to the insertion step of this mechanism, underpinning the strength of the technique for examining subtle chemical changes upon gas adsorption.
- Research Organization:
- Univ. of Minnesota, Minneapolis, MN (United States). Nanoporous Materials Genome Center
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Contributing Organization:
- High Performance Computing Services Group; GENCI; Beamline 6.3.2; National Energy Research Scientific Computing Center
- Grant/Contract Number:
- FG02-12ER16362; SC0008688
- OSTI ID:
- 1488857
- Journal Information:
- Physical Chemistry Chemical Physics. PCCP, Vol. 17, Issue 33; ISSN 1463-9076
- Publisher:
- Royal Society of ChemistryCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Engineered Transport in Microporous Materials and Membranes for Clean Energy Technologies
|
journal | January 2018 |
Adsorption of Carbon Dioxide on Unsaturated Metal Sites in M 2 (dobpdc) Frameworks with Exceptional Structural Stability and Relation between Lewis Acidity and Adsorption Enthalpy
|
journal | April 2016 |
The chemistry of metal–organic frameworks for CO2 capture, regeneration and conversion
|
journal | July 2017 |
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