Carbon Dioxide Capture Chemistry of Amino Acid Functionalized Metal-Organic Frameworks in Humid Flue Gas

Abstract

Metal-organic framework-808 has been functionalized with 11 amino acids (AA) to produce a series of MOF-808-AA structures. The adsorption of CO2 under flue gas conditions revealed that glycine- and DL-lysine-functionalized MOF-808 (MOF-808-Gly and -DL-Lys) have the highest uptake capacities. Enhanced CO2 capture performance in the presence of water was observed and studied using single-component sorption isotherms, CO2/H2O binary isotherm, and dynamic breakthrough measurements. The key to the favorable performance was uncovered by deciphering the mechanism of CO2 capture in the pores and attributed to the formation of bicarbonate as evidenced by 13C and 15N solid-state nuclear magnetic resonance spectroscopy studies. Based on these results, we examined the performance of MOF-808-Gly in simulated coal flue gas conditions and found that it is possible to capture and release CO2 by vacuum swing adsorption. MOF-808-Gly was cycled at least 80 times with full retention of performance. This study significantly advances our understanding of CO2 chemistry in MOFs by revealing how strongly bound amine moieties to the MOF backbone create the chemistry and environment within the pores, leading to the binding and release of CO2 under mild conditions without application of heat.

Modular Functionalization of Metal‐Organic Frameworks for Nitrogen Recovery from Fresh Urine**

“…[9,44] In order to introduce ammonium binding affinity to MOF-808 backbone, we selected a series of dicarboxylate compounds, namely oxalic acid (OA), malonic acid (MA), and succinic acid (SA), as anionic functional group. For each dicarboxylate compound, one carboxylate stitches strongly to the Zr 6 O 8 cluster via bidentate chelating, [45] whereas the other remains dangling inside the pore to serve as the ammonium adsorption sites (Scheme 3). Successful incorporation of MA and SA was confirmed and quantified with 1 H NMR spectra of the digested samples (Figure S6 and S7), whereas the incorporated OA was determined via colorimetric assay of the digested MOF-808-OA.…”

Molecular driving forces for water adsorption in MOF-808: A comparative analysis with UiO-66

“…28,89,120,121 Moreover, MOF-808 demonstrates increased CO 2 uptake upon functionalization compared to its pristine form, as reported in previous investigations. 122,123 Ongoing research in our group focuses on developing molecular models for various amino acid-functionalized derivatives of MOF-808 to explore ion separation and selectivity from water. In summary, our work contributes a molecular-level understanding of how variations in structure and topology among MOFs with similar architectures influence the overall performance of water harvesting.…”

Surface, Interface and Structure Optimization of Metal‐Organic Frameworks: Towards Efficient Resourceful Conversion of Industrial Waste Gases

“…Yaghi et al introduced different amino acids into the zirconium site of MOF-808. [120] Specifically, by preremoval of the original formic acid molecule, suitable conditions were created for grafting different kinds of amino acids. The carboxylic acid group end of the amino acid is stably bound to the Zr(IV) site, while the amino acid end is exposed in the pore channel (Figure 6Ca-b).…”

“…Copyright 2022, Elsevier. C) (a, b) Modification scheme of MOF-808 and its partial loading with amino acids, (c) CO 2 adsorption isotherm changes before and after amino loading of MOF-808, (d) Stacked maps of solid-state CP-MAS ssNMR spectra of15 N-labeled MOF-808-gly before and after adsorption of13 CO 2 under dry or humid conditions and (e) CO 2 adsorption mechanism of MOF-808-AA under dry and humid conditions [120]. Copyright 2022, American Chemical Society.…”