Thomas M. McDonald

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTCarbon Dioxide Capture in Metal–Organic FrameworksKenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, and Jeffrey R. Long*View Author Information Department of Chemistry, University of California, Berkeley, California 94720-1460, United States*E-mail: [email protected]Cite this: Chem. Rev. 2012, 112, 2, 724–781Publication Date (Web):December 28, 2011Publication History Received19 August 2011Published online28 December 2011Published inissue 8 February 2012https://pubs.acs.org/doi/10.1021/cr2003272https://doi.org/10.1021/cr2003272review-articleACS PublicationsCopyright © 2011 American Chemical SocietyRequest reuse permissionsArticle Views81380Altmetric-Citations5582LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Adsorption,Materials,Membranes,Metal organic frameworks,Selectivity Get e-Alerts

Two new metal-organic frameworks, M(2)(dobpdc) (M = Zn (1), Mg (2); dobpdc(4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate), adopting an expanded MOF-74 structure type, were synthesized via solvothermal and microwave methods. Coordinatively unsaturated Mg(2+) cations lining the 18.4-Å-diameter channels of 2 were functionalized with N,N'-dimethylethylenediamine (mmen) to afford Mg(2)(dobpdc)(mmen)(1.6)(H(2)O)(0.4) (mmen-Mg(2)(dobpdc)). This compound displays an exceptional capacity for CO(2) adsorption at low pressures, taking up 2.0 mmol/g (8.1 wt %) at 0.39 mbar and 25 °C, conditions relevant to removal of CO(2) from air, and 3.14 mmol/g (12.1 wt %) at 0.15 bar and 40 °C, conditions relevant to CO(2) capture from flue gas. Dynamic gas adsorption/desorption cycling experiments demonstrate that mmen-Mg(2)(dobpdc) can be regenerated upon repeated exposures to simulated air and flue gas mixtures, with cycling capacities of 1.05 mmol/g (4.4 wt %) after 1 h of exposure to flowing 390 ppm CO(2) in simulated air at 25 °C and 2.52 mmol/g (9.9 wt %) after 15 min of exposure to flowing 15% CO(2) in N(2) at 40 °C. The purity of the CO(2) removed from dry air and flue gas in these processes was estimated to be 96% and 98%, respectively. As a flue gas adsorbent, the regeneration energy was estimated through differential scanning calorimetry experiments to be 2.34 MJ/kg CO(2) adsorbed. Overall, the performance characteristics of mmen-Mg(2)(dobpdc) indicate it to be an exceptional new adsorbent for CO(2) capture, comparing favorably with both amine-grafted silicas and aqueous amine solutions.

High capacity, high selectivity, and low-cost regeneration conditions are the most important criteria by which new adsorbents for post-combustion carbon dioxide capture will be judged. The incorporation of N,N′-dimethylethylenediamine (mmen) into H3[(Cu4Cl)3(BTTri)8 (CuBTTri; H3BTTri = 1,3,5-tri(1H-1,2,3-triazol-4-yl)benzene), a water-stable, triazolate-bridged framework, is shown to drastically enhance CO2 adsorption, resulting in one of the best performing metal–organic frameworks for CO2 separation reported to date. High porosity was maintained despite stoichiometric attachment of mmen to the open metal sites of the framework, resulting in a BET surface area of 870 m2 g−1. At 25 °C under a 0.15 bar CO2/0.75 bar N2 mixture, mmen-CuBTTri adsorbs 2.38 mmol CO2 g−1 (9.5 wt%) with a selectivity of 327, as determined using Ideal Adsorbed Solution Theory (IAST). The high capacity and selectivity are consequences of the exceptionally large isosteric heat of CO2 adsorption, calculated to be −96 kJ mol−1 at zero coverage. Infrared spectra support chemisorption between amines and CO2 as one of the primary mechanisms of uptake. Despite the large initial heat of adsorption, the CO2 uptake was fully reversible and the framework could be easily regenerated at 60 °C, enabling a cycling time of just 27 min with no loss of capacity over the course of 72 adsorption/desorption cycles.

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 ± 0.2 mmol/g (16 wt %) at 0.1 bar and 40 °C in the presence of a high partial pressure of H2O.