Capture of Carbon Dioxide from Air and Flue Gas in the Alkylamine-Appended Metal鈥揙rganic Framework mmen-Mg2(dobpdc)
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- 作者：Thomas M. McDonald ; Woo Ram Lee ; Jarad A. Mason ; Brian M. Wiers ; Chang Seop Hong ; Jeffrey R. Long
- 刊名：The Journal of the American Chemical Society
- 出版年：2012
- 出版时间：April 25, 2012
- 年：2012
- 卷：134
- 期：16
- 页码：7056-7065
- 全文大小：527K
- 年卷期：v.134,no.16(April 25, 2012)
- ISSN：1520-5126
文摘
Two new metal鈥搊rganic frameworks, M2(dobpdc) (M = Zn (1), Mg (2); dobpdc4鈥?/sup> = 4,4鈥?dioxido-3,3鈥?biphenyldicarboxylate), adopting an expanded MOF-74 structure type, were synthesized via solvothermal and microwave methods. Coordinatively unsaturated Mg2+ cations lining the 18.4-脜-diameter channels of 2 were functionalized with N,N鈥?dimethylethylenediamine (mmen) to afford Mg2(dobpdc)(mmen)1.6(H2O)0.4 (mmen-Mg2(dobpdc)). This compound displays an exceptional capacity for CO2 adsorption at low pressures, taking up 2.0 mmol/g (8.1 wt %) at 0.39 mbar and 25 掳C, conditions relevant to removal of CO2 from air, and 3.14 mmol/g (12.1 wt %) at 0.15 bar and 40 掳C, conditions relevant to CO2 capture from flue gas. Dynamic gas adsorption/desorption cycling experiments demonstrate that mmen-Mg2(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 CO2 in simulated air at 25 掳C and 2.52 mmol/g (9.9 wt %) after 15 min of exposure to flowing 15% CO2 in N2 at 40 掳C. The purity of the CO2 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 CO2 adsorbed. Overall, the performance characteristics of mmen-Mg2(dobpdc) indicate it to be an exceptional new adsorbent for CO2 capture, comparing favorably with both amine-grafted silicas and aqueous amine solutions.