Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long

Carbon Dioxide Capture in Metal–Organic Frameworks

Metal–organic frameworks (MOFs) have recently attracted intense research interest because of their permanent porous structures, large surface areas, and potential applications as novel adsorbents The recent progress in adsorption-based CO2 capture by MOFs is reviewed and summarized in this critical review CO2 adsorption in MOFs has been divided into two sections, adsorption at high pressures and selective adsorption at approximate atmospheric pressures Keys to CO2 adsorption in MOFs at high pressures and low pressures are summarized to be pore volumes of MOFs, and heats of adsorption, respectively Many MOFs have high CO2 selectivities over N2 and CH4 Water effects on CO2 adsorption in MOFs are presented and compared with benchmark zeolites In addition, strategies appeared in the literature to enhance CO2 adsorption capacities and/or selectivities in MOFs have been summarized into three main categories, catenation and interpenetration, chemical bonding enhancement, and electrostatic force involvement Besides the advantages, two main challenges of using MOFs in CO2 capture, the cost of synthesis and the stability toward water vapor, have been analyzed and possible solutions and path forward have been proposed to address the two challenges as well (150 references)

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Progress in adsorption-based CO2 capture by metal–organic frameworks

Proton conducting materials have garnered immense attention for their role as electrolytes in fuel cells. Metal Organic Frameworks (MOFs) and coordination polymers have recently been investigated as possible candidates for proton-conducting applications. Their crystallinity, chemically functionalizable pores and options for systematic structural variation are some of the factors that allow for the targeted design of better proton conductors operating over a wide variety of temperatures and/or humidity conditions. This review will examine selected examples from this nascent field, and will focus on the design and synthesis of proton conducting MOFs, their properties and conditions under which they operate.

MOFs as proton conductors – challenges and opportunities

Two representative metal–organic frameworks, Zn4O(BTB)2 (BTB3− = 1,3,5-benzenetribenzoate; MOF-177) and Mg2(dobdc) (dobdc4− = 1,4-dioxido-2,5-benzenedicarboxylate; Mg-MOF-74, CPO-27-Mg), are evaluated in detail for their potential use in post-combustion CO2 capture via temperature swing adsorption (TSA). Low-pressure single-component CO2 and N2 adsorption isotherms were measured every 10 °C from 20 to 200 °C, allowing the performance of each material to be analyzed precisely. In order to gain a more complete understanding of the separation phenomena and the thermodynamics of CO2 adsorption, the isotherms were analyzed using a variety of methods. With regard to the isosteric heat of CO2 adsorption, Mg2(dobdc) exhibits an abrupt drop at loadings approaching the saturation of the Mg2+ sites, which has significant implications for regeneration in different industrial applications. The CO2/N2 selectivities were calculated using ideal adsorbed solution theory (IAST) for MOF-177, Mg2(dobdc), and zeolite NaX, and working capacities were estimated using a simplified TSA model. Significantly, MOF-177 fails to exhibit a positive working capacity even at regeneration temperatures as high as 200 °C, while Mg2(dobdc) reaches a working capacity of 17.6 wt % at this temperature. Breakthrough simulations were also performed for the three materials, demonstrating the superior performance of Mg2(dobdc) over MOF-177 and zeolite NaX. These results show that the presence of strong CO2 adsorption sites is essential for a metal–organic framework to be of utility in post-combustion CO2 capture via a TSA process, and present a methodology for the evaluation of new metal–organic frameworks via analysis of single-component gas adsorption isotherms.

Evaluating metal–organic frameworks for post-combustion carbon dioxide capture via temperature swing adsorption

This Review focuses on research oriented toward elucidation of the various aspects that determine adsorption of CO2 in metal–organic frameworks and its separation from gas mixtures found in industrial processes. It includes theoretical, experimental, and combined approaches able to characterize the materials, investigate the adsorption/desorption/reaction properties of the adsorbates inside such environments, screen and design new materials, and analyze additional factors such as material regenerability, stability, effects of impurities, and cost among several factors that influence the effectiveness of the separations. CO2 adsorption, separations, and membranes are reviewed followed by an analysis of the effects of stability, impurities, and process operation conditions on practical applications.

CO2 Capture and Separations Using MOFs: Computational and Experimental Studies

In this work, CO2 adsorption on a laboratory-synthesized polymeric copper(II) benzene-1,3,5-tricarboxylate (Cu-BTC) metal-organic framework was modeled by means of the semiempirical Sips equation in order to obtain parameters of engineering interest. Produced Cu-BTC samples were characterized by X-ray diffraction, thermogravimetry, and microporosimetric analysis; high crystallinity and very high specific surface area and pore volume were found. CO2 adsorption isotherms on Cu-BTC were evaluated at T ) (283, 293, 318, and 343) K for p e 1 bar by means of a volumetric technique. In order to establish a comparison, CO2 adsorption isotherms on samples of commercial 13X zeolite were determined under the same experimental conditions and then modeled in the same way as those for Cu-BTC. The modeling and experimental results indicated that relative to 13X zeolite, Cu-BTC showed higher CO2 adsorption capacities at near-ambient temperature and a lower heat release during the adsorption phase.

Modeling Carbon Dioxide Adsorption on Microporous Substrates: Comparison between Cu-BTC Metal-Organic Framework and 13X Zeolitic Molecular Sieve

Fibre-reinforced lime-based mortars: A possible resource for ancient masonry restoration

Equilibrium data and diffusion characteristics of propane and propylene were determined on mesoporous adsorbents modified with an organic molecule (APTES) and/or impregnated with AgNO3, in order to obtain a separation by adsorption via π-complexation.

F. Iucolano

Papers

Modeling Carbon Dioxide Adsorption on Microporous Substrates: Comparison between Cu-BTC Metal-Organic Framework and 13X Zeolitic Molecular Sieve

Fibre-reinforced lime-based mortars: A possible resource for ancient masonry restoration

Adsorption and diffusion of propane and propylene in Ag+-impregnated MCM-41

Entrapping of Cs and Sr in heat-treated zeolite matrices

Permanent and safe storage of Ba2+ in hardened phillipsite-rich tuff/cement pastes