Metal–Organic Frameworks for Separations

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

The escalating level of atmospheric carbon dioxide is one of the most pressing environmental concerns of our age. Carbon capture and storage (CCS) from large point sources such as power plants is one option for reducing anthropogenic CO(2) emissions; however, currently the capture alone will increase the energy requirements of a plant by 25-40%. This Review highlights the challenges for capture technologies which have the greatest likelihood of reducing CO(2) emissions to the atmosphere, namely postcombustion (predominantly CO(2)/N(2) separation), precombustion (CO(2)/H(2)) capture, and natural gas sweetening (CO(2)/CH(4)). The key factor which underlies significant advancements lies in improved materials that perform the separations. In this regard, the most recent developments and emerging concepts in CO(2) separations by solvent absorption, chemical and physical adsorption, and membranes, amongst others, will be discussed, with particular attention on progress in the burgeoning field of metal-organic frameworks.

Carbon Dioxide Capture: Prospects for New Materials

Since the time of the industrial revolution, the atmospheric CO(2) concentration has risen by nearly 35 % to its current level of 383 ppm. The increased carbon dioxide concentration in the atmosphere has been suggested to be a leading contributor to global climate change. To slow the increase, reductions in anthropogenic CO(2) emissions are necessary. Large emission point sources, such as fossil-fuel-based power generation facilities, are the first targets for these reductions. A benchmark, mature technology for the separation of dilute CO(2) from gas streams is via absorption with aqueous amines. However, the use of solid adsorbents is now being widely considered as an alternative, potentially less-energy-intensive separation technology. This Review describes the CO(2) adsorption behavior of several different classes of solid carbon dioxide adsorbents, including zeolites, activated carbons, calcium oxides, hydrotalcites, organic-inorganic hybrids, and metal-organic frameworks. These adsorbents are evaluated in terms of their equilibrium CO(2) capacities as well as other important parameters such as adsorption-desorption kinetics, operating windows, stability, and regenerability. The scope of currently available CO(2) adsorbents and their critical properties that will ultimately affect their incorporation into large-scale separation processes is presented.

Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

Combination of Advanced Oxidation Processes and biological treatments for wastewater decontamination—A review

Simulation as a tool in the development of metal-organic frameworks for the separation of carbon dioxide

Introduction One approach to reduce greenhouse gas emissions from fossil fuel combustion and so maintain the future viability of coal fired power generation is to capture and then sequester the product CO2. Thus, there is growing interest in the development of improved CO2 capture and separation technologies. The development of high capacity, CO2 selective adsorbents that can be used in pressure swing adsorption (PSA) processes is one way forward. Adsorbents based on high surface area inorganic supports that incorporate basic organic groups, usually amines, are of particular interest. The interaction between the basic surface and acidic CO2 molecules may result in the formation of surface ammonium carbamates (Figure 1). Thus, in dry CO2, adsorption capacities are limited to 1 mole CO2 for every 2 moles surface bound amine groups. Therefore it is desirable to develop adsorbents with the highest possible concentration of basic nitrogen groups accessible to CO2.

Aminopropyl-functionalised silicas as high capacity CO2 adsorbents

Mesopore-bound melamine-type dendrimers and their CO2 adsorption properties

The use of flexible ligands in coordination polymers provides both opportunities and unpredictability. A new series of flexible ligands derived from p-xylylenediamine, which vary in the positioning of carboxylic acid functional groups, have been found to form a series of coordination polymers and a discrete coordination complex. Use of the tetra-substituted meta-carboxylic acid ligand N,N,N′,N′-tetra(3-carboxybenzyl)-p-xylylenediamine, isolated as its dihydrochloride salt (H6M4pxy)Cl2, resulted in the simultaneous formation of two products from the same synthetic conditions. One of these products was a discrete cage-type coordination complex of the form [Cu4(M4pxy)2(DMF)2(OH2)] (1), while the other product was the two-dimensional coordination polymer poly-[Cu2(M4pxy)(OH2)2] (2). Synthesis utilising the tetra-substituted para-carboxylic acid ligand, isolated as N,N,N′,N′-tetra(4-carboxybenzyl)-p-xylylenediamine dihydrochloride (H6P4pxy)Cl2, resulted in the formation of multiple two-dimensional coordination polymers, poly-[Cu2(P4pxy)(DMF)(OH2)]·2DMF·3H2O (3·2DMF·3H2O), poly-[Mn2(P4pxy)(DMA)2] (4), poly-[Co4(P4pxy)2(DMF)2(μ-OH2)2(OH2)2]·6DMF·4H2O (5·6DMF·4H2O) and poly-[Cd2(P4pxy)(OH2)2]·DMA·3H2O (6·DMA·3H2O). The last of these materials, a three-dimensional coordination polymer, was found to adsorb approximately 32 cm3 g−1 STP of CO2 at atmospheric pressure at 273 K.

Alan L. Chaffee

Papers

Simulation as a tool in the development of metal-organic frameworks for the separation of carbon dioxide

Aminopropyl-functionalised silicas as high capacity CO2 adsorbents

Mesopore-bound melamine-type dendrimers and their CO2 adsorption properties

P -Xylylenediamine derived ligands as flexible connectors in the design of porous coordination polymers

Oil recovery from Jordan oil shale