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

The molecular representations of coal – A review

The potential for the metal organic framework (MOF) Cu-BTC to selectively adsorb and separate CO2 is considered. Isotherms for CO2, CH4, and N2 were measured from 0 to 15 bar and at temperatures between 25 and 105 °C. The isotherms suggest a much higher working capacity (×4) for CO2 adsorption on Cu-BTC relative to the benchmark zeolite 13X over the same pressure range. Higher CO2/N2 and CO2/CH4 selectivities in the higher pressure range (1−15 bar) and with lower heats of adsorption were also demonstrated. Cu-BTC was observed to be stable in O2 at 25 °C, but its crystallinity was reduced in humid environments. The CO2 adsorption capacity was progressively reduced upon cyclic exposure to water vapor at low relative humidity (<30%), but leveled out at 75% of its original value after several water adsorption/desorption cycles.

CO2 Adsorption-Based Separation by Metal Organic Framework (Cu-BTC) versus Zeolite (13X)

CO2 capture by adsorption: Materials and process development

Aminopropyl-functionalized mesoporous silicas as CO2 adsorbents

Mesoporous silica substrates were functionalized with N-[3-(trimethoxysilyl)propyl]diethylenetriamine to form diethylenetriamine[propyl(silyl)]- (DT-) functionalized hybrid products suitable for CO2 adsorption. The materials prepared were characterized by N2 adsorption/desorption at 77 K, C and N elemental analysis, helium pycnometry, X-ray diffraction (XRD), CO2 adsorption, and thermal decomposition and were compared to analogous aminopropylsilyl- (AP-) and ethylenediamine[propyl(silyl)]- (ED-) functionalized materials. The extent of surface functionalization varied with substrate morphology. CO2 adsorption capacities and heats of adsorption were determined via combined thermogravimetric analysis and differential thermal analysis (TGA/DTA). Functionalization of the substrates was found to enhance their CO2 adsorption capacities at 20 °C under anhydrous conditions. Higher temperature led to reduced adsorption capacities but higher heats of adsorption (Hads) of CO2, thought to be due to the reduced role of...

Alan L. Chaffee

Papers

The molecular representations of coal – A review

CO2 Adsorption-Based Separation by Metal Organic Framework (Cu-BTC) versus Zeolite (13X)

CO2 capture by adsorption: Materials and process development

Aminopropyl-functionalized mesoporous silicas as CO2 adsorbents

Diethylenetriamine[propyl(silyl)]-Functionalized (DT) Mesoporous Silicas as CO2 Adsorbents