High Gas Uptake Capacities Research Articles

Simple biphenyl derived porous aromatic frameworks with attractive xenon/krypton separation

Porous Aromatic Frameworks (PAFs) with ultramicropores have emerged as a significant contributor to the gas separation field. However, there is a lack of efficient and cost-effective methods for the practical application of PAFs. In this study, we successfully synthesized QS-PAFs economically using Friedel-Crafts arylation of biphenyl derivatives. The QS-PAFs were analyzed using nuclear magnetic resonance spectroscopy, Fourier transform infrared spectrum, thermogravimetric analysis, and N2 adsorption experiment. We found that the QS-PAFs have comparable pore size, considerable surface areas, and good stabilities. The results demonstrated their high gas uptake capacities for Xe and attractive selectivity for Xe/Kr separation.

Construction of microporous covalent organic frameworks for high gas uptake capacities

Covalent organic frameworks (COFs) show excellent stability, high porosity, and a designable skeleton, making them an ideal platform for gas capture.

Comparison of SDS and L-Methionine in promoting CO2 hydrate kinetics: Implication for hydrate-based CO2 storage

The continuously increasing CO2 emissions since industrialization has sparked widespread concerns on environmental and climate change issues. Carbon sequestration and storage technologies (e.g., hydrate-based CO2 sequestration) present promising potential for the disposing of excessive CO2 in geological media. High gas uptake capacity and rapid CO2 hydrate formation kinetics are required for the application of such a technology. In this study, we compared the kinetic promotion effects of sodium dodecyl sulfate (SDS) and L-methionine (L-Met) on CO2 hydrate with the objective of identification of an effective and eco-friendly CO2 hydrate kinetic promoter. The experimental results suggested that L-Met (0.1 wt%) promotes CO2 hydrates formation significantly with a gas uptake in CO2 hydrate five times more than SDS at the same concentration. The hydrate morphology observations indicated that the wall-climbing hydrates associated with the addition of L-Met induced by the capillary driving force offer a possible explanation for the difference in the observed kinetics. A novel calculation method was developed to quantify the partition of CO2 in gas, liquid and hydrate phases. Increasing the initial gas–liquid ratio promotes CO2 stored in the hydrate phase as solid rather than in the liquid phase as dissolution. We further demonstrated the reusability of L-Met in five consecutive cycles of CO2 hydrate formation and dissociation. It was assessed that L-Met as a CO2 hydrate kinetic promoter is superior to SDS and can be employed as an efficient, reliable and eco-friendly kinetic promoter for the hydrate-based CO2 sequestration technology.

Ultrahigh-Uptake Capacity-Enabled Gas Separation and Fruit Preservation by a New Single-Walled Nickel-Organic Framework.

High gas‐uptake capacity is desirable for many reasons such as gas storage and sequestration. Moreover, ultrahigh capacity can enable a practical separation process by mitigating the selectivity factor that sometimes compromises separation efficiency. Herein, a single‐walled nickel–organic framework with an exceptionally high gas capture capability is reported. For example, C2H4 and C2H6 uptake capacities are at record‐setting levels of 224 and 289 cm3 g−1 at 273 K and 1 bar (169 and 110 cm3 g−1 at 298 K and 1 bar), respectively. Such ultrahigh capacities for both gases give rise to an excellent separation performance, as shown for C2H6/C2H4 with breakthrough times of 100, 60 and 30 min at 273, 283 and 298 K and under 1 atm. This new material is also shown to readily remove ethylene released from fruits, and once again, its ultrahigh capacity plays a key role in the extraordinary length of time achieved in the preservation of the fruit freshness.

Highly structured metal-organic framework nanofibers for methane storage

Porous materials such as metal-organic frameworks (MOFs) with high theoretical volumetric gas uptake capacity are promising materials for gas storage and separation, but the structuring for practical applications is challenging. Herein, we report a general and feasible strategy to combine electrospinning with a phase conversion method to decorate polyacrylonitrile nanofibers (PAN NFs) with Cu-MOF (HKUST-1). The strategy is based on the combination of surface pretreatment of the NFs with Cu(OH)2 and a subsequent phase conversion into HKUST-1 crystals (PC-HKUST-1). A significant higher loading of HKUST-1 in the PAN NF matrix was achieved by the phase conversion method compared with direct electrospinning of MOF slurries or in-situ growth of MOF crystals on NFs. As a result, the hierarchical structured PC (phase conversion)-HKUST-1 NFs revealed the highest gravimetric storage capacity of 86 cm3 g−1 (STP) at 3500 kPa and 298 K for methane (CH4), which is higher than other HKUST 1 NFs reported previously. The improved CH4 uptake can be explained by the high loading of HKUST-1 due to the high availability of Cu-ions localized on the surface of the NFs during the phase conversion process, resulting in high surface area and excellent gas access of the phase converted HKUST-1. Thus, the developed strategy of structuring MOFs could be of interest for the fabrication of tailor-made MOF NF architectures for other energy and environmental applications.

Bio-tar-derived porous carbon with high gas uptake capacities

The separation of CO2 from the nature gas is a challenge for solid sorbents. Bio-tar, a low cost and renewable carbon source, is employed to synthesis the ultra-microporous carbon materials. Carbonization of bio-tar with potassium hydroxide (KOH) at high temperatures (>700 °C) yields porous carbon materials with high surface areas of up to 2595 m2 g−1 and high CO2 uptake performance of 5.35 mmol g−1 at 1 bar and 0 °C. This carbon material also shows good CO2/CH4 selectivity in mixed gas and excellent cyclability. In gas breakthrough test, the retention time of bio-tar-derived carbon for carbon dioxide and methane adsorption is 849 s g−1 and 337 s g−1, respectively. The retention time of CO2 is 157 s g−1 at 150 °C while CH4 is nearly non-adsorption. The carbon material has good cycle performance for carbon dioxide adsorption. Molecular simulations suggest that CO2 density in micro and narrow mesopores will be increased at high pressures. This is consistent with the observation that these pores are mainly responsible for the material’s high-pressure CO2 capacity. This study provides insights in designing of bio-tar material and further developing for CO2 capture from natural gas.

A Robust 3D Cage‐like Ultramicroporous Network Structure with High Gas‐Uptake Capacity

AbstractA three‐dimensional (3D) cage‐like organic network (3D‐CON) structure synthesized by the straightforward condensation of building blocks designed with gas adsorption properties is presented. The 3D‐CON can be prepared using an easy but powerful route, which is essential for commercial scale‐up. The resulting fused aromatic 3D‐CON exhibited a high Brunauer–Emmett–Teller (BET) specific surface area of up to 2247 m2 g−1. More importantly, the 3D‐CON displayed outstanding low pressure hydrogen (H2, 2.64 wt %, 1.0 bar and 77 K), methane (CH4, 2.4 wt %, 1.0 bar and 273 K), and carbon dioxide (CO2, 26.7 wt %, 1.0 bar and 273 K) uptake with a high isosteric heat of adsorption (H2, 8.10 kJ mol−1; CH4, 18.72 kJ mol−1; CO2, 31.87 kJ mol−1). These values are among the best reported for organic networks with high thermal stability (ca. 600 °C).

Nitrogen-Doped Porous Carbons Derived from Triarylisocyanurate-Cored Polymers with High CO2 Adsorption Properties

A series of N-doped porous carbon materials have been successfully prepared by using nitrogen-rich triarylisocyanurate-cored polymers as carbon precursor. The cross-linked networks explain the precursor with high carbonaceous residues in the following carbonization. The influence of KOH dosage and activation temperature on the specific surface area and nitrogen content of the resultant carbon materials is investigated in detail. Eventually, a maximum specific surface area of 2341 m2 g–1 and nitrogen content of 1.7 wt % are achieved in the resultant carbon materials. High CO2 capacity (30.2 wt % at 273 K/1 bar and 17.2 wt % at 298 K/1 bar) is attributed to abundant microporous structures and basic sites, superior to that of the most porous carbon materials reported in the previous literature. In addition, the carbon materials also demonstrate high H2 and CH4 uptake (2.7 wt % at 77.3 K/1.13 bar and 3.8 wt % at 273 K/1.13 bar, respectively). The characters of easy preparation and high gas uptake capacity end...

An ultra-tunable platform for molecular engineering of high-performance crystalline porous materials.

Metal-organic frameworks are a class of crystalline porous materials with potential applications in catalysis, gas separation and storage, and so on. Of great importance is the development of innovative synthetic strategies to optimize porosity, composition and functionality to target specific applications. Here we show a platform for the development of metal-organic materials and control of their gas sorption properties. This platform can accommodate a large variety of organic ligands and homo- or hetero-metallic clusters, which allows for extraordinary tunability in gas sorption properties. Even without any strong binding sites, most members of this platform exhibit high gas uptake capacity. The high capacity is accomplished with an isosteric heat of adsorption as low as 20 kJ mol−1 for carbon dioxide, which could bring a distinct economic advantage because of the significantly reduced energy consumption for activation and regeneration of adsorbents.

Straightforward synthesis of a triazine-based porous carbon with high gas-uptake capacities

A triazine-based porous carbon material (TPC-1) was prepared directly from a fluorinated aromatic nitrile in molten zinc chloride. Trimerization of the nitrile and subsequent defluorination carbonization of the polymeric network result in the formation of TPC-1. The defluorination process is reversible and can etch the polymeric network to release CFn, thereby generating additional porosity and rendering TPC-1 a nitrogen-rich porous material. TPC-1 shows a high BET surface area of 1940 m2 g−1 and contains both micropores and mesopores, which facilitate the diffusion and adsorption of gas molecules. Gas adsorption experiments demonstrate outstanding uptake capacities of TPC-1 for CO2 (4.9 mmol g−1, 273 K and 1.0 bar), CH4 (3.9 mmol g−1, 273 K and 1.0 bar), and H2 (10.1 mmol g−1, 77 K and 1.0 bar). This straightforward synthesis procedure provides an alternative pathway to prepare high-performance porous carbon materials.

Facile Preparation of Dibenzoheterocycle-Functional Nanoporous Polymeric Networks with High Gas Uptake Capacities

A consolidated ionothermal strategy was developed for the polymerization of thermally unstable nitriles to construct high performance materials with permanent porosity, and carbazole, dibenzofuran, and dibenzothiophene were separately introduced into covalent triazine-based networks to investigate the effects of heterocycles on the gas adsorption performance. Three nitriles, namely 3,6-dicyanocarbazole, 3,6-dicyanodibenzofuran, and 3,6-dicyanodibenzothiophene, were designed and synthesized, which were readily converted to heat-resistant intermediates at a moderate temperature and then polymerized to create highly porous poly(triazine) networks instead of the traditional one-step procedure. This documents an improved strategy for the successful construction of heterocyclic-functional triazine-based materials. The chemical structures of monomers and polymers were confirmed by 1H NMR, FTIR, and elemental analysis. Such polymers with high physical–chemical stability and comparable BET surface areas can uptake 1.44 wt % H2 at 77 K/1 bar and 14.0 wt % CO2 at 273 K/1 bar and present a high selectivity for gas adsorption of CO2 (CO2/N2 ideal selectivity up to 45 at 273K/1.0 bar). The nitrogen- and oxygen-rich characteristics of carbazole and dibenzofuran feature the networks strong affinity for CO2 and thereby high CO2 adsorption capacity. This also helps to thoroughly understand the influence of pore structure and chemical composition on the adsorption properties of small gas molecules.

A highly-connected metal–organic framework based on [Co2(μ2-OH2)] units and mononuclear Co centers with high gas uptake capacity

A porous 3D framework based on [Co2(μ2-OH2)] clusters and mononuclear Co centers, is presented. The [Co2(μ2-OH2)] units act as 7-connected and 8-connected nodes, respectively. The desolvated form of 1 shows high CO2 and H2 adsorption.

From a supramolecular tetranitrile to a porous covalent triazine-based framework with high gas uptake capacities

Transformation of tetra(4-cyanophenyl)ethylene under Lewis acidic (ZnCl2) conditions at 400 °C leads to the formation of a porous covalent triazine-based organic framework (CTF) with a high surface area (2235 m(2) g(-1)), high CO2 and CH4 uptakes and the highest hydrogen uptake for a CTF material (1.86 wt% at 77 K, 1 bar).

Metal-organic frameworks and porous polymer networks for carbon capture

Abstract The ability to rationally design materials for specific applications and synthesize materials to these exact specifications at the molecular level makes it possible to make a huge impact in carbon dioxide capture applications. Recently, advanced porous materials, in particular metal-organic frameworks (MOFs) and porous polymer networks (PPNs) have shown tremendous potential for this and related applications because they have high adsorption selectivities and record breaking gas uptake capacities. By appending chemical functional groups to the surface of these materials it is possible to tune gas molecule specific interactions. The results presented herein are a summary of the fundamentals of synthesizing several MOF and PPN series through applying structure property relationships.

Development of composite inorganic building blocks for MOFs.

A general direction for diversifying metal-organic frameworks (MOFs) is demonstrated by the synthesis of composite inorganic clusters between indium and s-, d-, and f-block elements. These previously unknown heterometallic clusters, with various nuclearity, geometry, charge, and metal-to-metal ratios, significantly expand the pool of inorganic building blocks that are highly effective for the construction of porous MOFs with high gas uptake capacity.

A Highly Porous and Robust (3,3,4)‐Connected Metal–Organic Framework Assembled with a 90° Bridging‐Angle Embedded Octacarboxylate Ligand

Picky cage: A dicopper(II)-paddle-wheel-based metal–organic framework (PCN-80, see picture) with a rare (3,3,4)-connected topology has been synthesized by using a unique octatopic ligand featuring 90° bridging-angle dicarboxylate moieties. PCN-80 has Brunauer-Emmett-Teller (BET) and Langmuir surface areas of 3850 and 4150 m2 g−1, respectively. It exhibits high gas-uptake capacity for H2 and large adsorption selectivity of CO2 over N2.

Mixed-motif interpenetration and cross-linking of high-connectivity networks led to robust and porous metal–organic frameworks with high gas uptake capacities

Two high-connectivity MOFs with very interesting modes of mixed-motif interpenetration and cross-linking were synthesized using the elongated and aromatic-rich methanetetra(biphenyl-p-carboxylic acid) bridging ligand (H4MTBPC, H4L). [Zn4(L)(H2L)2]·12DEF·40H2O (1) contains an interpenetrating 4,8-connected 3D framework of the alb/P topology and 4,4-connected 3D network of the lon topology, whereas [Co5(L)(HL)2]·15DMF·37H2O (2) is the first 4,12-connected 4-nodal net with the Schlafli symbol of {422.639.85}{45.6}2{46}. The structure of 2 can be visualized as cross-linking of three 4,4-connected 3D networks of the lon topology. The seemingly different structures of 1 and 2 are in fact closely related as the structure of 1 can be obtained by removing one of the Co centers in the penta-cobalt secondary building unit (SBU). Unusual mixed-motif interpenetration in 1 and cross-linking in 2 rigidify and stabilize the frameworks, leading to highly porous MOFs with high uptake capacities for H2 and CO2.

Doping copper into ZIF-67 for enhancing gas uptake capacity and visible-light-driven photocatalytic degradation of organic dye

A doping strategy was successfully applied to tune the gas sorption and photocatalytic properties of a microporous material ZIF-67. The Cu-doped phase integrated both structural features and functions of ZIF-67 showed high gas uptake capacity and highly efficient visible-light-driven photocatalytic property on the degradation of methyl orange.

A high connectivity metal–organic framework with exceptional hydrogen and methane uptake capacities

A 6,8-connected 3-dimensional metal–organic framework (2) of the tph topology was constructed from a new aromatic-rich, tetraphenylmethane-derived octa-carboxylate bridging ligand and trizinc cluster secondary building units (SBUs), and exhibited exceptionally high hydrogen (58 mg g−1 and 39 g L−1 at 52 bar and 77 K) and methane (276 mg g−1 and 189 g L−1 at 80 bar and 298 K) uptake capacities. 2 has the highest hydrogen uptake at 298 K among all of the MOFs that have been examined to date. The gravimetric and volumetric methane uptake capacities for 2 are the highest among thousands of MOFs that have been evaluated. We attribute the exceptionally high gas uptake capacities of 2 to the highly branched, aromatic-rich nature of the bridging ligand, optimal pore size, and the open metal sites in the trizinc SBUs in a stable high-connectivity MOF.

A non-interpenetrated porous metal–organic framework with high gas-uptake capacity

A novel microporous polyhedral framework [Zn(6)(btb)(4)(4,4'-bipy)(3)(dmf)(55)(H(2)O)(32)] with high surface area has been designed and synthesized, which shows high multigas-uptake capacity via supercritical carbon dioxide (SCD) activation.