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1.
Zeolite ZIF-8 has been etched with acid to form microporous ZIF-8-E crystals. These were then introduced into a polyethersulfone (PES) membrane matrix to enhance its CO2/N2 separation performance. Open through pores of size about 100 nm formed in the ZIF-8 crystals allow the ingrowth of polyethersulfone chains, ensuring a reduction in the number of nonselective voids, thereby achieving better interaction between ZIF-8-E and PES. As a result, the CO2/N2 separation performance of the ZIF-8-E/PES membrane increased significantly, showing a CO2 permeability of 15.7 Barrer and a CO2/N2 ideal selectivity of 6.5.  相似文献   

2.
We present a facile approach to encapsulate functional porous organic cages (POCs) into a robust MOF by an incipient‐wetness impregnation method. Porous cucurbit[6]uril (CB6) cages with high CO2 affinity were successfully encapsulated into the nanospace of Cr‐based MIL‐101 while retaining the crystal framework, morphology, and high stability of MIL‐101. The encapsulated CB6 amount is controllable. Importantly, as the CB6 molecule with intrinsic micropores is smaller than the inner mesopores of MIL‐101, more affinity sites for CO2 are created in the resulting CB6@MIL‐101 composites, leading to enhanced CO2 uptake capacity and CO2/N2, CO2/CH4 separation performance at low pressures. This POC@MOF encapsulation strategy provides a facile route to introduce functional POCs into stable MOFs for various potential applications.  相似文献   

3.
This Concept examines strategies to design advanced polymers with high CO2 permeability and high CO2/N2 selectivity, which are the key to the success of membrane technology for CO2 capture from fossil fuel‐fired power plants. Specifically, polymers with enhanced CO2 solubility and thus CO2/N2 selectivity are designed by incorporating CO2‐philic groups in polymers such as poly(ethylene oxide)‐containing polymers and poly(ionic liquids); polymers with enhanced CO2 diffusivity and thus CO2 permeability are designed with contorted rigid polymer chains to obtain high free volume, such as polymers with intrinsic microporosity and thermally rearranged polymers. The underlying rationales for materials design are discussed and polymers with promising CO2/N2 separation properties for CO2 capture from flue gas are highlighted.  相似文献   

4.
喻娜  丁慧敏  汪成 《化学进展》2016,28(12):1721-1731
近年来,作为一类具有永久空腔结构的三维有机分子,有机分子笼引起了科研工作者的广泛关注,在超分子化学中(主要是主客体相互作用)扮演着重要角色。早期研究中通常采用不可逆法制备有机分子笼,往往存在反应步骤多、分离提纯复杂、合成难度大等问题。为了有效解决上述问题,研究人员将动态共价化学引入到有机分子笼的合成中,从而简单、高效地制备出一系列不同的有机分子笼。关于有机分子笼的应用研究也在不断拓展中。研究发现,有机分子笼不仅在分子识别、分子反应器等方面存在广阔的应用前景,而且其可以通过自组装形成多孔材料,在气体吸附、分离等领域展现了巨大的应用潜能。本文中,我们综述了有机分子笼在合成方法(主要基于动态共价化学反应)及应用研究方面的最新进展。  相似文献   

5.
Research into extended porous materials such as metal‐organic frameworks (MOFs) and porous organic frameworks (POFs), as well as the analogous metal‐organic polyhedra (MOPs) and porous organic cages (POCs), has blossomed over the last decade. Given their chemical and structural variability and notable porosity, MOFs have been proposed as adsorbents for industrial gas separations and also as promising filler components for high‐performance mixed‐matrix membranes (MMMs). Research in this area has focused on enhancing the chemical compatibility of the MOF and polymer phases by judiciously functionalizing the organic linkers of the MOF, modifying the MOF surface chemistry, and, more recently, exploring how particle size, morphology, and distribution enhance separation performance. Other filler materials, including POFs, MOPs, and POCs, are also being explored as additives for MMMs and have shown remarkable anti‐aging performance and excellent chemical compatibility with commercially available polymers. This Review briefly outlines the state‐of‐the‐art in MOF‐MMM fabrication, and the more recent use of POFs and molecular additives.  相似文献   

6.
Utilization of porous materials for gas capture and separation is a hot research topic. Removal of acetylene (C2H2) from ethylene (C2H4) is important in the oil refining and petrochemical industries, since C2H2 impurities deactivate the catalysts and terminate the polymerization of C2H4. Carbon dioxide (CO2) emission from power plants contributes to global climate change and threatens the survival of life on this planet. Herein, 2D crystalline polyimide porous organic framework PAF-120, which was constructed by imidization of linear naphthalene-1,4,5,8-tetracarboxylic dianhydride and triangular 1,3,5-tris(4-aminophenyl)benzene, showed significant thermal and chemical stability. Low-pressure gas adsorption isotherms revealed that PAF-120 exhibits good selective adsorption of C2H2 over C2H4 and CO2 over N2. At 298 K and 1 bar, its C2H2 and CO2 selectivities were predicted to be 4.1 and 68.7, respectively. More importantly, PAF-120 exhibits the highest selectivity for C2H2/C2H4 separation among porous organic frameworks. Thus PAF-120 could be a suitable candidate for selective separation of C2H2 over C2H4 and CO2 over N2.  相似文献   

7.
Porous liquids are a type of porous materials that engineer permanent porosity into unique flowing liquids, exhibiting promising functionalities for a variety of applications. Here a Type I porous liquid is synthesized by transforming porous organic cages into porous ionic liquids via a supramolecular complexation strategy. Simple physical mixing of 18‐crown‐6 with task‐specific anionic porous organic cages affords a porous ionic liquid with anionic porous organic cages as the anionic parts and 18‐crown‐6/potassium ion complexes as the cationic parts. In contrast, mixing of 15‐crown‐5 and anionic porous organic cages in a 2:1 ratio gives only solids, while the addition of excess 15‐crown‐5 affords a Type II porous liquid. The permanent porosity in the cage‐based porous liquids has been also confirmed by molecular simulation, positron (e+) annihilation lifetime spectroscopy, and enhanced gas sorption capacity compared with pure crown ethers.  相似文献   

8.
Traditional films cannot fully adapt to industrial applications and to intensified processes. Advanced mixed‐matrix membranes comprising metal–organic frameworks (MOF) embedded in a polymer matrix have been developed with the goal of breaking the trade‐off effect of traditional polymer membranes and achieving separation performance beyond Robeson's upper limit. The key challenges in the fabrication of MOF‐based mixed‐matrix membranes are an enhancement in compatibility between the inorganic filler and the polymer matrix, elimination of the irregular morphology and non‐selective interfacial defects, and further improvement in the gas‐separation performance. This review summarizes the recent advances in protocols and strategies in terms of designing interfacial interactions to enhance the MOF/polymer interface compatibility. This review aims at providing some meaningful insights into preparing MOF‐based mixed‐matrix membranes targeting ideal interfacial morphology and leading to excellent gas‐separation performance.  相似文献   

9.
Investigating gas separation by emerging porous organic cage(POC) solids is still on its initial stage. In this work, two novel [2+4] organic cages with distinguished structures have been prepared based on the Schiff-based condensation reaction between tetraformyl-functionalized calix[4]resorcinarene building blocks and xylylenediamine(XDA) isomers. Specifically, the use of para-position XDA affords lantern-shaped cage(CPOC-105) with a medium cavity of ca. 0.526 nm3, while the meta-position produces peanut-shaped structure(CPOC-106) with two small cavities of ca. 0.181 nm3. Both CPOC-105 and CPOC-106 exhibit high selectivity capture of CO2 over CH4 with calculated selectivity coefficients of 4.5 and 3.1, respectively, under ambient conditions, and are capable of separating CO2/CH4 mixtures by fixed-bed column breakthrough experiments.  相似文献   

10.
Highly permeable montmorillonite layers bonded and aligned with the chain stretching orientation of polyvinylamineacid are immobilized onto a porous polysulfone substrate to fabricate aligned montmorillonite/polysulfone mixed‐matrix membranes for CO2 separation. High‐speed gas‐transport channels are formed by the aligned interlayer gaps of the modified montmorillonite, through which CO2 transport primarily occurs. High CO2 permeance of about 800 GPU is achieved combined with a high mixed‐gas selectivity for CO2 that is stable over a period of 600 h and independent of the water content in the feed.  相似文献   

11.
Membrane separation of CO2 from natural gas, biogas, synthesis gas, and flu gas is a simple and energy‐efficient alternative to other separation techniques. But results for CO2‐selective permeance have always been achieved by randomly oriented and thick zeolite membranes. Thin, oriented membranes have great potential to realize high‐flux and high‐selectivity separation of mixtures at low energy cost. We now report a facile method for preparing silica MFI membranes in fluoride media on a graded alumina support. In the resulting membrane straight channels are uniformly vertically aligned and the membrane has a thickness of 0.5 μm. The membrane showed a separation selectivity of 109 for CO2/H2 mixtures and a CO2 permeance of 51×10?7 mol m?2 s?1 Pa?1 at ?35 °C, making it promising for practical CO2 separation from mixtures.  相似文献   

12.
《中国化学》2017,35(8):1289-1293
We have successfully designed and synthesized a new tetracarboxylic linker, which constructed its first three‐dimensional microporous metal‐organic framework (MOF ), [Cu2(DDPD )(H2O )2]•Gx ( ZJU ‐13 , H4DDPD =5,5'‐(2,6‐dihydroxynaphthalene‐1,5‐diyl)diisophthalic acid, ZJU =Zhejiang University, G = guest molecules) via solvothermal reaction. Due to open Cu2+ sites and optimized pore size, the activated ZJU ‐13a displays high separation selectivity for C2H2 /CH4 of 74 and C2H2 /CO2 of 12.5 at low pressure by using Ideal Adsorbed Solution Theory (IAST ) simulation at room temperature.  相似文献   

13.
The porphyrin boxes ( PB‐1 and PB‐2 ), which are rationally designed porous organic cages with a large cavity using well‐defined and rigid 3‐connected triangular and 4‐connected square shaped building units are reported. PB‐1 has a cavity as large as 1.95 nm in diameter and shows high chemical stability in a broad pH range (4.8 to 13) in aqueous media. The crystalline nature as well as cavity structure of the shape‐persistent organic cage crystals were intact even after complete removal of guest molecules, leading to one of the highest surface areas (1370 m2g?1) among the known porous organic molecular solids. The size of the cavities and windows of the porous organic cages can be modulated using different sized building units while maintaining the topology of the cages, as illustrated with PB‐2 . Interestingly, PB‐2 crystals showed unusual N2 sorption isotherms as well as high selectivity for CO2 over N2 and CH4 (201 and 47.9, respectively at 273 K at 1 bar).  相似文献   

14.
Defect‐free mixed‐matrix membranes (MMMs) were prepared by incorporating hydrophilic metal‐organic polyhedra (MOPs) into cross‐linked polyethylene oxide (XLPEO) for efficient CO2 separation. Hydrophilic MOPs with triethylene glycol pendant groups, which were assembled by 5‐tri(ethylene glycol) monomethyl ether isophthalic acid and CuII ions, were uniformly dispersed in XLPEO without particle agglomeration. Compared to conventional neat XLPEO, the homogenous dispersion of EG3‐MOPs in XLPEO enhanced CO2 permeability of MMMs. Upon increasing the amount of EG3‐MOPs, the membrane performance such as CO2/N2 selectivity was steadily improved because of unsaturated CuII sites at paddle‐wheel units, which was confirmed by Cu K‐edge XANES and TPD analysis. Therefore, such defect‐free MMMs with unsaturated metal sites would contribute to enhance CO2 separation performance.  相似文献   

15.
Achieving homogeneous dispersion of nanoporous fillers within membrane architectures remains a great challenge for mixed‐matrix membrane (MMMs) technology. Imparting solution processability of nanoporous materials would help advance the development of MMMs for membrane‐based gas separations. A mechanochemically assisted oxidative coupling polymerization strategy was used to create a new family of soluble nanoporous polymer networks. The solid‐state ball‐milling method affords inherent molecular weight control over polymer growth and therefore provides unexpected solubility for the resulting nanoporous frameworks. MMM‐based CO2/CH4 separation performance was significantly accelerated by these new soluble fillers. We anticipate this facile method will facilitate new possibilities for the rational design and synthesis of soluble nanoporous polymer networks and promote their applications in membrane‐based gas separations.  相似文献   

16.
Mixed-matrix membranes (MMMs) with combination of two distinct dimensional nanofillers (such as 1D-3D, 2D-3D, or 3D-3D, etc.) have drawn special attention for gas separation applications due to their concerted effects on gas permeation and mechanical properties. An amine-functionalized 1D multiwalled carbon nanotube (NH2-MWCNT) with exceptional mechanical strength and rapid gas transport was crosslinked with an amine-functionalized 3D metal-organic framework (UiO-66-NH2) with high CO2 affinity in a Schiff base reaction. The resultant crosslinked mixed-dimensional nanostructure was used as a nanofiller in a polysulfone (PSf) polymer matrix to explore the underlying synergy between 1D and 3D nanostructures on the gas separation performance of MMMs. Cross-sectional scanning electron microscopy and mapping revealed the homogenous dispersion of UiO-66@MWCNT in the polymer matrix. The MMM containing 5.0 wt. % UiO-66@MWCNT demonstrated a superior permeability 8.3 Barrer as compared to the 4.2 Barrer of pure PSf membrane for CO2. Moreover, the selectivity (CO2/CH4) of this MMM was enhanced to 39.5 from the 28.0 observed for pure PSf under similar conditions of pressure and temperature.  相似文献   

17.
This work aims to explore the gas permeation performance of two newly-designed ionic liquids, [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2], in supported ionic liquid membranes (SILM) configuration, as another effort to provide an overall insight on the gas permeation performance of functionalized-ionic liquids with the [C2mim]+ cation. [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] single gas separation performance towards CO2, N2, and CH4 at T = 293 K and T = 308 K were measured using the time-lag method. Assessing the CO2 permeation results, [C2mim][CF3BF3] showed an undermined value of 710 Barrer at 293.15 K and 1 bar of feed pressure when compared to [C2mim][BF4], whereas for the [C2mim][CF3SO2C(CN)2] IL an unexpected CO2 permeability of 1095 Barrer was attained at the same experimental conditions, overcoming the results for the remaining ILs used for comparison. The prepared membranes exhibited diverse permselectivities, varying from 16.9 to 22.2 for CO2/CH4 and 37.0 to 44.4 for CO2/N2 gas pairs. The thermophysical properties of the [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] ILs were also determined in the range of T = 293.15 K up to T = 353.15 K at atmospheric pressure and compared with those for other ILs with the same cation and anion’s with similar chemical moieties.  相似文献   

18.
Highly flexible, TpPa‐1@PBI‐BuI and TpBD@PBI‐BuI hybrid membranes based on chemically stable covalent organic frameworks (COFs) could be obtained with the polymer. The loading obtained was substantially higher (50 %) than generally observed with MOFs. These hybrid membranes show an exciting enhancement in permeability (about sevenfold) with appreciable separation factors for CO2/N2 and CO2/CH4. Further, we found that with COF pore modulation, the gas permeability can be systematically enhanced.  相似文献   

19.
Mixed‐matrix membranes (MMMs) comprising Matrimid and a microporous azine‐linked covalent organic frameworks (ACOF‐1) were prepared and tested in the separation of CO2 from an equimolar CO2/CH4 mixture. The COF‐based MMMs show a more than doubling of the CO2 permeability upon 16 wt % ACOF‐1 loading together with a slight increase in selectivity compared to the bare polymer. These results show the potential of COFs in the preparation of MMMs.  相似文献   

20.
The novel coordination polymers [Cu(Hoxonic)(H2O)]n ( 1 ) and [Cu(Hoxonic)(bpy)0.5]n ? 1.5 n H2O ( 2?H2O ) (H3oxonic: 4,6‐dihydroxy‐1,3,5‐triazine‐2‐carboxylic acid; bpy: 4,4′‐bipyridine) have been isolated and structurally characterised by ab initio X‐ray powder diffraction. The dense phase 1 contains 1D zig‐zag chains in which Hoxonic dianions bridge square‐pyramidal copper(II) ions, apically coordinated by water molecules. On the contrary, 2?H2O , prepared by solution and solventless methods, is based on 2D layers of octahedral copper(II) ions bridged by Hoxonic ligands, further pillared by bpy spacers. The resulting pro‐porous 3D network possesses small hydrated cavities. The reactivity, thermal, magnetic and adsorptive properties of these materials have been investigated. Notably, the adsorption studies on 2 show that this material possesses unusual adsorption behaviour. Indeed, guest uptake is facilitated by increasing the thermal energy of both the guest and the framework. Thus, neither N2 at 77 K nor CO2 at 195 K are incorporated, and CH4 is only minimally adsorbed at 273 K and high pressures (0.5 mmol g?1 at 2500 kPa). By contrast, CO2 is readily incorporated at 273 K (up to 2.5 mmol g?1 at 2500 kPa). The selectivity of 2 towards CO2 over CH4 has been investigated by means of variable‐temperature zero coverage adsorption experiments and measurement of breakthrough curves of CO2/CH4 mixtures. The results show the highly selective incorporation of CO2 in 2 , which can be rationalised on the basis of the framework flexibility and polar nature of its voids.  相似文献   

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