Membrane materials with excellent selectivity and high permeability are crucial to efficient membrane gas separation. Microporous organic materials have evolved as an alternative candidate for ...fabricating membranes due to their inherent attributes, such as permanent porosity, high surface area, and good processability. Herein, a unique pore‐chemistry concept for the designed synthesis of microporous organic membranes, with an emphasis on the relationship between pore structures and membrane performances, is introduced. The latest advances in microporous organic materials for potential membrane application in gas separation of H2, CO2, O2, and other industrially relevant gases are summarized. Representative examples of the recent progress in highly selective and permeable membranes are highlighted with some fundamental analyses from pore characteristics, followed by a brief perspective on future research directions.
Recent advances regarding microporous organic materials for membrane gas separation are reviewed. Critical challenges associated with the designed synthesis of membrane materials with defined porous structures, and the correlations between pore chemistry and membrane separation performance, in terms of selectivity and permeability, are discussed.
Porous aromatic frameworks (PAFs), which are well-known for their large surface areas, associated porosity, diverse structures, and superb stability, have recently attracted broad interest. Taking ...advantage of widely available building blocks and various coupling strategies, customized porous architectures can be prepared exclusively through covalent bonding to satisfy necessary requirements. In addition, PAFs are composed of phenyl-ring-derived fragments that are easily modified with desired functional groups with the help of established synthetic chemistry techniques. On the basis of material design and preparative chemistry, this review mainly focuses on recent advances in the structural and chemical characteristics of PAFs for potential utilizations, including molecule storage, gas separation, catalysis, and ion extraction. Additionally, a concise outlook on the rational construction of functional PAFs is discussed in terms of developing next-generation porous materials for broader applications.
Carbon dioxide (CO2), as the primary greenhouse gas in the atmosphere, triggers a series of environmental and energy related problems in the world. Therefore, there is an urgent need to develop ...multiple methods to capture and convert CO2 into useful chemical products, which can significantly improve the environment and promote sustainable development. Over the past several decades, metal‐organic frameworks (MOFs) have shown outstanding heterogeneous catalytic activity due in part to their high internal surface area and chemical functionalities. These properties and the ability to synthesize MOF platforms allow experiments to test structure‐function relationships for transforming CO2 into useful chemicals. Herein, recent developments are highlighted for MOFs participating as catalysts for the chemical fixation and photochemical reduction of CO2. Finally, opportunities and challenges facing MOF catalysts are discussed in this ongoing research area.
CO2 triggers a series of environmental and energy problems as the primary greenhouse gas in our daily life. MOFs (metal‐organic frameworks) are applied as outstanding heterogeneous catalysts for CO2 chemical transformations. A systematic overview of the development of MOF‐based catalysts for CO2 chemical transformations are reviewed, from the first example to the most recent publication.
Integrating covalent organic frameworks (COFs) with other functional materials is a useful route to enhancing their performances and extending their applications. We report herein a simple ...encapsulation method for incorporating catalytically active Au nanoparticles with different sizes, shapes, and contents in a two-dimensional (2D) COF material constructed by condensing 1,3,5-tris(4-aminophenyl)benzene (TAPB) with 2,5-dimethoxyterephthaldehyde (DMTP). The encapsulation is assisted by the surface functionalization of Au nanoparticles with polyvinylpyrrolidone (PVP) and follows a mechanism based on the adsorption of nanoparticles onto surfaces of the initially formed polymeric precursor of COF. The incorporation of nanoparticles does not alter obviously the crystallinity, thermal stability, and pore structures of the framework matrices. The obtained COF composites with embedded but accessible Au nanoparticles possess large surface areas and highly open mesopores and display recyclable catalytic performance for reduction of 4-nitrophenol, which cannot be catalyzed by the pure COF material, with activities relevant to contents and geometric structures of the incorporated nanoparticles.
Mimicking proton conduction mechanism of Nafion to construct novel proton-conducting materials with low cost and high proton conductivity is of wide interest. Herein, we have designed and synthesized ...a cationic covalent organic framework with high thermal and chemical stability by combining a cationic monomer, ethidium bromide (EB) (3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide), with 1,3,5-triformylphloroglucinol (TFP) in Schiff base reactions. This is the first time that the stable cationic crystalline frameworks allowed for the fabrication of a series of charged COFs (EB-COF:X, X = F, Cl, Br, I) through ion exchange processes. Exchange of the extra framework ions can finely modulate the COFs’ porosity and pore sizes at nanoscale. More importantly, by introducing PW12O40 3– into this porous cationic framework, we can greatly enhance the proton conductivity of ionic COF-based material. To the best of our knowledge, EB-COF:PW 12 shows the best proton conductivity at room temperature among ever reported porous organic materials.
The separation of acetylene from ethylene is a crucial process in the petrochemical industry, as even small acetylene impurities can lead to premature termination of ethylene polymerization. Herein, ...we present the synthesis of a robust, crystalline naphthalene diimide porous aromatic framework via imidization of linear naphthalene-1,4,5,8-tetracarboxylic dianhydride and triangular tris(4-aminophenyl)amine. The resulting material, PAF-110, exhibits impressive thermal and long-term structural stability, as indicated by thermogravimetric analysis and powder X-ray diffraction characterization. Gas adsorption characterization reveals that PAF-110 has a capacity for acetylene that is more than twice its ethylene capacity at 273 K and 1 bar, and it exhibits a moderate acetylene selectivity of 3.9 at 298 K and 1 bar. Complementary computational investigation of each guest binding in PAF-110 suggests that this affinity and selectivity for acetylene arises from its stronger electrostatic interaction with the carbonyl oxygen atoms of the framework. To the best of our knowledge, PAF-110 is the first crystalline porous organic material to exhibit selective adsorption of acetylene over ethylene, and its properties may provide insight into the further optimized design of porous organic materials for this key gas separation.
A majority of metal–organic frameworks (MOFs) fail to preserve their physical and chemical properties after exposure to acidic, neutral, or alkaline aqueous solutions, therefore limiting their ...practical applications in many areas. The strategy demonstrated herein is the design and synthesis of an organic ligand that behaves as a buffer to drastically boost the aqueous stability of a porous MOF (JUC‐1000), which maintains its structural integrity at low and high pH values. The local buffer environment resulting from the weak acid–base pairs of the custom‐designed organic ligand also greatly facilitates the performance of JUC‐1000 in the chemical fixation of carbon dioxide under ambient conditions, outperforming a series of benchmark catalysts.
A buffer strategy boosts the aqueous stability of a MOF over a broad range of pH values. The local buffer environment resulting from the weak acid–base pairs (green/blue bars on right of picture) of the custom‐designed organic ligand also greatly facilitates the performance of MOF in chemical fixation of carbon dioxide under ambient conditions.
Water contamination by emerging organic pollutants, such as pharmaceuticals and personal care products (PPCPs), is becoming more and more serious. Porous aromatic frameworks (PAFs) are considered as ...promising adsorbents to remove the PPCPs. To overcome the limitation of PAFs in their powder forms for large-scale applications, herein, we proposed a strategy to covalently anchor PAFs onto electrospun polymer fiber membranes. Polyaniline (PANI) played the role of aromatic seed layer, which was coated on the electrospun polyacrylonitrile (PAN) fiber membrane first. Then, PAF-45 modification was in situ synthesized in the presence of the PANI-coated electrospun PAN fiber membrane. This study could make the PAF-based materials be handled more easily and improve the surface area of electrospun fiber membrane. The obtained composite adsorbent (PAF-45-PP FM) was applied for the adsorption of three PPCPs: ibuprofen (IBPF), chloroxylenol (CLXN), and N,N-diethyl-meta-toluamide (DEET), which exhibited high adsorption capacity and good recycling ability. According to the Langmuir model, the maximum adsorption capacities of PAF-45-PP FM toward IBPF, CLXN and DEET were 613.50, 429.18, and 384.61 mg/g, respectively. In addition, after ten adsorption–desorption cycles, the adsorption capacities toward the three PPCPs decreased slightly. Through an adsorption comparison test, the adsorption capacity of PAF-45-PP FM almost attributed to the loading PAF-45. The adsorption mechanism analysis illustrated that there were pore capture, hydrophobic interaction and π–π interaction between PPCPs and PAF-45-PP FM. Therefore, the PAF-45-PP FM can be potential adsorbents to purify water contaminated with PPCPs.
Light hydrocarbons (C1–C3) are used as basic energy feedstocks and as commodity organic compounds for the production of many industrially necessary chemicals. Due to the nature of the raw materials ...and production processes, light hydrocarbons are generated as mixtures, but the high‐purity single‐component products are of vital importance to the petrochemical industry. Consequently, the separation of these C1–C3 products is a crucial industrial procedure that comprises a significant share of the total global energy consumption per year. As a complement to traditional separation methods (distillation, partial hydrogenation, etc.), adsorptive separations using porous solids have received widespread attention due to their lower energy costs and higher efficiency. Extensive research has been devoted to the use of porous materials such as zeolites and metal‐organic frameworks (MOFs) as solid adsorbents for these key separations, owing to the high porosity, tunable pore structures, and unsaturated metal sites present in these materials. Recently, porous organic framework (POF) materials composed of organic building blocks linked by covalent bonds have also shown excellent properties in light hydrocarbon adsorption and separation, sparking interest in the use of these materials as adsorbents in separation processes. This Minireview summarizes the recent advances in the use of POFs for light hydrocarbon separations, including the separation of mixtures of methane/ethane, methane/propane, ethylene/ethane, acetylene/ethylene, and propylene/propane, while highlighting the relationships between the structural features of these materials and their separation performances. Finally, the difficulties, challenges, and opportunities associated with leveraging POFs for light hydrocarbon separations are discussed to conclude the review.
As an emerging family of porous materials, porous organic frameworks (POFs) represent a promising avenue for development in the separation and purification of light hydrocarbons (C1–C3) due to their advantageous features. This Minireview summarizes the recent advances in the use of POFs for light hydrocarbon separations, while highlighting the relationships between the structural features of POFs and their separation performances.
Compositional catalysts based on porous supports and incorporated catalytic nanoparticles have achieved great successes during the past decades. However, rational design of synergic catalysts and ...modulating the interactions between functional supports and catalytic sites are still far from being well developed. In this work, aiming at overcoming the difficulties of comprehensive screening of porous supports and correspondingly matched catalytic sites, a cationic porous aromatic framework as a capturing platform and polyoxometalate anions as conversion materials are separately designed, and their combination is modularly controlled. The resulting composites show higher catalytic activities than the corresponding conversion sites themselves. Notably, the resulting composites uncommonly exhibit increased surface area and enlarged pore openings after the incorporation of nanoparticles, and lead to the promotion of mass transfer within the porous supports. The emergence of a hierarchical structure with increased surface area induced by guest loading is desired in heterogeneous catalysis. The reciprocal modulation of both capture and conversion materials results in enhanced conversion and increased reaction rate, indicating the successful preparation of synergic catalysts by this separate design approach.
A cationic porous aromatic framework is combined with catalytically active polyoxometalate anions for oxidative catalysis. The preferential substance‐capturing by the cationic framework enhances the catalytic activity of the active sites. In turn, anion incorporation creates hierarchical structures within the framework and promotes the mass transfer. The structural alteration and the synergistic effect of the compositional catalyst are discussed.
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