Constructing Connected Paths between UiO‐66 and PIM‐1 to Improve Membrane CO2 Separation with Crystal‐Like Gas Selectivity

Most metal–organic‐framework‐ (MOF‐) based hybrid membranes face the challenge of low gas permeability in CO₂ separation. This study presents a new strategy of interweaving UiO‐66 and PIM‐1 to build freeways in UiO‐66‐CN@sPIM‐1 membranes for fast CO₂ transport. In this strategy, sPIM‐1 is rigidified via thermal treatment to make polymer voids permanent, and concurrently polymer chains are mutually linked onto UiO‐66‐CN crystals to minimize interfacial defects. The pore chemistry of UiO‐66‐CN is kept intact in hybrid membranes, allowing full utilization of MOF pores and selective adsorption for CO₂. Separation results show that UiO‐66‐CN@sPIM‐1 membranes possess exceptionally high CO₂ permeability (15433.4–22665 Barrer), approaching to that of UiO‐66‐NH₂ crystal (65–75% of crystal‐derived permeability). Additionally, the CO₂/N₂ permeation selectivity for a representative membrane (23.9–28.6) moves toward that of single crystal (24.6–29.6). The unique structure and superior CO₂/N₂ separation performance make UiO‐66‐CN@sPIM‐1 membranes promising in practical CO₂ separations.     

Microstructural Engineering and Architectural Design of Metal–Organic Framework Membranes

In the past decade, a huge development in rational design, synthesis, and application of molecular sieve membranes, which typically included zeolites, metal–organic frameworks (MOFs), and graphene oxides, has been witnessed. Owing to high flexibility in both pore apertures and functionality, MOFs in the form of membranes have offered unprecedented opportunities for energy‐efficient gas separations. Reports on the fabrication of well‐intergrown MOF membranes first appeared in 2009. Since then there has been tremendous growth in this area along with an exponential increase of MOF‐membrane‐related publications. In order to compete with other separation and purification technologies, like cryogenic distillation, pressure swing adsorption, and chemical absorption, separation performance (including permeability, selectivity, and long‐term stability) of molecular sieve membranes must be further improved in an attempt to reach an economically attractive region. Therefore, microstructural engineering and architectural design of MOF membranes at mesoscopic and microscopic levels become indispensable. This review summarizes some intriguing research that may potentially contribute to large‐scale applications of MOF membranes in the future.     

Microporous Organic Materials for Membrane‐Based Gas Separation

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.     

Graphynes for Water Desalination and Gas Separation

Selective transport of mass through membranes, so‐called separation, is fundamental to many industrial applications, e.g., water desalination and gas separation. Graphynes, graphene analogs yet containing intrinsic uniformly distributed pores, are excellent candidates for highly permeable and selective membranes owing to their extreme thinness and high porosity. Graphynes exhibit computationally determined separation performance far beyond experimentally measured values of commercial state‐of‐the‐art polyamide membranes; they also offer advantages over other atomically thin membranes like porous graphene in terms of controllability in pore geometry. Here, recent progress in proof‐of‐concept computational research into various graphynes for water desalination and gas separation is discussed, and their theoretically predicted outstanding permeability and selectivity are highlighted. Challenges associated with the future development of graphyne‐based membranes are further analyzed, concentrating on controlled synthesis of graphyne, maintenance of high structural stability to withstand loading pressures, as well asthe demand for accurate computational characterization of separation performance. Finally, possible directions are discussed to align future efforts in order to push graphynes and other 2D material membranes toward practical separation applications.     

几种混合导体陶瓷膜反应器的比较研究

用湿化学方法合成了SrCo_0.5FeO_3.25（SC5FO）,La_0.15Sr_0.85Ga_0.3Fe_0.7O3-δ（LSGFO）和Ba_0.5Sr_0.5Co_0.8Fe_0.2O3-δ（BSCFO）三种透氧膜材料.采用H₂-TPR、XRD和透氧测定,并结合膜反应等方法对它们的性质进行了比较研究.LSGFO与BSCFO具有较高的相结构稳定性,而SC5FO较差.LSGFO具有很高的抗还原能力,而BSCFO较差,但它具有优异的相结构可逆性.在air/He氧浓差梯度下,LSGFO和SC5FO导体膜的透氧量较低;BSCFO具有很高的氧渗透能力,850℃下,透氧量高达1.16[STP]mL/cm²·min.SC5FO膜反应器在POM反应开始不久,因为反应端膜表面的材料组成被反应气还原而出现严重的漏气现象,并最终导致实验失败.BSCFO与LSGFO膜反应器成功地应用到POM反应中,进行了长时间的稳定操作,稳态下透氧量分别高达11.5[STP]mL/cm²·min（875℃）与4.0[STP]mL/cm²·min（950℃）.     

Amino‐Functionalized ZIF‐7 Nanocrystals: Improved Intrinsic Separation Ability and Interfacial Compatibility in Mixed‐Matrix Membranes for CO2/CH4 Separation

Highly permeable and selective, as well as plasticization‐resistant membranes are desired as promising alternatives for cost‐ and energy‐effective CO₂ separation. Here, robust mixed‐matrix membranes based on an amino‐functionalized zeolitic imidazolate framework ZIF‐7 (ZIF‐7‐NH₂) and crosslinked poly(ethylene oxide) rubbery polymer are successfully fabricated with filler loadings up to 36 wt%. The ZIF‐7‐NH₂ materials synthesized from in situ substitution of 2‐aminobenzimidazole into the ZIF‐7 structure exhibit enlarged aperture size compared with monoligand ZIF‐7. The intrinsic separation ability for CO₂/CH₄ on ZIF‐7‐NH₂ is remarkably enhanced as a result of improved CO₂ uptake capacity and diffusion selectivity. The incorporation of ZIF‐7‐NH₂ fillers simultaneously makes the neat polymer more permeable and more selective, surpassing the state‐of‐the‐art 2008 Robeson upper bound. The chelating effect between metal (zinc) nodes of fillers and ester groups of a polymer provides good bonding, enhancing the mechanical strength and plasticization resistance of the neat polymer membrane. The developed novel ZIF‐7 structure with amino‐function and the resulting nanocomposite membranes are very attractive for applications like natural‐gas sweetening or biogas purification.     

CO2‐Philic Separation Membrane: Deep Eutectic Solvent Filled Graphene Oxide Nanoslits

CO₂ capture and sequestration is an energy‐intensive industry to deal with the global greenhouse effect. Membrane separation is considered a cost‐effective method to mitigate the emission of CO₂. Though good separation performance and stability have been reported, supported ionic liquid membranes are still not widely applied for CO₂ separation due to the high cost. As a novel analogous solvent to ionic liquid, deep eutectic solvent retains the excellent merits of ionic liquid and is cheap with facile preparation. Herein, a highly CO₂‐philic separation membrane is constructed by nanoconfining choline chloride/ethylene glycol (ChCl/EG) deep eutectic solvent into graphene oxide nanoslits. Molecular dynamic simulation results indicate that the confinement makes a difference to the structure of the nanoconfined ChCl/EG liquid from their bulk, which remarkably facilitates CO₂ transport. By tuning the molar ratio of ChCl/EG and thickness of the membrane, the resultant membrane exhibits outstanding separation performance for CO₂ with excellent selectivity over other light gases, good long‐term durability, and thermal stability. This makes it a promising membrane for selective CO₂ separation.     

无机膜及无机膜反应器研究进展

无机膜具有耐温、耐化学腐蚀、耐细菌和强度高等优点 ,在化工、环保、生物等工业具有广泛的应用领域 .膜反应器是将膜分离与催化反应结合在一个单元中同时进行的设备 .许多研究结果表明 ,膜反应器在提高可逆反应的转化率、选择性及产率等方面均有明显的效果 ,是化学工程学科具有很好发展前景的领域 .结合研究工作综述了无机膜技术的发展状况 ,包括无机膜的制备、无机膜反应器的形式、应用及无机膜组件结构的研究现状 .提出了无机膜技术需要深入研究的几个主要课题     

MXene Materials for Designing Advanced Separation Membranes

MXenes are emerging rapidly as a new family of multifunctional nanomaterials with prospective applications rivaling that of graphenes. Herein, a timely account of the design and performance evaluation of MXene-based membranes is provided. First, the preparation and physicochemical characteristics of MXenes are outlined, with a focus on exfoliation, dispersion stability, and processability, which are crucial factors for membrane fabrication. Then, different formats of MXene-based membranes in the literature are introduced, comprising pristine or intercalated nanolaminates and polymer-based nanocomposites. Next, the major membrane processes so far pursued by MXenes are evaluated, covering gas separation, wastewater treatment, desalination, and organic solvent purification. The potential utility of MXenes in phase inversion and interfacial polymerization, as well as layer-by-layer assembly for the preparation of nanocomposite membranes, is also critically discussed. Looking forward, exploiting the high electrical conductivity and catalytic activity of certain MXenes is put into perspective for niche applications that are not easily achievable by other nanomaterials. Furthermore, the benefits of simulation/modeling approaches for designing MXene-based membranes are exemplified. Overall, critical insights are provided for materials science and membrane communities to navigate better while exploring the potential of MXenes for developing advanced separation membranes.     

Controlling the Morphology of PVDF Hollow Fiber Membranes by Promotion of Liquid–Liquid Phase Separation

In literature, liquid–liquid (L–L) phase separation has been widely adopted as the principle technique by which polymeric membranes are produced. However, the promotion of L–L phase separation as the means of controlling membrane morphology is still debatable. Thus, this work aims to introduce a facile and cost‐effective technique for controlling the morphology of poly(vinylidene fluoride) (PVDF) hollow fiber membranes (HFMs). The proposed technique is based on promotion of L–L phase separation which can be achieved through two different approaches: 1) reducing the distance between locations of dope and binodal curve through locating spinning dope on nonsolvent (water)/solvent (2‐pyrrolidone)/polymer (PVDF) ternary phase diagram by increasing of nonsolvent content and maintaining of polymer concentration at initial level; 2) simultaneous occurrence of thermally and nonsolvent induced phase separation (TNIPS). It is found that L–L phase separation promotion based on the above described approaches yields to PVDF HFM with partially double‐layered structure, enhanced mechanical properties, higher porosity, and smaller average pore radius with the potential to purify textile wastewater containing C.I. Disperse Violet 33. The proposed technique is advantageous due to lack of need for additives or post‐treatment process for HFM synthesis.

     

Polycrystalline Advanced Microporous Framework Membranes for Efficient Separation of Small Molecules and Ions

Advanced porous framework membranes with excellent selectivity and high permeability of small molecules and ions are highly desirable for many important industrial separation applications. There has been significant progress in the fabrication of polycrystalline microporous framework membranes (PMFMs) in recent years, such as metal–organic framework and covalent organic framework membranes. These membranes possess small pore sizes, which are comparable to the kinetic diameter of small molecules and ions on the angstrom scale, very low thickness, down to tens to hundreds of nanometers, highly oriented crystalline structures, hybrid membrane structures, and specific functional groups for enhancing membrane selectivity and permeability. Recent advances in the fabrication methods of advanced PMFMs are summarized. Following this, four emerging separation applications of these advanced microporous framework membranes, including gas separation, water desalination, ion separation, and chiral separation, are highlighted and discussed in detail. Finally, a summary and some perspectives of future developments and challenges in this exciting research field are presented.     

Mixed Fluorinated/Hydrogenated Self‐Assembled Monolayer‐Protected Gold Nanoparticles: In Silico and In Vitro Behavior

Gold nanoparticles (AuNPs) covered with mixtures of immiscible ligands present potentially anisotropic surfaces that can modulate their interactions at complex nano–bio interfaces. Mixed, self‐assembled, monolayer (SAM)‐protected AuNPs, prepared with incompatible hydrocarbon and fluorocarbon amphiphilic ligands, are used here to probe the molecular basis of surface phase separation and disclose the role of fluorinated ligands on the interaction with lipid model membranes and cells, by integrating in silico and experimental approaches. These results indicate that the presence of fluorinated amphiphilic ligands enhances the membrane binding ability and cellular uptake of gold nanoparticles with respect to those coated only with hydrogenated amphiphilic ligands. For mixed monolayers, computational results suggest that ligand phase separation occurs on the gold surface, and the resulting anisotropy affects the number of contacts and adhesion energies with a membrane bilayer. This reflects in a diverse membrane interaction for NPs with different surface morphologies, as determined by surface plasmon resonance, as well as differential effects on cells, as observed by flow cytometry and confocal microscopy. Overall, limited changes in monolayer features can significantly affect NP surface interfacial properties, which, in turn, affect the interaction of SAM‐AuNPs with cellular membranes and subsequent effects on cells.     

Dual‐Layer Superamphiphobic/Superhydrophobic‐Oleophilic Nanofibrous Membranes with Unidirectional Oil‐Transport Ability and Strengthened Oil–Water Separation Performance

Thin porous membranes with unidirectional oil‐transport capacity offer great opportunities for intelligent manipulation of oil fluids and development of advanced membrane technologies. However, directional oil‐transport membranes and their unique membrane properties have seldom been reported in research literature. Here, it is proven that a dual‐layer nanofibrous membrane comprising a layer of superamphiphobic nanofibers and a layer of superhydrophobic oleophilic nanofibers has an unexpected directional oil‐transport ability, but is highly superhydrophobic to liquid water. This novel fibrous membrane is prepared by a layered electrospinning technique using poly(vinylidene fluoride‐hexafluoropropylene) (PVDF‐HFP), PVDP‐HFP containing well‐dispersed FD‐POSS (fluorinated decyl polyhedral oligomeric silsesquioxanes), and FAS (fluorinated alkyl silane) as materials. The directional oil‐transport is selective only to oil fluids with a surface tension in the range of 23.8–34.0 mN m^–1. By using a mixture of diesel and water, it is further proven that this dual‐layer nanofibrous membrane has a higher diesel–water separation ability than the single‐layer nanofiber membranes. This novel nanofibrous membrane and the incredible oil‐transport ability may lead to the development of intelligent membrane materials and advanced oil–water separation technologies for diverse applications in daily life and industry.     

Membrane Separation in Organic Liquid: Technologies,Achievements, and Opportunities

Membrane technology is one of the most promising technologies for separation and purification that is routinely and commercially employed in aqueous solutions. In comparison, its applications in organic solvents are severely underdeveloped mainly due to the poor stability of traditional polymer membranes in organic solvents. The emerging materials such as crosslinked polymers, covalent organic frameworks, metal–organic frameworks, conjugated microporous polymers, carbon molecular sieves, and graphene provide the solutions to address this problem. The membranes constructed with these novel materials show outstanding separation performance in regard to both high selectivity and solvent permeability, greatly pushing forward utilization of membrane technology in organic media. Here, an overview of the most important organic mixtures that need to be separated, the major separation processes adopted nowadays in organic solvents, and the recent progress in new developed membranes is provided.     

Defect‐Tailoring Mediated Electron–Hole Separation in Single‐Unit‐Cell Bi3O4Br Nanosheets for Boosting Photocatalytic Hydrogen Evolution and Nitrogen Fixation

Solar photocatalysis is a potential solution to satisfying energy demand and its resulting environmental impact. However, the low electron–hole separation efficiency in semiconductors has slowed the development of this technology. The effect of defects on electron–hole separation is not always clear. A model atomically thin structure of single‐unit‐cell Bi₃O₄Br nanosheets with surface defects is proposed to boost photocatalytic efficiency by simultaneously promoting bulk‐ and surface‐charge separation. Defect‐rich single‐unit‐cell Bi₃O₄Br displays 4.9 and 30.9 times enhanced photocatalytic hydrogen evolution and nitrogen fixation activity, respectively, than bulk Bi₃O₄Br. After the preparation of single‐unit‐cell structure, the bismuth defects are controlled to tune the oxygen defects. Benefiting from the unique single‐unit‐cell architecture and defects, the local atomic arrangement and electronic structure are tuned so as to greatly increase the charge separation efficiency and subsequently boost photocatalytic activity. This strategy provides an accessible pathway for next‐generation photocatalysts.     

负载型TiO2-聚丙烯疏水复合膜的制备与表征

采用热致相分离 (TIPS)技术制备浸涂型和反应型硅藻土 -聚丙烯疏水复合膜 ,用SEM、氮吸附、红外光谱和气体渗透性能测试装置等方法表征不同的制膜方法、浸膜液浓度及冷却方式等因素对膜形态、结构和气体渗透性能的影响 .结果表明 :浸涂型聚丙烯膜球形颗粒和孔径尺寸均小于反应型聚丙烯膜 ;TiO2 -聚丙烯膜与硅藻土陶瓷支承体是通过Si—O—Ti—O—C键的价联方式形成键联型复合膜层 ;在膜内 ,气体渗透由Knudsen扩散控制 ,H2 O与N2 的分离因子分别为 2 .4 6和 2 .2 2 .     

PAN/CA共混复合膜的气体分离与力学性能

聚丙烯腈（PAN）具有较高的气体渗透性,但拉伸强度低,不适宜直接制膜。为达到气体分离膜在力学强度方面的使用要求,利用PAN与乙酸纤维素（CA）共混改善其拉伸性能。结果表明,采用相转化法制备的PAN/CA共混基膜,随着CA与PAN共混比的增加,拉伸强度有明显的上升趋势,由1.74MPa增加到2.08MPa。当共混比为0....     

聚酰亚胺/TiO2 复合膜的制备、表征和气体渗透性测定

以硅藻土-莫来石陶瓷膜管为支撑体，以TiO2为过渡层，通过溶胶-凝胶法制备了负载型聚酰亚胺／TiO2复合膜．采用FTIR、NMR、TG／DTA、TEM、BET和气体渗透法对复合膜进行了表征和测试．结果表明：TiO2相通过与聚酰亚胺链上羧酸基支链发生键连形成有机无机组分交错分布的网状结构；复合膜具有良好的热稳定性和有机无机兼容性；相对于聚酰亚胺膜，复合膜对H2、CO2、N2和H2O具有较高的分离性；TiO2含量为15wt％的复合膜对H2／N2、C02／N2和H20／N2的分离因子分别为64．2、42．5和80．8．     

Charged Layered Boron Nitride‐Nanoflake Membranes for Efficient Ion Separation and Water Purification

2D layered nanomaterials have attracted considerable attention for their potential for highly efficient separations, among other applications. Here, a 2D lamellar membrane synthesized using hexagonal boron nitride nanoflakes (h‐BNF) for highly efficient ion separation is reported. The ion‐rejection performance and the water permeance of the membrane as a function of the ionic radius, ion valance, and solution pH are investigated. The nonfunctionalized h‐BNF membranes show excellent ion rejection for small sized salt ions as well as for anionic dyes (>97%) while maintaining a high water permeability, ≈1.0 × 10^?3 L m m^?2 h^?1 bar^?1). Experiments show that the ion‐rejection performance of the membrane can be tuned by changing the solution pH. The results also suggest that the rejection is influenced by the ionic size and the electrostatic repulsion between fixed negative charges on the BN surface and the mobile ions, and is consistent with the Donnan equilibrium model. These simple‐to‐fabricate h‐BNF membranes show a unique combination of excellent ion selectivity and high permeability compared to other 2D membranes.     

Separation of Chemical Reaction Intermediates by Metal–Organic Frameworks

HPLC columns custom‐packed with metal–organic framework (MOF) materials are used for the separation of four small intermediates and byproducts found in the commercial synthesis of an important active pharmaceutical ingredient in methanol. In particular, two closely related amines can be separated in the methanol reaction medium using MOFs, but not with traditional C18 columns using an optimized aqueous mobile phase. Infrared spectroscopy, UV–vis spectroscopy, X‐ray diffraction, and thermogravimetric analysis are used in combination with molecular dynamic simulations to study the separation mechanism for the best‐performing MOF materials. It is found that separation with ZIF‐8 is the result of an interplay between the thermodynamic driving force for solute adsorption within the framework pores and the kinetics of solute diffusion into the material pores, while the separation with Basolite F300 is achieved because of the specific interactions between the solutes and Fe³⁺ sites. This work, and the exceptional ability to tailor the porous properties of MOF materials, points to prospects for using MOF materials for the continuous separation and synthesis of pharmaceutical compounds.