An Ideal Molecular Sieve for Acetylene Removal from Ethylene with Record Selectivity and Productivity

Realization of ideal molecular sieves, in which the larger gas molecules are completely blocked without sacrificing high adsorption capacities of the preferred smaller gas molecules, can significantly reduce energy costs for gas separation and purification and thus facilitate a possible technological transformation from the traditional energy‐intensive cryogenic distillation to the energy‐efficient, adsorbent‐based separation and purification in the future. Although extensive research endeavors are pursued to target ideal molecular sieves among diverse porous materials, over the past several decades, ideal molecular sieves for the separation and purification of light hydrocarbons are rarely realized. Herein, an ideal porous material, SIFSIX‐14‐Cu‐i (also termed as UTSA‐200), is reported with ultrafine tuning of pore size (3.4 Å) to effectively block ethylene (C₂H₄) molecules but to take up a record‐high amount of acetylene (C₂H₂, 58 cm³ cm^?3 under 0.01 bar and 298 K). The material therefore sets up new benchmarks for both the adsorption capacity and selectivity, and thus provides a record purification capacity for the removal of trace C₂H₂ from C₂H₄ with 1.18 mmol g^?1 C₂H₂ uptake capacity from a 1/99 C₂H₂/C₂H₄ mixture to produce 99.9999% pure C₂H₄ (much higher than the acceptable purity of 99.996% for polymer‐grade C₂H₄), as demonstrated by experimental breakthrough curves.     

氮气中乙烯、丙烯、乙炔、1,3-丁二烯、一氯甲烷、氯乙烷、乙烯基乙炔混合气体标准样品的研制

叙述了氮气中乙烯、丙烯、乙炔、1,3-丁二烯、一氯甲烷、氯乙烷、乙烯基乙炔混合气体标准样品的制备,用称量法配制,采用气相色谱法对其均匀性、稳定性进行考核,气体标准样品经一年多考察,其数据的相对不确定度（k=2）为3%,可在氯乙烯生产工艺中使用。     

Anion Substitution in Porous Aromatic Frameworks: Boosting Molecular Permeability and Selectivity for Membrane Acetylene Separation

Precise tailoring of pore chemistry is indispensable for efficient membrane gas separation, particularly for the challenging acetylene system. Here, a strategy called “anion substitution” is reported, to strengthen the interaction between anions and acetylene within the pores, for radically improving gas selectivity and permeability. The anions F⁻ and OH⁻ are infixed in iPAF-1 to replace the original Cl⁻ ion. Their small anionic radii allow retention of the original high porosity of iPAF-1-Cl in iPAF-1-F and iPAF-1-OH. Highly basic F⁻ and OH⁻ confined in the pores attract acidic acetylene strongly and preferentially. Nanoparticles of iPAF-1 are processed to form mixed matrix membranes, represented by iPAF-1-OH/6FDA-ODA. The prepared membranes exhibit remarkable performance in separating acetylene from ethylene and ethane. Transplantation of porous and functional iPAF-1-OH into 6FDA-ODA significantly enhances both acetylene permeability (sevenfold) and permselectivity (fivefold) for acetylene over ethylene and ethane, which is crucial for membrane acetylene gas separation.     

热致重排聚合物的制备及其气体分离应用研究

近年来,以酰亚胺环邻位官能化的聚酰亚胺或聚酰胺为前驱体,经一定热处理发生结构重排,可得到另一种刚性结构聚合物——热致重排聚合物。热致重排聚合物作为一种新型的刚性微孔聚合物材料,具有较高的自由体积和比表面积,表现出非常优异的气体渗透性和分离性,因此在气体分离等领域受到了广泛关注。前驱体聚合物的化学结构、制备方法、物理性状和热处理条件(氛围、时间、温度)等都将影响热致重排反应及最终热致重排聚合物的各项性能。因此,本文介绍了热致重排聚合物的重排反应机理、研究进展及改性研究情况,并对热致重排聚合物今后的发展趋势进行了展望。     

具有手性分离功能的MOCPs的构建

就手性在药物分离中的重要性及手性分离剂的分离机制进行了概述.以此为基础,对一类在手性分离领域有巨大发展潜力的功能材料--金属有机络合聚合物(MOCPs)在分子设计和合成方面的研究现状进行了综述.MOCPs优异的理化性能、孔结构特性和手性分离功能可通过其构建分子的选择和修饰进行设计,其手性结构可通过手性配体与非手性配体进行构建.MOCPs有望在手性分离,特别是在手性药物分离领域形成新的研究和应用的热点.     

离子液体对聚合物相转变影响的研究进展

离子液体除了是许多聚合物的良溶剂外,对聚合物的相转变也有一定的影响。综述了国内外关于离子液体对聚合物相转变影响的研究现状,包括玻璃化转变、结晶、凝胶等。离子液体对许多聚合物表现出增塑作用,显著降低了聚合物的玻璃化转变温度,甚至熔点。另外,离子液体能够促进蛋白质等聚合物结晶结构的形成。在离子液体作用下,聚甲基丙烯酸甲酯的立构混合物形成了可逆性热凝胶。     

混合超微孔材料中CO2/N2吸附与分离的理论研究

碳捕获与封存技术是一种具有前景的CO₂减排策略。本工作采用巨正则蒙特卡洛模拟研究了温度为298 K、压强在0~5 kPa范围内三种混合超微孔材料SIFSIX-X-Cu(以SiF₆ ^2-排列, Cu为金属中心, X=2, 3, O)中CO₂/N₂吸附与分离的行为。结果显示, 相比于SIFSIX-2-Cu, SIFSIX-3-Cu和SIFSIX-O-Cu中CO₂在0.5 kPa就达到吸附饱和, 且在1 kPa下的吸附量分别达到了2.70与2.39 mmol·g ^-1。CO₂/N₂混合气体中CO₂的吸附量几乎没有下降。SIFSIX-3-Cu和SIFSIX-O-Cu具有接近于CO₂分子动力学直径的孔径, 对CO₂亲和力较大, 吸附热分别达到了59和66 kJ·mol ^-1。密度泛函理论分析发现, 在两种结构中每个孔隙只吸附一个CO₂分子, 且几乎处于孔道的中心。本工作为低压下吸附与分离CO₂的混合超微孔材料的开发提供了理论指导。     

离子液体在萃取分离中的应用进展

作为环境友好型功能材料——离子液体以其独特的物理化学性质已引起人们的广泛关注。离子液体在萃取分离有机物、无机金属离子领域的应用越来越多。概述了离子液体在萃取分离中的应用。总结了离子液体的萃取机理,介绍了离子液体的结构如阴、阳离子的类型对萃取效率的影响规律,讨论了静电作用、疏水作用、氢键等作用力在萃取分离过程中所扮演的角色。最后展望了离子液体在萃取分离领域的发展方向。     

Modulating the Interlayer Stacking of Covalent Organic Frameworks for Efficient Acetylene Separation

Controllable modulation of the stacking modes of 2D (two-dimensional) materials can significantly influence their properties and functionalities but remains a formidable synthetic challenge. Here, an effective strategy is proposed to control the layer stacking of imide-linked 2D covalent organic frameworks (COFs) by altering the synthetic methods. Specifically, a modulator-assisted method can afford a COF with rare ABC stacking without the need for any additives, while solvothermal synthesis leads to AA stacking. The variation of interlayer stacking significantly influences their chemical and physical properties, including morphology, porosity, and gas adsorption performance. The resultant COF with ABC stacking shows much higher C₂H₂ capacity and selectivity over CO₂ and C₂H₄ than the COF with AA stacking, which is not demonstrated in the COF field yet. Furthermore, the outstanding practical separation ability of ABC stacking COF is confirmed by breakthrough experiments of C₂H₂/CO₂ (50/50, v/v) and C₂H₂/C₂H₄ (1/99, v/v), which can selectively remove C₂H₂ with good recyclability. This work provides a new direction to produce COFs with controllable interlayer stacking modes.     

Photothermal‐Responsive Microporous Nanosheets Confined Ionic Liquid for Efficient CO2 Separation

2D materials hold promising potential for novel gas separation. However, a lack of in‐plane pores and the randomly stacked interplane channels of these membranes still hinder their separation performance. In this work, ferrocene based‐MOFs (Zr‐Fc MOF) nanosheets, which contain abundant of in‐plane micropores, are synthesized as porous supports to fabricate Zr‐Fc MOF supported ionic liquid membrane (Zr‐Fc‐SILM) for highly efficient CO₂ separation. The micropores of Zr‐Fc MOF nanosheets not only provide extra paths for CO₂ transportation, and thus increase its permeance up to 145.15 GPU, but also endow the Zr‐Fc‐SILM with high selectivity (216.9) of CO₂/N₂ through the nanoconfinement effect, which is almost ten times higher than common porous polymer SILM. Furthermore, based on the photothermal‐responsive properties of Zr‐Fc MOF, the performance is further enhanced (35%) by light irradiation through a photothermal heating process. This provides a brand new way to design light facilitating gas separation membranes.     

Pd Single‐Atom Catalysts on Nitrogen‐Doped Graphene for the Highly Selective Photothermal Hydrogenation of Acetylene to Ethylene

The selective hydrogenation of acetylene to ethylene in an ethylene‐rich gas stream is an important process in the chemical industry. Pd‐based catalysts are widely used in this reaction due to their excellent hydrogenation activity, though their selectivity for acetylene hydrogenation and durability need improvement. Herein, the successful synthesis of atomically dispersed Pd single‐atom catalysts on nitrogen‐doped graphene (Pd₁/N‐graphene) by a freeze‐drying‐assisted method is reported. The Pd₁/N‐graphene catalyst exhibits outstanding activity and selectivity for the hydrogenation of C₂H₂ with H₂ in the presence of excess C₂H₄ under photothermal heating (UV and visible‐light irradiation from a Xe lamp), achieving 99% conversion of acetylene and 93.5% selectivity to ethylene at 125 °C. This remarkable catalytic performance is attributed to the high concentration of Pd active sites on the catalyst surface and the weak adsorption energy of ethylene on isolated Pd atoms, which prevents C₂H₄ hydrogenation. Importantly, the Pd₁/N‐graphene catalyst exhibits excellent durability at the optimal reaction temperature of 125 °C, which is explained by the strong local coordination of Pd atoms by nitrogen atoms, which suppresses the Pd aggregation. The results presented here encourage the wider pursuit of solar‐driven photothermal catalyst systems based on single‐atom active sites for selective hydrogenation reactions.     

Polymers with Side Chain Porosity for Ultrapermeable and Plasticization Resistant Materials for Gas Separations

Polymer membranes with ultrahigh CO₂ permeabilities and high selectivities are needed to address some of the critical separation challenges related to energy and the environment, especially in natural gas purification and postcombustion carbon capture. However, very few solution‐processable, linear polymers are known today that access these types of characteristics, and all of the known structures achieve their separation performance through the design of rigid backbone chemistries that concomitantly increase chain stiffness and interchain spacing, thereby resulting in ultramicroporosity in solid‐state chain‐entangled films. Herein, the separation performance of a porous polymer obtained via ring‐opening metathesis polymerization is reported, which possesses a flexible backbone with rigid, fluorinated side chains. This polymer exhibits ultrahigh CO₂ permeability (>21 000 Barrer) and exceptional plasticization resistance (CO₂ plasticization pressure > 51 bar). Compared to traditional polymers of intrinsic microporosity, the rate of physical aging is slower, especially for gases with small effective diameters (i.e., He, H₂, and O₂). This structural design strategy, coupled with studies on fluorination, demonstrates a generalizable approach to create new polymers with flexible backbones and pore‐forming side chains that have unexplored promise for small‐molecule separations.     

Water-Induced Separation of Polymers from High Nanoparticle-Content Nanocomposite Films

Polymer nanocomposites with high loadings of nanoparticles (NPs) exhibit exceptional mechanical and transport properties. Separation of polymers and NPs from such nanocomposites is a critical step in enabling the recycling of these components and reducing the potential environmental hazards that can be caused by the accumulation of nanocomposite wastes in landfills. However, the separation typically requires the use of organic solvents or energy-intensive processes. Using polydimethylsiloxane (PDMS)-infiltrated SiO₂ NP films, we demonstrate that the polymers can be separated from the SiO₂ NP packings when these nanocomposites are exposed to high humidity and water. The findings indicate that the charge state of the NPs plays a significant role in the propensity of water to undergo capillary condensation within the PDMS-filled interstitial pores. We also show that the size of NPs has a crucial impact on the kinetics and extent of PDMS expulsion, illustrating the importance of capillary forces in inducing PDMS expulsion. We demonstrate that the separated polymer can be collected and reused to produce a new nanocomposite film. The work provides insightful guidelines on how to design and fabricate end-of-life recyclable high-performance nanocomposites.     

氢键酸性聚合物神经毒剂敏感材料的研究进展

神经毒剂由于呈现氢键碱性,因此以氢键酸性物质作敏感材料可以提高传感器的灵敏度、增强选择性、缩短响应时间.综述了氢键酸性敏感材料的研究现状,结果表明超支碳硅聚合物与线形、超支碳硅氧烷聚合物相比具有响应幅度大、工作温度高、抗干扰性强等优点.     

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.     

Synthetic Two‐Dimensional Materials: A New Paradigm of Membranes for Ultimate Separation

Microporous membranes act as selective barriers and play an important role in industrial gas separation and water purification. The permeability of such membranes is inversely proportional to their thickness. Synthetic two‐dimensional materials (2DMs), with a thickness of one to a few atoms or monomer units are ideal candidates for developing separation membranes. Here, groundbreaking advances in the design, synthesis, processing, and application of 2DMs for gas and ion separations, as well as water desalination are presented. This report describes the syntheses, structures, and mechanical properties of 2DMs. The established methods for processing 2DMs into selective permeation membranes are also discussed and the separation mechanism and their performances addressed. Current challenges and emerging research directions, which need to be addressed for developing next‐generation separation membranes, are summarized.