金属有机框架材料的制备及在吸附分离CO2中的应用

金属有机框架（MOFs）材料是当今的研究热点之一,是一类颇有潜力成为适用于CO₂吸附和分离的重要材料。本文从MOFs的发展及其所具有的特点、MOFs用于CO₂的吸附与分离所取得的突破性进展以及MOFs的传统合成及绿色制备方法三个方面展开论述。主要论述了MOFs适用于CO₂吸附的原理,及其相对于传统的CO₂吸附材料所具有的特点和优势,亦阐述了MOFs修饰与调变的方法。列出了MOFs用于单组分CO₂吸附及CO₂/CH₄、CO₂/N₂吸附分离的结果。同时,针对传统MOFs制备方法不适宜大规模CO₂捕集材料的生产,特别论述了机械化学合成法和新兴的潮湿矿物风化法,其均具有绿色化、无溶剂、低能耗和简单等特点,是一类较有研究价值和应用潜力的技术。随着温室效应和不可再生石化燃料的消耗等环境和能源问题的日趋严峻,研究及开发适用于CO₂捕集与封存技术的MOFs新材料迫在眉睫,且任重而道远。     

金属有机框架材料在分离分析领域的研究进展

金属有机框架材料是由金属离子节点和有机配体通过配位键连接形成的具有序多孔骨架的材料, 因其具有比表面积大、 孔隙可调及表面性质可控等优点而备受关注. 通过对有机配体和金属离子进行选择及对金属有机框架材料进行后修饰处理, 可实现对金属有机框架材料表面性质的调控, 以提升其选择性吸附及特异性识别等性能, 进而拓展其在分离分析等领域的应用. 本文从金属有机框架材料的表面性质调控出发, 介绍了其表面性质与分离分析性能的关系, 总结了近年来该领域的代表性工作, 并展望了金属有机框架材料在分离分析领域的应用前景.     

基于机器学习和高通量计算筛选金属有机框架的甲烷/乙烷/丙烷分离性能

针对天然气中的甲烷、乙烷、丙烷(C₁、C₂、C₃)气体分离困难的问题,本工作采用高通量计算了137953种假设的金属有机框架(Metal-organicframework,MOF)对这三种混合气体的吸附分离吸能.为了避免水蒸气的竞争吸附,首先,筛选出31399种疏水性MOF.然后,单变量分析了这些MOF的最大孔径(LCD)、孔隙率(Φ)、体积比表面积(VSA)、亨利系数(K)、吸附热(Q_st)、密度(ρ)共六种MOF结构/能量描述符与MOF对C₁、C₂、C₃的选择性、吸附量及两者权衡值(Trade-off between S_i/j and N_i, TSN)的关系,发现了吸附量和选择性"第二峰值"的存在;尤其对于C₁、C₂的分离,所有最优MOF都分布在第二峰值区间.随后采用决策树、随机森林(Random forest, RF)、支持向量机和反向传播神...     

生物金属有机框架ZnBTCA对CO2的选择性吸附性能

采用溶剂热法制备的生物金属有机框架ZnBTCA,在CO_2的吸附过程中表现出有趣的主客体化学现象,通过计算发现随着CO_2吸附量的增加,吸附焓逐渐增大。采用4种模型分别对其进行拟合,并通过理想吸附溶液理论模拟预测ZnBTCA对二元混合气体的选择性,试图找到ZnBTCA反常吸附行为的合理解释:ZnBTCA带有氨基和N-活性位点,且孔道内含有大量的客体离子。虽然ZnBTCA孔径较大,但由于其本身的阴离子框架,孔道中的(CH3)2NH2+抗衡离子并未完全去除而降低了可接触的微孔体积,在吸附过程中存在分子筛效应,在二元混合气体中对CO_2具有很高的吸附选择性。     

机器学习与分子模拟协同的CH4/H2分离金属有机框架高通量计算筛选

在减少CO₂排放、实现碳中和的背景下, 金属有机框架(MOFs)在清洁能源领域展现出广阔应用前景. 提出一种机器学习和分子模拟协同的分层筛选策略, 快速、准确地从134185个假设MOFs中识别出具有最佳CH₄/H₂分离性能的吸附剂. 首先, 根据MOFs的结构性质, 筛掉孔径或体积比表面积不恰当的吸附剂, 初筛后MOFs的数量减至62278个. 接下来, 抽取10% MOFs将结构和化学混合描述符作为特征, 利用随机森林分别构建变压吸附和真空变压吸附过程中其对CH₄的吸附剂性能得分(APS)预测模型. 相比于其他模型构建策略, 基于本策略构建的模型具有最优预测准确性, 可用于余下MOFs的性能预测. 随后根据APS预测值排序, 筛选出Top 1000的MOFs并利用分子模拟修正预测结果, 进一步确定了10个最佳MOFs. 最后, 对描述符的重要性进行解释, 揭示了实现模型在不同操作场景下的迁移具有潜力, 为未来开发适用于多操作场景下的高性能MOFs筛选方法提供了一条高效的研究路径和方法.     

机器学习筛选用于气体吸附分离和存储的金属有机骨架材料

金属有机框架（Metal-organic framework ,MOF）因其高孔隙率、高比表面积和结构可调性,在气体吸附分离领域广泛应用。随着MOF数量激增,传统分子模拟和实验方法验证MOF性能成本高且速度慢,因此目前MOF筛选工作已转向高通量计算辅助的机器学习（Machine-learning,ML）。机器学习作为一种高效的大数据处理方法,能够在高通量筛选（High-Throughput Computational Screening,HTCS）的基础上对数据进行拟合,从而快速而准确地筛选出气体吸附分离材料,并深入挖掘其结构与性能之间的关系。本文回顾了近年机器学习应用于MOF筛选的研究。本文重点讨论了一些运用机器学习从大量结构中筛选出可用于CH4、H2和CO2等气体吸附分离与储存的MOF材料的工作。同时,我们梳理了当前MOF材料筛选工作中的研究思路和进展,并指出了机器学习在筛选MOF材料工作中面临的一些瓶颈和挑战。最后,对该领域的未来发展前景进行了展望。     

金属有机框架分离纯化C4～C6碳氢化合物的研究

C₄～C₆碳氢化合物作为重要的化工原料和能源,在传统的石化工业生产中,主要通过精馏进行分离提纯,此过程能耗高、设备费用昂贵、经济效益低.利用固体吸附剂进行吸附式分离,不仅可以降低能源成本,而且可以提高效率.金属有机框架（metal-organic frameworks,MOFs）作为一类由金属离子或团簇和有机单体组装而成的晶态多孔材料,具有高孔隙率、规整开放的孔道、丰富的官能团和多样的结构,在气体储存与分离中有着良好的应用前景.介绍了C₄～C₆碳氢化合物分离的重要性,并从MOFs分离机制出发,概述了目前MOF材料用于分离纯化C₄～C₆碳氢化合物的分离机理和研究进展,为开发新型具有良好分离性能的MOF材料提供研究思路.     

镁金属有机框架材料应用研究进展

镁金属有机框架材料（Mg-MOFs）作为一类高比表面积、结构可设计的多孔功能材料,有其独特的优势,其应用涉及到诸多领域,为镁资源的开发利用开拓了新领域,近年来受到了广大科研工作者的关注。本文阐述了Mg-MOFs在气体吸附与分离、电极材料、荧光传感、催化、染料吸附、药物传递六个方面的应用,提出了Mg-MOFs今后研究重点,并展望了其应用前景。     

极性基团修饰金属有机框架材料吸附分离CO2的研究进展

基于从废气中脱除回收CO_2的迫切现实需求,通过对金属有机框架材料(MOFs)进行功能化修饰,构筑具有高容量、高选择性CO_2吸附的耐水MOFs材料成为当前的研究热点。本文首先对MOFs材料的高压CO_2吸附进行了简单的介绍;进而,针对实际工业应用中低压条件下的CO_2捕集,对作为调节MOFs材料CO_2低压吸附分离性能的有效手段的含氮以及杂原子极性基团修饰进行了综述。     

含茂基咔唑镧系金属有机配合物的合成

以咔唑和正丁基锂为原料,采用schlenk技术合成了一系列新的含茂基咔唑镧系金属有机配合物--Cp2LnL(Cp=环戊二烯基;Ln=Yb,Er,Ho,Tb,Gd,Sm;L=咔唑基),其结构经IR,MS和元素分析表征.     

Separation of CO2/CH4 and CH4/N2 mixtures using MOF-5 and Cu3(BTC)2

In this paper we used MOF-5 and Cu₃(BTC)₂ to separate CO₂/CH₄ and CH₄/N₂ mixtures under dynamic conditions. Both materials were synthesized and pelletized, thus allowing for a meaningful characterization in view of process scale-up. The materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). By performing breakthrough experiments, we found that Cu₃(BTC)₂ separated CO₂/CH₄ slightly better than MOF-5. Because the crystal structure of Cu₃(BTC)₂ includes unsaturated accessible metal sites formed via dehydration, it predominantly interacted with CO₂ molecules and more easily captured them. Conversely, MOF-5 with a suitable pore size separated CH₄/N₂ more efficiently in our breakthrough test.     

Synthesis,Structures and Properties of Three New Compounds Based on Multidentate Ligand Containing Triazole and Pyrimidine

Three new compounds, namely, [Zn(mtpo)₂(H₂O)4](1), [Cd(mtpo)₂·CH₃CH₂OH]_n(2) and [Mn(mtpo)₂·CH₃CH₂OH]_n(3)(Hmtpo=4,7-dihydro-5-methyl-7-oxo-[1,2,4]triazolo[1,5-a]pyrimidine), have been synthesized via hydrothermal or solvothermal methods and characterized by means of elemental analyses, Fourier transform infrared(FTIR) spectroscopy, powder X-ray diffraction(PXRD), thermogravimetric analysis(TGA) and single-crystal X-ray diffraction. The results obtained from the single-crystal X-ray diffraction indicate that compound 1 has a mononuclear structure, and crystallizes in a monoclinic crystal system with P2₁/c space group, which exhibits a 2D supramolecular network constructed by hydrogen bonds and π-π interactions. Compounds 2 and 3 are isomorphous and crystallize in a tetragonal system with space group of I4₁/a. The M²⁺(M=Cd, Mn) ions in compounds 2 and 3 have the octahedral coordination geometry. Hmtpo acts as a bridging ligand linking the metal ions to form an infinite 3D framework with 4-connected {4²·8⁴} topology. There are hydrogen bonds between the guest ethanol molecules and the mtpoligands, which make the ethanol molecules exist in a 3D framework. In addition, luminescent properties of compounds 1 and 2 as well as magnetic property of compound 3 were investigated and water vapor adsorption and nitrogen sorption for compounds 2 and 3 were researched at 298 and 77 K, respectively.     

Ultra‐Tuning of the Aperture Size in Stiffened ZIF‐8_Cm Frameworks with Mixed‐Linker Strategy for Enhanced CO2/CH4 Separation

ZIF‐8 membrane has the potential for CO₂/CH₄ separation based on size exclusion. But if traditionally prepared by solvothermal methods, it shows only negligible selectivity due to the linker mobility. Here, ≈500 nm‐thin hybrid ZIF‐7_x‐8 membranes with suppressed linker mobility and narrowed window aperture are prepared by a fast current‐driven synthesis (FCDS) within 20 min. The in situ electric field during FCDS allows the formation of stiffened ZIF‐8_Cm as parent skeleton and the mixed‐linker strategy is applied to narrow the aperture size simultaneously. The ZIF‐7₂₂‐8 membrane shows significantly sharpened molecular sieving for CO₂/CH₄ with a separation factor above 25, which soared tenfold compared with other unmodified ZIF‐8 membranes. Additionally, the membrane shows exceptional separation performance for H₂/CH₄ and CO₂/N₂, with separation factors of 71 and 20, respectively. After 180 h temperature swing operation, it still maintains the excellent separation performance.     

Dimeric Calix[4]resorcinarene-based Porous Organic Cages for CO2/CH4 Separation

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.     

Novel Porous Aromatic Framework with Excellent Separation Capability of CO2 in N2 or CH4

A novel porous aromatic framework, PAF-52, was obtained via the polymerization of tetrahedral mono- mer tetrakis（4-cyanodiphenyl） methane（TCDPM） with the aid of a facile ionothermal method. PAF-52 has a surface area of 1159 m2/g（BET）, and shows a considerable high separation ability of CO2 in N2 or CH4 respectively at room temperature, using gas-chromatography experiments as evidence,     

金属有机骨架材料/聚酰亚胺混合基质膜的制备及气体分离性能

合成了3种不同结构、 粒径和气体吸附性能的金属有机骨架材料(MOFs): 微米级Cu₃(BTC)₂、 亚微米级ZIF-8和S-Cu₃(BTC)₂. 氮气吸附等温线分析结果表明, ZIF-8和Cu₃(BTC)₂具有较大比表面积(1653和1439 m²/g), S-Cu₃(BTC)₂的比表面积为171.4 m²/g. 用共混法将MOFs直接引入聚酰亚胺中制备了MOFs/聚酰亚胺混合基质膜(MMMs). X射线衍射(XRD)和全反射红外光谱(FTIR-ATR)分析结果表明, MOFs在混合基质膜中保持物理和化学稳定. 气体渗透测试结果表明, MOFs的加入使膜的气体渗透分离性能明显提高, S-Cu₃(BTC)₂使渗透系数增加了1.75倍; ZIF-8和Cu₃(BTC)₂使渗透系数增加了3倍左右; 同时, 膜的气体分离系数变化很小.     

In-situ Etching Synthesis of Defective CuBTC for CO2/CH4 Separation

We report a facile in-situ etching method for the synthesis of defective CuBTC (H-CuBTC) with hierarchical pore structure. The fabricated mixed matrix membranes (MMMs) containing H-CuBTC was prepared for the separation of CO₂/CH₄, showing superior separation performance due to the defective structure with larger pore size and more open Cu sites, which enhance the interactions between H-CuBTC and the polymer.     

Absolute CO2/Xenon Separation in Ultramicropore MOF for Anesthetic Gases Regeneration

Xe is an ideal anesthetic gas, but it has not been widely used in practice due to its high cost and low output. Closed-circuit Xe recovery and recycling is an economically viable method to ensure adequate supply in medical use. Herein, we design an innovative way to recover Xe by using a stable fluorinated metal-organic framework (MOF) NbOFFIVE-1-Ni to eliminate CO₂ from moist exhaled anesthetic gases. Unlike other Xe recovery MOFs with low Xe/CO₂ selectivity (less than 10), NbOFFIVE-1-Ni could achieve absolute molecular sieve separation of CO₂/Xe with excellent CO₂ selectivity (825). Mixed-gas breakthrough experiments assert the potential of NbOFFIVE-1-Ni as a molecular sieve adsorbent for the effective and energy-efficient removal of carbon dioxide with 99.16 % Xe recovery. Absolute CO₂/Xe separation in NbOFFIVE-1-Ni makes closed-circuit Xe recovery and recycling can be easily realized, demonstrating the potential of NbOFFIVE-1-Ni for important anesthetic gas regeneration under ambient conditions.     

气体分离用MOF基混合基质膜的界面构建策略

混合基质膜结合多孔填料优异的气体分离性能和聚合物材料良好的加工性能,被认为是最具有应用前景的一种气体分离膜材料。金属-有机框架材料(MOF)由于具有高比表面积和孔隙率、可调节的孔径以及可修饰的表面性能,成为制备混合基质膜的重要多孔材料。本文针对MOF基混合基质膜制备中所面临的主要挑战,聚焦于MOF和聚合物界面缺陷问题,分析了界面缺陷的产生原因及其对性能的影响,重点阐述了改善MOF填料和聚合物基质界面相容性的策略,以期为制备具有良好的界面形态和优异的气体分离性能的混合基质膜提供借鉴思路。