金属有机骨架材料储存CO_2的研究进展

随着温室效应日益严重,研发高效捕获CO_2的新型材料对于缓解环境压力具有重要意义。金属有机骨架材料具有高比表面积、结构多样性和孔道可调控性等优点,尤其在储存CO_2方面展现出惊人潜质。简要介绍金属有机骨架材料及其延伸化合物——沸石咪唑酯骨架材料和共价有机骨架材料作为新型储存CO_2材料,在结构、储存CO_2性能和机理等方面的研究进展,并阐述了该类材料在研究过程中存在的不足与发展前景。     

Facile preparation of high-capacity hydrogen storage metal-organic frameworks: A combination of microwave-assisted solvothermal synthesis and supercritical activation

The Cu₃(BTC)₂ Metal—oragnic frameworks (MOFs) are synthesized by four different processes, i.e. solvothermal method (sample 1), microwave-assisted solvothermal method (sample 2), a combination of solvothermal method and supercritical carbon dioxide (Sc-CO₂) activation (sample 3) and a combination of microwave-assisted solvothermal method and Sc-CO₂ activation (sample 4). By comparing the N₂ adsorption isotherms of the four samples, it is found that the sample 4 displays the greatest N₂ uptake. Due to the best performance of sample 4 in N₂ adsorption, we further study H₂ adsorption in the sample 4. Results indicate that the excess and absolute hydrogen uptakes of this material reach 4.12 and 4.49 wt% at T=77 K and P=18 bar, respectively, which is the largest one among all these reports on Cu₃(BTC)₂ for H₂ storage at the same condition. Therefore, it is believed that a combination of the two technologies of microwave-assisted method and supercritical Sc-CO₂ activation provides a new approach for chemical engineers rapidly and efficiently preparing MOFs for high-capacity H₂ storage.     

Stability of acetylene/methane and acetylene/hydrogen/methane gas mixtures at elevated temperatures and pressures

Hydrogen-enriched natural gas (HENG) containing a mixture of acetylene, hydrogen, and methane is produced from natural gas feedstock in our plasma dissociation process. Storage of this HENG fuel at pressures up to 4000 psig is required for rapid vehicle refueling. Little information on the stability of acetylene mixtures at elevated pressures is presently available; therefore we have performed stability testing on gas mixtures that simulate our HENG fuel. This report describes the stability testing of binary gas mixtures of acetylene and methane containing up to 10%(v) acetylene, and a ternary gas mixture of 4%(v) acetylene, 20%(v) hydrogen, and 76%(v) methane, at pressures up to 3600 psig and temperatures up to 200 °C. The mixtures tested were found to be stable to rapid spontaneous decomposition at all test conditions; however, some degree of hydrogenation of acetylene to ethylene may have occurred in an intermediate mixture of acetylene and hydrogen while preparing the highest pressure ternary test mixture.     

金属有机框架材料在光催化产氢领域的研究进展

综述了近年来金属-有机框架材料(MOFs)及其复合材料在光催化产氢领域中的研究进展情况,总结了该类材料在设计、合成等方面的相关策略,同时在光催化产氢领域中表现出的优异性能,最后提出了MOFs及其复合材料在光催化产氢领域中面临的挑战以及展望。     

金属有机框架材料在光催化产氢领域的研究进展

综述了近年来金属-有机框架材料(MOFs)及其复合材料在光催化产氢领域中的研究进展情况,总结了该类材料在设计、合成等方面的相关策略,同时在光催化产氢领域中表现出的优异性能,最后提出了MOFs及其复合材料在光催化产氢领域中面临的挑战以及展望。     

Large-scale simulations of CO2 diffusion in metal-organic frameworks with open Cu sites

Understanding CO₂ diffusion behavior in functional nanoporous materials is beneficial for improving the CO₂ adsorption, separation, and conversion performances. However, it is a great challenge for studying the diffusion process in experiments. Herein, CO₂ diffusion in 962 metal-organic frameworks (MOFs) with open Cu sites was systematically investigated by theoretical methods in the combination of molecular dynamic simulations and density functional theory (DFT) calculations. A specific force field was derived from DFT-D2 method combined with Grimme's dispersion-corrected (D2) density functional to well describe the interaction energies between Cu and CO₂. It is observed that the suitable topology is conductive to CO₂ diffusion, and 2D-MOFs are more flexible in tuning and balancing the CO₂ adsorption and diffusion behaviors than 3D-MOFs. In addition, analysis of diffusive trajectories and the residence times on different positions indicate that CO₂ diffusion is mainly along with the frameworks in these MOFs, jumping from one strong adsorption site to another. It is also influenced by the electrostatic interaction of the frameworks. Therefore, the obtained information may provide useful guidance for the rational design and synthesis of MOFs with enhanced CO₂ diffusion performance for specific applications.     

Prediction of methane storage in covalent organic frameworks using big-data-mining approach

A combination of computational materials screening and machine learning (ML) technique is being adopted as a popular approach to study various materials toward application of interest. In this work, we began with high-throughput molecular simulations to calculate the methane storage (6.5 MPa) and deliverable (6.5-0.58 MPa) capacities of 404,460 covalent organic frameworks (COFs) at 298 K. Then, the full data sets with 23 features were randomly split into training and test sets in a ratio of 20:80, which were applied to evaluate the prediction abilities of several ML algorithms, including gradient boosting decision tree (GBDT), neural network (NN), support vector machine (SVM), random forest (RF) and decision tree (DT). The results indicate that the RF model has the highest prediction accuracy, which was further employed to reduce the dimension of features space and quantitatively analyze the relative importance of each feature value. The binary classification predictors built using the features with the highest influence weight can give a successful identification of top-performing candidates from the test set containing 323,168 COFs with an accuracy exceeding 96%. The deliverable capacities of the identified COFs were found to outperform those reported so far for various adsorbents. The findings may provide a useful guidance for the design and synthesis of new high-performance materials for methane storage application.     

金属-有机框架材料在色谱分析中的应用研究进展

简单介绍了金属-有机框架材料的发展过程及MOFs在分析化学中的应用现状,主要综述了金属-有机框架色谱柱的研究进展,详细介绍了目前MOFs色谱柱的制备技术、对有机物质的分离机理和分析物类型.并对MOFs色谱柱的发展方向和应用前景进行了展望.     

Multi-scale theoretical investigation of hydrogen storage in covalent organic frameworks

The quest for efficient hydrogen storage materials has been the limiting step towards the commercialization of hydrogen as an energy carrier and has attracted a lot of attention from the scientific community. Sophisticated multi-scale theoretical techniques have been considered as a valuable tool for the prediction of materials storage properties. Such techniques have also been used for the investigation of hydrogen storage in a novel category of porous materials known as Covalent Organic Frameworks (COFs). These framework materials are consisted of light elements and are characterized by exceptional physicochemical properties such as large surface areas and pore volumes. Combinations of ab initio, Molecular Dynamics (MD) and Grand Canonical Monte-Carlo (GCMC) calculations have been performed to investigate the hydrogen adsorption in these ultra-light materials. The purpose of the present review is to summarize the theoretical hydrogen storage studies that have been published after the discovery of COFs. Experimental and theoretical studies have proven that COFs have comparable or better hydrogen storage abilities than other competitive materials such as MOF. The key factors that can lead to the improvement of the hydrogen storage properties of COFs are highlighted, accompanied with some recently presented theoretical multi-scale studies concerning these factors.     

Ionothermal synthesis of zeolites, metal-organic frameworks, and inorganic-organic hybrids

Ionothermal synthesis, the use of ionic liquids as both solvent and template (structure-directing agent), has been used to prepare zeolites and inorganic-organic hybrids such as metal-organic frameworks. The underlying properties of the ionothermal method are discussed, and it is compared with traditional hydrothermal preparative methods. The materials resulting from ionothermal synthesis are described, and any structural features that can be related to the ionic liquid used as the solvent are discussed. Future areas of potential interest are also considered.     

金属-有机配合物的合成途径研究进展

综述了金属-有机配位聚合物在设计与合成途径上的新思路和新方向,并结合近几年有代表性的实例加以证明,为今后金属-有机配位聚合物的合成、发展与应用提供有力的参考。     

金属有机骨架材料在吸附脱硫领域的应用

燃油中的含硫化合物燃烧产生的SO_x是环境污染的主要来源之一,近年来随着环保法规的日趋严格,油品的超深度脱硫已成为当务之急。吸附脱硫（ADS）因具有低能耗、条件温和、操作简单和反应高效等优点,被认为是实现深度脱硫的最有前景的技术之一。目前,作为多孔材料族的新成员,金属有机骨架（MOFs）已显示出良好的吸附脱硫性能。本文综述了近10年来MOFs在吸附脱硫中的最新研究成果。首先,简述了MOFs的不同分类,包括IRMOFs、ZIFs、MILs、PCNs、HKUST-1、UiOs、CPOs等类型,详细介绍了每一类MOFs中具有代表性的材料及其复合物在吸附脱硫中的研究和应用进展,对每种材料的吸附脱硫效果及回收再生、循环利用情况进行了分析;然后总结了不同MOFs的吸附脱硫机理,概述了MOFs吸附剂的稳定性;最后,指出了MOFs在今后应用中应着重解决的问题,并对MOFs在吸附脱硫领域的应用前景进行了展望。     

离子热合成金属-有机骨架材料最新研究进展

离子热合成是近年来新兴的合成具有新颖拓扑结构的金属-有机骨架材料的方法。本文综述了离子热合成金属-有机骨架材料的研究进展,介绍了离子热合成金属-有机骨架的具体合成方法,重点探讨了离子液体的阴阳离子对骨架结构的影响及离子液体在手性金属-有机骨架材料合成方面的研究情况。另外,还将离子热合成方法与传统水热/溶剂热合成方法进行了详细地比较,并针对几种代表性的金属-有机骨架材料的合成,探讨了不同合成方法得到的材料在结构上的差异。离子液体的种类和结构对金属-有机骨架材料结构方面的影响机理还有待于进一步的探讨。     

金属有机框架孔径调控进展

金属有机框架(MOFs)以其可灵活调节的孔道结构、大孔隙率和大比表面积等特点受到广泛关注。设计并构建能够实现目标功能的、具有合适孔径分布的MOFs材料关系到MOFs材料在分离、催化以及质子传导等领域中的应用。综述了MOFs材料孔径的主要调控方法,包括原位合成调控、后合成修饰调控、穿插调控以及辅助合成调控,总结了四种调控方法的特点和不足,并对未来MOFs孔径调控的发展方向进行了展望。     

金属-有机框架材料在石化环保领域的应用

石油化工是我国的支柱产业,也是环境污染的主要来源。近年来,随着国家环保形势的日益严峻和相应环保法规的陆续出台,高效处理石化行业所涉及的各类污染问题已成为重中之重。作为一种新型的纳米多孔材料,金属-有机框架（MOF）在石化环保领域展现出了广阔的应用前景。该材料可作为高性能吸附剂、分离膜以及催化材料去除或降解石化行业中的典型污染物。本文系统梳理了MOF材料及其相关工艺在石化环保领域的潜在应用,重点介绍了近年来国内外取得的突破性进展,并在此基础上深入分析了该材料的应用现状、存在问题及未来的研发方向。总体而言,MOF材料具有比传统多孔材料更优异的结构特征和应用性能;展望未来,其能够作为吸附剂、分离膜或是催化材料在石化环保领域得到更大规模的推广与应用。     

柔性金属有机骨架材料(MOFs)用于气体吸附分离

柔性金属有机骨架材料(MOFs)具有高度有序的网络结构与可变形的骨架,其骨架结构会对外界的温度、压力及客体分子的刺激产生独特的结构响应。近几年来,柔性MOFs在气体吸附、气体分离、传感等领域显示出巨大的应用潜力。截至目前,研究者们对柔性MOFs的研究仅局限于对其结构形变的机理解释,而缺乏对柔性MOFs应用于相关化工过程的性能研究。本文着重对近年来柔性MOFs在气体吸附分离领域的研究进展进行了综述,并详细地分析了柔性MOFs结构与其气体吸附分离性能之间的构效关系。通过分子模拟结合实验,讨论了柔性MOFs结构对气体分子的平衡吸附与动力学扩散的影响。分析表明,设计合成具有良好吸附选择性与扩散性能的柔性MOFs是其应用于绿色、高效气体分离过程的重要发展方向。     

Unusual metal-organic frameworks built from 2D layers through Cl⋯Cl contacts and hydrogen bonds

Unusual metal-organic frameworks [M(dtcp)₂](SCN)₂ [M = Zn, Mn; dtcp = 2,6-di(1,2,4-triazol-1-ylmethyl)-4-chlorophenol] are composed of 2D rhombus-type grid networks associated mutually by remarkable Cl⋯Cl contacts and hydrogen bonds (C–H⋯N and C–H⋯S). Both thermogravimetric analysis and photoluminescence measurements are performed as well to characterize these supramolecular frameworks.