Room temperature solution-phase synthesis of flower-like nanostructures of [Ni3(BTC)2·12H2O] and their conversion to porous NiO

Hierarchical flower-like architectures of[Ni₃（BTC）₂·12H₂O]（BTC³=benzene-1,3,5-tricarboxylate） were successfully prepared by a simple solution-phase method under mild conditions without any template or surfactant.Phase-pure porous NiO nanocrystals were obtained by annealing the Ni-BTC complex without significant alteration in morphology.The product was characterized by X-ray diffraction techniques,field-emission scanning electron microscopy（FESEM）.transmission electron microscopy（TEM） and high-resolution TEM（HRTEM）.The catalytic effect of the NiO product was investigated on the thermal decomposition of ammonium perchlorate（AP） and it was found that the annealed NiO product has higher catalytic activity than the commercial NiO.     

Continuous synthesis for zirconium metal-organic frameworks with high quality and productivity via microdroplet flow reaction

A series of Zr-based metal-organic frameworks were continuously synthesized with high quality and high productivity through microdroplet flow reaction.     

Recent advances of hexaazatriphenylene (HAT) derivatives: Their applications in self-assembly and porous organic materials

As a rigid and planar aza-based heteroaromatic scaffold, hexaazatriphenylene (HAT) exhibits excellent electron-deficient property and high π-π stacking tendency, which makes it an ideal building block in the construction of supramolecular architectures and functional materials. In addition, HATs have also been picked out as building blocks for the construction of novel porous organic polymers, one of the most attractive fields of porous materials in the past decade, which includes intrinsic microporosity (PIMs), π-conjugated microporous polymers (CMPs), and covalent organic frameworks (COFs). In this digest paper, the synthetic methods of HAT derivatives have been briefly introduced and some recent advances of HATs in the applications of supramolecular self-assembly and porous organic materials have been highlighted.     

Control of pore environment in highly porous carbon materials for C2H6/C2H4 separation with exceptional ethane uptake

Adsorptive separation of C₂H₆ from C₂H₄ by adsorbents is an energy-efficient and promising method to boost the polymer grades C₂H₄ production. However, that C₂H₆ and C₂H₄ display very similar physical properties, making their separation extremely challenging. In this work, by regulating the pore environment in a family of chitosan-based carbon materials (C-CTS-1, C-CTS-2, C-CTS-4, and C-CTS-6)- we target ultrahigh C₂H₆ uptake and C₂H₆/C₂H₄ separation, which exceeds most benchmark carbon materials. Explicitly, the C₂H₆ uptake of C-CTS-2 (166 cm³/g at 100 kPa and 298 K) has the second-highest adsorption capacity among all the porous materials. In addition, C-CTS-2 gives C₂H₆/C₂H₄ selectivity of 1.75 toward a 1:15 mixture of C₂H₆/C₂H₄. Notably, the adsorption enthalpies for C₂H₆ in C-CTS-2 are low (21.3 kJ/mol), which will facilitate regeneration in mild conditions. Furthermore, C₂H₆/C₂H₄ separation performance was confirmed by binary breakthrough experiments. Under different ethane/ethylene ratios, C-CTS-X extracts a low ethane concentration from an ethane/ethylene mixture and produces high-purity C₂H₄ in one step. Spectroscopic measurement and diffraction analysis provide critical insight into the adsorption/separation mechanism. The nitrogen functional groups on the surface play a vital role in improving C₂H₆/C₂H₄ selectivity, and the adsorption capacities depend on the pore size and micropore volume. Moreover, these robust porous materials exhibit outstanding stability (up to 800 °C) and can be easily prepared on a large scale (kg) at a low cost (～$26 per kg), which is very significant for potential industrial applications.     

Continuous flow techniques in organic synthesis

As part of the dramatic changes associated with the need for preparing compound libraries in pharmaceutical and agrochemical research laboratories, the search for new technologies that allow automation of synthetic processes has become one of the main topics. Despite this strong trend for automation high-throughput chemistry is still carried out in batches, whereas flow-through processes are rather restricted to production processes. This is far from understandable because the main advantages of that approach are facile automation, reproducibility, safety, and process reliability, because constant reaction parameters can be assured. Indeed, methods and technologies are missing that allow rapid transfer from the research level to process development without time-consuming adaptation and optimization of methods from the laboratory scale to production plant scale. Continuous-flow processes are considered as a universal lever to overcome these restrictions and, only recently, joint efforts between synthetic and polymer chemists and chemical engineers have resulted in the first continuous-flow devices and microreactors; these allow rapid preparation of compounds with minimum workup. Many of these approaches use immobilized reagents and catalysts, which are embedded in a structured flow-through reactor. It is generally accepted, that for achieving best reaction and kinetic parameters for convective-flow processes monolithic materials are ideally suited as solid phases or polymer supports. In addition, immobilization techniques have to be developed that allow facile regeneration of the active species in the reactor.     

Recent Advances of Precise Cu Nanoclusters in Microporous Materials

This minireview highlights some recent advances in the rational design of precise Cu nanoclusters supported on microporous materials, including zeolites and metal‐organic frameworks. The development of comprehensive characterisation techniques enables scientists to elucidate the structure‐activity relationship of these catalysts, which aids the subsequent engineering of more superior catalytic systems at an atomistic perspective.     

Predicting adsorption isotherms of asphaltenes in porous materials

In this paper we present a molecular thermodynamics approach for the modeling of adsorption isotherms of asphaltenes adsorbed on Berea sandstone, Bedford limestone and dolomite rock, using a model for bulk asphaltenes precipitation and a quasi-two-dimensional approach for confined fluids [E. Buenrostro-González, C. Lira-Galeana, A. Gil-Villegas, J. Wu, AIChE J., 50 (2004) 2552–2570; A. Martínez, M. Castro, C. McCabe A. Gil-Villegas, J. Chem. Phys. 126 (2007) 074707, respectively], both based on the Statistical Associating Fluid Theory for Potentials of Variable Range [A. Gil-Villegas, A. Galindo, P.J. Whitehead, S.J. Mills, G. Jackson, A.N. Burgess, J. Chem. Phys. 106 (1997) 4168–4186]. The theory is applied to model adsorption isotherms from experimental data of asphaltenes extracted from a dead sample of heavy crude oil from a Mexican reservoir. The theoretical results give the right Langmuir Type II adsorption isotherms observed experimentally. The model requires the determination of ten molecular parameters related to the size of the particles and the square-well potentials used to describe the particle–surface and particle–particle interactions at the bulk and adsorbed phases. Nine parameters are taken from previous published results about the behavior of asphaltenes in bulk phases and the adsorption of several molecular fluids onto activated carbon and graphite surfaces. The remaining parameter, the energy strength of the particle–surface interaction, is adjusted to reproduce the experimental data, obtaining values that are consistent with Molecular Mechanics calculations for asphaltenes adsorbed on different surfaces and solutions. Although the agreement between theory and experiments shows some deviations at low bulk concentrations, the model reproduces adsorption data at high concentrations where other semi-empirical approaches fail.     

Functional materials: from hard to soft porous frameworks

This Review aims to give an overview of recent research in the area of porous, organic-inorganic and purely organic, functional materials. Possibilities for introducing organic groups that exhibit chemical and/or physical functions into porous materials will be described, with a focus on the incorporation of such functional groups as a supporting part of the pore walls. The number of organic groups in the network can be increased such that porous, purely organic materials are obtained.     

Effect of Micropores of a Porous Coordination Polymer on the Product Selectivity in RuII Complex-catalyzed CO2 Reduction

To develop an efficient CO2 reduction catalyst, hybridizing a molecular catalyst and a porous coordination polymer (PCP) is a promising strategy because it can combine both advantages of the precise reactivity control of the former and the CO2 adsorption property of the latter. Although several PCP hybrid catalysts have been reported to date, the CO2 sorption behavior and the CO2 reduction reactivity have been investigated separately, and the CO2 enrichment during the catalysis is still unclear. We report CO2 photoreduction under different temperatures and pressures using a PCP-RuII complex hybrid catalyst. The product selectivity (CO or HCOOH) varied depending on the reaction conditions. The altered selectivity could be interpreted in terms of the CO2 capture in the micropores of a PCP.     

共价有机骨架材料设计及其在分离领域的应用

共价有机骨架(COFs)材料是由有机小分子单体通过共价键连接形成的结晶多孔聚合物。与传统的线性聚合物不同的是,COFs可以在二维和三维空间上对其骨架结构进行控制,从而合成具有高度有序的刚性多孔结构,并且能够调节骨架的化学和物理性质。这种由COF形成的纳米级孔道和空间为分子存储、释放和分离提供了理想的环境。因此它在能量储存、分离、催化等领域有着广泛的应用前景。本文综述了近年来COFs材料的研究进展,主要包括材料的合成策略及其在分离领域的应用,并对COFs材料未来的发展方向进行了展望。     

Uranyl carboxyphosphonates that incorporate Cd(II)

The hydrothermal treatment of UO₃, Cd(CH₃CO₂)₂·2H₂O, and triethyl phosphonoacetate results in the formation of Cd₂[(UO₂)₆(PO₃CH₂CO₂)₃O₃(OH)(H₂O)₂]·16H₂O (CdUPAA-1), [Cd₃(UO₂)₆(PO₃CH₂CO₂)₆(H₂O)₁₃]·6H₂O (CdUPAA-2), and Cd(H₂O)₂[(UO₂)(PO₃CH₂CO₂)(H₂O)]₂ (CdUPAA-3). CdUPAA-1 adopts a cubic three-dimensional structure constructed from planar uranyl oxide clusters containing both UO₇ pentagonal bipyramids and UO₈ hexagonal bipyramids that are linked by Cd(II) cations and phosphonoacetate to yield large cavities approximately 16 Å across that are filled with disordered water molecules. CdUPAA-2 forms a rhombohedral three-dimensional channel structure that is assembled from UO₇ pentagonal bipyramids that are bridged by phosphonoacetate. CdUPAA-3 is layered with the hydrated Cd(II) cations incorporated directly into the layers linking one-dimensional uranyl phosphonate substructures together. In this structure, there are complex networks of hydrogen bonds that exist within the sheets, and also stitch the sheets together.     

Assembly of metal ions and ligands with adaptable coordinative tendencies as a route to functional metal-organic solids

The majority of efforts on metal-organic frameworks (MOFs) concern their rational design and, intuitively, researchers are drawn to assembly units with well-defined, reliable coordinating tendencies. Assembly units with less well-defined properties are generally less employed. This concept paper discusses the merits of using adaptable components for the assembly of functional MOFs. “Adaptable” components, whether for the metal ion or for the ligating group, are defined as those having several coordination modes within a narrow energetic range. Use of these assembly units can lead to new solids with: (i) highly dynamic properties; (ii) new inorganic structural motifs; and possibly (iii) high thermal stabilities. The article, to facilitate comparison, considers a framework on the basis of metal ion, coordinating functionality, and organic spacer. Networks with one, two and three “adaptable” units are then discussed. Ultimately, the illustration that less well-defined properties does not necessarily translate to less functional materials will be made.     

Strategies for design and synthesis of porous liquids toward carbon capture and separation

Porous liquids (PLs) represent a promising category of sorbents in carbon capture and separation capable of integrating the advantages of flowing liquid and porous solid systems. Well-defined pores were engineered into liquid sorbents via liquifying molecules with stiff interior voids, dissolving rigid porous hosts in flowing liquids, or dispersing porous frameworks in high steric hindrance solvents, producing type I, II, or III PLs, respectively. Unique features of PLs have triggered broad interest in exploring their applications in carbon capture and separation, in which diverse design strategies, synthesis approaches, and enhanced performance have been reported. In this minireview, recent progress in the design, synthesis, and structural engineering of PLs and efforts towards the optimization of their carbon capture and separation behavior will be summarized, including the comparison between PLs with varied types. Porosity engineering into liquid sorbents provides opportunities to resolve challenging issues in conventional sorption and separation systems.     

An improved test method for characterising touch properties of porous polymeric materials

A new test method and instrument was developed to provide overall evaluation and characterisation of touch properties of porous polymeric materials. The test method and instrument can simulate the dynamic contact process between human skin and porous polymeric materials and obtain the mechanical and physical performance during contact. In the improved test method, a new measurement principle was proposed, and the mechanical device was redesigned, including surface friction measurement components. Most indices were redefined and the grading and classification methods were studied to give a direct overall evaluation of the touch properties for industrial applications. The objective test results and analysis, subjective evaluation method and prediction model of touch properties are also presented. The improved test method provides an objective measurement of thermal-mechanical properties using a single measuring instrument for new product development and quality control of porous polymeric materials.     

Crystalline oxyfluorinated open-framework compounds: Silicates, metal phosphates, metal fluorides and metal-organic frameworks (MOF)

This contribution is dedicated to a short overview on the utilization of fluorine for the preparation of crystalline microporous frameworks including different families of solids: zeolites, metal phosphates and metal-organic frameworks (MOF-type). Beside the silicates compounds, this presentation is focused on the different types of fluorinated aluminum or gallium phosphates hydrothermally obtained in the presence of organic structure-directing agent or templates. The structural features of aluminum fluorides synthesized with amines are also detailed as well as the influence of fluorine in the synthesis of the metal-organic frameworks involving trivalent metals. The role of fluorine is described for the hydrothermal synthesis of the different classes of materials. Fluorine is known for playing the role of mineralizing agent and favors the formation of well crystalline phases. The use of HF modifies the pH of the reaction, which allows for the insertion of additional metallic cations on the mineral network. From the structural point of view, fluoride anions can be located within small cavities of the 3D framework and interactions with metals T (T = Si, Al, Ga, …) are often observed, resulting in the coordination change (from tetrahedral unit TO₄ to trigonal bipyramid TO₄F or octahedron TO₄F₂). Several configurations are found for fluorine and it seems to favor the stabilization of the specific cubane-like building unit (D4R), in which it is trapped, or participates to the coordination sphere of the metal atoms with bridging or terminal bondings. In general, new three-dimensional topologies with extra-large pores are obtained. The synthesis of purely aluminum fluorides with structure-directing agent is considered but only molecular or low-dimensional structures (chain-like or layered) compounds have been described. Fluorine is also used as a mineralizing agent for the preparation of well crystalline porous aluminum or chromium carboxylates and it was observed to partly substitute the aquo ligands in the giant pore of the compound MIL-100.     

Development and evaluation of porous materials for carbon dioxide separation and capture

The development of new microporous materials for adsorption separation processes is a rapidly growing field because of potential applications such as carbon capture and sequestration (CCS) and purification of clean-burning natural gas. In particular, new metal-organic frameworks (MOFs) and other porous coordination polymers are being generated at a rapid and growing pace. Herein, we address the question of how this large number of materials can be quickly evaluated for their practical application in carbon dioxide separation processes. Five adsorbent evaluation criteria from the chemical engineering literature are described and used to assess over 40 MOFs for their potential in CO(2) separation processes for natural gas purification, landfill gas separation, and capture of CO(2) from power-plant flue gas. Comparisons with other materials such as zeolites are made, and the relationships between MOF properties and CO(2) separation potential are investigated from the large data set. In addition, strategies for tailoring and designing MOFs to enhance CO(2) adsorption are briefly reviewed.     

Recent progress in scanning electron microscopy for the characterization of fine structural details of nano materials

Research concerning nano-materials (metal-organic frameworks (MOFs), zeolites, mesoporous silicas, etc.) and the nano-scale, including potential barriers for the particulates to diffusion to/from is of increasing importance to the understanding of the catalytic utility of porous materials when combined with any potential super structures (such as hierarchically porous materials). However, it is difficult to characterize the structure of for example MOFs via X-ray powder diffraction because of the serious overlapping of reflections caused by their large unit cells, and it is also difficult to directly observe the opening of surface pores using ordinary methods. Electron-microscopic methods including high-resolution scanning electron microscopy (HRSEM) have therefore become imperative for the above challenges. Here, we present the theory and practical application of recent advances such as through-the-lens detection systems, which permit a reduced landing energy and the selection of high-resolution, topographically specific emitted electrons, even from electrically insulating nano-materials.     

Facile synthesis of palladium nanoparticles supported on urea-based porous organic polymers and its catalytic properties in Suzuki-Miyaura coupling

By using urea linked porous organic polymers as template, a new nano palladium catalyst with low Pd loading can be easily prepared (1.0 wt% Pd only). Although such less amount of Pd was contained in this new catalyst, it is still an effective catalyst for the Suzuki-Miyaura coupling of aryl iodines and aryl boric acids, affording biphenyl products in excellent yields with outstandingly enhanced turnover numbers (up to 10,536) under green solvent (water).     

Foam flow through porous media

There are two parts to the interaction of foam with porous media. How the foam interacts with the surface and the flow within the substrate, which is the focus of this review. Flow-through porous media has been investigated experimentally with the main focus in literature being on enhanced oil recovery and remediation. Recently, investigation of the flow of foam through a deformable substrate for dishwashing application has led to the development of mathematical models. It has been proposed that foam flow through pore channels is similar to the behaviour observed within microchannels. Meaning that to investigate the effects these properties have on foam flow it is best to observe them within a model channel then build up to a 3D structure of interlinking channels to resemble porous media. In this review, it is highlighted that a large amount of work is needed in understanding the interaction of foam and/or liquid within porous networks. Methods that can be applied to better represent foam and liquid flow in porous media are discussed within this review, including both using microchannels to simulate individual pores and using these systems to build up to a 3D structure of interlinking pores. In addition, more advanced imaging techniques to observe the flow through porous materials are discussed, including computed tomography scanning nuclear magnetic resentence and confocal microscopy. There is still more work required to fully understand the flow within porous media, including observing the affect of dead-end pores, closed loops and rough channel walls have on the flow.