Polyamine-Tethered Porous Polymer Networks for Carbon Dioxide Capture from Flue Gas

Nanoporous ionic organic networks: from synthesis to materials applications

This review highlights the recent progress made in the study of the synthesis of nanoporous ionic organic networks (NIONs) and their promising applications.

Porous cationic polymers: the impact of counteranions and charges on CO2capture and conversion

Porous cationic polymers (PCPs) with surface areas up to 755 m²g⁻¹bearing positively charged viologen units in their backbones and different counteranions have been prepared.

Rational design and synthesis of a porous, task-specific polycarbazole for efficient CO2 capture

A novel porous pyridine-functionalized polycarbazole, prepared based on in silico simulations, exhibits a superior CO₂ uptake at 1.0 bar and 273 K (5.57 mmol g⁻¹).

Monodispersed ultramicroporous semi-cycloaliphatic polyimides for the highly efficient adsorption of CO2, H2and organic vapors

Monodispersed ultramicroporous semi-cycloaliphatic polyimides (sPIs) were synthesizedviasolution polycondensation and possess high uptakes for CO₂, H₂, aromatic and aliphatic vapors, exhibiting potential in gas storage and the recovery of toxic organic vapors.

Aminal linked inorganic–organic hybrid nanoporous materials (HNMs) for CO2 capture and H2 storage applications

Cyclophosphazene based nitrogen-rich aminal-linked inorganic–organic hybrid nanoporous materials were synthesized by a Schiff-base condensation reaction, which captures 18.9 wt% of CO₂.

A unique 3D ultramicroporous triptycene-based polyimide framework for efficient gas sorption applications

A novel 3D ultramicroporous triptycene-based polyimide framework with high surface area (1050 m² g⁻¹) and high CO₂ sorption capacity (3.4 mmol g⁻¹ at 273 K and 1 bar), good CO₂/N₂ (45) and CO₂/CH₄ (9.6) selectivity was synthesized and characterized.

Thiophene-based conjugated microporous polymers: preparation, porosity, exceptional carbon dioxide absorption and selectivity

Thiophene-based conjugated microporous polymers show high CO₂ uptake ability of 756–817 (60 bar/318 K) and good adsorption selectivity for CO₂ over N₂ and CH₄.

Heptazine-Based Porous Framework for Selective CO2 Sorption and Organocatalytic Performances

A new heptazine-based polymer network (Cy-pip) with highly rich nitrogen sites has been synthesized via catalyst-free direct coupling of cyameluric chloride (Cy) and piperazine (Pip). Cy-pip exhibits large CO2 uptake capacity (103.4 mg/g, 9.4 wt %, 1 bar/273 K) with high selectivity (117) toward CO2 over N2. Furthermore, this framework with high Lewis basic nitrogen sites has also been exploited as heterogeneous catalyst for Knoevenagel reaction of aromatic and heterocyclic aldehydes with active methylene compounds. Moreover, the catalyst can recycle up to four times with only a minor loss of activity.

Creation of a new type of ion exchange material for rapid, high-capacity, reversible and selective ion exchange without swelling and entrainment

A new model for ion exchange materials has been proposed on the basis of ion exchange sites grafted to a porous organic polymer.

Ion-exchange materials, currently dominated by resins, are widely used in a plethora of areas. However, the drawbacks of conventional resins necessitate the creation of a new model of ion exchange materials that feature controllable swelling, easily accessible ion exchange sites, high ion exchange capacity, fast ion exchange kinetics, and high chemical stability as illustrated herein in the context of functionalizing a porous organic polymer (POP) with ion exchange groups. The advantages of POP-based ion exchange materials in comparison with conventional resins and other types of ion exchange materials have been highlighted through an evaluation of their performances in scavenging precious metals at trace concentrations, removal of nuclear waste model ions, and size-selective ion capture. Our work thereby provides a new perspective to develop ion functionalized POPs as a versatile type of ion exchange materials for various applications.

Tailor-made porosities of fluorene-based porous organic frameworks for the pre-designable fabrication of palladium nanoparticles with size, location and distribution control

Porous organic frameworks (POFs) are a promising new class of support for metal nanoparticles (NPs), with the size, location and distribution of metal NPs are closely related to the porous nature of the POFs. In this contribution, three fluorene-based POFs containing coordination-inert hydrogen, propyl and benzyl substituents at the 9-position of the fluorene units (POF-1, POF-2 and POF-3) were synthesized through a simple click reaction. The substituents exerted important influences on the surface area, pore volume and pore size of the POFs. Palladium NPs with a pre-designable size, location and distribution were synthesized through a substituent-controlled strategy. When POF-1 was employed as a support, ultrafine palladium NPs in the interior pores were generated, while the introduction of propyl at the 9-position of fluorene in POF-2 gave rise to dual-distributed palladium NPs in the interior pores and on the external surface. The use of the bulkier benzyl substituent resulted in the formation of palladium NPs on the external surface of POF-3. The hydrogenation of olefins has demonstrated that palladium NPs on the external surface possessed higher catalytic activity, while palladium NPs in the interior pores exhibited higher stability and recyclability. In addition, after Pd/POF-1, Pd/POF-2 and Pd/POF-3 were stored in air over half a year, palladium NPs in the interior pores showed a negligible change in comparison with fresh samples, while an obvious agglomeration was observed for palladium NPs on the external surface.

Development Trends in Porous Adsorbents for Carbon Capture

Accumulation of greenhouse gases especially CO2 in the atmosphere leading to global warming with undesirable climate changes has been a serious global concern. Major power generation in the world is from coal based power plants. Carbon capture through pre- and post- combustion technologies with various technical options like adsorption, absorption, membrane separations, and chemical looping combustion with and without oxygen uncoupling have received considerable attention of researchers, environmentalists and the stake holders. Carbon capture from flue gases can be achieved with micro and meso porous adsorbents. This review covers carbonaceous (organic and metal organic frameworks) and noncarbonaceous (inorganic) porous adsorbents for CO2 adsorption at different process conditions and pore sizes. Focus is also given to noncarbonaceous micro and meso porous adsorbents in chemical looping combustion involving insitu CO2 capture at high temperature (>400 °C). Adsorption mechanisms, material characteristics, and synthesis methods are discussed. Attention is given to isosteric heats and characterization techniques. The options to enhance the techno-economic viability of carbon capture techniques by integrating with CO2 utilization to produce industrially important chemicals like ammonia and urea are analyzed. From the reader's perspective, for different classes of materials, each section has been summarized in the form of tables or figures to get a quick glance of the developments.

Amine-Oxide Hybrid Materials for CO2 Capture from Ambient Air

Oxide supports functionalized with amine moieties have been used for decades as catalysts and chromatographic media. Owing to the recognized impact of atmospheric CO2 on global climate change, the study of the use of amine-oxide hybrid materials as CO2 sorbents has exploded in the past decade. While the majority of the work has concerned separation of CO2 from dilute mixtures such as flue gas from coal-fired power plants, it has been recognized by us and others that such supported amine materials are also perhaps uniquely suited to extract CO2 from ultradilute gas mixtures, such as ambient air. As unique, low temperature chemisorbents, they can operate under ambient conditions, spontaneously extracting CO2 from ambient air, while being regenerated under mild conditions using heat or the combination of heat and vacuum. This Account describes the evolution of our activities on the design of amine-functionalized silica materials for catalysis to the design, characterization, and utilization of these materials in CO2 separations. New materials developed in our laboratory, such as hyperbranched aminosilica materials, and previously known amine-oxide hybrid compositions, have been extensively studied for CO2 extraction from simulated ambient air (400 ppm of CO2). The role of amine type and structure (molecular, polymeric), support type and structure, the stability of the various compositions under simulated operating conditions, and the nature of the adsorbed CO2 have been investigated in detail. The requirements for an effective, practical air capture process have been outlined and the ability of amine-oxide hybrid materials to meet these needs has been discussed. Ultimately, the practicality of such a "direct air capture" process is predicated not only on the physicochemical properties of the sorbent, but also how the sorbent operates in a practical process that offers a scalable gas-solid contacting strategy. In this regard, the utility of low pressure drop monolith contactors is suggested to offer a practical mode of amine sorbent/air contacting for direct air capture.

Direct Carbonization of Cyanopyridinium Crystalline Dicationic Salts into Nitrogen-Enriched Ultra-Microporous Carbons toward Excellent CO2 Adsorption

A family of nitrogen-enriched ultramicroporous carbon materials was prepared by direct carbonization of task-specifically designed molecular carbon precursors of cyanopyridinium-based crystalline dicationic salts (CISs). Varying the molecular structure of CISs, large surface area (918 m(2) g(-1)), high N content (20.10 wt %), and narrow distributed ultramicropores (0.59 nm) can be simultaneously achieved on the sample PCN-14 derived from methyl-linked 4-cyanopyridinium D[4-CNPyMe]Tf2N. It therefore exhibited exceptional performance in greenhouse gas CO2 capture, i.e., simultaneously possessing (1) high CO2 adsorption uptakes: 5.33 mmol g(-1) at 273 K, and 3.68 mmol g(-1) at 298 K (both at 1.0 bar); (2) unprecedented selectivity of CO2 versus N2: 156; and (3) a high adsorption ratio of CO2 to N2: 148 (at 1.0 bar). This is the first time such a high selectivity and adsorption ratio over carbon materials has been achieved, which is among the highest values over solid adsorbents.

Ag-Modified In₂O₃/ZnO Nanobundles with High Formaldehyde Gas-Sensing Performance

Ag-modified In₂O₃/ZnO bundles with micro/nano porous structures have been designed and synthesized with by hydrothermal method continuing with dehydration process. Each bundle consists of nanoparticles, where nanogaps of 10–30 nm are present between the nanoparticles, leading to a porous structure. This porous structure brings high surface area and fast gas diffusion, enhancing the gas sensitivity. Consequently, the HCHO gas-sensing performance of the Ag-modified In₂O₃/ZnO bundles have been tested, with the formaldehyde-detection limit of 100 ppb (parts per billion) and the response and recover times as short as 6 s and 3 s, respectively, at 300 °C and the detection limit of 100 ppb, response time of 12 s and recover times of 6 s at 100 °C. The HCHO sensing detect limitation matches the health standard limitation on the concentration of formaldehyde for indoor air. Moreover, the strategy to synthesize the nanobundles is just two-step heating and easy to scale up. Therefore, the Ag-modified In₂O₃/ZnO bundles are ready for industrialization and practical applications.

Exceptional CO2 working capacity in a heterodiamine-grafted metal-organic framework

An amine-functionalized metal-organic framework (MOF), dmen-Mg2(dobpdc) (dmen = N,N-dimethylethylenediamine), which contains a heterodiamine with both primary and tertiary amines, was prepared via a post-synthetic method. This material exhibits a significant selectivity factor for CO2 over N2 that is commensurate with top-performing MOFs. It is remarkable that the solid is fully regenerated under vacuum or flowing Ar at low desorption temperatures, and following this can take up CO2 at more than 13 wt%. An exceptionally high working capacity is achieved at low regeneration temperatures and after exposure to humid conditions, which are important parameters for a real post-combustion CO2 capture process.

Microporous polymer network films covalently bound to gold electrodes

Covalent attachment of a microporous polymer network (MPN) on a gold surface is presented. A functional bromophenyl-based self-assembled monolayer (SAM) formed on the gold surface acts as co-monomer in the polymerisation of the MPN yielding homogeneous and robust coatings. Covalent binding of the films to the electrode is confirmed by SEIRAS measurements.

Synthesis of polybenzoxazine based nitrogen-rich porous carbons for carbon dioxide capture

Nitrogen-rich porous carbons (NPCs) were synthesized from 1,5-dihydroxynaphthalene, urea, and formaldehyde based on benzoxazine chemistry by a soft-templating method with KOH chemical activation. They possess high surface areas of 856.8-1257.8 m(2) g(-1), a large pore volume of 0.15-0.65 cm(3) g(-1), tunable pore structure, high nitrogen content (5.21-5.32 wt%), and high char yields. The amount of the soft-templating agent F127 has multiple influences on the textural and chemical properties of the carbons, affecting the surface area and pore structure, impacting the compositions of nitrogen species and resulting in an improvement of the CO2 capture performance. At 1 bar, high CO2 uptake of 4.02 and 6.35 mmol g(-1) at 25 and 0 °C was achieved for the sample NPC-2 with a molar ratio of F127:urea = 0.010:1. This can be attributed to its well-developed micropore structure and abundant pyridinic nitrogen, pyrrolic nitrogen and pyridonic nitrogen functionalities. The sample NPC-2 also exhibits a remarkable selectivity for CO2/N2 separation and a fast adsorption/desorption rate and can be easily regenerated. This suggests that the polybenzoxazine-based NPCs are desirable for CO2 capture because of possessing a high micropore surface area, a large micropore volume, appropriate pore size distribution, and a large number of basic nitrogen functionalities.

Cascade exciton-pumping engines with manipulated speed and efficiency in light-harvesting porous π-network films

Light-harvesting antennae are the machinery for exciton pumping in natural photosynthesis, whereas cascade energy transfer through chlorophyll is key to long-distance, efficient energy transduction. Numerous artificial antennae have been developed. However, they are limited in their cascade energy-transfer abilities because of a lack of control over complex chromophore aggregation processes, which has impeded their advancement. Here we report a viable approach for addressing this issue by using a light-harvesting porous polymer film in which a three-dimensional π-network serves as the antenna and micropores segregate multiple dyes to prevent aggregation. Cascade energy-transfer engines are integrated into the films; the rate and efficiency of the energy-funneling engines are precisely manipulated by tailoring the dye components and contents. The nanofilms allow accurate and versatile luminescence engineering, resulting in the production of thirty emission hues, including blue, green, red and white. This advance may open new pathways for realising photosynthesis and photoenergy conversion.

Two-dimensional covalent organic frameworks for carbon dioxide capture through channel-wall functionalization

Ordered open channels found in two-dimensional covalent organic frameworks (2D COFs) could enable them to adsorb carbon dioxide. However, the frameworks' dense layer architecture results in low porosity that has thus far restricted their potential for carbon dioxide adsorption. Here we report a strategy for converting a conventional 2D COF into an outstanding platform for carbon dioxide capture through channel-wall functionalization. The dense layer structure enables the dense integration of functional groups on the channel walls, creating a new version of COFs with high capacity, reusability, selectivity, and separation productivity for flue gas. These results suggest that channel-wall functional engineering could be a facile and powerful strategy to develop 2D COFs for high-performance gas storage and separation.

Cost-effective synthesis of amine-tethered porous materials for carbon capture

A truly cost-effective strategy for the synthesis of amine-tethered porous polymer networks (PPNs) has been developed. A network containing diethylenetriamine (PPN-125-DETA) exhibits a high working capacity comparable to current state-of-art technology (30 % monoethanolamine solutions), yet it requires only one third as much energy for regeneration. It has also been demonstrated to retain over 90 % capacity after 50 adsorption-desorption cycles of CO2 in a temperature-swing adsorption process. The results suggest that PPN-125-DETA is a very promising new material for carbon capture from flue gas streams.

Coordination polymers from a highly flexible alkyldiamine-derived ligand: structure, magnetism and gas adsorption studies

Studies into a series of coordination polymers from a new diamine polycarboxylate ligand reveal an interplay between flexibility and material properties.

Highly selective CO2 adsorption performance of carbazole based microporous polymers

Non-coplanar shaped carbazole based monomers were used to synthesize microporous polycarbazole materials utilizing an inexpensive FeCl₃ catalyzed reaction.

N-rich porous organic polymer with suitable donor–donor–acceptor functionality for the sensing of nucleic acid bases and CO2storage application

A new porous polymer has been synthesizedviaradical polymerization of divinylbenzene and (+)-N,N₀-diallyltartardiamide under solvothermal conditions. It showed selective biosensing of cytosine and high CO₂uptake.

The microwave-assisted solvothermal synthesis of a crystalline two-dimensional covalent organic framework with high CO2 capacity

A covalent organic framework was synthesized by using a rapid microwave-assisted solvothermal method via a Schiff base reaction with a high CO₂ capacity.

Mannitol-based acetal-linked porous organic polymers for selective capture of carbon dioxide over methane

Synthesis of mannitol-based acetal-linked porous organic polymers with considerable CO₂/CH₄ selectivity is reported.

Syntheses, structures, photoluminescence and photocatalysis of chiral 3D Cd(ii) frameworks from achiral mixed flexible ligands by spontaneous resolution

Two three-interpenetrating chiral cadmium MOF enantiomers with good photocatalytic activities for degradation of dyes were constructed from achiral flexible ligands.

Microporous carbonaceous adsorbents for CO2separation via selective adsorption

This article reviews recently developed microporous carbonaceous adsorbents including inorganic carbons and organic polymers for CO₂separationviaselective adsorption.

Design and fabrication of mesoporous heterogeneous basic catalysts

Recent advances in mesoporous solid bases were reviewed, and fundamental principles of how to fabricate efficient basic catalysts were highlighted.