Fabrication of ultramicroporous triphenylamine-based polyaminal networks for low-pressure carbon dioxide capture

Schiff-base Polymer Immobilized Ruthenium for Efficient Catalytic Cross-coupling of Secondary Alcohols with 2-amino- and γ-aminobenzyl Alcohols to Give Quinolines and Pyridines

A Schiff-base porous polymer has been impregnated with ruthenium trichloride for acceptor-free dehydrogenation coupling (ADC) of secondary alcohols with γ-amino- and 2-aminobenzyl alcohols to give pyridines and quinolines. This heterogenous catalyst exhibited high catalytic efficiency over repeated cycles with wide functional group tolerance.

Synthesis and Characterization of Bipyridine-Based Polyaminal Network for CO2 Capture

The response to the high demand for decreasing the amount of CO₂ in the atmosphere, a new polyaminal-based polymer network was designed and successfully prepared through one-pot polycondensation reaction of melamine and [2,2′-Bipyridine]-5,5′-dicarbaldehyde. The formation of the polymer structure was confirmed by FT-IR, solid-state ¹³C NMR, and powder-X-ray diffraction. The porous properties of the polymeric structure were confirmed by field-emission scanning electron microscope and N₂ adsorption–desorption methods at 77 K. The prepared polymer can take up 1.02 mmol/g and 0.71 mmol/g CO₂ at 273 K and 298 K, respectively, despite its relatively modest Brunauer–Emmett–Teller (BET) surface area (160.7 m²/g), due to the existence of superabundant polar groups on the pore surfaces.

One-Pot Synthesis of Rubber Seed Shell-Derived N-Doped Ultramicroporous Carbons for Efficient CO2 Adsorption

In this work, a series of novel rubber seed shell-derived N-doped ultramicroporous carbons (NPCs) were prepared by one-step high-temperature activation (500–1000 °C), using melamine as the nitrogen source and KOH as the activator. The effects of the melamine dosage and the activation temperatures on the surface chemical properties (doped N contents and N species), textural properties (surface area, pore structure, and microporosity), CO₂ adsorption capacities, and CO₂/N₂ selectivity were thoroughly investigated and characterized. These as-prepared NPCs demonstrate controllable BET surface areas (398–2163 m²/g), ultramicroporosity, and doped nitrogen contents (0.82–7.52 wt%). It was found that the ultramicroporosity and the doped nitrogens significantly affected the CO₂ adsorption and the separation performance at low pressure. Among the NPCs, highly microporous NPC-600-4 demonstrates the largest CO₂ adsorption capacity of 5.81 mmol/g (273 K, 1.0 bar) and 3.82 mmol/g (298 K, 1.0 bar), as well as a high CO₂/N₂ selectivity of 36.6, surpassing a lot of reported biomass-based porous carbons. In addition, NPC-600-4 also shows excellent thermal stability and recycle performance, indicating the competitive application potential in practical CO₂ capture. This work also presents a facile one-pot synthesis method to prepare high-performance biomass-based NPCs.

Synthesis of Naphthalene-Based Polyaminal-Linked Porous Polymers for Highly Effective Uptake of CO2 and Heavy Metals

Studying the effect of functional groups on the porosity structure and adsorption efficiency of polymer materials is becoming increasingly interesting. In this work, a novel porous polyaminal-linked polymer, based on naphthalene and melamine (PAN-NA) building blocks, was successfully synthesized by a one-pot polycondensation method, and used as an adsorbent for both CO₂ and heavy metals. Fourier transform infrared spectroscopy, solid-state ¹³ C NMR, powder X-ray diffraction, and thermogravimetry were used to characterize the prepared polymer. The porous material structure was established by field-emission scanning electron microscope and N₂ adsorption–desorption methods at 77 K. The polymer exhibited excellent uptake of CO₂, 133 mg/g at 273 K and 1 bar. In addition, the adsorption behavior of PAN-NA for different metal cations, including Pb(II), Cr(III), Cu(II), Cd(II), Ni(II), and Ba(II), was investigated; a significant adsorption selectivity toward the Pb(II) cation was detected. The influence of pH, adsorbent dose, initial concentrations, and contact time was also assessed. Our results prove that the introduction of naphthalene in the polymer network improves the porosity and, thus, CO₂ adsorption, as well as the adsorption of heavy metals.

A facile one-pot preparation of porphyrin-based microporous organic polymers for adsorption of carbon dioxide, ethane, and methane

Achieving a cost-effective preparation of 3D porphyrin-based microporous organic polymers (PMOPs) for the adsorption and separation of carbon dioxide (CO2), ethane (C2H6), and methane (CH4) remains difficult.

Microporous polyimides with high surface area and CO2 selectivity fabricated from cross-linkable linear polyimides

Linear polyimides of intrinsic microporosity have been intensively investigated for gas separation due to their microporous structure and high surface area. The microporous structure in the linear polyimides of intrinsic microporosity comes from their contorted structure. Therefore, most linear polyimides without contorted structure do not have micropores. In this work, the microporous polyimides are constructed through the condensation of a cross-linkable dianhydride monomer with two novel nitrogen-rich diamine monomers and post crosslinking reaction. The linear polyimide precursors without contorted structure have the same main-chain structure. The introduction of crosslinked structure endow the crosslinked polyimides (PI-CLs) with microporous structure. The microporous structure in PI-CLs can be tuned by changing the substituents of the linear polyimide precursors. The PI-CLs have competitive CO₂ uptake capacity (7.3-9.4 wt%) at 273 K and 1 bar. Particularly, the crosslinked polyimide containing trifluoromethyl groups (CF₃-PI-CL) shows high CO₂/N₂ and CO₂/CH₄ selectivity (72 and 22) at 273 K, which are among the best results for reported porous materials. This work reveals that the introduction of crosslinked structure and changing substituents is an efficient method for constructing microporous polyimides with abundant micropores and excellent CO₂ selective adsorption capacity. This method also has great potential for fabricating high-performance microporous polymers based on other linear polymers without rigid contorted structure.

Micro- and Ultramicroporous Polyaminals for Highly Efficient Adsorption/Separation of C1-C3 Hydrocarbons and CO2 in Natural Gas

This paper presents a series of micro- and ultramicroporous polyaminals with BET surface areas up to 1304 m² g^-1, which are prepared from two triazine-based tetraamines and three dialdehydes or monoaldehyde through the A₄ + B₂ or A₄ + B₁ aminalization reaction. It is interesting to find that the para-substituted monomers are favorable to force the linking struts apart in the network to generate micropores (1.22 nm), whereas the meta-substituted monomers make the pores in the network squeezed by the twisted linking struts, resulting in the formation of ultramicropores (0.52 nm). Besides, the adsorption behaviors of the major components of natural gas, such as propane (C₃H₈), ethane (C₂H₆), methane (CH₄), and carbon dioxide (CO₂), are significantly different, strongly depending on the polarizabilities, critical temperatures, molecular sizes of gases, porosity parameters of polymers, and the interaction between gases and the polymer skeleton. At 298 K/1 bar, the polymers show high uptake for C₃H₈ (114.5 cm³ g^-1) and C₂H₆ (84.2 cm³ g^-1). Moreover, the adsorption selectivities of C₃H₈/CH₄, C₂H₆/CH₄, C₃H₈/C₂H₆, C₃H₈/CO₂, C₂H₆/CO₂, and CO₂/CH₄ also reach 296.3, 23.1, 9.0, 22.1, 4.1, and 5.0, respectively, exhibiting promising applications in adsorption/separation of C₁-C₃ hydrocarbons and stripping CO₂ gas from natural gas under the ambient condition.

Facile fabrication of triphenylamine-based conjugated porous polymers and their application in organic degradation under visible light

A facile fabrication method was developed for the one-pot synthesis of 1,3,5-triformylbenzene (TFB)-4,4′4′′-triaminotriphenylamine (TPA) and 1,3,5-triformylbenzene-terephthalaldehyde (TA) under ambient conditions via a Schiff-base reaction.