Fluorine-functionalized Porous Organic Polymers for Durable F-gas Capture from Semiconductor Etching Exhaust

Highly Selective SO2 Capture by Triazine-Functionalized Triphenylamine-Based Nanoporous Organic Polymers

The emissions of sulfur dioxide (SO2) from combustion exhaust gases pose significant risks to public health and the environment due to their harmful effects. Therefore, the development of highly efficient adsorbent polymers capable of capturing SO2 with high capacity and selectivity has emerged as a critical challenge in recent years. However, existing polymers often exhibit poor SO2/CO2 and SO2/N2 selectivity. Herein, we report two triazine-functionalized triphenylamine-based nanoporous organic polymers (ANOP-6 and ANOP-7) that demonstrate both good SO2 uptake and high SO2/CO2 and SO2/N2 selectivity. These polymers were synthesized through cost-effective Friedel-Crafts reactions using cyanuric chloride, 3,6-diphenylaminecarbazole, and 2,2',7,7'-tetrakis(diphenylamino)-9,9'-spirobifluorene. The resultant ANOPs are composed of triazine and triphenylamine units and feature an ultramicroporous structure. Remarkably, ANOPs exhibit impressive adsorption capacities for SO2, with uptakes of approximately 3.31-3.72 mmol·g-1 at 0.1 bar, increasing to 9.52-9.94 mmol·g-1 at 1 bar. The static adsorption isotherms effectively illustrate the ability of ANOPs to separate SO2 from SO2/CO2 and SO2/N2 mixtures. At 298 K and 1 bar, ANOP-6 shows outstanding selectivity toward SO2/CO2 (248) and SO2/N2 (13146), surpassing all previously reported triazine-based nanoporous organic polymers. Additionally, dynamic breakthrough tests demonstrate the superior separation properties of ANOPs for SO2 from an SO2/CO2/N2 mixture. ANOPs exhibit a breakthrough time of 73.1 min·g-1 and a saturated SO2 capacity of 0.53 mmol·g-1. These results highlight the exceptional adsorption properties of ANOPs for SO2, indicating their promising potential for the highly efficient capture of SO2 from flue gas.

Non-CO2 greenhouse gas separation using advanced porous materials

Global warming has become a growing concern over decades, prompting numerous research endeavours to reduce the carbon dioxide (CO2) emission, the major greenhouse gas (GHG). However, the contribution of other non-CO2 GHGs including methane (CH4), nitrous oxide (N2O), fluorocarbons, perfluorinated gases, etc. should not be overlooked, due to their high global warming potential and environmental hazards. In order to reduce the emission of non-CO2 GHGs, advanced separation technologies with high efficiency and low energy consumption such as adsorptive separation or membrane separation are highly desirable. Advanced porous materials (APMs) including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen-bonded organic frameworks (HOFs), porous organic polymers (POPs), etc. have been developed to boost the adsorptive and membrane separation, due to their tunable pore structure and surface functionality. This review summarizes the progress of APM adsorbents and membranes for non-CO2 GHG separation. The material design and fabrication strategies, along with the molecular-level separation mechanisms are discussed. Besides, the state-of-the-art separation performance and challenges of various APM materials towards each type of non-CO2 GHG are analyzed, offering insightful guidance for future research. Moreover, practical industrial challenges and opportunities from the aspect of engineering are also discussed, to facilitate the industrial implementation of APMs for non-CO2 GHG separation.

Polypyrene Porous Organic Framework for Efficiently Capturing Electron Specialty Gases

The polypyrene polymer with an extended π-conjugated skeleton is attractive for perfluorinated electron specialty gas (F-gas) capture as the high electronegativity of fluorine atoms makes F-gases strongly electronegative gases. Herein, a polypyrene porous organic framework (termed as Ppy-POF) with an extended π-conjugated structure and excellent acid resistance was constructed. Systematic studies have shown that the abundant π-conjugated structures and gradient electric field distribution in Ppy-POF can endow it exceptional adsorption selectivity for high polarizable F-gases and xenon (Xe), which has been collaboratively confirmed by single-component gas adsorption experiments, time-dependent adsorption rate tests, dynamic breakthrough experiments, etc. Electrostatic potential distribution and charge density difference based on Grand Canonical Monte Carlo simulations and density functional theory calculations demonstrate that the selective adsorption of F-gases and Xe in Ppy-POF is attributed to the strong charge-transfer effect and polarization effect between Ppy-POF and gases. These results manifest that the POF with an extended π-conjugated structure and gradient electric field distribution has great potential in efficiently capturing electron specialty gases.

Amino-Functionalized Microporous MOFs for Capturing Greenhouse Gases CF4 and NF3 with Record Selectivity

The capture and separation of fluorinated gases (F-gases) from N₂ has the potential to not only reduce greenhouse gas emissions but also provide economic benefits for the semiconductor industry. In this work, two Ni-based metal-organic frameworks (MOFs), Ni-MOF (Ni(ina)₂, ina = isonicotinic acid) and amine-functionalized NH₂-Ni-MOF (Ni(3-ain)₂, 3-ain = 3-aminoisonicotinic acid), were constructed for capturing F-gases (CF₄ and NF₃). At ambient conditions, both materials exhibit very high CF₄ sorption capacities (2.92 mmol g^-1 for Ni-MOF and 2.69 mmol g^-1 for NH₂-Ni-MOF). In addition, NH₂-Ni-MOF exhibited a record selectivity of 46.3 for the CF₄/N₂ mixture at 298 K and 100 kPa, surpassing all benchmark adsorbents, including Ni-MOF (34.7). The kinetic adsorption tests demonstrated that Ni-MOF and NH₂-Ni-MOF performed well for CF₄/N₂ and NF₃/N₂ mixtures. According to grand canonical Monte Carlo (GCMC) simulations, CF₄ or NF₃ interacts with NH₂-Ni-MOF by multiple van der Waals interactions, resulting in stronger interaction than N₂. More importantly, dynamic breakthrough experiments verified the practical separation potential of the two materials for CF₄/N₂ and NF₃/N₂ mixtures.