Predicted influence of the combination of two different chemical functional groups on the separation of gas mixtures by porous aromatic frameworks

Yuxiang Wang; Chang Han; Susan B. Sinnott

doi:10.1016/j.commatsci.2025.113672

Predicted influence of the combination of two different chemical functional groups on the separation of gas mixtures by porous aromatic frameworks

Yuxiang Wang, Chang Han, Susan B. Sinnott

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Abstract

The selective adsorption of porous aromatic frameworks (PAFs) with two different functional groups per aromatic ring from three types of acid gas/N₂ binary mixtures was investigated and compared with the comparable performance of PAFs with two of the same functional groups, using Grand Canonical Monte Carlo (GCMC) simulations. The functional groups selected include three electron-donating groups (EDGs: –OH, –NH₂, and –CH₃) and three electron-withdrawing groups (EWGs: –COOH, –CN, and –NO₂). The binary gas mixtures considered for selective capture simulations included CO₂/N₂ (0.15:0.85), SO₂/N₂ (0.05:0.95), and H₂S/N₂ (0.15:0.85). The adsorption isotherms were constructed based on GCMC gas loading, the selectivity was calculated from the adsorption isotherm, and the isosteric enthalpy of adsorption (Q_st) of the acid gases was calculated by the fluctuation formula. The results indicate that in general PAFs with two mixed EWGs (mix-EWGs-PAF) have better acid gas capture and selectivity than PAFs with two mixed EDGs (mix-EDGs-PAF). However, the best mix-EDGs-PAF (PAF-3-OH-5-NH₂) has as good acid gas loading and selectivity as mix-EWGs-PAF, with the advantage of much higher maximum adsorption limit. In addition, PAF-3-OH-5-NH₂ has significantly higher adsorption and selectivity than any other PAFs functionalized with two of the same EDGs, indicating the great potential of mixing two different functional groups on PAF aromatic rings. The results indicate that by mixing two different functional groups, the acid gas loading may follow one of two predicted scenarios: 1. PAF-R-R’ has higher acid gas loading at low pressures with little to no impact on high-pressure adsorption, which is the most desired outcome for the selective adsorption with PAFs; 2. PAF-R-R’ has intermediate acid gas loading compared with PAF-R₂ and PAF-R’₂, showing no benefit to mixing the two functional groups. Calculations carried out using isosteric enthalpy of adsorption strongly support the predictions of the GCMC adsorption isotherms.

Original language	English (US)
Article number	113672
Journal	Computational Materials Science
Volume	250
DOIs	https://doi.org/10.1016/j.commatsci.2025.113672
State	Published - Feb 20 2025

All Science Journal Classification (ASJC) codes

General Computer Science
General Chemistry
General Materials Science
Mechanics of Materials
General Physics and Astronomy
Computational Mathematics

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10.1016/j.commatsci.2025.113672

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@article{ad2e2b68845041ccbedfcaad03585dc6,

title = "Predicted influence of the combination of two different chemical functional groups on the separation of gas mixtures by porous aromatic frameworks",

abstract = "The selective adsorption of porous aromatic frameworks (PAFs) with two different functional groups per aromatic ring from three types of acid gas/N2 binary mixtures was investigated and compared with the comparable performance of PAFs with two of the same functional groups, using Grand Canonical Monte Carlo (GCMC) simulations. The functional groups selected include three electron-donating groups (EDGs: –OH, –NH2, and –CH3) and three electron-withdrawing groups (EWGs: –COOH, –CN, and –NO2). The binary gas mixtures considered for selective capture simulations included CO2/N2 (0.15:0.85), SO2/N2 (0.05:0.95), and H2S/N2 (0.15:0.85). The adsorption isotherms were constructed based on GCMC gas loading, the selectivity was calculated from the adsorption isotherm, and the isosteric enthalpy of adsorption (Qst) of the acid gases was calculated by the fluctuation formula. The results indicate that in general PAFs with two mixed EWGs (mix-EWGs-PAF) have better acid gas capture and selectivity than PAFs with two mixed EDGs (mix-EDGs-PAF). However, the best mix-EDGs-PAF (PAF-3-OH-5-NH2) has as good acid gas loading and selectivity as mix-EWGs-PAF, with the advantage of much higher maximum adsorption limit. In addition, PAF-3-OH-5-NH2 has significantly higher adsorption and selectivity than any other PAFs functionalized with two of the same EDGs, indicating the great potential of mixing two different functional groups on PAF aromatic rings. The results indicate that by mixing two different functional groups, the acid gas loading may follow one of two predicted scenarios: 1. PAF-R-R{\textquoteright} has higher acid gas loading at low pressures with little to no impact on high-pressure adsorption, which is the most desired outcome for the selective adsorption with PAFs; 2. PAF-R-R{\textquoteright} has intermediate acid gas loading compared with PAF-R2 and PAF-R{\textquoteright}2, showing no benefit to mixing the two functional groups. Calculations carried out using isosteric enthalpy of adsorption strongly support the predictions of the GCMC adsorption isotherms.",

author = "Yuxiang Wang and Chang Han and Sinnott, {Susan B.}",

note = "Publisher Copyright: {\textcopyright} 2025",

year = "2025",

month = feb,

day = "20",

doi = "10.1016/j.commatsci.2025.113672",

language = "English (US)",

volume = "250",

journal = "Computational Materials Science",

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TY - JOUR

T1 - Predicted influence of the combination of two different chemical functional groups on the separation of gas mixtures by porous aromatic frameworks

AU - Wang, Yuxiang

AU - Han, Chang

AU - Sinnott, Susan B.

PY - 2025/2/20

Y1 - 2025/2/20

N2 - The selective adsorption of porous aromatic frameworks (PAFs) with two different functional groups per aromatic ring from three types of acid gas/N2 binary mixtures was investigated and compared with the comparable performance of PAFs with two of the same functional groups, using Grand Canonical Monte Carlo (GCMC) simulations. The functional groups selected include three electron-donating groups (EDGs: –OH, –NH2, and –CH3) and three electron-withdrawing groups (EWGs: –COOH, –CN, and –NO2). The binary gas mixtures considered for selective capture simulations included CO2/N2 (0.15:0.85), SO2/N2 (0.05:0.95), and H2S/N2 (0.15:0.85). The adsorption isotherms were constructed based on GCMC gas loading, the selectivity was calculated from the adsorption isotherm, and the isosteric enthalpy of adsorption (Qst) of the acid gases was calculated by the fluctuation formula. The results indicate that in general PAFs with two mixed EWGs (mix-EWGs-PAF) have better acid gas capture and selectivity than PAFs with two mixed EDGs (mix-EDGs-PAF). However, the best mix-EDGs-PAF (PAF-3-OH-5-NH2) has as good acid gas loading and selectivity as mix-EWGs-PAF, with the advantage of much higher maximum adsorption limit. In addition, PAF-3-OH-5-NH2 has significantly higher adsorption and selectivity than any other PAFs functionalized with two of the same EDGs, indicating the great potential of mixing two different functional groups on PAF aromatic rings. The results indicate that by mixing two different functional groups, the acid gas loading may follow one of two predicted scenarios: 1. PAF-R-R’ has higher acid gas loading at low pressures with little to no impact on high-pressure adsorption, which is the most desired outcome for the selective adsorption with PAFs; 2. PAF-R-R’ has intermediate acid gas loading compared with PAF-R2 and PAF-R’2, showing no benefit to mixing the two functional groups. Calculations carried out using isosteric enthalpy of adsorption strongly support the predictions of the GCMC adsorption isotherms.

AB - The selective adsorption of porous aromatic frameworks (PAFs) with two different functional groups per aromatic ring from three types of acid gas/N2 binary mixtures was investigated and compared with the comparable performance of PAFs with two of the same functional groups, using Grand Canonical Monte Carlo (GCMC) simulations. The functional groups selected include three electron-donating groups (EDGs: –OH, –NH2, and –CH3) and three electron-withdrawing groups (EWGs: –COOH, –CN, and –NO2). The binary gas mixtures considered for selective capture simulations included CO2/N2 (0.15:0.85), SO2/N2 (0.05:0.95), and H2S/N2 (0.15:0.85). The adsorption isotherms were constructed based on GCMC gas loading, the selectivity was calculated from the adsorption isotherm, and the isosteric enthalpy of adsorption (Qst) of the acid gases was calculated by the fluctuation formula. The results indicate that in general PAFs with two mixed EWGs (mix-EWGs-PAF) have better acid gas capture and selectivity than PAFs with two mixed EDGs (mix-EDGs-PAF). However, the best mix-EDGs-PAF (PAF-3-OH-5-NH2) has as good acid gas loading and selectivity as mix-EWGs-PAF, with the advantage of much higher maximum adsorption limit. In addition, PAF-3-OH-5-NH2 has significantly higher adsorption and selectivity than any other PAFs functionalized with two of the same EDGs, indicating the great potential of mixing two different functional groups on PAF aromatic rings. The results indicate that by mixing two different functional groups, the acid gas loading may follow one of two predicted scenarios: 1. PAF-R-R’ has higher acid gas loading at low pressures with little to no impact on high-pressure adsorption, which is the most desired outcome for the selective adsorption with PAFs; 2. PAF-R-R’ has intermediate acid gas loading compared with PAF-R2 and PAF-R’2, showing no benefit to mixing the two functional groups. Calculations carried out using isosteric enthalpy of adsorption strongly support the predictions of the GCMC adsorption isotherms.

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DO - 10.1016/j.commatsci.2025.113672

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VL - 250

JO - Computational Materials Science

JF - Computational Materials Science

M1 - 113672

ER -

Predicted influence of the combination of two different chemical functional groups on the separation of gas mixtures by porous aromatic frameworks

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