Engineering\nNanoporous\nPolyaminal Networks for Superior\nSO<sub>2</sub> Capture and Selectivity

Designing adsorbent materials with\nhigh SO<sub>2</sub> adsorption\ncapacities and selectivity remains a significant challenge in flue\ngas desulfurization. This work focuses on developing two nitrogen-rich\nnanoporous polyaminal networks (NPANs), which demonstrate promising\ncapabilities for SO<sub>2</sub> adsorption and separation. Two nitrogen-rich\nnanoporous polyaminal networks, NPAN-5 and NPAN-6, were synthesized\nvia a one-pot method using thiophene-2,5-dicarbaldehyde and furan-2,5-dicarbaldehyde\nwith 1,4-bis­(2,4-diamino-1,3,5-triazine)-benzene, respectively. The\nBrunauer–Emmett–Teller (BET) specific surface areas\nof NPANs range from 838 to 956 m<sup>2</sup>·g<sup>–1</sup>. At 298 K and pressures of 0.1 and 1.0 bar, NPAN-5, featuring thiophene\nunits, demonstrates a SO<sub>2</sub> adsorption uptake of 5.14 and\n9.63 mmol·g<sup>–1</sup>, respectively, surpassing many\npreviously reported materials. Furthermore, at room temperature, NPAN-6,\ncontaining furan moieties, exhibits unprecedented selectivity for\nSO<sub>2</sub> over CO<sub>2</sub> and N<sub>2</sub>, with ratios\nreaching up to 78 and 9321, respectively. Dynamic breakthrough experiments\nreveal that NPANs effectively separate SO<sub>2</sub> from a ternary\ngas mixture comprising SO<sub>2</sub>, CO<sub>2</sub>, and N<sub>2</sub> at concentrations of 0.2, 10, and 89.8%, respectively. Notably,\nNPAN-6 achieves a prolonged SO<sub>2</sub> retention time of 218 min·g<sup>–1</sup> and a saturation adsorption uptake of 0.42 mmol·g<sup>–1</sup>. The remarkable SO<sub>2</sub> adsorption capacities\nand selectivities demonstrated by these nitrogen-rich nanoporous polyaminal\nnetworks underscore their potential to revolutionize industrial flue\ngas desulfurization.