Synthesis of triphenylamine-based nanoporous organic polymers for highly efficient capture of SO2 and CO2

Abstract

The fabrication of nanoporous organic polymers (NOPs) for the highly efficient capture of sulfur dioxide (SO₂) and carbon dioxide (CO₂) through the self-polymerization of AB₂ monomers presents significant challenges. In this study, two triphenylamine-based NOPs (ANOP-3 and ANOP-4) were synthesized via the self-condensation of 4-(N,N-diphenylamino)benzaldehyde and 4′-(diphenylamino)biphenyl-4-carbaldehyde. The resultant polymers exhibited a large BET surface area of up to 1016 m² g⁻¹ and a small pore size of <0.7 nm. ANOP-4 demonstrated an SO₂ adsorption uptake of 21.9 mmol g⁻¹ at 273 K and 100 kPa. At 298 K and 100 kPa, ANOP-3 and ANOP-4 exhibited remarkable SO₂/CO₂ selectivities of up to 64.7 and 50.5, respectively, when applying the ideal adsorbed solution theory (IAST). The exceptional adsorption and separation performance of the ANOPs can be attributed to the ultramicroporous structure and the strong affinity between the adsorbents and polymers. This robust affinity has been revealed by theoretical simulations. This study presents a novel building block for the development of highly efficient SO₂ sorbents.