Precise Construction of Nitrogen-Enriched Porous Ionic Polymers as Highly Efficient Sulfur Dioxide Adsorbent

Abstract

Porous ionic polymers with unique features have exhibited high performance in various applications. However, the fabrication of functional porous ionic polymers with custom functionality and porosity for efficient removal of low-concentration SO₂ remains challenging. Herein, a novel nitrogen-enriched porous ionic polymer NH₂Py-PIP is prepared featuring high-content nitrogen sites (15.9 wt.%), adequate ionic sites (1.22 mmol g^-1), and a hierarchical porous structure. The proposed construction pathway relies on a tailored nitrogen-functionalized cross-linker NH₂Py, which effectively introduces abundant functional sites and improves the porosity of porous ionic polymers. NH₂Py-PIP with a well-engineered SO₂-affinity environment achieves excellent SO₂/CO₂ selectivity (1165) and high SO₂ adsorption capacity (1.13 mmol g^-1 at 0.002 bar), as well as enables highly efficient and reversible dynamic separation performance. Modeling studies further elucidate that the nitrogen sites and bromide anions collaboratively promote preferential adsorption of SO₂. The unique design in this work provides new insights into constructing functional porous ionic polymers for high-efficiency separations.

Keywords: adsorption; functionalization; gas separation; porous ionic polymers; sulfur dioxide.