N‐Doped Porous Carbon Derived from Waste Polystyrene Polymers for Efficient CO ₂ /N ₂ Separation

Abstract The selective adsorption and separation of CO 2 are critical for achieving carbon neutrality. In this study, a series of N‐doped porous carbons (NPCs) was synthesized using waste polystyrene hyper crosslinked polymers as precursors and KOH as an activator. Among the samples, NPC‐700, activated at 700 °C, exhibited exceptional pore properties with a specific surface area of 1579 m 2 ·g −1 and a pore volume of 1.87 cm 3 ·g −1 . It achieved a CO 2 adsorption capacity of 5.97 mmol·g −1 at 273 K and 1 bar, along with excellent cyclic performance for long‐term CO 2 capture. Breakthrough experiments confirmed its ability to completely separate a CO 2 /N 2 (15/85) mixture at ambient temperature. Kinetic diffusion analysis further revealed its high adsorption efficiency, reinforcing its suitability as an adsorbent for CO 2 capture. Overall. by utilizing waste polystyrene hyper crosslinked polymers, we have established a sustainable and efficient strategy for designing CO 2 capture adsorbents.