Nitrogen-doped composite aerogels from ZIF-8 derived porous carbon and chitosan for CO2 adsorption

Abstract

It is well known that adsorbent material is the key to determine the CO₂ adsorption performance. Herein, ZIF-8 derived porous carbon (ZIF-8-C) is anchored into the framework of a novel composite aerogel (ZCPx), which utilizes chitosan (CS) and polyvinyl alcohol (PVA) as raw materials. By controlling the ratio of ZIF-8-C, the developed hierarchical porous structures combine the advantages of micropores, mesopores, and macropores. Besides, the ligand material of ZIF-8-C and the amino group from CS are two sources of the high nitrogen content of ZCPx. The optimized sample ZCP4 shows a high nitrogen content of 6.78%, which can create more active centers and supply basic sites, thereby enhancing the CO₂ adsorption capacity. Moreover, ZCP4 composite aerogel presents a CO₂ adsorption capacity of 2.26 mmol·g⁻¹ (298 K, 1 bar (equivalent to 100 kPa)) and CO₂/N₂ selectivity ($S_{{\mathrm{CO}}_2/{\text{N}}_2}$) can reach 20.02, and the dynamic breakthrough experiment is performed to confirm the feasibility of CO₂/N₂ actual separation performance, proving that the composite aerogel is potential candidates for CO₂ adsorption.