The impact of neglected potassium in KOH-activated porous carbon on CO2 capture and CO2/N2 selectivity: Experimental and molecular simulation studies

• Published in: Applied surface science 2025-02, Vol.681, p.161571, Article 161571
• Main Authors: Luo, Yiting, Gong, Jiayi, Yang, Ziyi, Liu, Zhao, Chen, Yonghua, Huang, Shunhong, Su, Rongkui, Ma, Xiancheng, Yan, Wende
• Format: Article
• Language: English
• Subjects: CO2 capture; CO2/N2 selectivity; K groups; Pore structure; Porous carbon
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.161571

[Display omitted] •The effects of K-groups in different pore size on CO2 capture and separation were studied.•GCMC and DFT reveal the mechanism of K group for CO2 capture and separation.•K doping can improve CO2 capture and separation is higher than N and O doping.•Provide a foundation for the design and development of high-performance CO2 adsorbents. Porous carbons with high CO2 capture are typically prepared through potassium-based activators, which are difficult to completely remove potassium (K) through acid or water washing. K in porous carbon has strong alkalinity and can form strong acid-base interactions with acidic CO2 molecules, an effect that has often been overlooked in previous research. Here, the effects of K groups in different pore sizes on CO2 capture and CO2/N2 selectivity were investigated using molecular simulation methods. The results show that potassium doping can improve CO2 capture and CO2/N2 selectivity of the slit-pore model (SPM) at 0.15 and 1 bar, and it is also much higher than nitrogen and oxygen doping. To validate our theoretical findings, we synthesized potassium-free and potassium-doped porous carbons with similar pore structures, nitrogen and oxygen contents. The effects of potassium doping on CO2 uptake and CO2/N2 selectivity are compared and found to be consistent with the theoretical calculations.