Postsynthetic Imidation of Conjugated Porous Polymers: Enhanced CO₂ Capture and Selectivity

Abstract

Developing porous materials for efficient and selective capture of CO 2 is necessary to fight climate change. Although amine scrubbing is widely utilized for CO 2 capture, it is energy-intensive and not eco-friendly. In this context, utilizing solid adsorbents for postcombustion carbon capture presents a promising method for reducing carbon emissions. Here, we report the postsynthetic imidation strategy for synthesizing robust N-functionalized porous conjugated polymers (CPPs), NH-CPP, NH 2 -CPP, and EDA-CPP which provides CO 2 -philic groups. Postsynthetic imidation significantly improves the uptake of CO 2 , up to 53% for NH 2 -CPP and 48% for NH-CPP at 1 bar and 273 K. The uptake capacity for CO 2 was evaluated at high pressures up to 30 bar and ambient temperature of 298 K, demonstrating a notable increase after postimidation, with the highest uptake reaching 4.5 mmol/g for NH 2 -CPP. More importantly, increased CO 2 uptake leads to a 200% increase in the CO 2 /N 2 selectivity under typical flue gas conditions at 273 K (1 bar and 15% CO 2 , 85% N 2 ). These findings carry significant implications for their potential application in postcombustion carbon capture.