Functional Group Modification of Metal–Organic Frameworks for CO₂ Capture

Abstract

Reducing the anthropogenic emission of CO2is currently a top priority due to its global warming effect. Capturing CO2 by porous materials is a promising approach due to its energetic efficiency and technical feasibility. A promising adsorbent for capturing CO2 should possess not only large BET specific surface areas (SSAs) but also high heat of adsorption. Since the intrinsic quadrupole moment of the CO2 molecule exists, introduction of a polar functional group in the framework of porous materials could enhance CO2 uptake. In this work, we adopt the postsynthetic modification approach to synthesize UMCM-1-NH2-MA (MA = maleic anhydride) material on the basis of UMCM-1-NH2 with an extremely high BET SSA of 4064 m2 g–1 and further explore the effects of free acid functionalities and aromatic amino groups on CO2 capture. The experimental and theoretical results show that, besides amino groups, the polar acidic functionalities also exhibit excellent capability for CO2 capture. Moreover, our first-principles calculations indicate that the aromatic imino group loses affinity toward CO2 significantly, compared with the aromatic amino group. In short, we believe that incorporating polar acidic functionalities into the porous materials could be an alternatively suitable approach for enhancing CO2 capture.