Facilely Grafting Small Amine Molecules into Co-Exchanged Zeolite for Enhancing CO₂ Adsorption

Zeolites are promising materials for CO₂ adsorption, yet they still face the challenges of low adsorption capacity and selectivity. Herein, we report a strategy of grafting ethylenediamine to a Co-exchanged Y zeolite to improve the CO₂ adsorption capacity of Y zeolite via strong interactions between Co²⁺ and amine groups. Functionalization of zeolite Y with amines (Co-Y-EN) enables significant improvement in the CO₂ adsorption capacity (4.36 mmol/g at 1 bar and 298 K), which is 1.73 times higher than that of pristine Na-Y zeolite. Moreover, Co-Y-EN demonstrates enhanced CO₂ selectivity, as confirmed by both single-component gas adsorption experiments and breakthrough tests. The superior selectivity is attributed to the strong affinity between the amine sites and CO₂ molecules, as well as the optimized pore sizes for CO₂ adsorption. Overall, this study presents a straightforward approach to enhancing the CO₂ adsorption performance of zeolite materials.