The Effect of unsaturated metal sites in Cu-Modified 13X for CO2 Capture

The excellent CO 2 adsorption capacity of 13X zeolite makes it a promising candidate for carbon capture, and its performance can be further improved by methods like metal incorporation. However, the definitive relationship between extra-framework unsaturated metal sites and CO 2 adsorption mechanisms remains poorly understood. In this work, a convenient strategy was developed to optimize the proportion of Cu 2+ species in CuX zeolites by adjusting the Cu loading and calcination temperature. Through dynamic and static adsorption measurements, the optimized sorbents 3CuX-450 (3 wt% Cu, calcined at 450 o C) exhibited significantly enhanced CO 2 uptake, adsorption rate, and adsorption heat. Comprehensive characterization, including XPS, H 2 -TPR, and DFT calculations, elucidated the evolution and the quantity of Cu 2+ species. The 3CuX-450 sorbent had relatively high CO 2 uptake, adsorption rate and adsorption heat. Meanwhile, it demonstrated excellent recyclability and maintains its performance for 10 successive adsorption-desorption cycles. This study deepens the understanding of mechanistic role of cations in FAU zeolites. The findings of this study can be applied to the rational design of optimized CO 2 active sites in zeolite-based sorbents.