Enhancement of microwave-assisted CO2 regeneration performance of 13X zeolite through CuO-loading

13X zeolite is widely used for CO 2 capture owing to its high adsorption capacity and well-defined microporous framework; however, its microwave-assisted regeneration efficiency is intrinsically limited by the density and spatial distribution of Na + cation sites responsible for dielectric heating. In this study, we propose the incorporation of a microwave susceptor strategy by incorporating a small amount of CuO into 13X zeolite, followed by NaCl post-treatment as a necessary Na + -replenishment step to recover microporosity and CO 2 adsorption capacity, thereby enhancing microwave–matter coupling while preserving adsorption performance. A systematic screening of metal oxides at 2.4–2.5 GHz identified CuO as the optimal candidate based on its favorable balance between microwave penetration and microwave-to-heat conversion efficiency. The 5 wt% CuO/13X-Na composite achieved a 23% increase in CO 2 desorption capacity (5.03 mmol g −1 vs. 4.09 mmol g −1 for pristine 13X), a 22% reduction in 90% desorption time, and an approximately 37% reduction in specific microwave energy input under identical applied microwave-power conditions. Structural analyses (XRD, TEM, STEM–EDS, and ICP) confirmed high CuO dispersion and reversible Na + modulation via NaCl treatment, enabling recovery of microporosity and adsorption capacity. These findings demonstrate that controlled introduction of secondary microwave-active sites effectively decouples CO 2 adsorption capacity from regeneration kinetics, providing a rational design principle for energy-efficient, high-throughput microwave-assisted carbon capture systems.