The template-free synthesis of zeolite NaY for CO2 capture

Sodium Y (NaY) zeolite is a promising adsorbent for carbon capture. The template-free synthesis of NaY zeolite has gained considerable interests to minimize its costs and environmental effects. However, NaY zeolites synthesized through template-free methods exhibited lower CO 2 adsorption capacities (∼4.07 mmol·g –1 ) compared to template-assisted counterparts, often requiring longer crystallization time and higher energy penalty. This study systematically compared the microstructural characteristics and CO 2 adsorption performance of NaY zeolites synthesized with and without templates, including those from the commercial markets. Through process optimization, the CO 2 adsorption capacity of the template-free NaY zeolite was significantly enhanced, surpassing those template-assisted samples. Notably, it achieved CO 2 adsorption capacities of 6.51 mmol·g –1 at 25 °C and 0.1 MPa, and 7.40 mmol·g –1 at 0 °C and 0.1 MPa, outperforming both commercial NaY and template-assisted samples. The structural differences, including crystal integrity, pore size distribution and surface properties, were systematically discussed. The optimized synthesis method increased the specific surface area and the ratio of microporous structures. The template-free NaY also showed superior CO 2 capture capacity, moisture resistance, breakthrough performance and stability, indicating its application potential for carbon capture.