Bio-templated and 3D-printed hierarchical NaY zeolite monolith for efficient and recyclable CO2 adsorption

Abstract

This study presents a systematic approach for synthesizing hierarchical bio-NaY zeolite using rice husk-derived silica (bio-SiO₂) as structural and compositional templates. The incorporation of bio-SiO₂ significantly increases mesoporous volume and optimizes the distribution of Lewis acid-base pairs within the zeolite framework. Comparative analysis demonstrates a marked improvement in CO₂ adsorption capacity for the bio-NaY zeolite (147.3 mg·g⁻¹) over conventional NaY (138.3 mg·g⁻¹). ZLC experimental results reveal that this enhancement is attributed to a dual mechanism: (i) the bio-SiO₂ template promotes the formation of a hierarchical pore system, improving mass transport; and (ii) it enhances the accessibility and exposure of active sites, facilitating CO₂ capture and intraparticle diffusion. Molecular dynamics simulations further reveal that the (100) crystallographic plane exhibits superior CO₂ adsorption affinity, kinetics, and selectivity compared to the (001) plane. Additionally, the integration of 3D printing technology enables the fabrication of mechanically robust monoliths (3D-bio-NaY), simplifying adsorbent handling and regeneration. These 3D-printed structures exhibit exceptional cyclic stability, retaining nearly 100% of their initial CO₂ capture capacity over eight consecutive cycles. The findings provide deep insights into the structure-property relationships of hierarchical zeolite and advance the design of efficient adsorbents for industrial CO₂ capture applications.