PVA-modulated hierarchical porous silica foam ceramics for efficient CO2 adsorption

Hierarchical PVA–SiO₂ foam ceramics with 93.67% porosity were developed. • Interconnected pores (228 m 2 ∙g −1 ) enhance amine utilization and mass transfer. • CO 2 adsorption capacity reaches 236.76 mg/g at 25 °C. • Stable performance with <7.5% capacity loss after 8 cycles. Solid amine porous adsorbents efficiently capture CO 2 through physical and chemical mechanisms, and are widely employed in CO 2 absorption. However, they suffer from drawbacks including insufficient stability, susceptibility to mass transfer channel blockage and high costs. Therefore, this study developed a novel strategy based on a polyvinyl alcohol (PVA)/silica sol hybrid system for the preparation of hierarchical porous foam ceramics (PVA-FC). The PVA-silica sol hybrid foam was sintered at 500 °C, and silica foam ceramics with coral-like micro/mesoporous pore walls were obtained. The PVA-FC exhibits a high porosity (93.67%), large specific surface area (228 m 2 ·g −1 ), and robust mechanical properties (compressive strength of 1.25 MPa) at 20% PVA loading. After loading with amine, the CO 2 adsorption capacity of the adsorbent is 236.76 mg·g −1 at 25 °C and 0.1 MPa. After eight adsorption-desorption cycles, it retained a capacity of 218.98 mg·g −1 (with a decay rate of <7.5%). The organic-inorganic hybridisation method was applied to the preparation of silica foam ceramics with micro/mesoporous foam walls. The macroporous and foam pore structures of the adsorbent improved the transport capacity for TEPA and CO 2 , while the high specific surface area enhanced the active sites for adsorption, resulting in highly efficient CO 2 capture. Download: Download high-res image (318KB) Download: Download full-size image