Titania spheres with nanochannel-restricted NaNO₂/MgO for improving cyclic CO₂ adsorption stability

NaNO₂/MgO/titania spheres prepared via aerosol-assisted self-assembly (AASA) were used as sorbents for CO₂ adsorption at moderate temperature. The titania framework as support would allow MgO to disperse well, thereby increasing the contact between MgO and NaNO₂ to enhance carbonation. In this study, the effect of Mg/Ti molar ratio and NaNO₂ addition amount on CO₂ adsorption was investigated. Results showed that the sorbent prepared by AASA with Mg/Ti molar ratio of 2 following the introduction of 30 wt% NaNO₂ presented ∼1 μm particle size with rough sphere surface morphology and mesoporous properties, where the surface area and pore volume were 72 m²/g and 0.18 cm³/g, respectively. With NaNO₂ addition, the kinetics and capacity of CO₂ adsorption significant increased. In the cyclic adsorption/desorption experiment, the superior stability over the NaNO₂/MgO/titania spheres was mainly ascribed to the confined space suppressed the degree of the sintering effect. These results indicated the potential application of the nanochannel-restricted sorbent for rapid, high-capacity, and stable CO₂ capture at moderate temperatures.