Effect of Na-doping on properties of lithium zirconate as CO ₂-absorbent

By using Li₂CO₃, ZrO₂, and Na ₂CO₃ as starting materials, sodium-doped Li _2(1-x)Na_2xZrO₃ absorbents were prepared by high-temperature solid-state reaction. The crystal structure of the lithium zirconate material was analyzed using a X-ray powder diffractometer (XRD), the microstructure of all the samples was observed using the method of scanning electron microscopy (SEM) and the CO₂-absorption ability of the lithium zirconate material was studied using a thermogravimetric analyzer (TG). It was found that Li_2(1-x)Na_2xZrO₃ absorbent with x=0.02 possesses the best performance. As much as (25 ± 0.4)% (wt) of CO₂ was absorbed by such an absorbent in an atmosphere consisting of 20% (wt) CO₂ and 80% (wt) air at 500 °C within 3 h. After 10 cycles of absorption-desorption this absorbent lost only 0.9% of its CO ₂-absorption capacity. No remarkable change in particle size and pH was observed.