محمدهاشم صدق کردار

Calcium (Ca) based sorbents utilized in the carbon dioxide (CO2) capture process at high temperatures have displayed considerable activity loss during extended use, due to sintering. Refractory zirconium-based ceramics, however, have shown excellent performances as thermal barrier coatings in many high-tech applications; and, the recent doping of zirconia in Ca-based sorbents has exhibited excellent sustainability in the activity stability in cyclic CO2 capture operations. In this work, we doped sorbents, at loadings of 10 wt%, with a few zirconium-based ceramics, such as alkaline earth metal zirconate (calcium zirconate, CaZrO3), which has the chemical structure of perovskite, and rare earth metal zirconates, which have the chemical structure of pyrochlore. These materials were prepared through the wet co-precipitation method, in order to achieve the optimal uptake capacity and stability in cyclic CO2 capture operations. Among the sorbents tested, the CaZrO3-doped sorbents exhibited excellent performance, remarkable thermal stability and sintering resistant. Therefore, the sorbents were stable though 30 carbonation–calcination cycles. The sorbent showed a CO2 capture capacity of 12 mol CO2/kg sorbent, with an activity loss of 19.6% through carbonation at 675 °C for 10 min and calcination at 850 °C for 10 min. Among the rare earth metal zirconate ceramics, samarium zirconate (Sm2Zr2O7) exhibited the best stability with an activity loss of 23.4% loss, but at a lower uptake of 7.2 mol CO2/kg sorbent at the same carbonation–calcination conditions. In comparison, Cadomin (a natural calcium carbonate) at the same conditions resulted in a capture capacity of 13.5 mol CO2/kg sorbent and an activity loss of 69%. Surface area characterizations showed that incorporation of the ceramics to the calcium based sorbents significantly improved the surface morphology and textural properties of the sorbents. X-ray diffraction results indicated that the improved resistance of the sorb