Gunugunuri K. Reddy

Influence of Foreign Metal Dopants on the Durability and Performance of Zr/Ca Sorbents during High Temperature CO2 Capture

The effect of foreign metal on the adsorption performance and stability of the Zr/Ca sorbents has been investigated for high temperature CO2 capture. For this purpose, M/Zr/Ca (M˭Al, W, Hf, Ce, and Y) sorbents are prepared by the flame spray pyrolysis method with the molar ratio 0.5:0.5:10. Improvement in the stability and sorption capacity were observed in Zr/Ca sorbents after doping with some foreign metals. The Al-doped Zr/Ca sorbent (Al/Zr/Ca) with the molar ratio of 0.5:0.5:10 exhibits excellent performance and remarkable stability among all the sorbents tested. The sorbent was stable up to about 50 carbonation-decarbonation cycles due to its high resistance towards sintering. The sorbent shows CO2 capture capacity of 0.54 g/g which is comparable to Zr/Ca (1/10) sorbent (0.53 g/g). Surface area measurements show that addition of a second metal to the Zr/Ca sorbents greatly influences both the surface area and pore volume of the sorbents. Our TPD results indicate that addition of second metal lowers the decarbonation temperature. XRD results show that the improved resistance of the Al/Zr/Ca (0.5/0.5/10) sorbent was attributed to the formation of structures like CaZrO3 and Ca12Al14O33, which provided a stable framework to the sorbent during the adsorption process.