Cyclic CO2 capture behavior of KMnO4-doped CaO-based sorbent

This study examines the CO2 capture behavior of KMnO4-doped CaO-based sorbent during the multiple calcination/carbonation cycles. The cyclic carbonation behavior of CaCO3 doped with KMnO4 and the untreated CaCO3 was investigated. The addition of KMnO4 improves the cyclic carbonation rate of the sorbent above carbonation time of 257 s at each carbonation cycle. When the mass ratio of KMnO4/CaCO3 is about 0.5–0.8 wt.%, the sorbent can achieve an optimum carbonation conversion during the long-term cycles. The carbonation temperature of 660–710 °C is beneficial to cyclic carbonation of KMnO4-doped CaCO3. The addition of KMnO4 improves the long-term performance of CaCO3, resulting in directly measured conversion as high as 0.35 after 100 cycles, while the untreated CaCO3 retains conversion less than 0.16 at the same reaction conditions. The addition of KMnO4 decreases the surface area and pore volume of CaCO3 after 1 cycle, but it maintains the surface area and pores between 26 nm and 175 nm of the sorbent during the multiple cycles. Calculation reveals that the addition of KMnO4 improves the CO2 capture efficiency significantly using a CaCO3 calcination/carbonation cycle and decreases the amount of the fresh sorbent.