CO2 capture and attrition performance of CaO pellets with aluminate cement under pressurized carbonation

Recent attempts to improve the attrition resistance and CO2 uptake of Ca-based sorbent by making pellets with aluminate cement have succeeded in enhancing their effectiveness. The effects of parameters on sorbent attrition were investigated. Batch experiments were also conducted in a fluidized bed at optimal reaction conditions from previous studies (Carbonation: 0.5 MPa and 700 °C in 15% CO2/air balance for 15 min; Calcination: 0.1 MPa and 950 °C in 100% CO2 for 10 min). The pore structure characteristics (BET, BJH) were measured as a supplement to the attrition and reaction studies. Results showed that the mechanical property of the pellets with the particle size of 1.0–1.43 mm were greatly enhanced, especially for the pellet CaO–0.5% CLS-A. A slow decay in CO2 capture capacity of the sorbents was observed after making pellets during multiple cycles. It was attributed to the attrition of sorbents and the exposure of inner core of the CaO sorbents, which are in favor of CO2 capture. The pore structure showed that the BET surface area and BJH pore volume did not change much, which benefits CO2 uptake of the sorbents during the cycling.

► Attrition resistance and CO2 uptake of sorbents were enhanced by pelletizing with aluminate cement.
► The slow decay in CO2 uptake was attributed to the slowdown in sintering by adding aluminates.
► Pellets of CaO–0.5% CLS-A displayed the best mechanical property.
► CO2 release during calcination on sorbent attrition is more serious than the thermal stress.