Calcium precursors for the production of CaO sorbents for multicycle CO2 capture.

A screening of potential calcium precursors for the production of CaO sorbents for CO(2) capture at high temperature was conducted in this work. The precursors studied include microsized calcium carbonate (CC-CaO), calcium hydroxide (CH-CaO), nanosized (<70 nm) calcium carbonate (CC70 nm-CaO), nanosized (<160 nm) calcium oxide (CaO160 nm-CaO), calcium acetate hydrate (CA-CaO), calcium l-lactate hydrate (CL-CaO), calcium formate (CF-CaO), calcium citrate tetrahydrate (CCi-CaO), and calcium d-gluconate monohydrate (CG-CaO). The capture capability of these sorbents was investigated using a thermogravimetric analyzer (TGA) for multiple capture cycles. CG-CaO exhibited the best capacity for capturing CO(2) with a 1-min conversion of 65.9% and a 30-min conversion of 83.8% at the ninth cycle. Subsequently, a further parametric study was conducted to examine the effect of reaction conditions such as reaction temperature (550-750 degrees C) and CO(2) gas concentration (1-15%) on the capture capacity of CG-CaO. The sorbent CG-CaO also showed a much lower decomposition temperature and higher predicted residual conversion after prolonged cycles, compared with CC-CaO.