CO2 capture by a novel CaO/MgO sorbent fabricated from industrial waste and dolomite under calcium looping conditions

Abstract

Herein, the novel CaO/MgO CO₂ sorbent was fabricated from carbide slag and dolomite by the combustion method during the calcium looping process. The carbide slag is a precursor of CaO, and dolomite is a precursor of both MgO and CaO. The effects of the mass ratio of the carbide slag to dolomite, calcination conditions and presence of steam during carbonation on the CO₂ capture performance of the novel CaO/MgO sorbent were studied during the calcium looping cycles. When the mass ratio of the carbide slag to dolomite was 74 : 26, the resulting CaO/MgO sorbent having the mass ratio of CaO to MgO = 90 : 10 achieved highest CO₂ capture capacity that was retained at 0.52 g g⁻¹ after 20 cycles (carbonation in 15% CO₂/85% N₂ at 700 °C for 20 min; calcination in 100% N₂ at 850 °C for 10 min), which was higher than those of the carbide slag and other reported CaO/MgO sorbents prepared from analytical reagents. Compared with that of the sample calcined under pure CO₂ at 950 °C, the CO₂ capture capacity of the CaO/MgO sorbent calcined in pure steam at 800 °C is apparently higher. This novel CaO/MgO sorbent fabricated from industrial waste and dolomite exhibits a more porous microstructure, which is promising for the calcium looping process for CO₂ capture.