Mechanism for self-reactivation of nano-CaO-based CO2 sorbent in calcium looping

This study investigated the mechanism for self-reactivation of nano-CaO-based CO2 sorbents. Nano-CaO, nano-CaO mixed with MgO, and CaTiO3-coated nano-CaO were prepared as CO2 sorbents to study. The influences of calcium looping conditions on self-reactivation of the sorbents by TGA. The research results showed that the self-reactivation will be found under a lower calcining temperature and short calcination holding time of the nano-CaO-based CO2 sorbents. The additive decreased the carbonation holding time to 5 min for self-reactivation and maintained the excellent durability of the nano-CaO-based sorbents. The nano-CaO-based sorbents exhibited self-reactivation with >50% conversion for >50 cycles under calcination conditions of 850 °C in 50% CO2 (N2 balance). A new grain-pore-core model was proposed for the self-reactivation process. This model considers the changes in the grains and structures of sorbents during pre-calcination and subsequent carbonation-calcination cycles.