Cyclic CO2 capture characteristics of a pellet derived from sol-gel CaO powder with Ca12Al14O33 support

A novel calcium-based pellet was prepared by extrusion of sol-gel CaO powder and cement with high aluminum-based content. Limestone was used for comparison. The cyclic CO capture performance and carbonation kinetics of the sorbents were investigated in a thermogravimetric analyzer (TGA). The changes in phase and microstructure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer Emmet Teller (BET) surface area, respectively. The results indicate that the pellet consisted of CaO and CaAlO after initial calcination. Limestone reactivity decreased dramatically with the increase in the cycle number, whereas the pellet showed a relatively stable cyclic CO capture performance with high reactivity. The CO capture capacity of the pellet achieved 0.43 g CO/g sorbent after 50 cycles at 650 °C and 850 °C for carbonation and calcination, respectively. Moreover, the pellet obtained fast carbonation rates with slight decay after multiple cycles. The porous microstructure of the pellet contributed to the high reactivity of the sorbent during high temperature reactions, and the support material of CaAlO, enhanced the cyclic durability of the calcium-based sorbents