Strengthening performance of Al-stabilized, CaO-based CO2 sorbent pellets by the combination of impregnated layer solution combustion and graphite-moulding

Abstract

Calcium looping (CaL) process is recognized as one of the most promising CO2 capture technologies. However, the CaO-based sorbents commonly encounter serious sintering and elutriation problem during CO2 capture cycles. In this work, Al-stabilized, CaO-based sorbents were synthesized by the impregnated layer solution combustion method, and cigarette butt was selected as the porous reactive skeleton. The Al-stabilized, CaO-based sorbent containing 15 wt% of Al2O3 exhibits the highly stable CO2 capture performance, whose CO2 capture capacity after 20 cycles is almost the same as its initial capacity, ∼0.354 g/g. It is mainly attributed to the synergistic effect of thermal pretreatment (cigarette butt-assisted combustion) and incorporation of Al-based stabilizer (i.e., Ca12Al14O33) provide a stable inert framework for the synthetic sorbents, ensuring their highly stable capability for CO2 sorption during cycles. Further, graphite-moulding is a facile and energy-saving approach to make Al-stabilized, CaO-based sorbent powders into pellets to enhance its resistance to elutriation. The produced sorbent pellets (85 wt% CaO/15 wt% Al2O3) exhibit excellent long-term CO2 capture capacity (∼0.248 g/g after 49 cycles) and high compression strength of 18.47 ± 3.47 MPa. Therefore, the combined method involved of impregnated layer solution combustion and graphite-moulding is promising to produce highly efficient CaO-based CO2 sorbent pellets used in CaL.