All-solid-waste-derived CaO-based sorbents for simultaneously enhanced calcium looping CO2 capture and thermochemical energy storage

Abstract

Calcium looping (CaL) process relying on CaO as high-temperature CO2 sorbents is a prospective alternative technology for simultaneously cyclic CO2 capture and thermochemical energy storage. However, the cyclic stability and the energy storage density of the CaO-based sorbents decay drastically over repeated carbonation-calcination cycles. Herein, we yielded CaO-based sorbents derived from all industrial solid wastes with carbide slag (CS) as precursor and coal fly ash (CFA) as stabilizer featuring superior carbonation characteristics, stable CO2 cyclic uptake and high thermochemical energy storage density over multiple operation cycles. The optimal sorbent (CCS–H-G-CFA-D) exhibited a high initial CO2 uptake of 0.38 gCO2/gsorbent, superior cyclic stability with an average decay rate of 1.05% per cycle and remarkably stable energy storage density of 1375 kJ/kg, retaining 89.5% after 10 repeated cycles. Thereby, the simultaneously enhanced cyclic CO2 capture and thermochemical energy storage are attributed to adding CFA stabilizers in CS-derived CaO-based sorbents, forming stable skeleton to alleviate sintering, improving the uniform mixing degree between sorbent particles and promoting the carbonation reaction via synergistic effect. This simple and eco-friendly approach of cost-effective sorbents totally derived from industrial solid wastes provides a new avenue for large-scale practical CO2 capture and energy storage processes.