A study on the CO₂ capture and attrition performance of construction and demolition waste

CaO-based sorbent deactivation is one of challenges to develop CaO-based chemical looping technology. The replacement of non-renewable natural or expensive synthetic CaO-based sorbents with cheap and environmental CaO-based waste sorbents is an effective way to overcome this challenge. As high CaO content, construction and demolition waste (CDW) has ability to capture CO₂. Due to the rapid development of cities, a great deal of CDW is produced every year. According to the characteristics of CDW, six components were selected in this paper. From the initial CO₂ carrying capacity, hydrated limestone had the highest initial CO₂ carrying capacity, about 0.592 g CO₂/g sorbent in TGA and 0.414 g CO₂/g sorbent in fluidized bed system, followed by limestone, cement-based limestone, hydrated cement, cement-based sand, cement raw and sand. For multiple carbonation-calcination cycles, cement played a positive role in maintaining high cyclic CO₂ carrying capture. Hydration degree and free lime content increased with the increase of hydration time, which improved the CO₂ capture performance of CDW. For cement-based sorbents, evidence from this study suggested that extending hydration time played a positive role in improving the attrition resistance and maintaining the initial specific surface area in fluidized bed system.