Accelerated weathering of construction‐grade limestone for CO2 absorption

Abstract

AbstractAccelerated weathering of limestone (AWL) process efficiently captures CO2 from point source emissions. However, despite achieving an outstanding capture efficiency of 73.51 %, lab‐grade (LG) limestone with 99.90 % CaCO3 as an absorbent is costly ($2757.70/t), making commercialization of AWL impractical. This work delves into the viability of utilizing construction‐grade (CG) limestone (93.26% purity) for the AWL process facilitated by potable water in an absorption tower for post‐combustion capture. The result shows that CG limestone achieves comparable CO2 capture efficiency of 8.0–74.68% and bicarbonate (Ca(HCO3)2) concentration of 0.63–3.10 mM compared with LG limestone. However, LG limestone has 0.29 mol CO2/mol CaCO3 higher CO2 absorption capacity and a faster absorption rate than CG limestone, indicating a somewhat better CO2 capture performance. Nevertheless, CG limestone offered a more cost‐effective alternative, with a $2735.24 lower cost per ton of CaCO3 and a $2651.63 per ton CO2 lower CO2 capturing cost at the highest carbon capture efficiency (HCCE) condition compared to LG limestone. The kinetic analysis shows that the forward reactions in the AWL process are significantly faster at elevated CO2 concentration, with the mass transfer coefficient affirming that CO2 dissolves faster than CaCO3, in line with prior research. Thus, this work validates that CG limestone‐based AWL achieves comparable CO2 capture performance to that of LG limestone, offering a cost‐efficient alternative. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.