Effect of Ca/Mg molar ratio on the calcium-based sorbents

Steelmaking industry faces urgent demands for both steel slag utilization and CO2 abatement. Ca and Mg of steel slag can be extracted by acid solution and used to prepare sorbents for CO2 capture. In this work, the calcium-based sorbents were prepared from stainless steel slag leachate by co-precipitation, and the initial CO2 chemisorption capacity of the calcium-based sorbent prepared from steel slag with the Ca and Mg molar ratio of 3.64:1 was 0.40 g/g. Moreover, the effect of Ca/Mg molar ratio on the morphology, structure, and CO2 chemisorption capacity of the calcium-based sorbents were investigated. The results show that the optimal Ca/Mg molar ratio of sorbent for CO2 capture was 4.2:1, and the skeleton support effect of MgO in calcium-based sorbents was determined. Meanwhile, the chemisorption kinetics of the sorbents was studied using the Avrami-Erofeev model. There were two processes of CO2 chemisorption, and the activation energy of the first stage (reaction control) was found to be lower than that of the second stage (diffusion control).