Effect of pH-controlled synthesis on the physical properties and intermediate-temperature CO₂ sorption behaviors of K-Mg double salt-based sorbents

High-temperature CO₂ sorption has been investigated as a new CO₂ capture technology, and the development of high-temperature CO₂ sorbents is critically important for the realization of this technology. In this study, K-Mg double salt-based sorbents were synthesized using a new pH-controlled precipitation method and the prepared sorbents were tested for medium high (intermediate) temperature CO₂ sorption. In the new method for the synthesis of K-Mg double salt-based sorbents, the pH of the reagent solution was controlled by adding K₂CO₃ and/or KOH, resulting in varied ratios of different components in the sorbent. The CO₂ sorption ability was enhanced in K-Mg double salt-based sorbents synthesized using the new pH-controlled method compared to the samples synthesized by the conventional precipitation method. The newly prepared K-Mg double salt-based sorbents had a high CO₂ sorption uptake of up to 2.09 mol kg^-1 at 300 °C and 1 bar. In addition, they showed fast sorption kinetics and good cyclic stability during multiple sorption/desorption procedures.