(398u) Development of Potassium- and Sodium-Promoted CaO Adsorbents for CO2 Capture at High Temperatures

Development of highly efficient adsorbents for high temperature CO₂ capture process is crucial for large scale implementation of this technology. In this work, development of novel potassium- and sodium-promoted CaO adsorbents (K-Ca and Na-Ca) is discussed and their CO₂ capture performance at high temperatures is presented. A series of K-Ca and Na-Ca adsorbents with various K/Ca or Na/Ca molar ratios were developed and tested for CO₂ capture at high temperatures ranging from 300 to 400 °C. The structural, chemical, and morphological characteristics of the double salts were systematically evaluated before and after exposure to CO₂. Our results indicated that CO₂ capacity is largely influenced by both K or Na concentration and adsorption temperature. A maximum capacity of 3.8 and 3.2 mmol/g were obtained for K-Ca and Na-Ca double salts, respectively, at 375 °C and 1 bar. Further investigation of the effect of temperature revealed that the window temperature for operation ranges from 300 to 650 °C while beyond 650 °C, the double salts start to decompose and lose capacity. Moreover, it was found that both adsorption kinetics and capacity improve with temperature, with CO₂ uptake reaching a maximum 10.7 mmol/g at 650 °C over K-Ca double salt. This study represents alkali metal-promoted CaO adsorbents as potential high-temperature adsorbents with similar performance to their MgO-based analogues.