Development of Potassium- and Sodium-Promoted CaO Adsorbents for CO₂ Capture at High Temperatures


Development of highly efficient adsorbents for the 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. Maximum capacities 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 at 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.


Chemical and Biochemical Engineering

Keywords and Phrases

Binary Alloys; Calcium; Carbon Dioxide; Potassium Alloys; Salts; Sodium Alloys; Adsorption Kinetics; Adsorption Temperature; Chemical Equations; Effect of Temperature; High Temperature; Morphological Characteristic; Na Concentration; Operation Range; Calcium Alloys

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Article - Journal

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© 2017 American Chemical Society (ACS), All rights reserved.

Publication Date

01 Jul 2017