(374k) Ca-Al Hydrotalcite-Based Mixed-Metal-Oxide for High-Temperature Carbon Dioxide Adsorption

Carbon dioxide (CO₂) is a detrimental gas that takes a large proportion of greenhouse gases emitted from fossil fuels and one of the major causes of global warming. For the reduction of CO₂ to achieve sustainable development, worldwide cooperation between international societies has been required. Among numerous countermeasures for its reduction, carbon capture and storage (CCS), a technology related to the separation, transportation, and storage of CO₂ gas produced from several emission sources, has been promising. Especially a separation process, the most cost-consuming process, has received attention to enhance its effectiveness so that the total cost of CCS can be reduced. CO₂ separation by applying adsorbents is a feasible method to capture CO₂ because of its lower energy consumption and simple regeneration process. In specific, hydrotalcite is a CO₂ adsorbent applicable to the temperature range between 200 and 500 ℃, while having a relatively low adsorption capacity. Additionally, hydrotalcite is a material of which structure is easily altered by preparation variations, leading to the change of CO₂ adsorption trend. In this study, to enhance the adsorption capacity of hydrotalcite, calcium (Ca) precursor was applied in the synthesis of hydrotalcite instead of magnesium (Mg) precursor. Moreover, variations such as calcination temperature, Ca to Al ratio, and anion types in hydrotalcite were applied to confirm their influences on CO₂ adsorption of the adsorbent.