Hydrothermal synthesis of K₂CO₃-promoted hydrotalcite from hydroxide-form precursors for novel high-temperature CO₂ sorbent

In many materials for CO₂ sorption, hydrotalcite is attracting substantial attention as a high temperature (200-500 °C) CO₂ sorbent because of its fast sorption/desorption kinetics and easy regenerability. However, the CO₂-sorption capacity of conventional hydrotalcite is relatively low for large-scale commercial use. To enhance CO₂-sorption capacity, hydrotalcite is conventionally impregnated with alkali metals such as K₂CO₃. Although K ₂CO₃-impregnated hydrotalcite has high CO ₂-sorption capacity, the preparation method takes long time and is inconvenient because hydrotalcite synthesis step and alkali metal impregnation step are separated. In this study, K₂CO₃-promoted hydrotalcite was newly synthesized from hydroxide-form percursors by a simple and eco-friendly method without a solvent-consuming washing step. Analysis based on X-ray diffraction indicated that the prepared samples had structures of well-defined hydrotalcite crystalline and un-reacted Mg(OH)₂ precursor. Moreover, K₂CO₃ was successfully incorporated in hydrotalcite during the synthesis step. The prepared K₂CO ₃-promoted hydrotalcite showed high CO₂-sorption capacity and had potential for use as a high-temperature CO₂ sorbent.