(446o) Synthesis of Sodium Promoted Hydrotalcite and Its CO2 Adsorption Properties at High Temperature

In the past centuries, global warming has been seriously accelerated since carbon dioxide (CO₂) emission caused by fossil fuel-based energy system has been gradually increasing. In this respect, CO₂ is classified into a main anthropogenic greenhouse gas so that the increase of CO₂ concentration in the atmosphere must be inhibited. To diminish CO₂ emission, lots of researches have been carried out. Among various CO₂ capture technologies, CO₂ can be directly captured using solid sorbent materials. Layered double hydroxide, also called as hydrotalcite, has been considered as a promising for CO₂ capture at high temperature range (200-500 °C). Hydrotalcite typically has fast adsorption and desorption kinetics, thermal stability, and ease of regeneration by pressure or temperature swing adsorption method. However, its low CO₂ adsorption capacity should be enhanced for practical sorption processes. Alkali metal precursors, usually potassium carbonate (K₂CO₃), are used for enhancing the CO₂ adsorption capacity of the hydrotalcite since alkali metal increases the basicity of hydrotalcite. However, as an alkali metal precursor, sodium nitrate (NaNO₃) has not been studied in previous studies. Therefore, in this study, NaNO₃-promoted hydrotalcite was synthesized and the effect of NaNO₃ on CO₂ adsorption properties of hydrotalcite was investigated using several analysis methods. The structural and textural properties were analyzed using X-ray diffraction (XRD) and N₂ adsorption analysis, and the CO₂ adsorption ability at high-temperature (200-400 °C) was measured using a thermogravimetric analyzer (TGA).