(377e) MgO-Based Sorbent Promoted with KNO3 for CO2 Capture at Medium Temperatures

The emission control and capture of CO₂ are always being a most challenging environmental issue facing to each country in over the world. The CO2 capture at medium temperature (200-400^oC) is one of important area in CCS technology because it can be applied to IGCC effluent gas without cooling step, sorption enhanced reaction or pre-combustion capture.  In this study, MgO was prepared by various synthesis methods of MgO (hydrothermal, polyol, aerogel methods) and the sorption capacity was compared by using sulfur compounds in gas mixture. The optimized MgO nanoparticle was used as a base material for CO₂ capture. Then, the developed MgO-based sorbent was promoted by KNO₃ to improve CO₂ capture capacity at medium temperature range. MgO·KNO₃ composites were synthesized using aerogel route and the CO₂ sorption capacity of as-prepared composites was evaluated at the intermediate temperature range of 250-400ºC by using a TGA. Effects of MgO/KNO₃ molar ratio and calcination method on CO₂ sorption capacity were compared and their structural and physical properties were investigated by SEM, XRD and N₂ adsorption/desorption isotherm. In addition, the sorption capacity of MgO/KNO₃ composite was compared to other MgO composites promoted by alkali metal salts (K₂CO₃, KOH, NaNO₃, Na₂CO₃, Na₂HPO₄ and LiNO₃) at the same condition. The sorption rate of CO₂ on MgO composite during initial 30 min was compared at different sorption temperature conditions, using a Fickian model. The cyclic working capacity and stability of MgO composite was evaluated by cyclic test.