Hydrotalcites for adsorption of CO2 at high temperature

Abstract

Adsorption of carbon dioxide by hydrotalcites was investigated by using a gravimetric method at 450 ‡C. Hydrotalcites possessed higher adsorption capacity of CO2 than other basic materials such as MgO and Al2O3. Two different preparation methods of hydrotalcite with varying Mg/Al ratio were employed to determine their effects on the adsorption capacity of CO2. In addition, varying amounts of K2CO3 were impregnated on the hydrotalcite to further increase its adsorption capacity of CO2. The hydrotalcite prepared by the high supersaturation method with Mg/Al=2 showed the most favorable adsorption-desorption pattern with high adsorption capacity of CO2. K2CO3 impregnation on the hydrotalcite increased the adsorption capacity of CO2 because it changed both the chemical and the physical properties of the hydrotalcite. The optimum amount of K2CO3 impregnation was 20 wt%. The hydrotalcite prepared by the high supersaturation method with Mg/Al=2 and 20 wt% K2CO3 impregnation has the highest adsorption capacity of CO2 with 0.77 mmol CO2/g at 450 ‡C and 800 mmHg.