Adsorption of CO2 on mixed oxides derived from hydrotalcites at several temperatures and high pressures

The adsorption of CO2 on Co, Fe and Ni mixed oxides derived from a commercial hydrotalcite and calcined at 500 degrees C was measured at several temperatures and pressures. Two types of experiments were considered in this work. In the first one, the adsorption temperatures were 25, 35 and 50 degrees C, with pressures of up to 1000 kPa. In the second, the adsorption temperature was 300 degrees C and the pressure up to 4400 kPa. The results obtained were compared with those found for four commercial microporous materials, namely the zeolite 13X, the MOF Basolite A100, an activated carbon and a synthetic alumina pillared clay. The microporous materials showed a higher CO2 adsorption capacity, from 4.54 to 6.94 mmol.g(-1), than the mixed oxides, up to 1.44 mmol.g(-1), at 25 degrees C and up to 1000 kPa. The calcined hydrotalcite and the Ni mixed oxide presented the highest CO2 adsorption capacity at 300 degrees C, 3.28 and 3.44 mmol.g(-1) at 4400 kPa, whereas the rest of materials gave values of up to 1.75 mmol.g(-1). Ni mixed oxide showed sorption capacity considerably higher than those reported in the literature for hydrotalcite based materials under similar conditions.