CO2 capture and release of Na0.7MnO2.05 under water vapor at 25–150?°C

Article abstract of DOI:10.1016/j.inoche.2019.01.029

Sodium manganates with a layered structure, Na_0.7MnO_2.05, have been applied to a novel material for CCUS (CO₂ capture, utilization, and storage), capable of capturing CO₂ at 25 °C in the presence of water vapor and releasing CO₂ at 150 °C. The temperatures of capturing and releasing CO₂ of Na_0.7MnO_2.05 were remarkably lower than those of other traditional metal oxides. The CO₂ absorption and desorption properties of Na_0.7MnO_2.05 were investigated by various methods, such as thermogravimetry, Fourier transform infrared spectroscopy, X-ray diffractometry, and gas chromatography. These investigations confirmed that Na_0.7MnO_2.05 absorbed CO₂ at 25 °C in the presence of water vapor to produce NaHCO₃ and a birnessite and the CO₂ absorption was promoted by increasing relative humidity and CO₂ concentration. The CO₂ absorption at 25 °C of Na_0.7MnO_2.05 was promoted by the formation of a strong basic solution on Na_0.7MnO_2.05, caused by the elution of Na ions from the interlayer of Na_0.7MnO_2.05 into water, adsorbed on the Na_0.7MnO_2.05 surface. Furthermore, Na_0.7MnO_2.05 was regenerated by heating the CO₂-absorbed Na_0.7MnO_2.05 at temperatures as low as 150 °C. The low-temperature regeneration indicates that Na_0.7MnO_2.05 can be a low-energy consumption material for capturing and releasing CO₂ at low temperatures.