CO2 absorption property of Li4SiO4 in the presence of water vapor at room temperature

Abstract Lithium orthosilicate (Li 4 SiO 4 ) powders were synthesized by heating a mixture of LiNO 3 and amorphous SiO 2 at 800 °C for 5 h in air. The formed powders were applied to capture CO 2 in the presence of water vapor at room temperature (RT). Thermogravimetric (TG) analysis showed that the CO 2 absorption reaction of Li 4 SiO 4 was promoted even at RT as the relative humidity increased, whereas little absorption occurred under a dry CO 2 flow. X-ray diffraction measurements, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy clarified that an amorphous phase and Li 2 CO 3 were produced on the Li 4 SiO 4 surface after the CO 2 reaction in the presence of water vapor. The adsorption of water vapor resulted in the formation of a basic solution on the surface of Li 4 SiO 4 particles. This solution promoted CO 2 absorption to Li 4 SiO 4 even at RT. As a result, the CO 2 absorption capacity of Li 4 SiO 4 in the presence of water vapor at RT was greater than that of Li 4 SiO 4 in the presence of dry CO 2 . Gas chromatography and TG revealed that the Li 4 SiO 4 absorbed CO 2 in the presence of water vapor and released CO 2 over two temperature regions, namely a region below 500 °C and one above 600 °C. The single phase of Li 4 SiO 4 was regenerated by heating the CO 2 -absorbed Li 4 SiO 4 at 700 °C.