Enhancement of CO₂ sorption uptake on hydrotalcite by impregnation with K₂CO₃

The awareness of symptoms of global warming and its seriousness urges the development of technologies to reduce greenhouse gas emissions. Carbon dioxide (CO₂) is a representative greenhouse gas, and numerous methods to capture and storage CO₂ have been considered. Recently, the technology to remove high-temperature CO₂ by sorption has received lots of attention. In this study, hydrotalcite, which has been known to have CO₂ sorption capability at high temperature, was impregnated with K₂CO₃ to enhance CO₂ sorption uptake, and the mechanism of CO₂ sorption enhancement on K₂CO ₃-promoted hydrotalcite was investigated. Thermogravimetric analysis was used to measure equilibrium CO₂ sorption uptake and to estimate CO₂ sorption kinetics. The analyses based on N₂ gas physisorption, X-ray diffractometry, Fourier transform infrared spectrometry, Raman spectrometry, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were carried out to elucidate the characteristics of sorbents and the mechanism of enhanced CO ₂ sorption. The equilibrium CO₂ sorption uptake on hydrotalcite could be increased up to 10 times by impregnation with K ₂CO₃, and there was an optimal amount of K ₂CO₃ for a maximum equilibrium CO₂ sorption uptake. In the K₂CO₃-promoted hydrotalcite, K ₂CO₃ was incorporated without changing the structure of hydrotalcite and it was thermally stabilized, resulting in the enhanced equilibrium CO₂ sorption uptake and fast CO₂ sorption kinetics.