Enhancement of CO2 Sorption Uptake on Hydrotalcite by Impregnation with K2CO3

Abstract

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 K2CO3-promoted hydrotalcite was investigated. Thermogravimetric analysis was used to measure equilibrium CO2 sorption uptake and to estimate CO2 sorption kinetics, The analyses based on N-2 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 CO2 sorption. The equilibrium CO2 sorption uptake on hydrotalcite could be increased up to 10 times by impregnation with K2CO3, and there was an optimal amount of K2CO3 for a maximum equilibrium CO2 sorption uptake. In the K2CO3-promoted hydrotalcite, K2CO3 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.