The role of nickel oxide additive in lowering the carbon dioxide sorption temperature of CaO

A new type of calcium-based regenerable carbon dioxide(CO2) sorbent, CaO-NiO, was synthesized via the sol-gel method. The as synthesized CO2 sorbent was in the form of nanoparticles. The CO2 sorption temperature and capacity of the sorbent were examined using thermogravimetric analysis(TGA). The CaO-NiO sorbent is able to capture CO2 at a lower sorption temperature(465C) than pure calcium oxide(CaO)(600C). The role of NiO in the CaO-NiO sorbent in lowering the CO2 sorption temperature was also investigated. The sorbent was characterized by X-ray diffractometer(XRD), N2adsorption-desorption analysis, high resolution transmission electron microscopy(HRTEM) and scanning electron microscopy(SEM). CaO and NiO were found to coexist in the sorbent. Neither solid solution nor mixed metal oxide was formed. NiO did not react with CO2 in the sorption process; but it worked like a catalyst to promote the CaO carbonation reaction. It is suggested that this new CaO-NiO sorbent may have a promising application as an effective CO2 sorbent with lower energy consumption.