Eutectic mixture promoted CO2 sorption on MgO-TiO2 composite at elevated temperature

The development of carbon dioxide (CO₂) sorbents that can operate at elevated temperatures is significant for the advancement of pre-combustion capture technologies. Recently, promoter-based systems composed of alkali/alkaline earth metal nitrates and/or carbonates have been considered as next-generation solid sorbents due to their improved CO₂ uptake and kinetics. However, obtaining stable MgO sorbents against temperature swing regeneration still remained challenging. Herein, we report MgO-TiO₂ solid sorbents promoted by eutectic mixture (KNO₃ and LiNO₃) for elevated temperature CO₂ sorption. The developed sorbents show improved CO₂ sorption capacity, which may be attributed to the alternative CO₂ sorption pathway provided by the ionization of highly dispersed MgO in the eutectic mixture. The MgO-TiO₂ framework was also shown to assist in retaining the MgO configuration by constraining its interaction with CO₂. Furthermore, it is demonstrated that constructing composite structures is essential to improve the CO₂ sorption characteristics, mainly recyclability, at elevated temperatures. The developed promoter integrated sorbents showed exceptionally high CO₂ sorption capacity of > 30 wt.% at an elevated temperature (300°C) with pronounced stability under temperature swing operation.