Interaction of Pristine Hydrocalumite-Like Layered Double Hydroxides with Carbon Dioxide

The layered double hydroxides (LDHs) of Ca²⁺ and trivalent cations, Al³⁺ and Fe³⁺, are single-source precursors to generate supported CaO, which picks up CO₂ from the gas phase in the temperature range 350-550 °C. The supports are ternary oxides, mayenite, and Ca₂Fe₂O₅. The uptake capacity of the Fe³⁺-containing LDH at 1.9 mmol g^-1 is two times the capacity of the Al³⁺-containing LDH. The product of CO₂ uptake is calcite CaCO₃. It is observed that the intercalated chloride ions reduce the thermal penalty by inducing the early decomposition of CaCO₃. In the case of the chloride-intercalated LDHs of Ca²⁺ and Fe³⁺, the CaCO₃ formed is completely decomposed at 900 °C. This is in contrast with the CaCO₃ formed from bare CaO, which shows no sign of decomposition at 900 °C under similar conditions. This work shows that the hydrocalumite-like LDHs are candidate materials for CO₂ mineralization.