Optimising the acid-base ratio of Mg-Al layered double oxides to enhance CO 2 capture performance: the critical role of calcination conditions.

The effect of calcination conditions (ramp rate, calcination temperature and time) on the formation of Mg ₂ Al layered double oxides (Mg ₂ Al LDOs) as well as their CO ₂ capture performance, has been systematically investigated. This study explores novel insights into the intricate relationship between these calcination conditions and the resulting surface characteristics, which play a vital role in CO ₂ capture efficiency. Notably, it is revealed that a rapid ramp rate (100 °C min ^-1 ) significantly increases surface area and hydroxyl concentration, leading to a 69% increase in CO ₂ capture efficiency compared to slower ramp rate. Conversely, short calcination times (1 h) and fast ramp rates (100 °C min ^-1 ) are observed to compromise CO ₂ adsorption due to the presence of dehydrated LDHs. A critical acid : base ratio of 0.37, achieved from a fast ramp rate (100 °C min ^-1 ) at 400 °C for 2 h, was found as a key threshold for optimising surface properties, effectively balancing favourable hydroxyl and less favourable strong acid sites, thereby maximizing CO ₂ capture performance.