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.