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 Al layered double oxides (Mg Al LDOs) as well as their CO 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 capture efficiency. Notably, it is revealed that a rapid ramp rate (100 °C min ) significantly increases surface area and hydroxyl concentration, leading to a 69% increase in CO capture efficiency compared to slower ramp rate. Conversely, short calcination times (1 h) and fast ramp rates (100 °C min ) are observed to compromise CO 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 ) 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 capture performance.