Abstract

Solid CaO-based sorbents for CO<inf>2</inf> capture represent a promising alternative technology compared to traditional amine scrubbing methods. However, CaO-based sorbents are rapidly sinter and easily decrease CO<inf>2</inf> uptake capacity with regenerated carbonation–calcination cycle. Thus, in this study, doping CaO with CeO<inf>2</inf> make it an excellent candidate for improving stability and facilitating CO<inf>2</inf> capture efficiency. The dual function of CaO bio-based sorbents with varying ratios of cerium (Ce) were derived from naturally occurring blood clam using the gel-combustion method. Their nanostructures and physicochemical properties were characterized through the specific methods, including in situ XAS, CO<inf>2</inf> chemisorption and physisorption, XPS, XRD, and SEM. An in-depth understanding of CO<inf>2</inf> adsorption mechanism was further emphasized using a density functional theory (DFT) simulation. The results demonstrate that nanosized CeO<inf>2</inf>-CaO, with a mole ratio of 1:9, exhibited the highest performance for CO<inf>2</inf> capture (6.44 mmol CO<inf>2</inf>/g sorbent). It is postulated that Ce serves as a physical barrier, effectively partitioning adjacent CaO grains and thereby diminishing the sintering rate. CaO is identified as the primary adsorption site, in contrast to CeO<inf>2</inf>. Mixing the Ce-Ca dual oxide initiates the electron-rich O at the O’ site. The electron localization at the O’ active site improves the activity of O’, making the performance CeCa(200) for capturing CO<inf>2</inf> capture dominant. This discovery suggests that CeO<inf>2</inf>-CaO holds promise as a sustainable alternative sorbent for future CO<inf>2</inf> capture applications.