Structural modification of salt-promoted MgO sorbents for intermediate temperature CO₂ capture

MgO-based sorbents are a promising option for CO₂ capture at intermediate temperatures. MgO-based sorbents are often hybridized with alkali metal salts to promote the CO₂ capture performance. However, MgO-based sorbents often suffer a rapid decrement of CO₂ capture performance during multicycle carbonation-calcination reactions due to the reduction of active sites. In this study, we attempted to enhance the durability of MgO-based sorbents by modifying their morphology. A tubular-shaped MgO-based sorbent was synthesized using a carbon nanotube template. Various characterization experiments and evaluations were performed with the synthesized MgO-based materials. The MgO sample with modified structure exhibited a specific morphology consisting of elongated plate-like structures separated by empty spaces. This separation is expected to prevent MgO agglomeration and preserve the modified morphology during iterative CO₂ capture reactions. The MgO with modified structure achieved higher cycling stability with four times slower performance decay than the control MgO, even though identical chemical compositions were applied.