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

Abstract

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.