Synthetic solid oxide sorbents for CO2 capture: state-of-the art and future perspectives

Abstract

Carbon capture is an important and effective approach to control the emission of CO₂ from point sources such as fossil fuel power plants, industrial furnaces and cement plants into the atmosphere. For an efficient CO₂ capture operation, many aspects of the CO₂ capture steps need to be carefully considered. Currently the most mature CO₂ capture technology is liquid amine scrubbing. Alternatively, solid sorbents can be used to effectively capture CO₂ while alleviating the disadvantages associated with liquid amine sorbents. In this review, we critically assess solid metal oxide CO₂ sorbents, especially oxides of group 1 (Li, Na and K) and group 2 (Mg, Ca, Sr and Ba) metals, for capturing CO₂ at moderate to high temperatures. In particular, we focus on the recent advances in developing synthetic metal oxide sorbents, and the correlation between the design, synthetic approaches and their cyclic CO₂ capture performance, which are characterised by CO₂ uptake capacity, rate of carbonation and cyclic stability. The state-of-the-art, challenges, opportunities and future research directions for these metal oxide sorbents are discussed. By devoting more research effort to address the issues identified, there can be great potential to utilise Group 1 and 2 metal oxides as cost-effective, highly efficient sorbents for CO₂ capture in a variety of carbon capture applications.