Post-combustion carbon capture

CCS, Carbon Capture and Storage, is considered a promising technology to abate CO₂ emissions from point sources. The present review deals with the principle of post-combustion capture techniques, including thermal or pressure swing principles, adsorption or absorption, and electrical swing or membrane separation processes. Opportunities and challenges are assessed. In the first section of absorption processes, several commercial technologies are compared and complemented by the aqueous or chilled ammonia (NH₃) process, and a dual or strong alkali absorption. The second section deals with adsorption where fixed beds, circulating fluidized beds and counter-current bed configurations will be discussed, with particular focus on the different adsorbents ranging from zeolites or activated carbon, to more complex amine-functionalized adsorbents, nanotubes or metal organic frameworks (MOFs), and alkali-promoted oxides. Thirdly, membrane processes will be analysed. The review will finally summarize challenges and opportunities. Several research groups confirmed that absorption is the most mature post-combustion capture process: among the assessment of post-combustion CCS, 57% apply absorption, 14% rely on adsorption, 8% use membranes, and 21% apply mineralization or bio-fixation. This conclusion was in-line with expectations since absorption gas separation has been largely applied in various petrochemical industries. All other systems need further development prior to large scale application.