Modelling and parameter estimation of breakthrough curves for amine-modified activated carbons under pre-combustion carbon capture conditions

Pressure swing adsorption (PSA) demonstrates high potential for capturing pre-combustion carbon dioxide in Integrated Gasification Combined Cycle (IGCC) power plants, due to a binary mixture of hydrogen and carbon dioxide entering the separation process. In this work, a seven-step PSA model was developed and compared to adsorption experiments under PSA conditions (25 bar and ambient temperatures) performed with tetraethylenepentamine (TEPA) and a novel blend of monoethanolamine-monodiethanolamine (MEA-MDEA) modified activated carbons, using nitrogen and carbon dioxide mixtures. The MEA-MDEA modified activated carbon showed promising results for pre-combustion PSA processes, due to their high carbon dioxide adsorption capacity and delayed break-point of about 200 s compared to the unmodified activated carbons. A sensitivity analysis carried out for the adsorbent parameters in a seven-step PSA process showed that high mass transfer coefficient values yielded to highly purified products, specifically for the light product stream (99.4%). A sensitivity analysis of the process variables showed that purity values of the heavy stream (carbon dioxide) were over 90% when the purge pressure was reduced to 0.5 bar and the carbon dioxide feed fraction increased to 60%.