Catalytic Solvent Regeneration Using Hot Water During Amine Based CO2 Capture Process

Experiments for CO2 stripping/amine regeneration were performed using single and blended amines (namely, MEA, MEA–MDEA, MEA–DEAB (4-(diethylamine)-2-butanol)) with and without solid acid catalysts (γ-Al2O3 or HZSM-5) at 90–95∘C. The heat duty to regenerate 5 M MEA without catalyst was taken as 100% and as the base line. The results showed that the amine regeneration performance in terms of lowest heat duty followed the order: MEA–DEAB with HZSM-5 (38%) > MEA–DEAB with γ-Al2O3 (40%) > MEA–DEAB with no catalyst (51%) > MEA with HZSM-5 (65%) > MEA with γ-Al2O3 (73%) > MEA–MDEA with γ-Al2O3/no catalyst (74%), all relative to MEA with no catalyst (100%). The results further showed that the addition of MDEA or DEAB (as tertiary amines) in a blended solvent provided R3N and HCO3−, which split and thus decreased the free energy gaps in the solvent regeneration pathway. The implication is that the use of blended amines in conjunction with solid acid catalysts could result in stripper size and heat duty reductions during solvent regeneration.