Insights into the Impact of Trace SO2 on Amine Absorbents for Chemical Absorption of CO2

The impact of trace SO₂ in industrial flue gas on the amine-based chemical absorption of the CO₂ process is a significant concern. This work investigates the impact of trace SO₂ on the chemical absorption of CO₂ by four representative amine absorbents containing a primary amine group of ethanolamine (MEA), a secondary amine group of 2-(ethylamino)ethanol (EMEA), a tertiary amine group of N,N-diethylethanolamine (DEEA), and a sterically hindered amine group of 2-amino-2-methyl-1-propanol (AMP), focusing on their absorption/desorption capacity, cyclic absorption performance, CO₂/SO₂ selectivity, and SO₂ resistance capability. Experimental results revealed that the amine absorbent of MEA with the primary amine group has the highest SO₂ resistance capability, while the amine absorbent of EMEA with the tertiary amine group exhibits the lowest. In addition, CO₂/SO₂ selectivity investigations indicated that the amine absorbent of MEA with the primary amine group has superior selectivity for CO₂ than others. Moreover, NMR analysis revealed that SO₂ more significantly inhibited bicarbonate formation compared to carbamate formation, suggesting that amine absorbents prone to carbamate formation after CO₂ absorption have greater SO₂ resistant capability. Altogether, this work provides valuable insight into the utilization of amine absorbents for the capture of CO₂ in the presence of SO₂.