Experimental studies on carbon dioxide absorption using potassium carbonate solutions with amino acid salts

Abstract

Absorption and desorption of CO2 using K2CO3 solutions promoted by three amino acid salts (AASs), potassium glycinate (PG), potassium lysinate (PL) and potassium L-argininate (PA), were evaluated using 40% CO2 at 40 °C and with pure N2 at 80 °C, respectively. The addition of all 3 AASs clearly enhanced both absorption and desorption of CO2 compared to single K2CO3 solution. PA + K2CO3 solution showed the highest CO2 cyclic capacity of 0.678 mol CO2/mol absorbent, while the highest CO2 absorption and desorption rates of 39.8 and 17.6 mol CO2 L−1 s−1 were achieved by PG + K2CO3 solution. Finally, simulated biogas containing 40% of CO2 and 60% of CH4 was used as test gas in a hollow fiber membrane contactor. PG and PA promoters presented higher CO2 absorption flux and removal efficiency than PL promoters in K2CO3 solution within low Gas/Liquid ratio region. Stable CO2 removal performances for all three promoters were observed at elevated temperature and pressure for 60 min operation.