A kinetic study of CO2 capture with potassium carbonate solutions promoted with various amino acids: Glycine, sarcosine and proline

• Glycine, sarcosine and proline improve the absorption of CO2 into a K2CO3 solvent.
• Reaction kinetics between CO2 and the aforementioned amino acids are reported.
• Glycine and MEA exhibit a comparable catalytic activity.
• Sarcosine and proline possess a larger catalytic activity than that of DEA.

The absorption kinetics of carbon dioxide (CO2) into amino acid promoted potassium carbonate (K2CO3) solutions has been studied using a wetted-wall column. Experiments were conducted under conditions resembling those found at industrial CO2 capture plants including concentrations up to 2.0 M and temperatures from 40 to 82 °C. Results presented here show that the addition of 1.0 M glycine, sarcosine and proline accelerates the overall rate of absorption of CO2 into a 30 wt% K2CO3 solvent by a factor of 22, 45 and 14, respectively, at 60 °C. The Arrhenius expressions for the reaction between CO2 and aforementioned amino acids are k2-Gly [M−1 s−1] = 1.22 × 1012 exp(−5434/T [K]), k2-Sar [M−1 s−1] = 6.24 × 1010 exp(−1699/T [K]) and k2-Pro [M−1 s−1] = 1.02 × 1011 exp(−2168/T [K]) where the activation energies are 45.2 kJ mol−1, 14.1 kJ mol−1 and 18.0 kJ mol−1, respectively. The reaction order with respect to glycine is found to be 1, while the reaction order with respect to sarcosine and proline is observed to be in the range of 1.3–1.6 and 1.2–1.3, respectively.