Structure and activity relationships for CO2 regeneration from aqueous amine-based absorbents

A study to determine the relationships between structure and activity of various amine-based CO2 solvents was performed. The desorption of CO2 from saturated solvents at 80 °C and atmospheric pressure was measured to assess the initial desorption rate and desorption capacities at pseudo-equilibrium. Evaluation of the desorption capacity at lower temperature, 80 °C, will give a better understanding for more energy efficient and lower circulation rate absorbent for CO2 absorption process. Results showed that an increase in chain length between the amine and different functional groups in the solvent structure up to four carbon, results in an increase in initial desorption rate and also an increase in the desorption capacity at pseudo-equilibrium was observed for most solvents. Steric hindrance effect was noticed when a side chain with an alkyl group was present at α-carbon position to amine group in the structure. Increase in the number of the amine group in solvent structure, results in higher desorption capacity up to 75% of CO2 is desorbed. Aromatic amines substituted with an amine group by a side chain at the cyclic ring shows an increase in desorption capacity at pseudo-equilibrium compare to other group substitution.