Amino acids/NH3 Mixtures for CO2 Capture: Effect of Neutralization Methods on CO2 Mass Transfer and NH3 Vapour Loss

Amino acid salts are effective promoters to improve CO2 absorption in NH3–based solutions, but at the expense of an increase in NH3 vapour loss. To address this issue, we proposed the neutralisation of amino acids using NH3 instead of KOH and investigated the effect of neutralisation methods on NH3 vapour loss and mass transfer coefficient of CO2 in amino acids/NH3 mixtures at 15oC. It has been found that NH3 neutralized amino acids solutions can enhance KG of CO2 in the NH3 solution and suppress NH3 loss at the same time. Among three amino acids investigated, taurine is most suitable for the NH3 neutralisation. We developed the chemical equilibrium model for amino acid–NH3–CO2–H2O and used the model to predict the species profiles in the mixture and explain the experimental results.