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 15°C. 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.