This work summarises the results of the design of novel separation processes for CO₂ removal from flue gas based on precipitating amino acid solvents. The processes here described (DECAB, DECAB Plus and pH-swing) use a combination of enhanced CO₂ absorption (based on the Le Chatelier;s principle) and / or enhanced CO₂ desorption (based on pH-shift), which contribute substantially to the reduction of regeneration energy. An evaluation of these processes has been developed based on literature data, thermodynamic principles and experimental data. As solvent example, the potassium salt of taurine was selected. The results show that these processes are environmentally friendly (no emissions to the air, lower ecotoxicity) and have lower energy consumption than conventional MEA. The DECAB Plus process has been identified as the option with lower energy consumption (66% of conventional MEA- ie ca 2.4 GJ/t CO₂). This study has established the potential of precipitating amino acids as an energy effective alternative to alkanol amines. The future work will focus on determining the cost of CO₂ avoidance and investigating other solvents that will further lead to benefits over conventional processes.

A major consideration for post-combustion CO₂ capture is the adverse effect of the presence of SO₂ on the absorption desorption process. The most common approach is to remove the SO₂ from the flue gases in a flue gas desulfurization (FGD) unit prior the CO₂ recovery process. This paper reports the experimental and modeling results of a new process for simultaneous removal of CO₂ and SO₂ for post-combustion applications. This process is named CASPER (CO ₂-capture And Sulphur Precipitation for Enhanced Removal), and is based on the precipitation of K₂SO₄ for sulphur removal. The selected CO₂ absorbing solvent is an amino-acid, preferably a potassium amino-acid salt solution. The presence of potassium leads to the subsequent formation of K₂SO₄, which solubility in the CO₂ loaded aqueous solvent solution changes depending on the applied conditions. The optimal crystallization conditions were first determined by characterization of K₂SO₄ solubility window and then evaluated in the lab-scale crystallization unit. In the next step the model system based on potassium beta-alanate solutions, also with addition of sulphate, were tested for CO₂ absorption and desorption pressures by performing VLE (Vapor Liquid Equilibrium) measurements at 40°C and 120°C, respectively. Obtained values were included in preliminary technical assessment, which showed an energetic improvement of 0.7%-points for the CASPER model solvent system in comparison to the baseline 30wt% MEA case.