(555b) Towards Industrially Viable Non-Aqueous Amine Solvent Systems

Ionic liquids represent
attractive solvents for CO₂ capture due to their tunable properties
and low vapor pressures. We have developed a class of amine solvents for use in
non-aqueous conditions that react reversibly with CO₂ to form ionic
liquids. We have also looked at several polyamine-containing compounds to
increase the number of reactive amine sites for added CO₂ capacity. We
are optimizing the solvents for CO₂ capture from coal-fired power
plants with a water-saturated flue gas stream. The solubility of water in both
the amine precursor and in the ionic liquid formed will influence the system
dynamics. The addition of water into the solvent system changes both capacity
and viscosity. Under the right conditions, the addition of water can boost
capacity by promoting bicarbonate formation. Water can lower viscosity by
disrupting packing of the ionic liquid. Since bicarbonate has a relatively low
temperature of reversal, the addition of water also affects the temperature at
which CO₂ is released from the solvent system. The merit
of these advantages will be compared against the parasitic energy penalty for
heating water during regeneration. We will additionally present opportunities for
further research and optimization of the solvents.