Water-lean solvents are typically
defined as mixtures between an
organic diluent and an amine. These solvents are thought to deliver
potential benefits in CO2 capture systems, such as enhanced
mass transfer properties, increased absorption capacities, and lower
regeneration heat duties. However, it is yet unclear what properties
of the organic diluent one should aim for when developing these solvents.
For example, while it is understood that high CO2 physical
solubility is desirable if one wants to enhance mass transfer rates,
the contributions of viscosity and electrostatic properties (e.g.,
dielectric permittivity) are still uncertain. Simultaneously, as low
vapor pressures are interesting for reducing latent heat duties in
the regeneration process, the effects of viscosity and thermal conductivity
in the cross-heat exchanger before the reboiler are often neglected
or underestimated. This work aims to address such drawbacks by carrying
out an explicit analysis, based on rigorous modeling, on the influences
of each individual parameter of the organic solvent when mixed with
monoethanolamine as a token amine. The contributions of CO2 solubility, viscosity, dielectric permittivity, heat capacity, thermal
conductivity, and vapor pressure to the performances in the absorber
and the desorber are exhaustively discussed. Finally, an overall assessment
on which properties are effectively desirable in a water-lean solvent
is performed, as well as some predictions on which kinds of challenges
these solvents will have to face upon implementation.