Kinetics and Thermodynamics of CO2 Absorption in Aqueous 3-Dimethylaminopropylamine and Its Blend with Poly(ethylene glycol) Dimethyl Ether Using a Wetted Wall Column Reactor

Biphasic solvent 3-dimethylaminopropylamine (DMAPA)/poly(ethylene glycol) dimethyl ether (NHD)/H2O solution is a promising absorbent for CO2 capture. The kinetics of CO2 absorption in both DMAPA/NHD/H2O system and DMAPA/H2O systems was investigated and compared in a wetted wall column reactor with different CO2 loadings at different CO2 partial pressures from 30 to 70 °C. The equilibrium CO2 loadings were also determined. Meanwhile, the density and viscosity for both systems were measured. In both systems, the mass transfer flux of CO2 increases linearly with the increase of CO2 partial pressure. The kinetic data were interpreted by the zwitterion mechanism. The overall mass transfer constant was determined according to the absorption rate experiments performed in the pseudo-first-order regime. The overall mass transfer resistances increase with the increase of CO2 loading and decrease with the increase of temperature. The addition of NHD decreases the equilibrium CO2 loadings at the same CO2 partial pressure and temperature. However, it increases the enhancement factor significantly and can promote both the absorption and the desorption process. It provides basic information not only for the further utilization of DMAPA/NHD/H2O solution, which is helpful for the design of absorption reactor, but also for developing new phase-change absorbents for CO2 capture.