Comprehensive solubility of N2O and mass transfer studies on an effective reactive N,N-dimethylethanolamine (DMEA) solvent for post-combustion CO2 capture

The physical solubility and mass transfer performance of CO 2 absorption into aqueous N,N-dimethylethanolamine (DMEA) solution were comprehensively studied in the present work. The physical solubility (Henry’s law constant ( He )) was measured using a stirred cell reactor for pure DMEA and aqueous DMEA at temperatures from 293.98 to 333.03 K. Then, the physical solubility of CO 2 was obtained based on the “N 2 O analogy” method. Furthermore, He was correlated successfully by using an empirical polynomial model with an average absolute relative deviation (AARD) of 4.23%. The mass transfer performance was studied in a laboratory scale structured packing absorption column at DMEA concentration of 1–4 kmol/m 3 , liquid feed temperature of 293.15–333.15 K, liquid flow rate of 3.90–11.7 m 3 /m 2 -hr, CO 2 partial pressure of 6–20 kPa, lean CO 2 loading of 0.050–0.300 mol/mol, over the inert gas flow rate range of 26.11–43.52 kmol/m 3 -hr. Based on the experimental values of He for CO 2 into aqueous DMEA solution, the effect of the gas concentration of A in gas-liquid equilibrium ( y A ∗ ) on gas phase volumetric overall mass transfer coefficient ( K G a v ) was considered in this study, but found to be an insignificant influence that can be ignored. Analogously, an attempt to correlate the mass transfer coefficient K G a v and outlet concentration of CO 2 ( y out ) using semiempirical models as function of the mentioned operational parameters was conducted. The predictive correlations for K G a v and y out of the DMEA-CO 2 -H 2 O system in structured packing column are K G a v = L 0.23 0.6144 a eq - a C / p C O 2 + 0.02327 and ln y out = l n y in - 0.77 PV G Ω L 0.23 0.6144 a eq - a C / p C O 2 + 0.02327 , with acceptable AARDs of 4.59% and 1.48%, respectively.