Mass transfer performance for CO2 absorption into aqueous blended DMEA/MEA solution with optimized molar ratio in a hollow fiber membrane contactor

摘要

Combination N,N-dimethylethanolamine(DMEA) and monoethanolamine (MEA) may represent a potential absorbent for CO2 capture due to the high absorption rate, high cyclic CO2 capacity and low energy requirement for solvent regeneration. Both the absorption and regeneration performances for 2 kmol/m(3) DMEA/MEA with molar ratios of 2.0:0.0, 1.5:0.5, 1.0:1.0, 0.5:1.5, and 0.0:2.0 were estimated in terms of the absorption rate, regeneration rate and cyclic CO2 capacity using an improved rapid screening method. The experimental results showed that the highest cyclic CO2 capacities (i.e. low energy requirement) for the cyclic reaction time of 30 min and 60 min were obtained both by 1.0 M DMEA + 1.0 M MEA solution, indicating the synergistic effects existing in CO2 absorption into DMEA/MEA solution. Additionally, the mass transfer performance of CO2 absorption into 1.0 M DMEA + 1.0 M MEA solution was investigated in a hollow fiber membrane contactor. The effects of key operational parameters such as liquid velocity, inlet gas flow rate, CO2 partial pressure, feed temperature range, CO2 lean loading, amine concentration and membrane contactor height on the CO2 flux and overall gas phase mass transfer coefficient were investigated. Furthermore, a developed correlation was successfully applied for the prediction of overall gas phase mass transfer coefficient (K-G) for CO2 absorption into DMEA/MEA solution, with an average absolute relative deviation (AARD) of 8.31%. Thus, a potential absorbent (i.e. DMEA/MEA) for CO2 capture was proposed in this work.