Enhancement of CO capture performance of aqueous MEA by mixing with [NHe-mim][BF].

Alcohol amine solutions have a high absorption capacity and rate for CO capture, however, there are some shortcomings such as high energy-consumption and low stability. To enhance CO capture performance of aqueous MEA, a functional ionic liquid ([NHe-mim][BF]) was introduced based on the advantages for CO capture. Absorbents were prepared with the molar concentration ratio of [NHe-mim][BF] to the 30 vol% aqueous MEA of 0 : 10, 1 : 9, 2 : 8, 3 : 7, 4 : 6 and 6 : 4. The density and the viscosity of the investigated absorbents were measured and the effects of the molar fraction of [NHe-mim][BF] ( ) and temperature on CO absorption performance were investigated. CO desorption performance of the solvent at different temperatures was discussed. The stability performance of the absorbent with of 2 : 8 (I/M) was examined by five consecutive cyclic tests. The results showed that for pure CO, the I/M displayed the highest absorption performance at 303 K under 1 bar: a comparable CO absorption capacity of the 30 vol% aqueous MEA and a higher CO absorption rate at the later absorption stage. Moreover, with the increase of temperature, CO absorption capacity and rate decreased, while CO desorption efficiency and rate increased. 393 K was chosen as the optimum desorption temperature with the desorption efficiency of 99.31%. The introducing of IL contributed to CO desorption performance of the absorbents significantly. The properties (CO absorption capacity, mass loss, density and viscosity) of the I/M during the cycles suggested that the IL-MEA mixture had an excellent stability performance.