Capturing volatile ester compounds from gas mixture with ionic liquids

As a promising absorbent, ionic liquid (IL) was first used for capturing the volatile ester compounds from gas mixture. Considering the solubility of ester in IL and the selectivity of ester to feeding gas, the hydrophobic IL [BMIM][Tf2N] was selected. In combination with the quantum chemistry calculation, the separation mechanism was revealed at the molecule level. The vapor-liquid equilibrium (VLE) data of the binary mixtures of ester and [BMIM][Tf2N] were obtained and compared with the calculated results by UNIFAC-Lei model. It was found that the popular UNIFAC-Lei model can predict the VLE of ester and [BMIM][Tf2N] well. Moreover, the ester vapor capture experiment with [BMIM][Tf2N] as absorbent was conducted, demonstrating the good separation performance. Furthermore, the process simulation on continuous ester vapor capture with [BMIM][Tf2N] as absorbent was carried out using the rigorous equilibrium (EQ) stage model built with the UNIFAC-Lei model as property method. This work confirmed that capturing ester vapor with ILs is a typical process intensification technology.