Capturing Condensable Gases with Ionic Liquids

Abstract

Ionic liquids (ILs) have been proposed to simultaneously capture a variety of condensable gases for the first time. The hydrophobic IL [EMIM][Tf 2 N] was selected as a suitable absorbent screened by the COSMO-RS (conductor-like screening model for real solvents) model, which in combination with the quantum chemistry calculation provided some theoretical insight into mechanisms with respect to condensable gas capture. Considering the simultaneous capture of volatile organic compounds (VOCs) and water, we selected benzene, toluene, and pxylene (BTX) as three kinds of VOC representatives, measured the vapor− liquid equilibrium (VLE) of BTX + [EMIM][Tf 2 N] mixture systems, and compared them with the predicted results by the UNIFAC−Lei model. The experiment of capturing condensable gases with [EMIM][Tf 2 N] as the absorbent was conducted. Furthermore, the conceptual design of continuous processes with [EMIM][Tf 2 N] and the conventional benchmark solvent triethylene glycol as absorbents at the industrial scale was performed using a rigorous equilibrium stage model with the UNIFAC− Lei model parameter input. It reveals that condensable gas capture with an IL belongs to a typical process intensification technology in chemical engineering.

Predictive molecular thermodynamic models for ionic liquids

“…Moreover, an EQ stage model based on the modified UNIFAC model was also established to simulate the air‐drying process, and there was good consistency between the simulated results and experimental data. Furthermore, the EQ model was broadened from noncondensable gas separation to capture processes for condensable gases (e.g., aromatics, esters, and sulfur‐containing organics, as well as methanol and dimethoxymethane) with ILs as absorbents in our previous works 130–133 . Reliable group interaction parameters in the UNIFAC model for condensable gas‐IL systems can be acquired and verified by regressing and comparing the experimental VLE data.…”

“…Furthermore, the EQ model was broadened from noncondensable gas separation to capture processes for condensable gases (e.g., aromatics, esters, and sulfur-containing organics, as well as methanol and dimethoxymethane) with ILs as absorbents in our previous works. [130][131][132][133] Reliable group interaction parameters in the UNIFAC model for condensable gas-IL systems can be acquired and verified by regressing and comparing the experimental VLE data.…”

The Absorption Performance of Ionic Liquids–PEG200 Complex Absorbent for VOCs

“…The infinite dilution activity coefficients of DCM or benzene in IL were calculated by the COSMO-SAC model. Moreover, the solubility of DCM or benzene in ILs is a result of the phase equilibrium [44][45][46][47]. Therefore, the Henry's constant, Hi(T), is defined as:…”

Liquid–Liquid Equilibrium for the Esterification System of Acrylic Acid with n-Butanol Catalyzed by Ionic Liquid [BMIm][HSO4] at Atmospheric Pressure

“…In this aspect, it is highly desirable to select an eligible solvent, which has immiscibility and affinity with the main product ester and the byproduct water, respectively. Recently, as a newly developed green solvent, , ionic liquids have gained widespread attention in various fields including reactive extraction due to their excellent physical and chemical properties, such as low vapor pressure, chemical stability, heat insensitivity, and noncombustibility. − For n -BA synthesis through an intensified reactive extraction process, it is necessary to comprehensively understand the thermodynamic behavior of the IL-involved esterification system.…”