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Ionic liquids (ILs) as separating agents have been extensively studied in chemical separation processes. For IL-containing systems, the UNIFAC model for ILs (i.e., UNIFAC-Lei model) has become a po...

The SAFT-γ Mie model is a recent version of statistical associating fluid theory (SAFT), which uses a group contribution approach to obtain a high-quality equation of state. In this work, this model is, for the first time, extended to ionic liquids (ILs). The SAFT-γ Mie calculated values agree well with the experimental data for one-component, binary and ternary systems that contain ILs, thus indicating the versatility and accuracy of this extension.

In this work, the solubility data and liquid-phase mass transfer coefficients of hydrogen (H2), methane (CH4) and their mixtures in vacuum gas oil (VGO) at temperatures (353.15–453.15 K) and pressures (1–7 MPa) were measured, which are necessary for catalytic cracking process simulation and design. The solubility of H2 and CH4 in VGO increases with the increase of pressure, but decreases with the increase of temperature. Henry's constants of H2 and CH4 follow the relation of ln H = − 413.05/T + 5.27 and ln H = − 990.67/T + 5.87, respectively. The molar fractions of H2 and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients. The results showed that with the increase of pressure, the liquid-phase mass transfer coefficients increase. Furthermore, the solubility of H2 and CH4 in VGO was predicted by the predictive COSMO-RS model, and the predicted values agree well with experimental data. In addition, the gas–liquid equilibrium (GLE) for H2 + CH4 + VGO system at different feeding gas ratios in volume fraction (i.e., H2 85% + CH4 15% and H2 90% + CH4 10%) was measured. The selectivity of H2 to CH4 predicted by the COSMO-RS model agrees well with experimental data. This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.

A united chemical thermodynamic model, that is, the COSMO-UNIFAC model, was first proposed to predict the phase equilibrium of multicomponent systems in which the UNIFAC model parameters are missing. This model combines the advantages of the UNIFAC model (accurate prediction) and the COSMO-based models (a priori prediction). The predicted vapor–liquid equilibrium results by the COSMO-UNIFAC model were compared with experimental data from the literature and this work, confirming that it can provide a moderate quantitative prediction even if the UNIFAC model parameters are missing.

Vapor pressure data for the binary systems (water/methanol/ethanol + 1-ethyl-3-methylimidazolium acetate ([EMIM]+[Ac]−)) and the ternary systems (methanol + water + [EMIM]+[Ac]−, ethanol + water + [EMIM]+[Ac]−, and methanol + ethanol + [EMIM]+[Ac]−) were measured by a modified equilibrium still. For the above systems, the maximum average relative deviation between experimental data and the UNIFAC-Lei model predicted values was 7%, confirming the prediction accuracy of the UNIFAC-Lei model. Thus, this model was further used to predict the isobaric vapor–liquid equilibrium (VLE) data at 101.3 kPa for the methanol + water + [EMIM]+[Ac]−, ethanol + water + [EMIM]+[Ac]−, and methanol + ethanol + [EMIM]+[Ac]− systems at a fixed mole fraction of ionic liquid (IL) (xIL = 0.2). It was demonstrated that the ionic liquid [EMIM]+[Ac]− was an appropriate entrainer to separate the methanol–ethanol–water mixture. On this basis, the extractive distillation process was simulated using the rigorous equilibrium (EQ) stage m...

Methylal is used as an important synthetic fuel blended with diesel oil to reduce the particulate emissions of toxic gas pollutants without affecting the energy density. The mixed entrainers (dimethylformamide (DMF) + ionic liquid (IL)) are proposed to replace conventional DMF for the separation of methylal and methanol by extractive distillation. [EMIM]+[Ac]− might be the most promising entrainer screened by COSMO-RS model considering relative volatility and solvent capacity together. Vapor–liquid equilibrium (VLE) experiments demonstrated that the relative volatility of methylal to methanol is obviously improved after the addition of [EMIM]+[Ac]− into DMF. Moreover, the UNIFAC-Lei model was extended to the methylal-methanol-DMF-IL system, and the corresponding interaction parameters were obtained and input into the equilibrium (EQ) stage model established in this work. Based on the thermodynamic study, process simulation was developed. It was found that the overall heat duty of reboilers decreased 9.25% using the proposed mixed entrainers when compared to pure DMF. In addition, the COSMO-RS model and DFT calculation provide some theoretical insights into the separation mechanism.

A combinatorial screening approach combining quantum chemical (QC) calculation and molecular dynamics (MD) simulation was presented for the selection of ionic liquid (IL) extractant to remove methanol from methylal. The thermodynamic properties of the distributional coefficient and selectivity were calculated by COSMO-RS based on QC calculation to qualitatively narrow down the IL candidates. The separation performance of these IL candidates was further evaluated through MD to determine the best IL extractant. Then, the methanol removal performance of the best IL was further evaluated by the liquid – liquid equilibrium experiments and the process simulation. Finally, the separation mechanism of the IL was investigated through QC calculations, wavefunction and MD analysis. The consistency between simulations and experiments indicates that this approach is a very useful tool to screen ILs for specific separation tasks.

This is the first work to investigate the hydrodynamics and gas-liquid mass transfer of carbon dioxide (CO2) absorbed into the amino-functionalized ionic liquid (IL) [NH2e-mim][BF4] and monoethanol-amine (MEA) mixture through a vertical circular monolith channel by means of computational fluid dynamics (CFD). It is shown that there are five flow patterns (i.e., bubbly flow, Taylor flow, slug-bubbly flow, slug-annular flow, and annular flow), and Taylor flow is the main flow pattern. The intrinsic kinetics of CO2 absorbed into the [NH2e-mim][BF4]-MEA mixture was obtained, the reaction orders relative to CO2, [NH2e-mim][BF4], and MEA being 1, and the activation energy Ea (19,313 and 28,991 J•mol−1) and pre-exponential factor k0 (3.34×105 and 7.04×106 mol-1•L•min−1) for CO2 absorbed in [NH2e-mim][BF4] and MEA were derived. After the kinetic parameters were imported into the mass transfer model, it was found that the liquid phase volumetric mass transfer coefficient (kLa) in the presence of a chemical reaction can be improved by three to eight times, indicating that mass transfer can be enhanced remarkably by chemical reaction. Moreover, a correlation formula is developed to predict kLa, which agrees well with the simulation results. This work provides a new way to capture CO2 with the combination of IL and MEA in a monolith reactor.