# Thermodynamic Assessment of the Suitability of the Limiting Selectivity to Screen Ionic Liquid Entrainers for Homogeneous Extractive Distillation Processes

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Theory

#### 2.1. Binary System

#### 2.2. Adding IL as Entrainer

#### 2.3. Using Limiting Selectivity

## 3. Application

#### 3.1. Ethanol(1)/Water(2)

#### 3.2. Tetrahydrofuran(1)/Ethanol(2)

#### 3.3. Methyl Acetate(1)/Methanol(2)

#### 3.4. Ethyl Acetate(1)/Ethanol(2)

## 4. Summary and Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Plot of the limiting relative volatility ($\alpha $ when ${x}_{1}^{0}\to 0$ and ${x}_{1}^{0}\to 1$) as a function of IL mole frac (${x}_{3}$) for the binary system ethanol(1)/water(2) at 351 K. The ILs correspond to the [C${}_{4}$mim]${}^{+}$ cation with the indicated anion, and the horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$), and is drawn as a reference.

**Figure 2.**Plot of the relative volatility ($\alpha $) as a function of the IL free mole frac of ethanol (${x}_{1}^{0}$) for the binary system ethanol(1)/water(2) at 351 K. The lines correspond to different, fixed values of ${x}_{3}$, as indicated in the legend. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$), and is drawn as a reference. The top pane corresponds to use of the IL [C${}_{4}$mim][CH${}_{3}$COO] and the bottom pane corresponds to [C${}_{4}$mim][Cl].

**Figure 3.**Plot of the limiting relative volatility ($\alpha $ when ${x}_{1}^{0}\to 0$ and ${x}_{1}^{0}\to 1$) as a function of IL mole frac (${x}_{3}$) for the binary system tetrahydrofuran(1)/ethanol(2) at 339 K. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$) and is drawn as a reference, and the IL is indicated in the figure panes.

**Figure 4.**Plot of the limiting relative volatility ($\alpha $ when ${x}_{1}^{0}\to 0$ and ${x}_{1}^{0}\to 1$) as a function of IL mole frac (${x}_{3}$) for the binary system methyl acetate(1)/methanol(2) at 327.31 K. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$) and is drawn as a reference, and the IL is indicated in the figure panes.

**Figure 5.**Plot of the limiting relative volatility ($\alpha $ when ${x}_{1}^{0}\to 0$ and ${x}_{1}^{0}\to 1$) as a function of IL mole frac (${x}_{3}$) for the binary system methyl acetate(1)/methanol(2) at 327.31 K. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$) and is drawn as a reference, and the IL is indicated in the figure panes.

**Figure 6.**Plot of the relative volatility ($\alpha $) as a function of the IL free mole frac of methanol (${x}_{1}^{0}$) for the binary system methyl acetate(1)/methanol(2) at 327.31 K. The lines correspond to different, fixed values of ${x}_{3}$, as indicated in the legend. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$), and is drawn as a reference. The top pane corresponds to use of the IL [C${}_{2}$mim][SCN] and the bottom pane corresponds to [C${}_{8}$mim][PF${}_{6}$].

**Figure 7.**Plot of the limiting relative volatility ($\alpha $ when ${x}_{1}^{0}\to 0$ and ${x}_{1}^{0}\to 1$) as a function of IL mole frac (${x}_{3}$) for the binary system ethyl acetate(1)/ethanol(2) at 313.15 K. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$) and is drawn as a reference, and the IL is indicated in the figure panes.

**Figure 8.**Plot of the relative volatility ($\alpha $) as a function of the IL free mole frac of methanol (${x}_{1}^{0}$) for the binary system ethyl acetate(1)/ethanol(2) at 313.15 K. The lines correspond to different, fixed values of ${x}_{3}$, as indicated in the legend. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$), and is drawn as a reference. The top pane corresponds to use of the IL [C${}_{2}$mim][Tf${}_{2}$N] and the bottom pane corresponds to [C${}_{4}$C${}_{1}$pyr][Tf${}_{2}$N].

**Figure 9.**Plot of the limiting relative volatility ($\alpha $ when ${x}_{1}^{0}\to 0$ and ${x}_{1}^{0}\to 1$) as a function of IL mole frac (${x}_{3}$) for the binary system ethyl acetate(1)/ethanol(2) at 313.15 K. The horizontal dashed line corresponds to $ln\alpha =0$ ($\alpha =1$) and is drawn as a reference, and the IL is indicated in the figure panes.

**Table 1.**The minimum mole frac of IL needed to break the azeotrope (${x}_{3}^{\mathrm{min}}$) for the binary system ethanol(1)/water(2) at 351 K. The ILs correspond to the [C${}_{4}$mim]${}^{+}$ cation with the indicated anion. The reference (ref) values were computed as the minimum ${x}_{3}$ necessary so that $\alpha >1$ or $\alpha <1$ for all values of ${x}_{1}^{0}$ over the range 0 to 1. This is compared to calculations using Equation (17) where we solve for the first value of ${x}_{3}$ where $\alpha \left(T,{x}_{1}^{0}\to 1,{x}_{3}\right)=1$.

${\mathit{x}}_{3}^{\mathbf{min}}$ | ||
---|---|---|

IL Anion | Equation (17) | Ref. |

[CH${}_{3}$COO]${}^{-}$ | 0.0144 | 0.0144 |

[BF${}_{4}$]${}^{-}$ | 0.0249 | 0.0249 |

[DCA]${}^{-}$ | 0.0255 | 0.0255 |

[Cl]${}^{-}$ | 0.0288 | 0.0289 |

**Table 2.**The minimum mole frac of IL needed to break the azeotrope (${x}_{3}^{\mathrm{min}}$) for the binary system tetrahydrofuran(1)/ethanol(2) at 339 K using the indicated IL. The reference (ref) values were computed as the minimum ${x}_{3}$ necessary so that $\alpha >1$ or $\alpha <1$ for all values of ${x}_{1}^{0}$ over the range 0 to 1. This is compared to calculations using Equation (17) where we solve for the first value of ${x}_{3}$ where $\alpha \left(T,{x}_{1}^{0}\to 1,{x}_{3}\right)=1$.

${\mathit{x}}_{3}^{\mathbf{min}}$ | ||
---|---|---|

IL Anion | Equation (17) | Ref. |

[C${}_{4}$mim][BF${}_{4}$] | 0.0065 | 0.0061 |

[C${}_{8}$mim][BF${}_{4}$] | 0.0089 | 0.0087 |

[C${}_{4}$mim][DCA] | 0.0007 | 0.0007 |

**Table 3.**The minimum mole frac of IL needed to break the azeotrope (${x}_{3}^{\mathrm{min}}$) for the binary system methyl acetate(1)/methanol(2) at 327.31 K using the indicated IL. The reference (ref) values were computed as the minimum ${x}_{3}$ necessary so that $\alpha >1$ or $\alpha <1$ for all values of ${x}_{1}^{0}$ over the range 0 to 1. This is compared to calculations using Equation (17) where we solve for the first value of ${x}_{3}$ where $\alpha \left(T,{x}_{1}^{0}\to 1,{x}_{3}\right)=1$.

${\mathit{x}}_{3}^{\mathbf{min}}$ | ||
---|---|---|

IL Anion | Equation (17) | Ref. |

[C${}_{4}$mim][Br] | 0.2307 | 0.2308 |

[C${}_{4}$mim][Cl] | 0.1203 | 0.1203 |

[C${}_{2}$mim][CH${}_{3}$COO] | 0.0953 | 0.0953 |

[C${}_{2}$mim][SCN] | 0.0391 | 0.0398 |

[C${}_{4}$C${}_{1}$pyr][DCA] | 0.0381 | 0.0419 |

[ClC${}_{2}$mim][Cl] | 0.1823 | 0.1823 |

[C${}_{8}$mim][PF${}_{6}$] | 0.3455 | 0.3456 |

**Table 4.**The minimum mole frac of IL needed to break the azeotrope (${x}_{3}^{\mathrm{min}}$) for the binary system ethyl acetate(1)/ethanol(2) at 313.15 K using the indicated IL. The reference (ref) values were computed as the minimum ${x}_{3}$ necessary so that $\alpha >1$ or $\alpha <1$ for all values of ${x}_{1}^{0}$ over the range 0 to 1. This is compared to calculations using Equation (17) where we solve for the first value of ${x}_{3}$ where $\alpha \left(T,{x}_{1}^{0}\to 1,{x}_{3}\right)=1$.

${\mathit{x}}_{3}^{\mathbf{min}}$ | ||
---|---|---|

IL Anion | Equation (17) | Ref. |

[C${}_{4}$mim][CF${}_{3}$SO${}_{2}$] | 0.0288 | 0.0595 |

[C${}_{4}$C${}_{1}$pyr][Tf${}_{2}$N] | 0.6659 | 0.6659 |

[C${}_{2}$mim][MeSO${}_{3}$] | 0.0226 | 0.0468 |

[C${}_{2}$mim][MeSO${}_{4}$] | 0.0208 | 0.0511 |

[C${}_{2}$mim][Tf${}_{2}$N] | 0.0010 | 0.3775 |

[C${}_{6}$mim][Tf${}_{2}$N] | 0.0016 | 0.5324 |

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**MDPI and ACS Style**

Paluch, A.S.; Dhakal, P.
Thermodynamic Assessment of the Suitability of the Limiting Selectivity to Screen Ionic Liquid Entrainers for Homogeneous Extractive Distillation Processes. *ChemEngineering* **2018**, *2*, 54.
https://doi.org/10.3390/chemengineering2040054

**AMA Style**

Paluch AS, Dhakal P.
Thermodynamic Assessment of the Suitability of the Limiting Selectivity to Screen Ionic Liquid Entrainers for Homogeneous Extractive Distillation Processes. *ChemEngineering*. 2018; 2(4):54.
https://doi.org/10.3390/chemengineering2040054

**Chicago/Turabian Style**

Paluch, Andrew S., and Pratik Dhakal.
2018. "Thermodynamic Assessment of the Suitability of the Limiting Selectivity to Screen Ionic Liquid Entrainers for Homogeneous Extractive Distillation Processes" *ChemEngineering* 2, no. 4: 54.
https://doi.org/10.3390/chemengineering2040054