Challenges and opportunities in improving the production of bio-ethanol

In this work the suitability of selected commercially available hyperbranched polymers and ionic liquids as entrainers for the extractive distillation and as extraction solvents for the liquid–liquid extraction is investigated. Based on thermodynamic studies on the influence of hyperbranched polymers and ionic liquids on the vapor–liquid and liquid–liquid equilibrium of the azeotropic ethanol–water and THF–water systems, process simulations are carried out, which allow evaluating the potential of hyperbranched polymers and ionic liquids as selective components for the mentioned applications in terms of feasibility and energetic efficiency. Both hyperbranched polymers and ionic liquids break a variety of azeotropic systems. Since their selectivity, capacity, viscosity, and thermal stability can be customized, they appear superior to many conventional entrainers and extraction solvents. For the ethanol–water separation, the nonvolatile substances hyperbranched polyglycerol and [EMIM][BF4] show a remarkable entrainer performance and therefore enable extractive distillation processes, which require less energy than the conventional process using 1,2-ethanediol as an entrainer. Evaluation of a new THF–water separation process indicates the competitiveness of the suggested process and a considerable potential of using hyperbranched polymers as extraction solvents. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2439 –2454, 2004

Separation of Azeotropic Mixtures Using Hyperbranched Polymers or Ionic Liquids

In this second article of the review on the applications of the CPA (Cubic-Plus-Association) equation of state, the focus is placed on cross-associating systems. Various such mixtures are investigated, including (i) systems with two self-associating compounds (e.g., water−alcohol systems or glycols, mixtures with organic acids, or two alcohols) but also binaries with only one self-associating substance, where solvation is expected (e.g., CO2 or styrene with water). The method of accounting for cross-association (combining rules) and the association scheme of alcohols are investigated. Finally, the manuscript concludes with a summary of current capabilities and limitations of CPA and a list of future challenges.

Ten Years with the CPA (Cubic-Plus-Association) Equation of State. Part 2. Cross-Associating and Multicomponent Systems

The use of ionic liquids (ILs) in chemistry and electrochemistry has been studied for some decades. Only recently, researchers have focused on the suitability of ILs as selective solvents in the field of separation technology. ILs represent suitable entrainers and extraction solvents for the separation of azeotropic mixtures by means of extractive distillation and solvent extraction. In this work, ternary vapor−liquid and liquid−liquid equilibria of the azeotropic mixtures ethanol + water and THF + water containing different kinds of commercially available ILs are presented. The four ionic liquids used are derived from butyl-methylimidazolium tetrafluoroborate [BMIM]+ [BF4]- by systematic variation of the cation or the anion. The influence of the IL structure on the relative volatility of the low boiling component in extractive distillation and on the selectivity in solvent extraction processes is discussed in this work.

Influence of Ionic Liquids on the Phase Behavior of Aqueous Azeotropic Systems

PRSV2: A cubic equation of state for accurate vapor—liquid equilibria calculations

Thermodynamic properties of aqueous non-electrolyte mixtures II. Vapour pressures and excess Gibbs energies for water + ethanol at 303.15 to 363.15 K determined by an accurate static method

R.C Pemberton

Papers

Thermodynamic properties of aqueous non-electrolyte mixtures II. Vapour pressures and excess Gibbs energies for water + ethanol at 303.15 to 363.15 K determined by an accurate static method