Ionic liquids in separations: applications for pyrolysis oil and emulsion systems

Xiaohua Li

Research output: ThesisPhD Thesis - Research UT, graduation UT

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Solvent extraction is one of the main separation techniques and has been developed for a wide range of industrial applications. Ionic liquids (ILs) are often considered as environmentally friendly solvents and have been studied widely in various laboratory applications. Aiming to design effective extraction processes, in this work ILs have been employed for fractionation of pyrolysis oil, for demulsifying oil-in-water emulsions to recover surfactant, and for the design of a novel smart separation process type: fixed liquid extraction. Pyrolysis oil, the liquid product of fast pyrolysis of lignocellulosic biomass, is a complex mixture containing hundreds of components. For the valorization of pyrolysis oil, value-added chemicals are required to be separated. A study on aromatics removal from pyrolytic sugar streams was described in chapter 2 and 3, and a study on fractionation of oxygenates (acetic acid, glycolaldehyde and acetol) from pyrolysis oil cuts in chapter 4. In chemical enhanced oil recovery (CEOR), surfactant together with alkali and polymer are injected in the reservoir to enhance oil recovery yield. The surfactant is usually blended with water and oil in stable emulsions. Therefore, the first step for surfactant recovery is to destabilize these oil emulsions which is called demulsification. In chapter 5, in total 13 ILs were evaluated as demulsifiers for a model oil-in-water emulsion, and the efficiency and mechanism of demulsification were discussed. Application of ILs at industrial scale is restricted by their major drawbacks, such as high viscosity and corrosivity. IL-based emulsion systems that make use of stabilizers can potentially overcome these drawbacks. In chapter 6 the formation of several IL-based emulsions stabilized by microgel particles was studied, including the parametric influences on the drop size distributions. The influence of microgel particles on the extraction capacity and kinetics were investigated as well. In chapter 7, a novel separation process concept was explored for the processes, referred to as fixed liquid extraction, aiming for the design of separation process for extremely small S/F. ILs can effectively remove aromatics from pyrolytic sugar streams. Value-added oxygenates can be fractionated by a two-step extraction process. The studied halogenide ILs and P666,14[N(CN)2] can demulsify heptane-in-water emulsions and the mechanism of demulsification is anion exchange. Several IL-based emulsions stabilized by microgel particles has been prepared, and the concept of fixed liquid extraction has been demonstrated for the first time.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Twente
  • University of Twente
  • Kersten, Sascha R.A., Supervisor
  • Schuur, Boelo, Co-Supervisor
Award date10 Feb 2017
Place of PublicationEnschede
Print ISBNs978-90-365-4293-7
Publication statusPublished - 10 Feb 2017


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