Maaike C. Kroon1, Vincent A. Toussaint2, Ali Shariati3, Louw J. Florusse3, Jaap Van Spronsen1, Geert-Jan Witkamp1, and Cor J. Peters3. (1) Section Process Equipment, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, Delft, 2628 CA, Netherlands, (2) Delft University of Technology, Faculty of Applied Sciences, DelftChemTech (PCMT), Julianalaan 136, Delft, 2628 BL, Netherlands, (3) Delft University of Technology, Faculty of Applied Sciences, DelftChemTech (PCMT), Julianalaan 136, Delft, 2628 BL, Netherlands
A relatively unexplored option that can be used to recover organic compounds from ionic liquids (ILs) is crystallization. So far, most crystallizations from ILs were carried out in combination with a reaction step, where the product precipitates upon reaction, as the reactants have a higher solubility in the IL than the product. Another method to crystallize a product from an IL described previously is the use of an additional co-solvent that increases the solubility of the product in the IL and is evaporated in a second step in order to induce crystallization. Here, we show that it is also possible to recover organic compounds from ILs by anti-solvent crystallization using carbon dioxide (CO2) as anti-solvent. As an example, the crystallization of the organic compound methyl-(Z)--acetamido cinnamate (MAAC) from the IL 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim+][BF4-]) using supercritical CO2 as anti-solvent is studied experimentally. It was found that MAAC can be recovered from [bmim+][BF4-] by either using a shift to higher CO2 concentrations at equal temperature (anti-solvent crystallization) or by using a shift to lower temperatures at equal CO2 concentration (thermal shift).