Primena eutektičkih rastvarača sa holin hloridom u heterogeno katalizovanoj etanolizi suncokretovog ulja

Abstract

In this doctoral dissertation the synthesis of fatty acid ethyl esters (FAEEs) from triacylglycerols’ derived from the expired sunflower oil was analyzed via chemically-catalyzed ethanolysis reaction. The ethanolysis was performed as a heterogeneous alkaline catalyzed reaction in which the catalyst was CaO (calcined and non-calcined) in the presence of different choline chloride (ChCl)-based deep eutectic solvents, namely ChCl:urea (ChCl:U), ChCl:1,3-dimethylurea (ChCl:DMU), ChCl:thiourea (ChCl:TU), ChCl:propylene glycol (ChCl:PG), ChCl:ethylene glycol (ChCl:EG) and ChCl:glycerol (ChCl:G) in ChCl:hydrogen bond donor molar ratio 1:2. The physical (density, dynamic viscosity, electrical conductivity and refractive index) and the thermodynamic (thermal expansion coefficient, molecular volume, lattice energy and heat capacity) properties of the prepared deep eutectic solvents were determined at atmospheric pressure over the temperature range of 293.15–363.15 K. These prepared deep eutectic solvents and their constituents were individually tested as cosolvents in the ethanolysis of expired sunflower oil catalyzed by either calcined or non-calcined CaO at temperature of 70 °C and ethanol-to-oil molar ratio of 12:1. All tested deep eutectic solvents promoted the ethanolysis by a successful activation of non-calcined CaO, which was attributed to the CaCO3 and Ca(OH)2 dissolution from the surface of the solid catalyst particles. Either with calcined or non-calcined CaO, the polyol-based deep eutectic solvents gave higher FAEEs’ content than the amide-based deep eutectic solvents. ChCl:EG and ChCl:PG were more efficient than ChCl:G even with non-calcined CaO. However, ChCl:G is more suitable since glycerol, as a by-product of the ethanolysis, can be used for preparation of this deep eutectic solvent, so the overall FAEE production costs could be reduced. The phase separation of the reaction mixture was faster in the presence of the deep eutectic solvents. After five reuses, non-calcined CaO activated by ChCl:U, ChCl:EG, ChCl:PG or ChCl:G yielded the FAEE content of 85.5±1.5%, 86.2±0.9%, 85.2±0.7% and 83.4±1.1%, respectively after 2 h.