Experimental and modelling approach to the catalytic coproduction of glycerol carbonate and ethylene glycol as a means to valorise glycerol

• Glycerol carbonate and ethylene glycol were simultaneously produced to valorise glycerol.
• The reacting system evolves from dispersion into a single phase liquid.
• Kinetic model accounts for phase transition and for deactivation of the catalyst.

Due to the current scenario of biodiesel industry facing a challenge in the management of its by-product glycerol, its conversion into value-added products is of the greatest significance. This work presents an experimental and modelling approach to the simultaneous production of glycerol carbonate and ethylene glycol, two highly valuable chemicals, under mild operating conditions reaching yields to the products as high as 96% using the inexpensive catalyst K2CO3. Physical (focused beam reflectance measurement) and chemical (HPLC) analyses were employed to monitor the evolution of the chemical reaction between glycerol and ethylene carbonate, finding that the reacting system evolves from liquid–liquid dispersion to single-liquid system at a conversion of glycerol of 0.34. After minimising mass transfer limitations (800 rpm), a study of the reaction kinetics was performed varying temperature, molar ratio of reactant species and catalyst concentration. The model offering the best fit reflected with high accuracy the physical transition of the system, the reversibility of the reaction and the deactivation of the catalyst, with the following parameters: 91.7 ± 2.7 kJ/mol and 93.9 ± 15.9 kJ/mol for the direct and reverse reactions, respectively, with the deactivation constant having a value of 0.36 ± 0.06 s−1.

Figure optionsDownload as PowerPoint slide