Reactive distillation for synthesis of glycerol carbonate via glycerolysis of urea

Abstract

This study developed a new process for synthesis of glycerol carbonate via glycerolysis of urea in reactive distillation using Aspen plus program. Missing thermodynamic parameters (e.g. Gibb’s free energy of formation) of glycerol carbonate were estimated by the group contribution methods including Joback’s, Gani’s and Benson’s methods. The results showed that Gani’s method provided the lowest deviation among the three methods. Equilibrium and kinetic model parameters were obtained from batch experiment and applied to the simulation. A RADFRAC module in Aspen Plus program with equilibrium stage was used in the simulation to investigate the effects of design and operating parameters of reactive distillation on conversion of glycerol and yield and purity of glycerol carbonate. The simulation results showed that high conversion of glycerol could be obtained by increasing the number of stripping and reaction stages as well as decreasing the number of rectifying stages due to reducing reactant loss in the distillate. Moreover, glycerol and urea in distillate were recycled to reactive section by increasing reflux ratio. The suitable design and operating parameters can achieve at 3 stripping stages, 3 reaction stages, no rectifying stage, reboiler heat duty of 15 kW and reflux ratio of 2 – this offers 93% conversion of glycerol, 96% yield, and 100% purity of glycerol carbonate in the final product. Compared to a conventional process, reactive distillation provided higher conversion of glycerol and lower energy consumption.