Kinetic modeling and simulation study for a sequential electrochemical extractive crude diesel desulfurization

Abstract

• A second order rate equation has been proposed for electrochemical desulfurization process. • A sequential electrochemical extractive of crude diesel desulfurization is modeled. • Dimethyl sulfoxide is selected as potent solvent for extraction process. • An optimization is performed to maximize extraction efficiency, oil and solvent recoveries. To reduce the sulfur content of crude diesel, several sets of experiments have been conducted using electrochemical oxidative desulfurization technique using electrolyte of NaOH at different applied voltages. Due to impacts of operating parameters on desulfurization, kinetic study is pursued and it is found that the kinetic follows a second order reaction rate with a high accuracy. The reaction of desulfurization was modeled using COMSOL and followed by coupled electrochemical oxidation-extraction, while the extraction process was particularly performed using process simulator. The effects of different solvents on extraction performance were studied and dimethyl sulfoxide was selected for further investigation. Sensitivity of operating and design parameters of solvent flow rate, operating pressure and the number of extraction stage were analyzed by adding new terms into consideration. The new terms of extraction efficiency, oil and solvent recoveries were calculated for each case. The sensitivity analysis showed that low solvent flow leads to high extraction efficiency, while low solvent recovery is obtained. Increasing the number of extraction stages resulted in a higher extraction efficiency and solvent recovery. To find the optimal condition, a multi-objective optimization for extraction process is applied by maximizing extraction efficiency, oil and solvent recoveries at different operating and design conditions. The optimal values were operating pressure of 4 bar, solvent flow rate of 80 kmol/h and ten extraction stages.