Deep extractive and oxidative desulfurization of dibenzothiophene with C5H9NO·SnCl2 coordinated ionic liquid.

A new C 5 H 9 NO·SnCl 2 coordinated ionic liquid (IL) was prepared by reacting N-methyl-pyrrolidone with anhydrous SnCl 2 . Desulfurization of dibenzothiophene (DBT) via extraction and oxidation with C 5 H 9 NO·SnCl 2 IL as extractant, H 2 O 2 and equal mol of CH 3 COOH as oxidants was investigated. The Nernst partition coefficients k N of C 5 H 9 NO·SnCl 2 IL for the DBT in n -octane was above 5.0, showing its excellent extraction ability. During the oxidative desulfurization process, the optimal molar ratio of H 2 O 2 /DBT was six. Sulfur removal of DBT in n -octane was 94.8% in 30   min at 30   °C under the conditions of H 2 O 2 /DBT molar ratio of six and V (IL):V (oil)   =   1:3. Moreover, the sulfur removal increased with increasing temperature because of the high reaction rate constant, low viscosity, and high solubility of dibenzothiophene-sulfone in the IL. The kinetics of oxidative desulfurization of DBT was also investigated, and the apparent activation energy was found to be 32.5   kJ/mol. The IL could be recycled six times without a significant decrease in activity.