Desulfurization of dibenzothiophene by chemical oxidation and solvent extraction with Me3NCH2C6H5Cl·2ZnCl2ionic liquid

Abstract

Desulfurization of dibenzothiophene (DBT) by a combination of both chemical oxidation and solvent extraction was investigated. Me₃NCH₂C₆H₅Cl·2ZnCl₂ ionic liquid was prepared from cheap starting materials and used as extractant for oxidative desulfurization of DBT in n-octane. DBT in oil phase was extracted into ionic liquid phase and then oxidized to its corresponding sulfone by H₂O₂ and equal volume of acetic acid. The desulfurization yield of DBT in n-octane was 94% at 30 min under the conditions of H₂O₂/DBT molar ratio at 6 and V (ionic liquid) : V (n-octane) = 1 : 5, which was remarkably higher than that by mere extraction with ionic liquid (28.9%). The Me₃NCH₂C₆H₅Cl·2ZnCl₂ ionic liquid could be recycled six times without a significant decrease in activity. Kinetics of oxidative desulfurization of DBT by H₂O₂ and acetic acid was first-order with an apparent rate constant of 0.0842 min⁻¹ and half-time of 8.23 min.