Removal of sulfone compounds formed in oxidative desulfurization of middle distillate

Abstract

How to remove the sulfone species formed in oxidative desulfurization (ODS) of middle distillates through an efficient method is crucial in a successful ODS process. In this study, the solubility of dibenzothiophene (DBT) sulfone in different hydrocarbon streams was assessed and investigated in detail, and the adsorptive removal of DBT-sulfone dissolved in a model hydrocarbon stream on activated carbon was also conducted. It was found that the saturation concentration of DBT-sulfone in the hydrocarbon streams is very low; being 0.0239wt.% in a toluene/hexadecane (20/80) mixture and 0.0181wt.% in a deep-hydrotreated middle distillate. The dissolved DBT-sulfone in the hydrocarbon stream can be removed easily by selective adsorption over an activated carbon adsorbent. On the basis of these findings, a two-step process for removing the sulfone species from the oxidation-treated middle distillate was proposed, which includes the first step of the centrifugal separation to remove the majority of the sulfone species (>80%) from the oxidation-treated middle distillate, followed by the second step of the selective adsorption to remove the remaining sulfone species. This two-step process may be more cost-efficient and environment-friendly to remove the sulfone species in the ODS process.