Removal of sulfur-containing compounds from liquid hydrocarbon streams

A method for regenerating sulfone oil comprising:

• combining and mixing a sulfone-rich oil with aqueous caustic thereby oxidizing sulfones in the sulfone-rich oil to one or more hydrocarbons and forming sulfite to provide a substantially sulfur-free diesel phase and an aqueous sulfite phase;
• separating the aqueous sulfite phase from the diesel phase;
• and
• recycling the diesel phase.

A method for desulfurizing a diesel stream, comprising:

• combining a thiophene-rich diesel stream with an oxidant stream to oxidize thiophenes to sulfones to provide a sulfone-rich diesel stream;
• extracting a sulfone oil stream from sulfone-rich diesel stream to provide the sulfone oil and a first low-sulfur diesel steam;
• combining the sulfone-rich oil stream with an aqueous hydroxide stream thereby oxidizing sulfones in the sulfone-rich oil stream to biphenyls and forming sulfite to provide a second low-sulfur diesel stream and an aqueous sulfite stream;
• separating the aqueous sulfite stream from the second low-sulfur diesel stream;
• and
• recycling the first and second low-sulfur diesel streams.