The present invention relates to a bio-assisted method for treatment of spent caustic by treating with haloalkaliphilic consortium of bacteria capable of reducing or transforming sulphides, thiols, mercaptants and other sulphur containing compounds, phenols, hydrocarbons, naphthenic acids and their derivatives in spent caustic.

An integrated refinery process for removing mercaptans from a hydrocarbon stream containing mercaptans and converting by-product disulfide oil to useful products. The process includes introducing the hydrocarbon stream containing mercaptans into an extraction vessel containing an alkaline solution and passing the hydrocarbon stream through an extraction section of the extraction vessel which includes one or more liquid-liquid contacting decks for reaction to convert the mercaptans to alkali metal alkanethiolates. Further, the process includes withdrawing a hydrocarbon product stream free of mercaptans from the extraction vessel and recovering spent caustic containing alkali metal alkanethiolates from the extraction vessel. Additionally, the process includes subjecting the spent caustic containing alkali metal alkanethiolates to air oxidation to produce a by-product stream containing disulfide oils (DSO) and sulfides and processing the by-product stream in a steam cracking unit to produce a DSO free product stream.

A method for removing alkali metal from a hydrocarbon feedstock comprising alkali metal, non-alkali metal and sulfur. The method includes separating out at least a portion of any alkali metal sulfide and a portion of any non-alkali metal from the hydrocarbon feedstock. Hydrogen sulfide can be added to the remaining hydrocarbon feedstock to form alkali hydrosulfide from any alkali metal remaining in the hydrocarbon feedstock. The alkali hydrosulfide is then separated from the hydrocarbon feedstock. Alkali metal may be removed from the alkali metal sulfide separated out from the hydrocarbon feedstock. Alkali hydrosulfide may be treated to form alkali metal sulfide, and alkali metal may also be removed from the formed alkali metal sulfide.

An integrated refinery process for removing mercaptans from a hydrocarbon stream containing mercaptans and converting by-product disulfide oil to useful products. The process includes introducing the hydrocarbon stream containing mercaptans into an extraction vessel containing an alkaline solution and passing the hydrocarbon stream through an extraction section of the extraction vessel which includes one or more liquid-liquid contacting decks for reaction to convert the mercaptans to alkali metal alkanethiolates. Further, the process includes withdrawing a hydrocarbon product stream free of mercaptans from the extraction vessel and recovering spent caustic containing alkali metal alkanethiolates from the extraction vessel. Additionally, the process includes subjecting the spent caustic containing alkali metal alkanethiolates to air oxidation to produce a by-product stream containing disulfide oils (DSO) and sulfides and processing the by-product stream in a steam cracking unit to produce a DSO free product stream.

The present disclosure relates to a process for reducing the amount of carbon disulphide (CS.sub.2) in a hydrocarbon feed containing C.sub.5-C.sub.8 fractions. The hydrocarbon feed is treated with an amine functionalized anion exchange resin (basic anion exchange resin) to obtain a mixture comprising a liquid fraction containing treated hydrocarbon and a solid mass containing an adduct of CS.sub.2 and the amine functionalized anion exchange resin. The so obtained liquid fraction containing the treated hydrocarbon is separated from the solid mass to obtain the hydrocarbon having CS.sub.2 content less than 2 ppm. The amine functionalized anion exchange resin can be regenerated from the solid mass.

A regeneration method for a liquefied gas thiol-removing alkaline solution comprising the following steps: performing an oxygenation reaction with respect to a liquefied gas thiol-removing alkaline solution and, at the same time, utilizing a high air-liquid condition to extract a disulfide and a polysulfide into a gas phase, thus completing the separation of the disulfide and the polysulfide from the alkaline solution, and implementing the regeneration of the liquefied gas thiol-removing alkaline solution.

A regeneration method for a liquefied gas thiol-removing alkaline solution comprising the following steps: performing an oxygenation reaction with respect to a liquefied gas thiol-removing alkaline solution and, at the same time, utilizing a high air-liquid condition to extract a disulfide and a polysulfide into a gas phase, thus completing the separation of the disulfide and the polysulfide from the alkaline solution, and implementing the regeneration of the liquefied gas thiol-removing alkaline solution.

The present disclosure relates to a process for reducing the amount of carbon disulphide (CS.sub.2) in a hydrocarbon feed containing C.sub.5-C.sub.8 fractions. The hydrocarbon feed is treated with an amine functionalized anion exchange resin (basic anion exchange resin) to obtain a mixture comprising a liquid fraction containing treated hydrocarbon and a solid mass containing an adduct of CS.sub.2 and the amine functionalized anion exchange resin. The so obtained liquid fraction containing the treated hydrocarbon is separated from the solid mass to obtain the hydrocarbon having CS.sub.2 content less than 2 ppm. The amine functionalized anion exchange resin can be regenerated from the solid mass.

A light naphtha feedstock containing olefins is introduced with hydrogen sulfide into a mercaptanization zone for conversion of the olefins into a mercaptan stream that is substantially free of olefins, after which the mercaptans are sent with an alkali caustic solution into a mercaptan oxidation treatment unit (MEROX) to produce a spent caustic stream and sweet light naphtha product stream that is substantially free of olefins and of mercaptans. Disulfide oils are produced from the wet air oxidation of the spent caustic, and the disulfide oils can be further processed to provide high purity olefin building blocks.

Provided are a layer-separation method of a spent caustic solution, and a recycling method of an additive, and more particularly, a layer-separation method of a spent caustic solution including: injecting an additive and an acidic compound to the spent caustic solution occurring from a refinery process to break down a red oil emulsion and to perform layer-separation into an upper layer fraction and a lower layer fraction, wherein the additive is an aliphatic hydrocarbon compound having a water solubility of 0.1 to 10 g/L at 20 C.