A method for producing ILSAC GF5 or higher compatible oils from used oil, comprising separating material having a boiling point less than about 350 F. from recovered oil to produce de-volatized oil fraction and light oil fraction. Separating material with a boiling point greater than about 350 F. and less than about 650 F. from the de-volatized oil fraction to produce fuel oil fraction and heavy oil fraction. Separating material with a boiling point greater than about 1200 F. from the heavy oil fraction to produce partially purified oil fraction and residual fraction. Treating the partially purified oil fraction to separate it into purified oil fraction and contaminant fraction. Hydrogenating the contaminant fraction to remove predetermined compounds, further saturating the fraction and thereby creating a saturated oil fraction. Fractionating the saturated oil stream to produce one or more of naphtha fraction, diesel oil fraction and base oil fraction.

A method for producing ILSAC GF5 or higher compatible oils from used oil, comprising separating material having a boiling point less than about 350 F. from recovered oil to produce de-volatized oil fraction and light oil fraction. Separating material with a boiling point greater than about 350 F. and less than about 650 F. from the de-volatized oil fraction to produce fuel oil fraction and heavy oil fraction. Separating material with a boiling point greater than about 1200 F. from the heavy oil fraction to produce partially purified oil fraction and residual fraction. Treating the partially purified oil fraction to separate it into purified oil fraction and contaminant fraction. Hydrogenating the contaminant fraction to remove predetermined compounds, further saturating the fraction and thereby creating a saturated oil fraction. Fractionating the saturated oil stream to produce one or more of naphtha fraction, diesel oil fraction and base oil fraction.

A method for recovering synthetic oils from a feed stream, the method comprising separating at least a portion of the non-synthetic oil constituents from a commingled stream to produce a partially purified synthetic oil stream and one or more contaminant streams. Extracting at least a portion of the synthetic oil from the partially purified synthetic oil stream to produce a synthetic oil stream and a second contaminant stream.

A method for recovering synthetic oils from a feed stream, the method comprising separating at least a portion of the non-synthetic oil constituents from a commingled stream to produce a partially purified synthetic oil stream and one or more contaminant streams. Extracting at least a portion of the synthetic oil from the partially purified synthetic oil stream to produce a synthetic oil stream and a second contaminant stream.

Processes for removing sulfur and nitrogen contaminants from hydrocarbon streams are described. The processes include contacting the hydrocarbon stream comprising the contaminant with lean halometallate ionic liquid an organohalide resulting in a mixture comprising the hydrocarbon and rich halometallate ionic liquid comprising the contaminant. The mixture is separated to produce a hydrocarbon effluent and a rich halometallate ionic liquid effluent comprising the rich halometallate ionic liquid comprising the contaminant.

The invention provides a method of desulfurizing an oil composition, the method comprising: flowing an oil composition comprising sulfur through a conduit comprising a constricted region, wherein oil-phase bubbles form in the constricted region and collapse in a turbulent zone downstream of the constricted region; contacting the oil composition with an immiscible deep eutectic solvent in the turbulent zone, thereby extracting at least a portion of the sulfur from the oil composition into association with the deep eutectic solvent; and separating the deep eutectic solvent and the extracted sulfur from the desulfurized oil composition.

The invention provides a method of desulfurizing an oil composition, the method comprising: flowing an oil composition comprising sulfur through a conduit comprising a constricted region, wherein oil-phase bubbles form in the constricted region and collapse in a turbulent zone downstream of the constricted region; contacting the oil composition with an immiscible deep eutectic solvent in the turbulent zone, thereby extracting at least a portion of the sulfur from the oil composition into association with the deep eutectic solvent; and separating the deep eutectic solvent and the extracted sulfur from the desulfurized oil composition.

A method for stepwise extraction of phenol and pyridine compounds in naphthalene oil by deep eutectic solvents includes: mixing the naphthalene oil with alkane and the deep eutectic solvents, and performing phase separation to obtain a eutectic extracting phase and a raffinate phase; mixing the extracting phase with a first stripping agent, and performing phase separation to obtain a first stripping phase and recyclable deep eutectic solvents; distilling the first stripping phase to obtain a heteroatom mixture; and mixing the heteroatom mixture with a hydrogen bond acceptor extractant and alkane, and performing phase separation to obtain a phenol-containing extracting phase and a pyridine-containing raffinate phase; and mixing the phenol-containing extracting phase with a second stripping agent, performing phase separation to obtain a phenol-dissolved stripping solution and the hydrogen bond acceptor, and distilling the second stripping solution or the pyridine-containing raffinate phase to obtain a phenol or a pyridine product.

A method for stepwise extraction of phenol and pyridine compounds in naphthalene oil by deep eutectic solvents includes: mixing the naphthalene oil with alkane and the deep eutectic solvents, and performing phase separation to obtain a eutectic extracting phase and a raffinate phase; mixing the extracting phase with a first stripping agent, and performing phase separation to obtain a first stripping phase and recyclable deep eutectic solvents; distilling the first stripping phase to obtain a heteroatom mixture; and mixing the heteroatom mixture with a hydrogen bond acceptor extractant and alkane, and performing phase separation to obtain a phenol-containing extracting phase and a pyridine-containing raffinate phase; and mixing the phenol-containing extracting phase with a second stripping agent, performing phase separation to obtain a phenol-dissolved stripping solution and the hydrogen bond acceptor, and distilling the second stripping solution or the pyridine-containing raffinate phase to obtain a phenol or a pyridine product.