Systems and methods are provided for production of base stocks with a viscosity index of at least 120 and/or a sulfur content of 300 wppm or less and/or a kinematic viscosity at 100° C. of 3.0 cSt to 8.0 cSt by hydroconversion of a raffinate from aromatic extraction of a feed. The base stocks can further have a reduced content of 3+ ring naphthenes, such as 4.0 wt % or less, or 1.0 wt % or less. The base stocks can be produced by performing an elevated amount of feed conversion relative to 370° C. during hydroconversion of the raffinate, and optionally additional conversion during catalytic dewaxing of the hydroconverted raffinate. The base stocks can optionally be blended with additional base stocks and/or lubricant additives for production of lubricant compositions.

Hydrocracked bottoms fractions are treated to separate HPNA compounds and/or HPNA precursor compounds and produce a reduced-HPNA hydrocracked bottoms fraction effective for recycle, in a configuration of a single-stage hydrocracking reactor, series-flow once through hydrocracking operation, or two-stage hydrocracking operation. A process for separation of HPNA and/or HPNA precursor compounds from a hydrocracked bottoms fraction of a hydroprocessing reaction effluent comprises contacting the hydrocracked bottoms fraction with an effective quantity of a sulfonation agent to produce corresponding sulfonated HPNA compounds and/or sulfonated HPNA precursor compounds, and to form a sulfonated hydrocracked bottoms fraction. The sulfonated hydrocracked bottoms fraction is separated into an HPNA-reduced hydrocracked bottoms portion and a sulfonated HPNA portion. All or a portion of the HPNA-reduced hydrocracked bottoms portion is recycled within the hydrocracking operation.

Hydrocracked bottoms fractions are treated to separate HPNA compounds and/or HPNA precursor compounds and produce a reduced-HPNA hydrocracked bottoms fraction effective for recycle, in a configuration of a single-stage hydrocracking reactor, series-flow once through hydrocracking operation, or two-stage hydrocracking operation. A process for separation of HPNA and/or HPNA precursor compounds from a hydrocracked bottoms fraction of a hydroprocessing reaction effluent comprises contacting the hydrocracked bottoms fraction with an effective quantity of a oxidizing agent to produce corresponding oxidized HPNA compounds and/or oxidized HPNA precursor compounds, and to form an oxidized hydrocracked bottoms fraction. The oxidized hydrocracked bottoms fraction is separated into an HPNA-reduced hydrocracked bottoms portion and an oxidized HPNA portion. All or a portion of the HPNA-reduced hydrocracked bottoms portion is recycled within the hydrocracking operation.

The invention relates to a process for the recovery of aliphatic hydrocarbons from a liquid stream comprising aliphatic hydrocarbons, heteroatom containing organic compounds and optionally aromatic hydrocarbons, involving a) contacting said liquid stream with a washing solvent thereby removing heteroatom containing organic compounds; b) liquid-liquid extraction of the washed stream with an extraction solvent; wherein heteroatom containing organic compounds, optional aromatic hydrocarbons and optional other contaminants are removed from said liquid stream and/or from a washed stream resulting from step a) and/or from a raffinate stream resulting from step b), respectively, by contacting the latter stream(s) with a sorption agent. Further, the invention relates to a process for the recovery of aliphatic hydrocarbons from plastics comprising the above-mentioned process; and to a process for steam cracking a hydrocarbon feed comprising aliphatic hydrocarbons as recovered in one of the above-mentioned processes.

The disclosure describes refinery processes and process units for suppressing the precipitation and deposition of heavy polynuclear aromatic (HPNA) compounds in a process unit of a refinery, by combining the effluent from a hydrocracking unit with an aromatic solvent stream. Certain costly HPNA treatment processes can be eliminated, downtime can be reduced, and overall distillate yield can be increased by suppressing HPNA precipitation. The aromatic bottoms—which are suitable solvents for this purpose—of an aromatic recovery complex can be used in certain embodiments to dissolve HPNAs and suppress HPNA precipitation.

A method of forming C.sub.6-C.sub.8 aromatics may include selectively dealkylating a Fluid Catalytic Cracking (FCC) heavy cut naphtha that has at least C.sub.9+ aromatics to selectively crack C.sub.2+ alkyl chains from the C.sub.9+ aromatics, thereby forming the C.sub.6-C.sub.8 aromatics. The selectively de-alkylated heavy cut naphtha is then combined with a FCC middle cut naphtha, and aromatics including the C.sub.6-C.sub.8 aromatics are separated from the combined stream. A system for forming C.sub.6-C.sub.8 aromatics may include a fluid catalytic cracking unit for producing a FCC heavy cut naphtha comprising at least C.sub.9+ aromatics; a de-alkylation reactor for selectively cracking C.sub.2+ alkyl chains from the C.sub.9+ aromatics, thereby forming the C.sub.6-C.sub.8 aromatics; and an aromatic extraction unit for extracting at least a portion of the C.sub.6-C.sub.8 aromatics.

A processing facility is provided that includes a feedstock separation system configured to separate a feed stream into a lights stream and a heavies stream, a hydrogen production system configured to produce hydrogen and carbon dioxide from the lights stream, and a carbon dioxide conversion system configured to produce synthetic hydrocarbons from the carbon dioxide. The processing facility includes a hydroprocessing system configured to process the heavies stream.

Hydrocracked bottoms fractions are treated to separate HPNA compounds and/or HPNA precursor compounds and produce a reduced-HPNA hydrocracked bottoms fraction effective for recycle, in a configuration of a single-stage hydrocracking reactor, series-flow once through hydrocracking operation, or two-stage hydrocracking operation. A process for separation of HPNA and/or HPNA precursor compounds from a hydrocracked bottoms fraction of a hydroprocessing reaction effluent comprises contacting the hydrocracked bottoms fraction with an effective quantity of a sulfonation agent to produce corresponding sulfonated HPNA compounds and/or sulfonated HPNA precursor compounds, and to form a sulfonated hydrocracked bottoms fraction. The sulfonated hydrocracked bottoms fraction is separated into an HPNA-reduced hydrocracked bottoms portion and a sulfonated HPNA portion. All or a portion of the HPNA-reduced hydrocracked bottoms portion is recycled within the hydrocracking operation.

Hydrocracked bottoms fractions are treated to separate HPNA compounds and/or HPNA precursor compounds and produce a reduced-HPNA hydrocracked bottoms fraction effective for recycle, in a configuration of a single-stage hydrocracking reactor, series-flow once through hydrocracking operation, or two-stage hydrocracking operation. A process for separation of HPNA and/or HPNA precursor compounds from a hydrocracked bottoms fraction of a hydroprocessing reaction effluent comprises contacting the hydrocracked bottoms fraction with an effective quantity of a oxidizing agent to produce corresponding oxidized HPNA compounds and/or oxidized HPNA precursor compounds, and to form an oxidized hydrocracked bottoms fraction. The oxidized hydrocracked bottoms fraction is separated into an HPNA-reduced hydrocracked bottoms portion and an oxidized HPNA portion. All or a portion of the HPNA-reduced hydrocracked bottoms portion is recycled within the hydrocracking operation.

A system includes a hydroprocessing zone configured to remove impurities from crude oil; a first separation unit configured to separate a liquid output from the hydroprocessing zone into a light fraction and a light fraction; an aromatic extraction subsystem configured to extract aromatic petrochemicals from the light fraction; and a fluid catalytic cracking unit configured to crack the heavy fraction into multiple products.