Removal of polynuclear aromatics from severely hydrotreated base stocks

A method for making lubricant base stock, comprising:

• performing solvent deasphalting, under effective solvent deasphalting conditions on a feedstock having a T5 boiling point of 370° C. or more and a T50 of 510° C. or more, the effective solvent deasphalting conditions producing a yield of deasphalted oil of 40 wt % or more of the feedstock;
• hydroprocessing at least a portion of the deasphalted oil under first effective hydroprocessing conditions to form a hydroprocessed effluent, the at least a portion of the deasphalted oil having an aromatics content of 60 wt % or more, the hydroprocessed effluent comprising a sulfur content of 300 wppm or less, a nitrogen content of 100 wppm or less, or a combination thereof;
• separating, from the hydroprocessed effluent, at least a fuels boiling range fraction, a first fraction comprising 6+ ring aromatics and having a T5 distillation point of at least 370° C., and a second fraction having a T5 distillation point of at least 370° C., the second fraction having a higher kinematic viscosity at 100° C. than the first fraction;
• hydroprocessing at least a portion of the second fraction under second effective hydroprocessing conditions, the second effective hydroprocessing conditions comprising catalytic dewaxing conditions, to form a twice-hydroprocessed effluent comprising a 370° C.+ portion having a kinematic viscosity at 100° C. of 16 cSt or greater;
• and
• i) exposing the at least a portion of the second fraction, prior to the hydroprocessing under second effective hydroprocessing conditions, to an adsorbent under aromatic adsorbent conditions to form an adsorbent effluent having a reduced content of polynuclear aromatics relative to the at least a portion of the second fraction prior to the exposing;
• ii) exposing at least a portion of the twice-hydroprocessed effluent, during or after the hydroprocessing under second effective hydroprocessing conditions, to an adsorbent under aromatic adsorbent conditions to form an adsorbent effluent having a reduced content of polynuclear aromatics relative to the at least a portion of the twice-hydroprocessed effluent prior to the exposing;
• or iii) a combination of i) and ii).

A method for making lubricant base stock, comprising:

• performing solvent deasphalting, under effective solvent deasphalting conditions on a feedstock having a T5 boiling point of 370° C. or more and a T50 of 510° C. or more, the effective solvent deasphalting conditions producing a yield of deasphalted oil of 40 wt % or more of the feedstock;
• hydroprocessing at least a portion of the deasphalted oil under first effective hydroprocessing conditions to form a hydroprocessed effluent, the at least a portion of the deasphalted oil having an aromatics content of 60 wt % or more, the hydroprocessed effluent comprising a sulfur content of 300 wppm or less, a nitrogen content of 100 wppm or less, or a combination thereof;
• separating, from the hydroprocessed effluent, at least a fuels boiling range fraction, a first fraction comprising 6+ ring aromatics and having a T5 distillation point of at least 370° C., and a second fraction having a T5 distillation point of at least 370° C., the second fraction having a higher kinematic viscosity at 100° C. than the first fraction;
• hydroprocessing at least a portion of the second fraction under second effective hydroprocessing conditions, the second effective hydroprocessing conditions comprising catalytic dewaxing conditions, to form a twice-hydroprocessed effluent comprising a 370° C.+ portion having a kinematic viscosity at 100° C. of 16 cSt or greater;
• separating from at least a portion of the twice-hydprocessed effluent a third fraction and a fourth fraction, the fourth fraction having a higher kinematic viscosity at 100° C. than the third fraction;
• and
• exposing at least a portion of the third fraction to an adsorbent under aromatic adsorbent conditions to form an effluent having a reduced content of polynuclear aromatics relative to the at least a portion of the third fraction prior to the exposing.

A method for making lubricant base stock, comprising:

• performing solvent deasphalting under effective solvent deasphalting conditions on a feedstock having a T5 boiling point of 370° C. or more and a T50 of 510° C. or more, the effective solvent deasphalting conditions producing a yield of deasphalted oil of 40 wt % or more of the feedstock;
• hydroprocessing at least a portion of the deasphalted oil, under hydroprocessing conditions comprising an average hydroprocessing temperature of 400° C. or more and a LHSV of 1.0 hr−1 or less, to form a hydroprocessed effluent, the at least a portion of the deasphalted oil comprising a sulfur content of 1000 wppm or more and an aromatics content of 60 wt % or more, the hydroprocessed effluent comprising a sulfur content of 300 wppm or less;
• and
• exposing at least a portion of the hydroprocessed effluent to an adsorbent under aromatic adsorbent conditions to form an adsorbent effluent having a reduced content of polynuclear aromatics relative to the at least a portion of the hydroprocessed effluent prior to the exposing.