Production of lubricating oil basestocks

摘要

Methods are provided for producing multiple lubricating oil basestocks from a feedstock. Prior to dewaxing, various fractions of the feedstock are exposed to hydrocracking conditions of different severity to produce a higher overall yield of basestocks. The hydrocracking conditions of different severity can represent exposing fractions of a feedstock to different processing conditions, exposing fractions of a feedstock to different amounts of hydrocracking catalyst, or a combination thereof.

主权项

1. A method for producing a plurality of basestocks, comprising:
contacting a feedstock containing at least about 90 wt % of hydrocarbons boiling above 370° C., the feedstock having at least one of a T95 boiling point of 621° C. or less or a final boiling point of 649° C. or less, with a first hydrocracking catalyst under first effective hydrocracking conditions to produce a first hydrocracked effluent, the first hydrocracked effluent having a sulfur content of less than about 250 wppm, the first effective hydrocracking conditions being effective for conversion of about 5 wt % to about 30 wt % of the feedstock to hydrocarbons boiling below 370° C.; fractionating the first hydrocracked effluent to form a first hydrocracked fraction and a second hydrocracked fraction contacting the first hydrocracked fraction with a second hydrocracking catalyst under second effective hydrocracking conditions to produce a third hydrocracked fraction, the third hydrocracked fraction having a viscosity index of at least about 100, the second effective hydrocracking conditions being effective for conversion of about 15 wt % to about 40 wt % of the first hydrocracked fraction to hydrocarbons boiling below 370° C.; contacting the second hydrocracked fraction with a third hydrocracking catalyst under third effective hydrocracking conditions to produce a fourth hydrocracked fraction, the fourth hydrocracked fraction having a viscosity index less than the viscosity index of the third hydrocracked fraction, the third effective hydrocracking conditions being effective for conversion of about 5 wt % to about 15 wt % of the second hydrocracked fraction to hydrocarbons boiling below 370° C.; dewaxing the third hydrocracked fraction and the fourth hydrocracked fraction under effective catalytic dewaxing conditions in the presence of a dewaxing catalyst; and fractionating the third dewaxed hydrocracked fraction and the fourth dewaxed hydrocracked fraction to form a first basestock and a second basestock, the first basestock having a viscosity of about 3.0 cSt to about 7.0 cSt at 100° C. and a Noack volatility of about 20 or less, the second basestock having a viscosity of about 8.0 cSt to about 12.0 cSt at 100° C.