Process for removing refractory nitrogen compounds from vacuum gas oil

A process for removing a refractory nitrogen compound from a vacuum gas oil comprising:

• (a) hydroprocessing the vacuum gas oil;
• (b) contacting the vacuum gas oil comprising the refractory nitrogen compound with a VGO-immiscible phosphonium ionic liquid to produce a mixture comprising the vacuum gas oil, and the VGO-immiscible phosphonium ionic liquid;
• (c) separating the mixture to produce a vacuum gas oil effluent with a refractory nitrogen compound level reduced in comparison to the hydroprocessed vacuum gas oil and a VGO-immiscible phosphonium ionic liquid effluent, the VGO-immiscible phosphonium ionic liquid effluent comprising the nitrogen compound;
• (d) washing at least a portion of the vacuum gas oil effluent with water to produce a washed vacuum gas oil stream and a spent water stream;
• (e) contacting the VGO-immiscible phosphonium ionic liquid effluent with a regeneration solvent and separating the VGO-immiscible phosphonium ionic liquid effluent from the regeneration solvent to produce an extract stream comprising the nitrogen compound and a regenerated VGO-immiscible phosphonium ionic liquid stream;
• and
• (f) drying at least a portion of at least one of the VGO-immiscible phosphonium ionic liquid effluent, the spent water stream, and the regenerated VGO-immiscible phosphonium ionic liquid stream to produce a dried VGO-immiscible phosphonium ionic liquid stream.

A process for removing a refractory nitrogen compound from a vacuum gas oil comprising:

• (a) contacting the vacuum gas oil comprising the refractory nitrogen compound with a VGO-immiscible phosphonium ionic liquid to produce a mixture comprising the vacuum gas oil, and the VGO-immiscible phosphonium ionic liquid;
• (b) separating the mixture to produce a vacuum gas oil effluent with a refractory nitrogen compound level reduced by greater than 25% by weight in comparison to the vacuum gas oil and a VGO-immiscible phosphonium ionic liquid effluent, the VGO-immiscible phosphonium ionic liquid effluent comprising the nitrogen compound;
• (c) contacting the VGO-immiscible phosphonium ionic liquid effluent with a regeneration solvent and separating the VGO-immiscible phosphonium ionic liquid effluent from the regeneration solvent to produce an extract stream comprising the nitrogen compound and a regenerated VGO-immiscible phosphonium ionic liquid stream;
• (d) drying at least a portion of at least one of the VGO-immiscible phosphonium ionic liquid effluent, and the regenerated VGO-immiscible phosphonium ionic liquid stream to produce a dried VGO-immiscible phosphonium ionic liquid stream;
• and
• (e) passing the vacuum gas oil effluent to a hydroprocessing step wherein the desulfurization efficiency of the hydroprocessing step is greater than that obtained by hydroprocessing the untreated vacuum gas oil.