Integrated methods for separation and extraction of polynuclear aromatic hydrocarbons, heterocyclic compounds, and organometallic compounds from hydrocarbon feedstocks

Patent metadata

Field	Value
Publication number	US-9688923-B2
Application number	US-201414300709-A
Country	US
Kind code	B2
Filing date	Jun 10, 2014
Priority date	Jun 10, 2014
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

Methods are provided for extracting heterocyclic compounds, organometallic compounds, and polynuclear aromatic hydrocarbons from a hydrocarbon feedstock such as crude oil or a crude fraction. The heterocyclic compounds and organometallic compounds are removed from the hydrocarbon feedstock through one or more successive extractions to form a first raffinate. The extractions use a first solvent system containing an ionic liquid formed from carbon dioxide and water. The polynuclear aromatic hydrocarbons are removed from the first raffinate using a second solvent system containing an aprotic solvent such as NMP, DMSO, aromatics, or combinations thereof. The extracted compounds remain chemically intact and may be fractionated for further applications. Further methods are provided for producing a hydrocarbon raffinate having reduced levels of heterocyclic compounds, organometallic compounds, and 2-4 cycle polynuclear aromatic hydrocarbons.

First claim

What is claimed is:

1. A method of producing a hydrocarbon raffinate having reduced levels of heteroatom compounds and 2-4 cycle polynuclear aromatic hydrocarbons, the method comprising:
providing a hydrocarbon feedstock containing crude oil fractions with a boiling point range of from about 165° C. to about 430° C., the crude oil fractions comprising heteroatom compounds and 2-4 cycle polynuclear aromatic hydrocarbons;
extracting at least a portion of the heteroatom compounds from the hydrocarbon feedstock with a tunable solvent in at least one extraction vessel of a heteroatom extraction system to form at least one heteroatom-compound rich stream containing heteroatom compounds and a heteroatom-compound lean stream containing the 2-4 cycle polynuclear aromatic hydrocarbons, the tunable solvent comprising an ionic liquid formed from pressurized carbon dioxide and water, wherein extracting at least a portion of the heteroatom compounds from the hydrocarbon feedstock comprises:
extracting from the hydrocarbon feedstock a first portion of the heteroatom compounds having a first polarity to form a first heteroatom compound rich stream and a first heteroatom compound lean stream, the first portion of the heteroatom compounds being extracted in a first extraction vessel of the heteroatom extraction system operating at a first pressure, the first heteroatom compound rich stream containing the tunable solvent;
extracting from the first heteroatom compound lean stream a second portion of the heteroatom compounds having a second polarity lower than the first polarity to form a second heteroatom compound rich stream and a second heteroatom compound lean stream, the second portion of the heteroatom compounds being extracted in a second extraction vessel of the heteroatom extraction system operating at a second pressure higher than the first pressure after extracting the first portion of the heteroatom compounds, the second heteroatom compound rich stream containing the tunable solvent; and
extracting from the second heteroatom compound lean stream a third portion of the heteroatom compounds having a third polarity lower than the second polarity to form the heteroatom-compound lean stream and a third heteroatom compound rich stream, the third portion of the heteroatom compounds being extracted in a third extraction vessel of the heteroatom extraction system operating at a third pressure greater than the second pressure after extracting the second portion of the heteroatom compounds, the third heteroatom compound rich stream containing the tunable solvent; and

extracting the 2-4 cycle polynuclear aromatic hydrocarbons from the heteroatom-compound lean stream with a solvent system to form the hydrocarbon raffinate, the solvent system comprising an aprotic solvent.

2. The method of claim 1 , wherein at least 99% of the heteroatom compounds by weight from the hydrocarbon feedstock are extracted into the heteroatom-compound rich streams.

3. The method of claim 1 , wherein the aprotic solvent is chosen from N-methylpyrrolidone, dimethylsulfoxide, and aromatic compounds.

4. The method of claim 1 , wherein the aprotic solvent is chosen from N-methylpyrrolidone, dimethylsulfoxide, and aromatic compounds and the solvent system further comprises a protic co-solvent.

5. A method for extracting heteroatom compounds and 2-4 cycle polynuclear aromatic hydrocarbons from a hydrocarbon feedstock containing the heteroatom compounds and the 2-4 cycle polynuclear aromatic hydrocarbons, the method comprising:
extracting at least one targeted portion of the heteroatom compounds from the hydrocarbon feedstock with an aqueous solvent comprising an ionic liquid formed from pressurized carbon dioxide and water, wherein the temperature of the aqueous solvent is from greater than the critical temperature of carbon dioxide to about 150° C., wherein the extraction of each targeted portion of the heteroatom compounds from the hydrocarbon feedstock comprises:
feeding into an extraction vessel separately or as a mixture:
the hydrocarbon feedstock or a feed stream derived from the hydrocarbon feedstock; and
the aqueous solvent,

whereby the combination of the hydrocarbon feedstock or the feed stream with the aqueous solvent in the extraction vessel forms an extraction mixture;
tuning the aqueous solvent to selectively form solvent complexes with the targeted portion of the heteroatom compounds in the extraction mixture, whereby the extraction mixture separates into at least a heteroatom-compound rich phase and a heteroatom-compound lean phase, the heteroatom-compound rich phase containing the aqueous solvent;
removing the heteroatom-compound lean phase from the extraction vessel as a heteroatom-compound lean stream;
removing the heteroatom-compound rich phase from the extraction vessel as a heteroatom-compound rich stream; and
optionally transferring the heteroatom-compound lean stream from the extraction vessel as a feed stream derived from the hydrocarbon feedstock to an additional extraction vessel for extraction of an additional targeted portion of heteroatom compounds from the feed stream;

transferring to a PAH extractor the heteroatom-compound lean stream containing the 2-4 cycle polynuclear aromatic hydrocarbons after all targeted portions of the heteroatom compounds have been extracted from the hydrocarbon feedstock; and
extracting the 2-4 cycle polynuclear aromatic hydrocarbons from the the heteroatom-compound lean stream in the PAH extractor with a solvent system comprising an aprotic solvent.

6. The method of claim 5 , wherein extracting at least one targeted portion of the heteroatom compounds from the hydrocarbon feedstock comprises:
extracting a first targeted portion of the heteroatom compounds having a first polarity in a first extraction vessel operating at a first pressure;
extracting a second targeted portion of the heteroatom compounds in a second extraction vessel after extracting the first portion, the second extraction vessel operating at a second pressure greater than the first pressure, the second portion of the heteroatom compounds having a second polarity that is lower than the first polarity; and
extracting a third targeted portion of the heteroatom compounds in a third extraction vessel after extracting the second portion of the heteroatom compounds, the third extraction vessel operating at a third pressure greater than the second pressure, the third portion of the heteroatom compounds having a third polarity lower that is lower than the second polarity.

7. The method of claim 5 , wherein tuning the aqueous solvent system comprises:
establishing an extraction pressure and an extraction temperature of the extraction mixture in the extraction vessel that together tune the aqueous solvent to selectively form a solvent complex with the targeted portion of the heteroatom compounds, wherein the extraction pressure is from 2 bar to 300 bar and the extraction temperature of the extraction mixture is from greater than the critical temperature of carbon dioxide to about 150° C.

8. The method of claim 5 , wherein at least two targeted portions of the heteroatom compounds are removed from the hydrocarbon feedstock, and extracting each targeted portion of the heteroatom compounds from the hydrocarbon feedstock further comprises:
transferring the heteroatom-compound rich stream to a respective ejector vessel;
depressurizing the respective ejector vessel to decrease the solubility of the heteroatom compounds in the aqueous solvent and eject a mixture of heteroatom compounds from the aqueous solvent; and
separating the mixture of heteroatom compounds from the aqueous solvent to form a heteroatom-compound recovery stream.

9. The method of claim 8 , fu

Assignees

• Saudi Arabian Oil Co

Inventors

• Yusuf Zaki
• Ballesteros Alberto Lozano

Classifications

• C10G21/20

  Nitrogen-containing compounds · CPC title

• C10G53/06 Primary

  including only extraction steps, e.g. deasphalting by solvent treatment followed by extraction of aromatics · CPC title

• C10G21/16 Primary

  Oxygen-containing compounds · CPC title

• C10G21/00

  Refining of hydrocarbon oils, in the absence of hydrogen, by extraction with selective solvents (C10G17/00, C10G19/00 take precedence) · CPC title

• C10G21/08

  Inorganic compounds only · CPC title