Claims
- 1. A method for extracting aromatic molecules from hydrocarbon oil using a combination extraction solvent containing (a) N-methyl pyrrolidone, (b) from about 1 to up to but not including 10 LV % of the combination of an additive selected from aliphatic-aromatics, polar naphthenes, morpholine and mixtures thereof, and (c) from 0 to 10 LV % water; wherein the amount of component (a) is suitably adjusted to reflect the presence of any water used, said extraction being conducted at a temperature above the haze point of the oil, but at least 30.degree. C. below the critical solution temperature of the mixture of hydrocarbon oil and combination extraction solvent.
- 2. The method of claim 1 wherein component (b) is present at about 2.5 to 5 LV % of the combination.
- 3. The method of claim 1 wherein the temperature of extraction is 40.degree. C. or more below the critical solution temperature of the hydrocarbon oil and the combination extraction solvent.
- 4. The method of claim 1 wherein component (b) is ethylbenzene, butylbenzene or morpholine.
- 5. The method of claim 2 wherein the temperature of extraction is 40.degree. C. or more below the critical solution temperature of the hydrocarbon oil and the combination extraction solvent.
- 6. The method of claim 2 wherein component (b) is ethylbenzene, butylbenzene or morpholine.
- 7. The method of claim 1 wherein the component (b) is a polar naphthene.
- 8. The method of claim 3 wherein component (b) is ethylbenzene, butylbenzene or morpholine.
- 9. The method of claim 5 wherein component (b) is ethylbenzene, butylbenzene or morpholine.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part application of U.S. Ser. No. 815,204, filed Dec. 31, 1985, abandoned.
This invention relates to a process for extracting hydrocarbon oils using polar extraction solvents, such an n-methyl-2-pyrrolidone (NMP), phenol or furfural, in combination with an additional component, selected from aliphatic aromatics, polar naphthenes or morpholine and mixtures thereof as the extraction solvent mixture. Use of this combination extraction solvent produces about the same yield of oil at the same level of quality, but at a significantly lower solvent treat ratio as compared to just polar extraction solvents, such as NMP, phenol or furfural. Extraction using the combination extraction solvent is conducted at a temperature above the haze point of the oil being extracted and above that required to maintain feed viscosity below about 200 cSt, but at least 30.degree. C., preferably 40.degree. C. or more, below the critical solution temperature of the feed and solvent mixture. Operation in this range avoids or minimizes detrimental effects on yields.
Solvent extraction of hydrocarbon oils using polar solvents to remove aromatic constituents has long been a standard processing procedure in the oil industry. The use of NMP to selectively extract aromatic components from an oil stream is the subject of many patents, see, for instance, U.S. Pat No. 3,843,525, U.S. Pat. No. 3,476,681, U.S. Pat. No. 4,125,458.
In U.S. Pat. No. 4,333,824 a solvent refining process is described which employs N-methyl-2-pyrrolidone plus recycled extract. In U.S. Pat. No. 4,325,818 an NMP extraction process is improved by contacting the extract in the extraction with a paraffinic backwash oil (BP 190.degree.-210.degree. C.) in order to further displace the non-aromatics into the raffinate.
U.S. Pat. No. 3,415,743 describes an extraction procedure for aromatic hydrocarbons. Heavy aromatics and heavy aliphatics are extracted from cracking cycle oil by extracting the cycle oil with DMF/water solvent solution plus a displacer oil. The displacer oil is preferably a heavy naphtha containing 10-50% lower alkyl benzenes, especially xylene.
U.S. Pat. No. 3,317,422 practices aromatics extraction using furfural, furfural alcohol and water. The process also employs light catalytic cycle oil and displacer oil as feed for respective extraction zones. The displacer oil is a mixture of non-aromatic compounds, such as heavy naphtha, and 10 to 50% xylenes.
US Referenced Citations (18)
Foreign Referenced Citations (4)
| Number |
Date |
Country |
| 859344 |
Aug 1981 |
SUX |
| 1150308 |
Oct 1966 |
GBX |
| 1283147 |
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GBX |
| 1341296 |
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Continuation in Parts (1)
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Number |
Date |
Country |
| Parent |
815204 |
Dec 1985 |
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Patent Grant
4909927
