US2092748A - Hydrocarbon oil treatment - Google Patents

Description

Patented Sept. 14, 1937 UNITED STATES PATENT OFFICE 2,092,748 HYD'ROCARBON OIL TREATMENT Edwin E. Birkhimer, Philadelphia, Pa., assignor to The Atlantic Refining phia, Pa., a corporation of Company, Philadel- Pennsylvania No Drawing. Application March as, 1933, Serial No. 663,242

20 Claims, (01. 19613) m-tolyl carbinol and others.

It is recognized in the art that mineral oils, such as petroleum, comprise essentially a mixture of hydrocarbons of various groups or homologous 'series of compounds, such for example, as paraf- 20 fins of the general formula CnH2n+2, olefines of the general formula C11H2n, hydroaromatics and polymethylenes of the same empirical formula, and various other series of compounds of chain and/or ring structures in which the hydrogen to carbon ratio is less than in the foregoing series.

A large number of individual compounds'of each' series and of differing boiling points are present in petroleum.

The various types of crude petroleum, which are generally classified into three groups, namely, paraffinicbase, naphthenic or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the paraffin base crude oils, such asthose obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structure and a high hydrogen to carbon ratio, whereasin the naphthenic or asphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and a lowhydrogen to carbon ratio. Mixed base crude oils, such as are obtained from the Mid-Continentoil fields, contain hydrocarbons in proportions intermediate these two extremes.

The variance in the proportion of the different series of hydrocarbons. in parafiinic, naphthenic, and mixed base oils is evidencedby the physical properties of the various oils; and particularly by the relationship of the specific gravity to the viscosity of one oil as compared with another. For example, oilsderived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt universal at 100 F., will show a specific gravity at F., of about0.8'78, whereasan oil of corresponding viscosity produced from a naphthenic crude, such as one from the Gulf Coast area, will show a specific gravity of about 0.933 at 60 F. The relationship between the viscosity and gravity indicates the degree of parafiinicity or naphthenicity of the oil, and such relationship. may be expressed by the viscosity-gravity constant as hereinafter described.

If a given crude petroleum be distilled into successive fractions and the specific gravities and viscosities of' the several viscous fractions be determined, it will be found that they conform to the general relationship expressed by the formulae.

in which G is the specific gravity at-GO F., V and V' are respectively Saybolt universal viscosities at F. and 210 F., and a is a constant known as the viscosity-gravity constant. Viscous fractions from each of the different types of crude have dilferent viscosity-gravity constants. While, in general, viscous fractions from a single crude have substantially the same viscosity-gravity constant, such constant 'islower for fractions of the paraffinic crudes than is the constant for fractionsof the naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubricating oils by J. B; Hill and H; B. Coats, which will be found in volume 20, page 641 et seq., Industrial and Engineering Chemistry for June, 1928, explains the determination of such constant for several typical oils.

The viscosity-gravity constant is, therefore, an index of the paraliinicity or naphthenicity of viscous oils, since when a given crude'is distilled, the fractions thereof collected, and the specific gravity and the viscosity of each of the viscous fractions determined, such specific gravit'ies and viscosities substituted in the formula, and the viscosity-gravityconstants of the fractions calculated, it will be found that such constants are substantially the same.

The viscosity-gravity constants of the viscous fractions for some of the typical crudes are as follows:

Milltown (Pennsylvania-)rn 0.8067 Burbank (Mid-Continent); 0.8367 Guadalupe (Gulf Coast) 0.8635 Mirand'o (Gulf Coast) -09025 While the above figures indicate the viscositygravity constants of specific oils from several types of crudes, it is to be understood that for any particular type of crude such constant may be within a range between values above and below the constant of the typical crude given. For example, viscous oils resulting from the distillation of Mid-Continent crudes have viscosity-gravity constants ranging from about .835 to about .855, whereas the viscous fractions resulting from the distillation of Pennsylvania type crudes range from about .805 to about .828, and in most instances, are below .820. Oils are increasingly parafiinic as their viscosity-gravity constants decrease.

My invention is based upon the discovery that oils containing both the parafiinic series of hydrocarbons and the various naphthenic series may be fractionally extracted with an aromatic alcohol. The various series of hydrocarbons possess a differential solubility in such solvent, the naphthenic hydrocarbons being much more soluble therein than the paraffinic hydrocarbons. By means of extraction with such solvent, it is therefore possible to effect a partial separation of the naphthenic hydrocarbons from the paraifinic, and to obtain from an oil containing both classes of hydrocarbons, an oil which is much more parafiinic than the original oil and one which is much more naphthenic. By my invention, for example, it is possible to produce an oil of the quality normally obtained from Appalachian crudes, from crudes of the mixed base type from the Mid-Continent area, and, conversely, to ob- .tain oils from mixed base crudes such as are normally obtained from the naphthenic oils of the Gulf Coast area. In general, from oils from any source there may be obtained by my process, oils which are respectively more paraffinic and more naphthenic than the oils normally obtained from such source by distillation.

In accordance with my invention, I first mix the oil to be treated with a suitable proportion of an aromatic alcohol at a temperature such that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture to a temperature at which separation of the liquid into a two-layer system will take place. The upper layer will contain a relatively small amount of the solvent dissoved in the paraffinic portion of the oil While the lower layer will contain the more naphthenic portion of the oil dissolved in the solvent. Or, I may agitate the mixture of solvent and oil at temperatures at which the liquids are only partially miscible, and thereby effect solution of the naphthenic portion of the oil in the solvent. In either of the above procedures I may take advantage of the principles of counter-current extraction.

After the extraction proper, I effect separation of the two layers which form, by any suitable procedure, as for example, by decantation. I then remove from each of the separated layers, the portion of solvent which each contains by suitable procedure, such as by vacuum distillation, thereby to obtain two oils of similar distillation ranges but of different chemical compositions and different physical charactertistics.

Before removing the solvent from the upper and more parafiinic layer, I may add a further quantity of solvent and repeat the extraction, thereby to remove additional naphthenic constituents from said layer. The extraction step may be repeated any desired number of times, each repetition producing an oil of higher paraffinicity as evidenced by its lower viscosity-gravity constant.

Where substantial quantities of waxy hydrocarbons belonging to the true paraffin series (CnHZn-l-Z) are present, such hydrocarbons remain in the upper or more paraffmic layer and may cause such layer to be solid or semi-solid. Such layer may be separated into solid and liquidhydrocarbons by any of the well-known dewaxing processes such as by cold-settling or by centrifuging. In many instances it may be advantageous to dewax the oil prior to extraction. However, it is to be understood that in accordance with my invention, dewaxing may be effected either prior or subsequent to extraction.

My invention will be further understood from the following specific example:

parts of a Mid-Continent distillate having a viscosity of 305 seconds Saybolt universal at 100 F., a specific gravity of 0.909 at 60 F., and a viscosity-gravity constant of 0.853 was mixed with 300 parts of phenylmethanol and heated to slightly above the temperature of complete miscibility, which was approximately 92 C. The homogeneous liquid which resulted was cooled with agitation to 65 C., and allowed to settle, whereupon a two-layer system formed. After separation, the layers were each freed of solvent by vacuum distillation. The undissolved oil fraction comprising 51.0% of the stock had a viscosity of 220 seconds Saybolt universal at 100 F., a specific gravity of 0.879, and a viscositygravity constant of 0.822. The dissolved oil fraction comprising 49.0% of the stock had a viscosity of 424 seconds Saybolt universal at 100 F., a specific gravity of 0.938 and a viscosity-gravity constant of 0.890.

From the above example it will be noted that by extraction of an oil with phenylmethanol, there may be obtained oil fractions which are respectively more paraffinic and more naphthenic than the original oil. By repetition of the extraction process upon the undissolved fraction, oils of even greater paraflinicity will result.

My process is practically independent of the particular nature or source of the crude oil or oil fractions to be extracted. There may be produced by my process oil products of desired charteristics from oils which by distillation will not produce such products.

Hereinabove, mixture of solvents have been referred to. It is to be understood that in such mixture the constituents will not react with one another nor with the oil upon which they are to be used, and that such mixtures will contain substantial amounts of aromatic alcohols.

For brevity, in the appended claims monohydroxy aromatic alcohol is employed in the generic sense to include one or a mixture of monohydroxy aromatic alcohols, or a mixture of solvents containing substantial amounts of monohydroxy aromatic alcohols.

Also, when herein and in the appended claims, oil is specifically referred to as being viscous, it is to be understood that the oil is of substantial viscosity, i. e., of the order of 50 seconds Sayboltuniversal at 100 F., or more.

What I claim is:

1. In the art of refining mineral oils, the process which comprises separating an oil containing parafiinic and naphthenic hydrocarbons into fractions respectively richer in paraffinic and naphthenic compounds by extracting said oil with a monohydroxy aromatic alcohol.

2. In the art of refining mineral oils, the process which comprises adding 'a monohydroxy aromatic alcohol to an oil containing paraffinic and naphthenic hydrocarbons, heating the mixture to such temperature as. to effect solution, cooling the solution to form. a two-layer system, and. separating the upper layer from the lower layer.

3. In the art of refining mineral oils, the process which comprises adding a monohydroxy aromatic alcohol to an oil containing paraffinic and naphthenic hydrocarbons, heating the mixture 7 to such temperature as to effect solution, cooling the solution to form a two layer system, removing the lower layer, and similarly retreating the upper layer with a monohydroxy aromatic alcohol.

4. In the art of refining mineral oils, the process which comprises bringing mineral oil containing parafiinic and naphthenic hydrocarbons into contact with a monohydroxy aromatic alcohol thereby to effect solution of a portion richer in naphthenic hydrocarbons in the aromatic alcohol, separating the solution so formed from the remainder of the oil, and removing the said alcohol from both portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

5. The process for separating mineral oils containing paraflinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with a monohydroxy aromatic alcohol thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in the aromatic alcohol, separating the solution so formed from the remainder of the oil, and distilling the said alcohol from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in paraflinic and naphthenic hydrocarbons.

6. The process of treating a viscous fraction of a crude oil of one type containing parafiinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of difierent type having a greater content of paraffinic hydrocarbons, which comprises extracting the viscous fraction with a monohydroxy aromatic alcohol, and separating the oil so treated into portions respectively richer in paraffinic and naphthenic hydrocarbons.

7. In the art of refining mineral oils, the process which comprises bringing a monohydroxy aromatic alcohol into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing parafiinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby toproduce an oil such as is normally obtained from Pennsylvania type crude by distillation.

8. In the art'of refining mineral oils, the process which comprises bringing a mineral oil containing parafiinic and naphthenic hydrocarbons into contact with a monohydroxy aromatic alcohol thereby to effect solution of a portion richer in naphthenic hydrocarbons in said alcohol, separating the solution so formed from the remainder of the oil, and retreating the oil remaining with additional amounts of a monohydroxy aromatic alcohol.

9. In the art of refining mineral oils, the process which comprises bringing a mineral oil containing paraffinic and naphthenic hydrocarbons into contact with phenyl methanol thereby to eftion having the feet solution of a portion richer in naphthenic hydrocarbons in the phenylmethanol, separating the solution so formed from the remainder of the oil, and removing the phenylmethanol from both portions of the oil, thereby to obtain fractions of the oil respectively richer in parafiinic and naphthenic hydrocarbons.

10. The method of producing parafiinic lubricating oil from mixed base crude which comprises distilling the crude and bringing a portion thereof into contact with phenylmethanol, thereby partially dissolving the oil, separating the phenylmethanol solution of oil so treated, and removing the phenylmethanol from the treated oil.

11. In the art of refining mineral lubricating oil containing parafiinic and naphthenic hydrocarbons, the step of fractionally extracting the oil with phenylmethanol, to efiect a separation of fractions respectively richer in parafiinic and naphthenic compounds.

12. The process of treating a viscous fraction of a crude oil of one type containing parafiinic and naphthenic hydrocarbons to procure a fracquality of a corresponding fraction of a crude oil of difierent type having a greater content of paraffinic hydrocarbons, which comprises extracting the viscous fraction with phenylmethanol, and separating the oil so treated into portions respectively richer in paraffinic and naphthenic hydrocarbons.

13. The process of treating a viscous fraction of a mixed base crude oil to produce a fraction having the quality of a corresponding fraction of a paraffinic base crude, which comprises extrac 'ng the viscous fraction with phenylmethanol, and separating the oil so treated into portions respectively richer in paraflinic and naphthenic compounds.

14. In the art of refining mineral oils, the process which comprises adding phenylmethanol to a viscous oil liquid at ordinary temperatures containing parafiinic and naphthenic hydrocarbons, heating the mixture to a temperature suificient to effect solution, cooling the solution to a temperature suificient to form two layers respectively richer in naphthenic hydrocarbons and parafiinic hydrocarbons other than wax, and separating the upper layer richer in paraffinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

15. In the art of refining mineral oils, the process which comprises bringing phenylmethanol into intimate contact with a viscous hydrocarbon oil of a quality other than that of a Pennsylvania type viscous oil, and containing parafiinic and naphthenic components, thereby to dissolve from the oil substantial amounts of its naphthenic components, thereafter removing the solvent and oil dissolved therein from that portion of the oil which remains undissolved, thereby to produce an oil such as is normally obtained from Pennsylvania type crude by distillation. 4

16. The process of decreasing the viscositygravity constant of a viscous mineral oil which comprises extracting the oil with a monohydroxy aromatic alcohol.

17. The process of decreasing the viscositygravity constant of a viscous mineral oil at least 0.015 which comprises extracting the oil with phenyl methanol.

18. The process of treating a viscous mineral oil of viscosity-gravity constant between substantially 0.850 and 0.875 to reduce the viscositygravity constant by at least 0.015, which comprises fractionally extracting said viscous oil with phenylmethanol.

19. The process of treating a viscous mineral oil of viscosity-gravit3 constant higher than 0.850 to produce an oil having a viscosity-gravity constant less than 0.830 which comprises fractionaliy extracting said viscous oil with phenylmethanol.

20 The process of treating a viscous mineral oil of viscosity-gravity constant higher than 0.835 to produce an oil having a viscosity-gravity constant of less than 0.828 which comprises fractionally extracting said viscous oil with 5 phenyl methanol.

EDWIN R. BIRKHIMER.