US1874946A - Treatment of hydrocarbon oils - Google Patents

Description

Patented Aug. .30, 1932 UNITED STATES PATENT OFFICE SEYMOUR FERRIS, OF LANSDOWNE, PENNSYLVANIA, ASSIGNOR TO THE ATLANTIC v REFINING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA TREATMENT or HYDROCARBON OILS No Drawing.

The present invention relates to the art of mineral oil refining, and has particular ref erence to the separation of crude petroleum or petroleum products into fractions of different chemical compositions while of approximately the same distillation range.

In accordance with my invention, crude petroleum or petroleum products, 'particularly oils 'of substantial viscosity, are separated into various fractions by means of fractional extraction with an aromatic formate or acetate or mixture of aromatic formates and/or acetates, or mixture of solvents containing substantial quantities of aromatic formates and/or acetates.

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 parafiins of the general formula C H olefines of the general formula C H 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 boil ing points are present in petroleum.

The various types of crude petroleum, which are "(generally classified into three groups, namely, paraflinic base, naphthenic q or asphaltic base, and mixed base, contain the various series of hydrocarbons mentioned heretofore in different proportions. For example, in the parafiin base'crude oils, such as those obtained from the oil fields of Pennsylvania, there is a relatively high proportion of hydrocarbons having a chain structureand a high hydrogen to carbon ratio, whereas in the naphthenic or a'sphaltic base crude oils, there is a relatively large proportion of hydrocarbons having ring structures and a low hydrogen to carbon ratio. Mixed base crude oils, such' as are obtained from the Mid-Continent oil fields, contain hydrocarbons "in proportions intermediate these two extremes.

As the use of practically all of the petroleum oils is almost entirely physical, the above described chemical nature of those compared with another.

Application filed May 15, 1931. Serial No. 537,751.

- oilsis important in reflecting certain physical characteristics.

naphthenic, and mixed base oils is evidenced by the physical properties of the various oils and particularly by the relationship of the specific gravity to the viscosity of one oil as For example, oil derived from a Pennsylvania crude and having a viscosity of 400 seconds Saybolt universal at 100 F., will show a specific gravity at 60 F. of about 0.878, whereas an 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 the paraflinic or naphthenic character of the oil.

If a given crude petroleum be distilled into successive fractions and the specific gravities and viscosities of the several fractions de termined, it will be found that they conform to the general relationship:

0= log (V-38) in which G.is the specific gravity at F., V is Saybolt universal viscosity at 100 F., and a is a "constant known as the viscositygravity constant. Fractions from each of the different types of crude have different vis I cosity-gravity constants. Such constants are lower for fractions of the paraflinic crudes than are the constants for fractions of the naphthenic crudes. An article entitled The viscosity-gravity constant of petroleum lubriin the formula and the viscosity-gravity constant of the fraction calculated, the constant will be substantially the same for each of the several fractions of the crude.

The viscosity gravity constants of the viscous fractions for some of-the typical crudes,

are as follows:

These oils are increasingly paraflinic as the viscosity-gravity constantsdecrease.

My invention is based upon the dlscovery that oils containing both the paraflinio series of hydrocarbons and the various naphthenic series may be fractionally extracted with an aromatic formate or acetate. Phenyl acetate is the selective solvent that I prefer to use, however, other aromatic compounds such as toluyl formate may beemplo-yed, and are considered within the scope of my invention.

The Various series of hydrocarbons possess a differential solubility in such solvents; the naphthenic hydrocarbons are much more soluble therein than the parafiinic hydrocarbons. I By meansof extraction with an aromatic formate or acetate, and more particularly with phenyl'acetate, it is, therefore, possible to effect a partial separation of the naphthenic hydrocarbons from the para fiinic, and to obtain from an oil containing both classes of hydrocarbons, an oil which is much more paraflinic 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 qualityfiiormally obtained from Appalachian .crudes, from crudes of the mixed ase type from the Mid-Continent area, and, conversely, to obtain oils from mixed base crudes such as are normally obtained from the naphthenio oils of the Gulf coast area. 5

v In practicing my invention, I prefer tomix the oil fraction to be treated with a suitable proportion of an aromatic formate or acetate or mixture of them, and more particularly with phenyl acetate, at a temperature sufficiently high so that complete solution is effected and a homogeneous liquid obtained. I then cool the mixture to a temperature suiiL, ciently low to cause a separation of the liquid into a two-layer system, the upper layer being a solution of a relatively small amount of thearomatic formate'or acetate in the more araffinic portion of the oil,.and the lower thenic portion of the oil in the aromatic for:

. mate or acetate. Instead of this heating and cooling to effect extraction, I may simply agitate the mixture of liquids at normal temperatures. Where substantial quantities of ayer comprising a solution of the more naphand may cause it to be solid or semi-solid.

Separation of the two layers is then efiected matic formate oracetate, and repeat the process for an extraction of additional naphthenic bodies from the oil.. The extraction may be repeated any desired number of times, thereby producing oils of progressively increasing paraffinicity as evidenced by a decreasing viscosity-gravity' constant. In waxbearing oils, the final undissolved product I is apmixture of solid and liquid hydrocarbons. While the exact chemical compositions of these compounds are not known, it is probable that the' liquid hydrocarbons are branched chain hydrocarbons of the paraffin series, whereas solid bodies are straight chain paraffin hydrocarbons. This product may be-further separated into solid and liquid hydrocarbons by any of the well-known dewaxing processes, such as the cold settling process.

11 many instances it will be found of ad vantage to dewax the oil prior to' the extraction process, as this expedites the manual operation of the latter.

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

parts of a previously untreated distillate obtained from a Gulf coast crude oil and having a viscosity of 61 2 seconds Saybolt,

universal at 100 VF, a specific gravity of 0.9303, and a consequent viscosity, gravity constant of 0.87 4 was mixed with 100 partsiof phenyl acetate and heated to slightly above he temperature of complete miscibility, which in the particular case was approximately 50 C. The homogeneous liquid which resulted was cooled with agitation to 25 0., and allowed to settle whereupon a two layer system formed, which consisted of an upper undissolved oil layer comprising 85 parts of the mixture and a lower layer of oil dissolved in phenyl acetate comprising approximately parts of the mixture. After separation, the layers were each freed from phenyl acetate by vacuum distillation. The phenyl acetate dissolved fraction yielded 82 parts of phenyl acetate and 33 parts of oil phenyl acetate and, 67 parts of'an oil having having a viscosity of 73 seconds Saybolt uninndissolved fraction, oils may be obtained which are" increasingly paraflinic, as evidenced by progressively decreasing viscositygravity constants.

It is evident that my process is practical 1y independent of the particular nature or source of the crude oil, and that there may be produced thereby oils of desired characteristics from oils which. heretofore have not been used as a source of oils of such desired characteristics.

For example, my process maybe employed to produce from petroleum of a mixed base type such as would, on normal batch distillation, give a residuum with a viscosity of 150 seconds Saybolt universal at 210 F. with a specific gravity of 0.928 or more, a. lubricating stock with a viscosity of at 210 F. 150 seconds Saybolt universal, or more, and \a specific gravity not higher than 0.910. This latter combination of properties is typical of cylinder stocks produced from Pennsylvania crudes.

In extracting oils containing appreciable amounts of wax, such oils may be dewaxed, for example, by cold settling or centrifuging prior to carrying out the extraction. My process is operable, however, in the absence of preliminary dewaxing. Hereinabove, mixtures of solvents have been referred to. It is to be understood that in such mixtures the c onstituent solvents 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 formates and/or acetates.

For brevity,'in the appended claims, the

"term aromatic acetate is employed in a generic sense to include one or a mixture of aromaticformates and/(Y acetates, or amixture of solvents which contains substantial quantities of aromatic formates and/or acetates.

Also where herein and in the appended claims, an 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 Saybolt universal at 100 F., or more.

What I claim is:

1. In the art oftrefining mineral oils, the process which comprises separating an oil containing parafiinic and naphthenic hydro-" carbons into fractions respectively richer in parafiinic and naphthenic compounds by extracting said oil with an aromatic acetate.

2. In the art of-refining mineral oils, the

' lower layer.

process which comprises fractionally extracting an oil containing paraflinic and naphthenic hydrocarbons with an aromatic acetate to produce fractions of the oil respectively richer in paraffinic and naphthenic compounds.

3. In the art of refining mineral oils, the

process which comprises adding an aromatic acetate to an oil containing paraflinic 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 p 4. In the art of refining mineral oils, the process which comprises adding an aromatic acetateto 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, removing the lower layer, and similarly retreating the upper layer with an aromatic acetate.

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

6. The process for separating mineral oils containing paraflinic and naphthenic hydrocarbons into fractions which comprises bringing the oil into contact with an aromatic acetate, thereby to effect solution of a portion of the oil richer in naphthenic hydrocarbons in" the aromatic acetate, separating; the solution so formed from the remainder of the oil, and distilling the aromatic acetate from both of the portions of the oil, thereby to obtain fractions of the oil respectively richer in paraf-.

acetate, thereby partially dissolving the oil, separatinmthe phenyl acetate solution of oil so treate and-removing the phenyl acetate from the treated oil.

9 The process of producing a lubricating stock of specific gravity less than .910 and of Saybolt universal viscosity greater than 150 seconds at 210 F. from a crude petroleum which on-normal distillation yields a residuumbf 150 seconds Saybolt universal viscosity at 210 F. and a specific gravity greater than .928, which comprises producing a residuum from the crude petroleum, and extracting said residuum from said crude petroleum with phenyl acetate.

10. In the art of refining mineral lubric-at: ing oil containing paraffinic and naphthenic hydrocarbons, the step of fractionally extracting the oilwith phenyl acetate, to effect a separation of fractions respectively richer in paraffinc and naphthenic compounds.

11. The process of producing a lubricating stock of specific gravity less than ,910 and of Saybolt universal'viscosity greater than 150 seconds at 210 F. from a crude petroleum which on. normal distillation yields a residuum of 150 seconds Saybolt universal viscosity at 210 F. and a specific gravity of, greater than .928, which comprises separating a residuum from said crude petroleum and bringing such residuum into contact with phenyl acetate, to effect solution of a portion thereof with phenyl acetate, separating the phenyl acetate solution of oil from the portion which does not disslove therein, and removing the phenyl acetate from the oil of said solution. 12. In a process for separating a viscous miner oil containing paraflinicand naphthenic hydrocarbons into fractions which are respectively richer in naphthenic hydrocarbons and paraffinic hydrocarbons other; than wax, the step which comprises extracting the oil with phenyl acetate.

13. In a process for separating viscous mineral oil liquid at ordinary temperature containing .paraffinic and naphthenic hydrocarbons into fractions respectively richer in paraflinic and naphthenic hydrocarbons, the step which comprises extractingthe oil with phenyl acetate.

14. In a process for separating a substantially wax free viscous mineral oilv containing paraffinic and naphthenic hydrocarbons into fractions respectively richer in paraffinic and naphthenic hydrocarbons, the step which tionofa mixed base crude oil to procure a. fraction having the quality of a corresponding fraction of a paraflinicbase crude, which comprises extracting the viscous fraction with phenyl acetate, and separating the oil so treated into portions respectively richer in paraffinic and naphthenic compoundsl v 17. In the art of refining mineral oils, the process which comprises adding phenyl acetate to a viscous oil liquid at ordinary temperatures containing parafiinic and naphthenic hydrocarbons, heating the mixture to a temperature sufficient to effect solution, cooling the solution to a temperature sufficient to form two layers respectively richer in naphthenic hydrocarbons and paraflinic hydrocarbons other than wax, and separating the upper layers richer in paraffinic hydrocarbons from the lower layer richer in naphthenic hydrocarbons.

18. In the art of refining mineral oils, the process which comprises adding phenyl acetate to a viscous oil liquid at ordinary temperatures containing paraflinic and naphthenic hydrocarbons, perature sufficient to effect solution, cooling the solution to a temperature sufficient to form two layers, separating phenyl acetate and paraffin wax from the upper layer, and separating phenyl acetate from the'lower layer to produce one fraction richer in parafiinic and a second fraction richer in naphthenic hydrocarbons than said viscous oil.

In testimony whereof I affix my signature.

SEYMOUR W. FERRIS.

comprises extracting the oil with phenyl acetate.

15. The process oftreating a viscous fraction of a crude oil of one type containing paraffinic and naphthenic hydrocarbons to procure a fraction having the quality of a corresponding fraction of a crude oil of different type having a greater content of paraflinic hydrocarbons, which comprises extracting the viscousfraction with phenyl acetate, and separating theoil so treated into portions respectively richer in paraflinic and naphthenic hydrocarbons.

16. The process of treating a viscous fracheating the mixture to a tern-