US1788569A - Fractional extraction of mineral oils - Google Patents

Description

Patented Jan. 13, 1931 UNITED STATES PATENT ol-"rics' LAN'I'IG DEFINING COMPANY, OF PHILA OF PENNSYLVANIA p smmoun w. rams, on rnrnnnnnrnm, rmmsvnvmm, ASSIGNOB T0 man u- DELPHIA, rmmsxmmmn, a common-r10! \I'BACTIONAL nx'r'nacrron or MINERAL one No Draw1ng.. Application filed July 16,

My invention relates to the art of'mineral oilrefining, with particular reference 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 pein these and some of which have a chain.

structure and some a ring structure. A large number of individual hydrocarbons of each series are present and have different boiling points.

In the various typesof crude petroleumcommonly known as paraffin base, naphthenic or asphalt base, and mixed base these various series of hydrocarbons are present in different proportions. For example, in the parafiin base crudes such as those from the Appalachian field there is a relatively high proportion of the hydrocarbons having a chain structure and a high hydrogen to carbon ra' tio, whereas in the so-called naphthenic crudes there is a relatively high proportion of hydrocarbons of the ring structures and lower hydrogen to carbon ratio. The mixed base crudes such as those fromthe Mid Continent area are intermediate between these two extreme cases.

, .In the normal refining processes for crude petroleum, the fractions of varying dlstllla- 'tion ranges which are successively obtained. tained upon the starting material before ex-- 1 in distillation of the oils partake of the general character of the crude; for example, Inbricating oils from A'ppalachian crudes will show paraflinic characteristics whereas the oils from the naphthenic crudes show naphthenic characteristics. The physical properties of the resultant oils are dependent in thls 1927. Serial no, 206,388.

way upon the chemical composition of the crude oils from which they are derived. For the same distillation range, a paraflinic oil will show a lower viscosity, a lower specific gravity, and a lower refractive index than a na hthenic oil.

imilarly a paraflinic oil of 9; given viscos ity will show a lower specific gravity and re-.

ity. The position of this curve is typical of I i the crude and of the oils which maybe pro duced from it by processes heretofore wellknown. For example, an oil of 80 seconds Saybolt universal viscosity at 210 F. from a certain Pennsylvania crude has a specific gravity of 0.885 whereas an oil of the same VISCOSltY from a typical .Gulf Coast crude has a specific gravity of 0.943. These relationships are fully discussed in Hill and Ferris, Industrial and Engineering Chemistry, vol. 17 page 1250 (1925).

Ience, if a fraction obtained .by distillation, for example froma Mid-Continent crude, be subjected to-an extraction and separation in accordance with my invention hereinafter set forth more in detail, the extract resulting, upon separation into a number of fractions by distillation, and upon determination of'the specific gravities and viscosities of said fractions and plotting said speeific gravities as ordinates and said viscosities asabscissae and drawing a curve through the points so plotted, the extract will be characterized by said curve. Furthermore, such curve will be found to lie definitely above a curve similarly plotted 'for similar data obtraction, that is to say, a fraction of the extract having agiven viscosity will have a greater s ecific gravity than the specific gravity 0 a fraction of thestarting material of the same viscosity; and in accordance with the terminology used herein and in .the ap pended claims, such extract is referred to as one richer in naphthenic hydrocarbons or compounds. The undissolved fraction, or that fraction remaining after extraction and separation as aforesaid, may also be represented by a curve plotted from similarly obtained data, which curve will fall definitely below the curve characteristic of the starting material before extraction; and in accordance with the terminology of this a plication and of the appended claims such raction is referred to as one richer in paraflinic hydrocarbons or compounds.

When the properties characteristic of naphthenic oils were desired, heretofore it has been necessary to obtain such oils from a naphthenic crude, whereas on the other hand where paraffinic properties were desired,-it has been necessary to start with a paraifinic crude. .On account of certain qualities of the oils produced, the paraflinic crudes have long been at a premium since even with a mixed base crude of relatively high parafiinic characteristics the oils produced have been somewhat more na hthenic than those from the strai ht para n base crudes and have, therefore, een less desirable for certain purposes.

'I have found that oils containing both the paraflinic series of hydrocarbons and the various naphthenic series maybe fractionally extracted with a suitable solvent such as a rious series of hydrocarbons possess a differential solubility in this solvent, the na hthenic compounds being much more solu le,

than the paraflinic hydrocarbons. By means of extraction with nitrobenzene, it is, therefore, possible to elfect a partial separation of the naphthenic compounds from the paraflinic and to obtain from an oil containing both classes an oil which is much more paraf- 1 finic than the'original and one which is much fnore 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 obtain oils from mixed base crudes such are normally obtained from the naphthenic oils from the Gulf Coast area.

In practicing my invention, I prefer to mix the oil fraction to be treated with a suitable proportion of nitrobenzene at elevated temperatures so that complete solution is offected and a'homogeneous liquid obtained.

Ithen cool the mixture and produce a separation into two layers, the upper one of which is a solution of nitrobenzene in the more paraflinic portion of the oil and the lower layer of which-is a solution of the more naphthenic portion of the oil in nitrobenzene. Instead of this heating and cooling I may also simply agitate the cold mixture. Where large quantities, of solid hydrocarbons are present which may belong to the true paraiiin series CHI-1 m, these solids or waxes remain in the upper layer and may cause it to be solid or seml-solid. I then effect separationof. the two layers by decantation or other means and remove the nitrobenzene from each of the separated oil layers by distillation or other means, obtaining thereby two oils of similar distlllation ranges but of widely different physlcal characteristics and correspondingly dlflerent chemical compositions.

Before removing the nitrobenzene from the upper layer obtained in the above described process, I may add a further quantity of nitrobenzene and repeat the process for an extractlon of further naphthenic bodies from the 011. The extraction may be so repeated two or three times, was often as desired. In wax-bearing oils, the finally extracted product so obtained is a mixture of solid and liquid hydrocarbons. While the exact chemical compositions of these compounds are not known, it is probably the fact that the llqllld hydrocarbons are branched chain hydrocarbons of the paraffin series Whereas the solid bodies are straight chain parafiln 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 in which the 011 is diluted with naphtha, chilled, the solid hydrocarbons allowed to settle, the clear supernatant liquid decanted oil", and the naphtha removed from both portions by distillation.

As an example of my process, there is descr bed below the treatment of a'high viscosrty wax-bearing distillate obtained from a typical Texas mixed base crude with the product-ion of oil fractions of a naphthenic character, an oil fractionof a parafiinic character, and a solid wax. To an oil of the aforesaid source havlng a viscosity of 90 seconds Saybolt universal at 210 F. and a specific gravity of .9156-at 15 C., I may add a quantity of nitrobenzene in the proportion of about two gallons per gallon of oil. The mixture is heated to about 60 C. and agitated until solution is effected. The oil is then cooled with gentle agitation to about 10 C.

obtained are shown in the table below I Specific Vis. Bays}? gravity bolt univ. 3 2 @g r. (actual) a 0 al 011 89.8 0.9168 Dls ii l ved oil lrom extraction #1.-." 148. 2 0. 9603 0.920 Dissolved oil from extraction #2.-." 96. 4 0. 9252 0. 916 Dissolved oil from extraction #3... 74. 0 0. 8997 0. 911 Undissolvcdoil (dewaxed) 69. 0 0. 8707 0. 910

A different chemical composition of the fractions is shown by the difierence between the actual specific gravities and the calculated specific gravities of the, oils produced by these extractions. This latter column indioates the specific gravity corresponding to. the viscosity if the oil had been obt ned from the crude from which the orig na 011 was produced, by normal distillation and refining processes. Thus, on extracted fraction #1, which is the oilobtained from the nitrobenzene'layer from the first extraction, a the actual specific gravity is much higher than the calculated, indicating that the fraction is much more naphthenic than would normally be'produced -from this type of crude. On the other, hand, in the case of the residual oil which is the oil port on obtained after the cold settling of the finally extracted product, the actual specific gravity is much lower than the calculated, showing that the oil is much more paraflinic than the original. The wax obtained 18 the high melting product such as would be obtained from such an original oil by any of the wellknown processes of wax removal- It will be noted that the oils obtained by the second and third extractions possess properties between the two extremes, i; e. the residue from extraction- #2 hasan actual specific gravity somewhat higher than the theoretical specific gravity, indicating a more naphthenic oil than ordinary distillation and refining processes would yield, while in the case of the residue from extraction #3, the actual specific gravity is lessthan the calculated value showing the oil to be more para'llinic.

That this process is one of separation into classes rather than one of chemical reaction between the oil and the nitrobenzene is shown by the fact that upon mixing the various oilv fractions and the wax in the proportions n which they were obtained from the original oil, the resultant product is the same astheoriginal oil, as indicated by the physical p p w f While I have described m' process with the use of nitrobenzene as the so vent, I do not intend to limit myself to this particular compound but ma mono-nitro-nap thalene-or' other suitable nitro derivatives of an aromatic h drocarbon.

It will be seen that by the use 0 myprocess I am practicall inde nden't' of the particuse instead nitrotoluene,

ular nature of t e cru e sources but may produce viscous oils of any required characteristics from practically any source.

For example, I am able, by my (process, to produce from petroleum of a mixe base type such as would, on normal batch distillation, give a residuum of a viscosity of 150 seconds aybolt universal at 210 F. with a specific gravity of .928 or more, a lubricatin stock with a viscosity of 150seconds Say It or.

more and a specific gravity not higher than .910. This latter combination of properties is typical of'cylinder stocks produced from Pennsylvania crude. V l

I find in many ins'tances'that the oils produced by my process are superior to those produced under the most favorable conditions by normal processes from selected crudes.- I

' For example, it is well-known that oils containing appreciable quantities of paraffinic constituents decomposeunder the action of the electric corona with the formation of an amorphous solid material, commonly known as corona wax. This property is highly detrimental in oilsfor electrical insulating purposes. It is diflicult, by normal processes, even from carefully selected crudes to obtain an oil'sufliciently low in paraflinic constituents to satisfactorily withstand the action of the corona. By my process, it isreadily possible to produce such'an oil as the nitrobenzene extract which will show no formation of coronawax on exposure to corona mally made.

herein for treatment in accordance with my process are those having a substantial viscosity, and are herein described as viscous when having a viscosity of '50 seconds Saybolt universal at 100 F., and upward.

For brevity in the appended claims the ,termnitrobenzene is employed in a ge- The mineral oils particularly contemplated neric sense to include that material and equivalent aromatic n tro compounds or mixtures of them.

By fractional extraction in the appended claims- I mean the process of contacting the material to be extracted with one or'more portions of a solvent and separating the solvent and soluble portion from the nsoluble portion after each contacting.

ieo

- theories.

Herein, while I have discussed the theories which I believe underlie my invention, it is to be understood that I do not intend to be held thereto, and that my invention Concerns actual physical phenomena, and is in no way predicated upon the correctness of said Furthermore, it is to be understood that the results attained by my process do not depend upon the presence in the oil to be treated of paraflins, solid at ordinary temper. tures, commonly known as wax. If present, such parafins may be removed either before the oil is subjected to my process, or if desired, from the fraction or fractions containing them attcr such treatment, as for example, by the well-known cold settling process. If the latter procedure is resorted to, the substantially dewaxed extract will be found to be richer in 'naphthenic hydrocarbons or compounds than the similarly-dewaxed original oil with out extract-ion, while the dewaxed undissolvcd oil will be found to be richer in paraffinic hydrocarbons or compounds than said dewaxed original oil. It will therefore be seen that my process is adapted to the treatment of wax-free oils as well as wax-containing oils. v

What I claim is: 4 I

- 1. In the art of refining mineral oils the process which comprises bringing a viscous oil containing paraflin and naphthenic hydro: carbons into contact with nitrobenzene, thereby effecting solution of a portion of the oil richer in naphthenic hydrocarbons in the nitrobenzene, separating the nitrobenzene solution of oil 'from the oil so treated, and removing. the nitrobenzene from each of the fractions so obtained.

2. The process of separating mineral oils into fractions .which comprises'bringing a viscous oil containing paraflin and naphthenic hydrocarbons into contact with nitrobenzene thereby effecting solution of a portion of the oil richer in naphthenic hydrocarbons in the nitrobenzene, separating the nitrobenzene solution of oil from the oil so treated, and distilling the nitrobenzene from each of the fractions so obtained.

temperature as to effect solution, cooling the solution to form a. two layer system, and sepmsaaee f arating the upper layer from the lower layer.

-5. In the artof refining mineral oils the process which comprises adding nitrobenzene to a viscous oil containing parafiinic and naphthenic hydrocarbons, heating the mixture to such a temperature as to effect solution, cooling the solution to form a; two layer system, removing the lowerlayer, and similarly retreating the upper layer with nitrobenzene.

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

7. 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 viscosity at 210 F. and a specific gravity greater than .928, which coinprises producing a residuum from the crude petroleum, and extracting said residuum from said crude petroleum with nitrobenzeno. 8.: In the art of refining mlneral oils, thc

process which comprises separating a viscous oil containing paraffinic and naphthcnic hy drocarbons into fractions respectively richer in paraifinic and naphthenic compounds by extracting said oil with nitrobenzene.

9. In the art of refining mineral oils. the process which comprises fractionally extracting aviscous oil containing parafiinic and naphthenic hydrocarbons with nitrobenzene to produce fractions of the oil respectively richer in paratfinic and naphthenic compounds. a i

10. In the art of refining mineral lubricating oil containing paraflinic and naphthenic hydrocarbons, the step of fractionally extractin g the oil with nitrobenzene, to effect a separation of fractions respectively richer in paratfinic and naththenic compounds.

11. The process of producing a lubricating stock of specific gravity less than .910 and ot' Saybolt universal viscosity greater than 150 seconds at 210 F. from a crude petroleum which on normal distillation yields a residuum of 150 seconds viscosity at 210 F. and a specific gravity greater'than .928, which comprises separating a residuum from said crude petroleum and bringing such residuum into contact with nitrobenzene, to effect solution of a portion thereof with nitrobenzene. separating the nitroben-zene solution of oil from the portion which does not dissolve therein, and removing the nit-robenzenc from the oil of said solution. 7

12. In a process for separating a viscous mineral oil containing paraffinic and naphthenic hydrocarbons into fractions which are respectively richer in naphthenic hydrocar amuse honsfand parafiinic hydrocarbonsother than u wax, the step which comprises extracting the oil'with nitrobenzene. s f 13. .In aprocess for separating viscous mineral oil liquid at ordinary temperature containing parafiinicand-naphthenic hydro carbons into fractions respectively richer in paraflinic 1 and naphthenic hydrocarbons, the v a p which comprises extracting the oil with nitroben'zene.

14. 1 In a process for separating a substan- 'tially wax free viscous mineral oil containing parafiinic and naphthenic hydrocarbons into fractions respectively richer inparafiinicand i naphthenic hydrocarbons, the step'which comprises extracting the oil with nitrobenzene. 15. The process of treating a viscous frac- T tion of a crude oilof one type containing go paraflinic 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 paraffinic hydrocarbons, which comprises extract- '25 in the viscous fraction with nitrobenzene,

and separating the oil so treated into portions respectively richer in paraifinic and naphthenic hydrocarbons, 16. The process of treating a viscous frac- 80 tion of a-mixed base crude oil to procure a fraction having the quality of a correspond- 4 ing fraction of a parafiinic base crude. which comprises extracting the viscous fraction with nitrobenzene, and separating the oil so 3 treated into portions respectively richer in paraflinic and naphthenic compounds.

17 In the art of refininn mineral oils, the process which comprises addingnitrobenzene to a viscous oil liquid at ordinary tempera- 40 .tures containing parafiinic and naphthenic Q hydrocarbons. heating the mixture to a temerature sufiicient to effect solution. cooling the solution to a temperature suflicient to form two layers respectively richer in naph- '45 thenic hvdrocarbons and paraflinic hydrocarbons other than wax, and se arating the upper'laver richer in paraflinic hydrocarbons from the lower layer richer in'naphthenic hydrocarbons. 18. In the art of refining mineral oils. the rocess which comprises addine'nitrobenzene to a viscous oil liquid t ordinary temperatures containing paraflinic and naphthenic hydrocarbons. heating the mixture to'a temerature sufiicient to eflect solutiom cooling the solution to a tem erature sufiicient to form two layers. se arating nitrobenzene and parafiin wax from the upper laver.'-and sepa-' rating nitrohenzene from the lower laver to .60 produce one fraction richer in parafiinic and a second fraction richer in n aphthenic hydrocarbons than said vi scnus oil;

SEYMOUR w. FERRISI.

M QERT'IFIGA'I'E 0F coRREcTIdN. e v Patent 1(0. 1, 788,569. I January 15f, l93.1,

. SEYHOUR'YW. FERRIS. e

it hereby. certified izhat error appears in the printed apeciticm'zien A of the afbove numbered patent requiring correetien eel-follows: Ifege L, i1nes 32 end-b2, "claims 1 and 2 respectively, for the word '"bareffin' read par -affinic; and that the said. Letters Patent should be read with this eer;-

rection' therein that the same nay'cenfonn' totherecbrd of the eerie in the" Patent Office.

Signed and sealed-this Z'jthfiay' 9f January, "A D. 1938.

v w Henry Van Arsda leg (Seal) Acting Commissioner of Patents.-