US2191972A - Production of high quality lubricating oils by cold fractionation, extraction, and synthesis - Google Patents

Description

Feb. 27, 1940.

C. L. 0 PRODUCTION OF HIGH QUALITY LUBRICATING OILS BY COLD FRACTIONATION, EXTRACTION, AND SYNTHESIS Filed Nov. 1, 1937 VISCOUS OILS ASPHALT ASPHALT- REMOVAL ZDEASPHALTIZED OIL DEWAXING i DE WAXED OIL SELECTWE SOLVENT RAFFIQMTE PRODUCTS EXTRA CTION EXTKACT SOLUTION WAX TREATMENT YUNDISSOLVED OIL MXM

INVENTOR.

Patented Feb. 27, 1940 "UNITED STATES PATENT orries PRODUCTION: OF Intel-i QUALITY LUBRI- ,CATING OILS BY ooLn FRAGTIONATION,

EXTRACTION, AND SYNTHESIS Cecilio L. Ocn, Yonkers, N. Y. I ,Ap plication November 1, 1937, Serial No. 172,088

Claims. (01. ice-1s) This invention relates particularly to a process for removing from viscous hydrocarbon oils containing desirable lubricating oil constituents, such desirable constituents and constituents hav- 5 ing properties which permit improvement to form desirable lubricating .oil constituents.

- One of the principal objects of this invention is to provide a method for recovering a larger yield of .high quality lubricating oil from inferior viscous oils than are obtained only by a solvent extraction of, such oils by a solvent or solvents intended to extract selectively aromatic, naphthenic, and unsaturated hydrocarbons which include undesirable lubricating oil constituents.

To attain thisobject, this invention provides,

among other things, for a differential separation of valuable, constituents removed by the selective solventextraction, such constituents being highly desirable lubricating oil constituents in spite of readily and economically convertible into highly desirable lubricating oil constituents by synthetic With the above and other objects in view,

which. will become apparent from a more detailed description following, reference also being made to the self-explanatory schematic flow diagram Which illustrates suitable principal steps taken in eifectingthis invention according to one embodiment.

The starting 'oil for this process may be any ents needed in a lubricating oil used in crank cases of internal combustion engines, such as fractions of crude, mixed base of Mid-Continental crude oils, naphthene base oils, asphalt base oils,or parafline base oils, especially fractions or residues boiling above 700 F. In the event that such initial oil is an unrefined oil containing undesirable constituents, such as asphaltic and resinous substances, it is first to be refined by using one or 'more of the following steps: Hydrogenation, distillation, filtration through an absorbent material such as clay, asphalt precipitation, as by means of a low boiling hydrocarbon, or an asphalt absorbent solvent.

The hydrogenation is most suitably one which their. cyclic or unsaturated. character and beingv hydrocarbon oil containing the viscous ingredi-.

- for the differential extraction of constituents deis of the type avoiding asphalt formation by use of low temperatures to avoid substantial cracking and dehydrogenation. The distillation is one which is most suitably carried out under vacuum, with the aid of a-gaseous distillation agent, or both. The filtration may be carried out in the vapor phase in conjunction, with the above described distillation or in the liquid phasewith an adsorbent contact agent and other known agents which aid in removing preformed and m formative asphaltic substances. The asphalt recipitation can be carried out in well known ways at low temperatures by the addition of normally gaseous constituents in the liquid phase,

such as light fractions obtained from'stabilizer B:

towers, the precipitated asphaltic material being. settled, centrifuged, or filtered from the dissolved oil. In the solvent extraction of the asphaltic material may be used such selective absorbents as liquid sulphur dioxide, aluminum chloride, aniline saturated with water, etc., the absorbent and conditions being adjusted to re- I movemainly asphaltic and very low viscosity index hydrocarbons.

After the asphalt removal, when necessary, the

low asphalt or deasphaltized oil is subjected to a dewaxing, if needed. Some oils will notrequire the dewaxing and in someinstances, such as in the refining with aluminum chloride, it might be found more desirable to remove the wax before attempting to remove the asphaltic constituents. Also, in using the liquefied normally gaseous hydrocarbons or similar wax precipitants it has been found desirable to first remove resinous and asphaltic materials, which interfere with wax precipitation and which contaminate the wax.

The oil with low wax and asphalt content, such as a dewaxed and deasphaltized oil, as explained, is subjected to a selective solvent extraction by a solvent which extracts mainly cyclic and unsaturated hydrocarbons to produce a rafiinate of high Viscosity index, such solvents as liquid sulphur dioxide, aniline, nitro-hydrocarbons, halogen-hydrocarbons, phenol, etc., being used, either alone, with one another or in mixtures with solubility enhancing agents, such as anthracene, benzene, turpentine, acetone, etc.

The wax constituents removed in a dewaxing step are conveniently employed through a wax treatment to produce an auxiliary solvent sirable. in a lubricating oil and susceptible to improvement. This wax treatment consists in an improvement involving mainly a splitting of the.

wax into normally liquid aliphatic molecules including .isomerization or polymerization into isoparaiiins. Primarily, this treatment is a pyrolytic splitting of the wax at low cracking temperatures to avoid the formation of large amounts of naphtha. This can be accomplished by a slow heat treatment of the Wax at temperatures between about 800 to 900 F., under a superatmospheric pressure of about 5 to 20 atmospheres or more, for a period of about 60 minutes or longer. Hydrogen or an inert gas may be used to aid in obtaining the'pressure and preventing drastic cracking. With extension of time the products can be made to polymerize and isomerize. To shorten the time of treatment the wax may be made to distill over a condensing agent or dehydrating catalyst. It is considered that the wax treatment should mainly produce aliphatic hydrocarbons boiling above 400 F., and largely composed of isoparaffins and monoolefins as well as paraffins. Such hydrocarbons as these have been found useful in the process of the present invention as auxiliary solvents in the difierential separation, which is next to be described.

The differential separation or diiierential solvent extraction in this invention is intended to separate from low viscosity index oils, such as, ordinary selective solvent extracts, constituents which are highly valuable present in lubricating oils and those which can readily be transformed into valuable lubricating oil constituents. This objectis achieved by the use of a solvent medium which tends to dissolve aliphatic, alkylate'd cyclic hydrocarbons, and substances of similar nature. Such media comprise low boiling organic liquids of low polarity such as carbon tetra-chloride, higher alcohols such as amyl alcohol or isobutanyl oil (synthetic higher alcohols from reduction of carbon monoxide), alcohol esters, and

such media diluted with gasoline hydrocarbons of paraiiinic character. To supplement the action of such media it has been found helpful to use a mutually soluble high boiling normally liquid aliphatic compound such as is obtained by the Wax treatment described above, or similar oils such as hydrogenated aliphatic polymers produced by the hydrogenation of polymers from gum forming constituents in gasoline and keroor more rings to a molecule, is commercially valuable for forming resins. It is believed that this differential separation is aided not only by the kind of auxiliary solvent described but also by the preliminary step of the deasphaltizing.

The dissolved desirable lubricating constituents may be removed from the diiferential solvent extract solution by distillation and be added directly to the raffinate from the selective solvent extraction to enhance the recovered lubricating oil without further treatment, or the solution may be subjected to a treatment for synthesizing improved lubricating oil constituents. In using a solvent such as carbon tetra-chloride, which remains more or-less inert or at least not detri mental to the synthesizing treatment, such a 5 medium need not be removed from the extract from the differential separation for it .is even The synthesizing treatbeneficial as 'a diluent. ment for improving the differential extracted constituents along with the auxiliary solvent constituents consists in a reaction of such constituents. to cause further alkylation of the ex-' tracted constituents and polymerization of aliphatics in the auxiliary solvent. This treatment may be accomplished by subjecting the extract solution from the difierential separation includ-j ing such a medium as carbon tetrachloride to the action of aluminum chloride or a similar Friedel-Crafts condensation agent, or to such an agent with the aid of a promoter, such as a. hydrogen halide. halogenating part of the treated wax. products lubricating oil to do the same.

This may be accomplished by d before they are added to the difierential separa- 1 I Asa specificexample, a lvIid-Continent crude lubricating stockcf viscosity index between 75' and is first deasphaltized by treatmentwith liquid sulphur dioxide added in an amount of about one third theweight of the oil treated,

after mixing at a temperature of about 30 F.,

the. mixture being allowed to stratify. An ex tract of very low viscosity index is removed. The deasphaltized oil is mixed with a butane-propane fraction from a stabilizer tower and coo-led to about 10 to cause separation of wax, which is filtered 01f. The dewaxed oil separated from volatiles, is cooled and mixed: with about an equal weight of aniline at about 30 'F., for selective solvent extraction. Waxobtained by the dewaxing: of the sulphur dioxide-treated oil is distilled.

at about 850 F., under a pressure of 15 at mospheres to collect a wax distillate boiling between about 400 and 600 F. The vapors from of steam and oxygen over 'acatalyst made up of pumice impregnated with phosphoric acid and dehydrated. The aniline is removed from the extract and the extract is mixed with hydrocarbons of the treated wax distillate in about equal proportion and with a similar proportion of car- I bon tetrachloride. Following thorough admixture of these liquids, aseparation of the carbon I tetrachloride solution at about 40 is made,"

or clay treated lubricating oil stock, the sulphur dioxide deasphaltizingmay' be dispensed with. In place of the butane-propane dewaxing agent,

After about 6 so the still are passed together with a small amount other agents such as ethylene dichloride may be used. In the Wax treatment dehydrating catalysts such as activated alumina, clay or thoria, may be used. Or, in place of using the hydrating-dehydrating step to accelerate the wax treatment, a halogenating-dehalogenating, or simply a halogenating action may be used, such as is obtained by injecting chlorine into the wax undergoing splitting and passing the vapor over a metal such as aluminum, zinc, etc. It is to be understood that numerous other modifications This process is designed to produce lubricat ing oils with remarkable tenacity or adherence to metal surfaces beside suitable characteristics of viscosity, viscosity-temperature coeflicient, low sludge and. residual carbon content, low pour point, and other proper qualities for a lubricating oil. 1

Although the present invention has been described with specific details, it is to be understood that such details are not intended to limit the invention, except in so far as set forth in the accompanying claims.

Having described my invention, what I claim and desire to secure by Letters Patent, is as follows:

'1. The method of recovering highquality lu-. bricating oils from inferior lubricating oil stocks which comprises subjecting .a lubricating oil stock to a deasphaltizing process, dewaxing such oil which has been deasphaltized, selectively sepsaturated character but having alkyl side chains which make said constituents soluble in said 501- vent medium. I

2. A process for obtaining high quality lubrieating oils from inferior lubricating stocks substantially free of asphalt and wax, which comprises subjecting said lubricating .oil stock to a selective solvent extraction by a' solventwhich extracts the relatively low -quality constituents of the oil, subjecting extracted constituents from said selective extraction to a differential separation by aliphatic compounds derived by splitting Wax hydrocarbons and a mutually solublesolvent to dissolve out constituents which are desirable as lubricating constituents and which are capable on transformation of forming lubricating constituents by alkylation.

3. A process as in claim 2, in which the mutually soluble solvent is carbon tetrachloride.

4. A process as in claim 2, in which aliphatic compounds used in the differential separation are derived from a distillate fraction higher boiling than gasoline obtained by a splitting of wax molecules.

5. Aprocess as in claim 2, in which the solution from the difierentialseparation is subjected to a treatment with a condensing catalyst to cause alkylation of constituents differentially separated from the selective solvent extract.

CECIIIO L. OCON.

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