US2044723A - Manufacture of lubricating oil - Google Patents

Description

June 16, 1936. F. x. GovERs A MANUFCTURE OF LUBRICATIG OIL Original Filed March 9, 1933 yPatented June 16, 19,36

UNITED STATES PATENT OFI-ics 2.044.723 l MANUFAc'rUnE or LUn'rcArlNG on.

Original application March 9,1933, Serial No. 660,098. Divided and this application June 4,

1934, Serial No. 728,960

1o claims. (ci. 19e-11) readily determined by resorting. to the methody This invention relates to the manufacture of minral lubricating oils and more particularly to the manufacture of high voscosity index, low pour test lubricating oil from wax bearingmineral oils.

This application is a division of my copending application Serial No. 660,098, filed March 9, 1933 for Manufacture of lubricating oil.

In its broadest aspect, the invention contemplates an improved process of treating hydrocarbon oils, particularly parain-bearing lubricating fractions of petroleum with solvents to selectively produce therefrom low pour test lubricating oils characterized by having a desired viscosity temperature relationship and improved lubricating qualities. The invention contemplates a process of manufacturing lubricating oils having low pour and cloud tests, low sulphur content, low Conradson carbon content, relatively high viscosity index and freedom from bodies of little or no lubricating value.

Lubricating oils, as ordinarily made from naphthene-base crudes, have low pou'r and cloud tests, low Conradson carbon content, but have low viscosity indices and fairly high sulphur content. On the other hand, lubricating oils, as ordinarily made from paraiiin-base crudes of the Pennsylvania type, have high pour and cloud tests, high Conradson carbon content and fairly high v sulphur content, depending on the source of particular crude used. Oils derived from mixed base crudes fall somewhere between these limits although usually high in sulphur content. Oils of the Pennsylvania type, as well as those derived from mixed base crude sources, are diflicult to reiine without undue loss and impairment of their lubricative-value. In all cases, it is difficult, by methods now employed, to reduce the sulphur content of these lubricating oil fractions to a desired point, regardless of their source of crude.

I have discovered that by the use of the meth- A ods herein disclosed lubricating oils of r any desired viscosity index and scale of purification coupled with low pour test and low cloud test,

can be made from mixed-bas o'r paraffin-base crudes and the oils so produced are characterized further by low Conradson carbon and low sulphur content. The obtaining of oils having these desired qualities does not depend on methods involving redistillation or acid treatment, although such redistillation or acid treatment can be coupled with the methods herein disclosed if so desired.

Lubricating oils -of high viscosity index are characterized by having a relatively'narrow increase inviscosity withy respect to temperature. Such oils have the property f possessing the desired viscosity at elevated temperature with not too great a loss of mobility at very low temperature. `The viscosity index of ya. given oil 1S ofDean and Davis, published on pages 618-619 of the 1929 issue of Chemical and Metallurgical Engineering.

More 'specifically the invention comprises mixing with a wax-bearing fraction of a mineral oil a solvent mixture composed of benzaldehyde and a modifying solvent selected from the group comprising isopropyl ether, ethyl ether, benzol, tolucl, and the like, in such proportion to each other and to the oil that the mixture has substantially complete solvent action on the oil at temperatures 'of around 100 F., and at temperatures of around 0 F. substantially complete solvent action on the 'liquid hydrocarbons thereinbut substantially no solvent action on the solid hydrocarbons therein and of such a nature that upon cooling a solution of the mineral oil fraction in such solvent mixture to 0 F. and removing the solid hydrocarbons so precipitated andthe solvent liquid the resulting oil has a cold test of substantially 0 F. or below.

The mixture is then chilled to form a precipitate of solid or semi-solid material comprising suspended wax or solid hydrocarbons which are insoluble in, and immiscible with, the desired solvent mixture. The mother liquor is separated from the chilled mixture, advantageously by lf tration. The separated mass of solid hydrocarbons is then washed free of mother liquor -containing dissolved oil by additional quantities of chilled solvent liquid of approximately the same composition as used in the original mix.

A portion of the first part of this wash filtrate may be added to the original ltrate, the extent of such addition depending on the amount or percentage of oil contained in such wash filtrate.

From the original filtrate or mixture of original filtrate and wash ltrate is then evaporated one of the component solvents in an amount suficient to eifect the desired alteration in the selective solvent action of the mixture.

This resulting mixture of altered composition may be cooled or chilled to still further affect its solvent action and is allowed to stand and effect aV sharp separation into two layers. The upper layer contains oils characterized by relatively high viscosity index and the lower layer contains oils of relatively low viscosity index.

The amount and character of the separation is inuenced by the amount of alteration in the percentage composition of the component parts comprising the solvent mix and the temperatures to which such altered composition mixture is chilled. If, desired the modifying solvent may be removed in successive stages, subjecting the remaining mixture of dissolved oil and solvent to cooling in each instance to thereby successively separate fractions of differing characteristics as may be desired.

It is contemplated that the wax-bearing fraction may be `subjected to preliminary refining either with acid or by extraction with a suitable solvent such as the selective solvent component of the mixture used in the subsequent steps. The resulting treated traction is dewaxed by means of a chilled selective solvent mixture composed of the selective solvent and a modifying solvent, followed by the separation o1' the dewaxed fraction into oils of differing viscosity indices by means of evaporation in whole or part of the modifying solvent. The solvent component may be benzaldehyde, or a solvent of like solvent nature and the modifying solvent may be isoproply ether, ethyl ether, toluol, benzol, or a solvent of like solvent nature.

As an example of the process:

An acid treated wax distillate having the following approximate characteristics, gravity 26 B., viscosity of Saybolt universal seconds at 210 F., and a pour test of 95 F. is well mixed with isopropyl ether. After the air in the mixture is displaced with carbon dioxide or other inert gas benzaldehyde is then added. The proportions of these two solvents used comprise about 60 parts ether to 40% benzaldehyde. The mixture is well stirred, chilled to 20 F., and while maintained in this chilled condition, introduced to a pressure type filter wherein the solid hydrocarbons are separated to,produce a filtrate substantially free from dissolved wax and solid hydrocarbons.

The filter cake, without removal from the filter, is washed with additional solvent liquid mixture of substantially the same composition and which has been chilled to a temperature of -20 F.

This wash filtrate is used for part of thesolvent mixture in a succeeding batch, allowance being made for the oil contained therein.

Thev wax slurry is drawn oif from the iilter and the solvent removed by evaporation or distillation in a. reducing or non-oxidizing atmosphere, such as carbon'dioxide for example. The wax. free from solvent, is then steam treated in the presence of clay and contact ltered.y The resulting wax is practically water white and will have a melting point of approximately 138 F.

From th dewaxed ltrate the isopropyl ether is \evaporated or distilled, while maintaining a non-oxidizing atmosphere. When the resulting mixture is cooled to about 30F. and allowed to stand, separation into two layers occurs. The lower layer is drawn ofi' and will contain oil of comparatively low viscosity index while Ythe remaining top layer will contain oil of comparatively high viscosity index.

The invention is not limited to the production of final products to the percentages of or characteiistics of those produced in the examples given above. Products of varying percentages and characteristics may be produced by varying the proportions of solvent liquids and their concentration and the temperature at which the treating steps are carried out. 4

Furthermore, the invention is not limited to the treatment of wax-distillate such as given in the examples herein but is adapted to' the treatment of other paraffin-containing fractions, precipitates or materials somewhat similar in nature derived in various ways from mineral oils.

Thus my invention is applicable to the treatment of hydrogenation products resulting from the hydrogenation of carbonaceous materials, or mineral oils including liquid or solid hydrocarbon ously be varied, depending upon the nature of the fraction undergoing treatment as Well as upon the particular characteristics desired in the nal product.

In order to more fully describe the invention reference may be made to the accompanying drawing comprising a now diagram of the process of this invention.

Wax-bearing oil from a source not shown is conducted to a mixer I and there mixed in the proper proportion with benzaldehyde, also conducted from a source not shown. y A

The mixture of oil and solvent is then delivered to a settling chamber 2 wherein the mixture separates into phases or layers. The bottom layer will comprise asphaltic and other low viscosity index constituents dissolved in the solvent liquid. This bottom layer is removed as a preliminary extract. The upper layer formed in the. settlingchamber 2 comprises partially refined wax-bearing oil mixed with some solvent and it is removed therefrom for introduction to a mixer 3. In the mixer I the partially refined wax-bearing oil is mixed with an additional quantity of selective solvent and a suitable proportion of modifying solvent liquid, such as isopropyl ether or benzol, is also added. The proportions of selective solvent and modifying solvent are such that' the solvent mixture has selective actionbetween wax and oil at temperatures around 0 F. and below.

The mixture is withdrawn from the mixer 3 and conducted to a chiller 4 wherein it is chilled to the dewaxing temperature, as, for example, 20 F. The chilled mixture is then introduced toa filter 5 wherein the solid wax constituents are, separated from the cold mixture to form directly to a settling chamber 8.

If desired the stripped filtrate may be introduced to a mixer 9 prior to introduction to the settling chamber 8. In the mixer 9 it may be mixed with an additional quantity of selective solvent.

On the other hand, the filtrate from the filter 5 may be passed directly to the mixer 9 for mixing with an additional quantity of the selectiye solvent and from there conducted to the settling chamber 8.

The mixture of oil and solvent in the settling chamber 8 separates into upper and lower layers. The upper layer comprises a dewaxed raihnate oil and some' solvent liquid. This layer is drawn oif to a still I0 wherein the solvent is removed, leaving a refined oil of high viscosity index.

The bottomlayer collecting in the settling chamber 8 comprises an extract phase oil dissolved in the main -body of, the solvent. This layer `is withdrawn and conducted to a still Il wherein the solvent is removed, leaving an oil of low viscosity index. 1

It is also contemplated; in many instances, that it may be of advantage to carry on the iiiy i tration step in the presence of a comminuted cosity index lubricating oil haying a low pour test from wax-bearing mineral oil which comsolid filter-aid material. Such material may be admixed with the chilled mixture of oil and solvent liquidprior to introduction to the filtering means.

Obviously many modications and variations of the invention, as herelnbefore set forth, may

be made without departing from the spirit and -scope thereof, and therefore only such limitations should be imposed as are indicated in th appended claims.

1. The method of manufacturing highvisprises mixing with the oil a solvent liquid mixturecomposed oi' benzaldehyde and a modifying solvent'liquid selected from the group consisting oi benzol and-toluol in proportions such` that at temperatures of around 0 F. and below the mixture has substantially completeV solvent. action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate wax constituents of oil, removing the wax thus precipitated, removing from the resulting dewaxed mixture a suitable portion of the lmodifying solvent to thereby render the remaining solvent 'y liquid selectivelas between constituents of the oil of differing viscosity index, and separating from the remaining mixture a fraction rich in' constituents of high viscosity index and of low pour test.

2. The method of manufacturing high viscosity index lubricating oil having a low` pour test from wax-bearing mineral oil which comprises mixing with the oil a solvent liquid mixture composed of benzaldehyde and benzol in proportions such that at temperatures of around 0 F. and

index lubricating oil having a low pour test from wax-bearing mineral oil which comprises mixing with the oil a solvent liquid mixture composed of benzaldehyde and toluol in proportions such that at, temperatures of around 0 F. and below the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate wax constituents'of oil, removing the wax thus precipitated, removing from the resulting dewaxed mixture a suitable portion of the toluol to thereby render the remaining solvent liquid selectivev as between constituents of the oil of differing viscosity index, and separating from tile remaining mixture a fraction rich in constituents of high viscosity index and of low pour test.

4. .The method according to claim 1 in which the' oil is preliminarily extracted with a selective solvent comprising benzaldehyde.

5. 'I'he method of manufacturing a low cold test lubricating oil from wax-bearing mineral oil which comprises mixing the oil with a solvent mixture composed of benzaldehyde and a modifying solvent selected from the group consisting of benzol andl toluol in such proportions that at temperatures of 0 F. and below the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate wax constituents of the oil, and removing the wax thus precipitated to produce a dewaxed oil of desired low pour test.

'6. 'I'he method o f manufacturing a low cold test lubricating oil from wax-bearing mineral oil which comprises mixing the oil with a solvent mixture composed of benzaldehyde and benzol in such proportions that at temperatures of 0 F.

lli

and below the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to` precipitate the waxconstituents of the oil, and removing the wax thus precipitated to produce a dewaxed oil of desired low pour test.

7. The method of manufacturing a low cold 30 test lubricating oil from wax-bearing mineral oil which comprises mixing the oil with a solvent mixture composed of benzaldehyde `and toluol in such proportions that at temperatures of 0 F. and below the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate the wax constituents of the oil, and removing' the wax thus precipitated to produce a dewaxed oil of desired low pour test.

8. 'I'he method according to claim 5 in which the oil is preliminarily extracted with a selective solvent comprising benzaldehyde.

9. The method of manufacturing high `viscosity index lubricating oil having a low pour test from wax-bearing mineral oil which comprises mixing with the oil benzaldehyde and a solvent comprising benzol in proportions such that at temperatures of around 0 F. and below the mixture has substantially complete solvent action on the oil and substantially no solvent action on the wax, chilling the mixture to precipitate wax constituents of the oil, removing the wax thus precipitated, removing from the resulting dewaxed mixture suiiicient benzol to thereby render the remaining solvent liquid se lective as between constituents of the oil of differing viscosityindex, ancLseparating from the remaining mixture a fraction of desired viscosity index and low pour test.

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