US2044724A - Manufacture of lubricating oil - Google Patents

Description

June 16, 1936. F. x. GovERs MANUFACTURE OF `LUBRIATING OIL` Original Filed March 29, 1935 Patented `une 1,6-, 193 Y MANUFACTURE oF LUBRICATING on.

Francis X. Govers, Vincennes', Ind., assignor ,to Y Indian Refining Y Company, Lawrenceville, Ill.,

a corporation of Maine Original applicationgMarch 29, 1933, Serial No. 663,341. Divided and this application Juncfl :1934, Serial No. 728.961

e claims. (ciales- 717) This invention relates to the manufacture 4of mineral lubricating oils and more particularly to the manufacture of high viscosity index, loW pour test lubricating oil .from wax bearing mineral oils. Y Y

This application is a division of my co-pending application Serial 1510.663341, `filed March 29, 1933, for Manufacture of lubricating oil.

In its broadest aspect, the invention contem-v plates `an improvedprocess of treating hydrocar- Abon oils, particularly parafnfbearing lubricating fractions of petroleum with solvents to Lselectively produce therefromlow 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 lsulphur 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 pour and cloud tests, low Conradson carbon content, but have W viscosity indices andfairly high sulphur content. On the other hand, lubricating oils, as ordinarily made from parain-base crudes of the `-Pennsylvania type, have Vhigh pour and cloud tests, high Conradsoncarbon content and fairly high sulphur content, depending on the source `of particular crude used. Oils derived from mixed Abase crudes fall somewhere between these limits although usually high in'sulphur content. Oils of the Pennsylvania type,.as well as those derived Y `from mixed base crude sources, are di'cult to renne Without undue loss and impairment of their lubricative value. In Vall cases, -it is dii`cult, by methods now employed, to reduce the sulphur `content of these lubricating oil `fractions to a desired point, regardless of theirsource of crude.

I have discovered that by the u se of the methods herein disclosed lubricating oils of anydesired viscosity index and scale of purication cou'- pled with low pour test and low cloudltest, can be made from mixed-base or paraffin-base crudes and the oils so produced'are characterized further by low Conradson Acarbon and low sulphur content. The obtaining of oils having I these desired qualities does not depend on methods involving redistillation or acid treatment, although such redistillation or acid treatment canbe coupled With the methods herein `disclosed ifso de sired.

Lubricating oils `of high viscosity index are characterized by Ahaving `a relatively rnarrow increase in viscosity With respect to temperature. Such oils have the property of `possessing the de Syed 4Viscosity fatelevated temperature withgnot ...too great. a loss lof; mobilityatyery jlovvrtemperature'. The viscosity index of a given oil is readily `Vent mixture.

determined ,by resorting to the method of Dean `and Davis, published on pages 618-619 of the complete solvent action Von the oil at temperatures of around 100 F., and ala-temperatures of Yaround (l-F. substantially completesolvent action on the 'liquid hydrocarbons therein but substantially no solvent action -on the solidhydrocarbons therein and of such a nature that uponvcooling a solution Vof the vmineral oil fraction in such solvent mixture to0 Rand removing `the solid hydrocarbons s o precipitated and the solvent liquid the resulting oil Vhas a cold test'oi substantiallyv 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 sol- The mother liquor is separated from-the chilled mixture, advantageouslyby ltration. Theyseparated mass of solid hydrocarbons is then Washed free of mother liquorcontaining dissolved oil by additional quantities of chilled solvent liquid of approximately the same composition as usedin the original mix.

A portion ofzjthe first part of this Wash filtrate maybe added to the original filtrate. The extent of :such addition'depending on the amount or percentageof oil contained in such Wash filtrate.

` Fromgthe original filtrate ormixture of originalltrate `and WashA filtrate is then evaporated oneof the component solvents in an amount suincientto'effect the desired alteration in the selectivesolvent action of the mixture. If desired this resulting mixture may be treated with addi- ,tional amounts of the remaining solvent component.

...Thisfresulting mixture of altered composition jmaysbe cooled or chilled to still further aiTect its' solventaction and is allowed to stand and effect a sharp separation into two layers. The upper layer contains oils characterizedkn7 relatively high viscosity index and the lower layer contains oils of relatively low viscosity index.

The amount and character of theseparation is influenced by the; amount of alteration in the percentage composition of the componentparts comprising the Solventfmix and the temperature to Which ,such altered composition mixture is chilled. V It desired the modifying solvent may be removed in successive stages, subjecting 'the remaining mixture of dissolvedoil .and solventto 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 fraction is then dewaxed by means of a chilled selective solvent mixture composed of the selective solvent and a modifying solvent, followed by the-*separation of the dewaxed fraction into oils of differing viscosity indices by means of evaporation in whole or part of the modifying solvent. The solvent component of relatively high selectivity may be aniline, or a solvent of like solvent nature and the modifying solvent of relatively less selectivity may be isopropyl 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 70 Saybolt universal seconds at 210 F., and a pour test of 95 F. is well mixed with isopropyl ether. Following this, aniline is then added. The proportions of these two solvents used comprise about 60 parts of ether to about 40 parts of aniline. 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 iiltrate substantially free from dissolved wax and solid hydrocarbons.

The lter cake, without removal from the lter, 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 the solvent mixture in a succeeding batch, allowance being made for the oil contained therein.

The wax slurry is drawn olf 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 filtered. The resulting wax is practically water white and will have a melting point of approximately 138 F.

From the dewaxed filtrate a portion, or substantially all, of the isopropyl ether is evaporated, depending upon the degree of separation desired. The resulting mixture may be chilled to any temperature desired, upon which separation into two layers will occur. One layer will comprise the high voscosity index constituents, while the other layer will contain the low viscosity index constituents.

In the event that substantially all of the isopropyl ether is evaporated from the dewaxed filtrate, it may be advantageous to extract the resulting mixture with an additional quantity of aniline. This extraction may be carried out by oountercurrent methods at a temperature of around 60 F., for example, using about one part of aniline to two parts of oil. As a result of this extraction, the oil will, upon settling, be separated into two layers, one of which contains relatively high viscosity oil while the other contains relatively low viscosity oil.

The aniline is advantageously removed from the separated layers by steam distillation and recovered for further use. The remaining oil may then be nished up by contact filtration in the usual manner.

The high viscosity index fraction obtained in the above manner will have a gravity of about 30.4 B., a viscosity of about 65 Saybolt Universal seconds at 210 F., a viscosity index of not less than 100, a pour test of not higher than 15 F., a Conradson carbon content not greater than 0.02% and a sulphur content not greater than 0.09%.

The invention is not limited to the production of nal products of the characteristics of those produced in the examples given above. Products of varying 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.

In order to more fully describe the invention reference may be made to the accompanying drawing comprising a flow 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 aniline, also conducted from a source not shown.

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 settling chamber 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 3 the partially rened 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 action between 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 to a iilter 5 wherein the solid wax constituents are separated from the cold mixture to form a wax cake or slurry. This Wax cake or slurry is removed from the lter and the retained solvent recovered therefrom.

The dewaxed filtrate is conducted to an evaporator 6 wherein a portion of the more volatile modifying solvent is vaporized and removed from the ltrate. Thereafter the partially stripped filtrate is withdrawn from the evaporator through a cooling coil 'I and may be introduced 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 selective 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 ramnate oil and some solvent liquid. This layer is drawn off to a still l0 wherein the solvent is removed, leavingl a refined oil of high viscosity index.

The bottom layer 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.

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

'I'hus 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 fractions derived from mineral oils. Hydrogenation 4products may contain substantial quantities of waxy or parafn material as well as other constituents of relatively low lubricating value. By treating such productsin accordance with my invention, nal products of desired characteristics can be obtained.

The invention is not restricted to am7 particular operating condition such as Vthat of temperature, or the composition of the solvent mixtures employed since these conditions may advantageously be varied, depending upon the nature of the fraction undergoing treatment as Well as upon the particular characteristics desired in the iinal product.

It is also contemplated, in many instances, thatV v it may be of advantage to carry on the ltration step in the presence of a comminuted solid filteraid material. Such material may be admixed with the chilled mixture of oil and solvent liquid prior to introduction to the filtering means. Y

Obviously many modifications and variations of the invention, as hereinbeiore set forth, may be made without vdeparting from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim: y

1. 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 aniline and a relatively more volatile modifying solvent liquid selected from the group consisting of benzol and toluol in proportions such that at temperatures of around rF. and below the mixturehas 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, Vremoving from the resulting dewaxed mixture a suitable portion of the modifying solvent to thereby render the remaining solvent liquid selective as betweenv constituents of the oil of differing viscosity index, and separating from the remaining mixture a fraction of desired viscosity index and 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 aniline and benzol in proportions such that at temperatures of around 0 F. 'and below themixture has substantially complete solvent action on Ythe oil andV 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 benzol to thereby render the remaining solvent liquid selective as 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.

3. 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 aniline 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 ing mixture a fraction rich in constituents of high viscosity index and of low P0111' test.

4. A. method according to claim 1 in which the cil is first partially extracted with a selective solvent comprising aniline. 5. The 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 aniline and a relatively more volatile modifying solvent selected from the group consisting of benzol 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 preq cipitate wax constituents of the oil, and removing the wax thus precipitated to produce a .dewaxed oil having a pour test corresponding substantially to the temperature at which the wax is removed from the cold mixture.

6. The method of manufacturing a Vlow cold test lubricating oil from wax-bearing mineral oil which comprises mixing the oil with a solvent mixture composed of aniline and benzol in such proportions that at temperatures of 0 F. and below the mixturey 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 having a pour test correspond- Ving substantially to the'temperature at which the wax is removed from the cold mixture.

'7. The 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 aniline and toluol in such proportions that at temperatures of 0 F. and below the mixture has substantially complete solvent action on the oil and Ysubstantially 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. The method according to claim 5 in which the oil is preliminarily extracted with a selective solvent comprising aniline.V

FRANCIS X. GOVERS.

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