US2107137A - Dewaxing lubricating oils - Google Patents

Description

settling or centrifuging.

TE orr cs nnwaxmc nunmca'rmc ons Chester a. sum and Frederick w. Sullivan, In.

Hammond, Ind and John A. Anderson, Chialso. 111., assignors to Standard Oil Company, Chicago. 111., acorporation or In No Drawing. Application November 1. 1933,

Serial No. seams 13 Claims.

This invention relates to the removal oi wax from oils and more particularly to the removal of mineral wax from mineral lubricating oils.

It has been the custom for many years to remove paraiiln wax from lubricating oil fractions oi petroleum by diluting said fractions with a light petroleum product such as naphtha, chilling the V diluted oil to low temperatures to precipitate the wax, and removing the wax by filtering, In this process, a certain amount of wax is dissolved 'in the diluted oil at the dewaxing temperature so that when the diluent is removed from the oil, said oil has, in general a pour point 16 (as defined m and determined by Method 1) 91-30 of the American Society for Testing Materials) at least 30* F. and sometimes as much as 50 F.

higher than the temperature ,of dewaxing. It therefore has been necessary to dewax at extremely low temperatures which necessitates expensive refrigeration and which results in decreased flltration rates because of the high viscosity of the diluted oil at the extremely low tem- 30 whereby extremely low de'waxing temperatures may be avoided.

A further object is to provide an improved diluent mixture and method of using the same in a dewaxing process. A further object is to provide a process which will dewax oils containing types of wax which were heretofore 'difllcult or impossible to remove. A further object is to. obtain increased fllter rates and to obtains wax in a more nearly oil-free condition and in larger yields than 40 has heretofore been obtained.- Other objects will be apparent from the following description.

lhis problem of providing a satisfactory dewaxing diluent has been dimcult because ordinary diluents dissolve a large amount oi wax, and diluents 45 which would not dissolve wax would likewise be immiscible with oil -atdewaxing temperatures. We have discovered that a wax antisolvent may be rendered miscible with a solvent as herein-- after defined by means oi certain oxygenated or 5o halogenated compounds which we have termed miscibility agents. We have also discovered that certain cracked petroleum products have remarkable new and unexpected properties as components in a dewaxing-diluent mixture. Our

.35 invention will be more clearly understood from.

the following description in which examples are described in detail.

To avoid confusion we have defined the meaning of certain terms as they are used in this speciflcationandinthefoilowing claims.

The term antisolvent refers to a liquid with which wax (and to a less extent oil) is not miscible in'all proportions at the desired dewaxing temperature (generally about F. or between liquids are benzol and .more icularly the cracked petroleum compounds w ch will be hereinafter described and oleflnic hydrocarbons.

The term miscibility agent" may be defined as an oxygenated or chlorinated hydrocarbon completely miscible with the oil at the dewaxing temperature and capable of preventing the separation of antisolvents from oil-diluent mixtures at dewaxing temperatures; among such liquids are ethyl acetate, ethylene dichloride and iso-propyl ether. 5

The term diluent refers to the whole mixture with which the oil is diluted and comprises the solvent and antisolvent; 'or solvent, antisolvent and miscibility agent.

When oils are diluted with ordinary diluents and dewaxed, a large amount of wax remains in the solution. In other words, wax is dissolved by the diluent at dewaxing temperatures. It oil is mixed with an antisolvent alone, on the other the oil separates from the antisolvent at the temperatures necessary for complete dewaxing. We have discovered, that oxygenated and chlorinated hydrocarbons particularly those above mentioned, have the peculiar property of renuent -mixtures used for dewaxing an overhead (distillate) Mid-Continent lubricating oil fraction having a viscosity of about 74 seconds Saybolt at21il F. In all of the preferred embodi-' ments we use two and one-half volumes of diluent mixture to one volume of oil, but it isto'be understood that these proportions will vary considerably withthe dewaxlng oi' diflerent oils under different conditions. From one =volume to four volumes of diluent mixture to one volume of oil hand, dewaxing is practically impossible because are more paramnic than Mid-Continent require greater quantities of solvent and less of anti- Solvent. Heavy oils generally require a higher ratio of solvent to antisolvent in a diluent mixv carbons.

ture than do lighter ones and also require a higher ratio of diluent mixture to oil.

Our preferred solvent is a naphtha or lighter fraction obtained from the reaction products formed by a pyrolytic cracking process, prei'erably a vapor phase cracking process wherein gasoil or other petroleum products are heated to temperatures of about 900-1100 F. under pressures 'of from -300 pounds per square inch.

' This product may be called cracked naphtha to distinguish it from the virgin or straight run naphtha produced by ordinary distillation. It.

contains a high proportion of olefinic hydrocarbons and it is to these that we attribute its outstanding advantages. Naphtha produced by liquid phase cracking is superior as a dewaxing diluent to ordinarynaphtha but it is not as good as that produced by vapor phase cracking. This may be due to its lower content of olefinic'hydrosince mixtures containing greater amounts of acetone tend to separate into two liquid bases at dewaxing temperatures. However, the addition of a miscibility agent permits the use of more acetone and decreases this diflerentlal.

When naphtha produced by liquid phase cracking is used, the maximum acetone content is markedly lower than with a naphtha produced by vapor phase cracking and the resultant oil has an even higher pour point. Any cracked naphtha, however, produces better results than straight run naphthas and it will thus be seen that cracked naphtha, particularly those produced by vapor phase cracking are highly desirable constituents of solvent-antisolvent mixtures whether or not a" miscibility agent is used. In general 15% to 60% of cracked naphtha can be used depending on the antisolvent used, the nature of the oil being dewaxed, the dewaxing temperature, the amount of diluent mixture used per-unit of 'oil, and other factors.

We have found that when a miscibility agent is used as a third component of the diluent mix- I Per cent Iso-propyl ether 15 Acetone 35 Vapor phase cracked naphtha 50 The use of this diluentat a dewaxing temperamixture.

2,101,187 is, in general, the preferred range. Oilswhichthe three components of high diluent mixture may vary over a considerable range. Compositions which have proved particularly useful are:

Under various conditions the above concentrations of each 01' these components can be varied as much as 10% or even 15% either up or down. The miscibility agent itself may have a certain antisolvent power but itsparticular usefulness lies in the fact that it has the power to keep large amounts of antisolvents from separating from the diluted oil at low temperatures.

As we have pointed out we believe that thepeculiar advantages oi vapor phase cracked naph thas are due in large part to their high oleflnic hydrocarbon content. This is borne out by the fact that olefinic hydrocarbons such as propylene, butylene, amylenes, etc., are desirable solvents and can be used together with antisolvents or antisolvents and miscibility agents. Thus, for example, from 30% ,to 80% of propylene, butylene, amylene or mixtures thereof can be used together with from to 70% of sulfur dioxide as a dewaxing diluent under pressures sufficient to cause liquefaction of the diluent mixture.

While we have disclosed preferred embodiments or our invention in detail it is understood that f we do not limit ourselves to the details hereinabove set forth except as defined by the following claims which should be construed as broadly as the prior art will removing the diluent from the dewaxed oil.

2. The process oi dewaxing a wax-bearing minerallubrica'ting oil which comprises diluting the oil with a diluent mixture comprising substantial amounts oi aiwax antisolvent, a cracked petroleum naphtha and a miscibility agent, chilling the diluted oil to a low temperature, whereby the wax is caused to precipitate therefrom while the oil is retained in solution'in the diluent mixture, separating the wax from the oil and diluent, and

subsequently removing the diluent from the dewaxed oil.

3. The process 01' dewaxing mineral lubricating oils according to claim 1 wherein the petroleum by a vapor phase cracking naphtha is produced process.

4. The-process of dewaxing lubricating mineral oils according to claim 1 wherein acetone is em+ ployed as the antisolvent in the diluent mixture.

a v Per cent lsopropyl ether Acetone 33 Vapor phase cracked naphtha 42 Percent Ethylene dichloride 43 Acetoneg 16 Cracked naphtha 41 5. The process of: dewaxlng lubricating mineral oils according to claim 2 wherein iso-propyl ether is employed as the miscibility agent in the diluent 6. The process 01' dewaxing lubricating mineral oils according to claim 2 wherein the diluent mix- 11. The process 0! claim 2 wherein the antiture employed is comprised of cracked petroleum solvent is sulfur dioxide.

naphtha, acetone and iso-propyl ether. 12. The process of claim 2 wherein the misci- 7. The process of claim 1 wherein the antibility agent is ethylene dichloride. I 5 solvent is methyl ethyl ketone. 13. The process of claim 2 wherein the created 5 8. The process oi claim 1 wherein the" antipetroleum naphtha is produced by vapor phase solvent is sulfur dioxide. cracking.

9. The process of claim 2 wherein the anti- CHESTER E. ADAMS. solvent is acetone. FREDERICK W. SUILIVAEJI.

10 10. The process of claim 2 wherein. the nntl- JOHN A. ANDERSON. l0

solvent is methyl ethyl ketone. l

CERTIFICATE OF CORRECTION. Patent No". 2,107,157. February l, 19 58. 7 CHIESI'ER E. ADAMS, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Page 2, second column, line 56, claim 2, after "agent" and before the comma Insert the words for antieolvent and oiliahd that the said Letters Patent should be read with this correction therein that the same may conform tothe record of the ease in the Patent Office.

Signed and sealed this 15th day of March, A. n. 1958.

l I Henry Van Arsdale, (Seal) 7 Acting Commissioner of Patents.

oils according to claim 2 wherein the diluent mix- 11. The process 0! claim 2 wherein the antiture employed is comprised of cracked petroleum solvent is sulfur dioxide.

naphtha, acetone and iso-propyl ether. 12. The process of claim 2 wherein the misci- 7. The process of claim 1 wherein the antibility agent is ethylene dichloride. I 5 solvent is methyl ethyl ketone. 13. The process of claim 2 wherein the created 5 8. The process oi claim 1 wherein the" antipetroleum naphtha is produced by vapor phase solvent is sulfur dioxide. cracking.

9. The process of claim 2 wherein the anti- CHESTER E. ADAMS. solvent is acetone. FREDERICK W. SUILIVAEJI.

10 10. The process of claim 2 wherein. the nntl- JOHN A. ANDERSON. l0

solvent is methyl ethyl ketone. l

CERTIFICATE OF CORRECTION. Patent No". 2,107,157. February l, 19 58. 7 CHIESI'ER E. ADAMS, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Page 2, second column, line 56, claim 2, after "agent" and before the comma Insert the words for antieolvent and oiliahd that the said Letters Patent should be read with this correction therein that the same may conform tothe record of the ease in the Patent Office.

Signed and sealed this 15th day of March, A. n. 1958.

l I Henry Van Arsdale, (Seal) 7 Acting Commissioner of Patents.