US2250998A - Wax suppressor - Google Patents

Description

' more effective for this purpose.

Patented July 29, 1941 wax surrnnsson Rene J. Narberes, Concord, and Frank Derbenwick, Martinez, CaliL, assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application December 1, 1939,

v Serial No. 307,083

6 Claims.

This invention relates to a processfor preventing or delaying the formation of solid wax in hydrocarbon oils, particularly petroleum oils such as gas oils, lubricating oils, coal tar oils, shale oils, and the like at temperatures which are either above or below the pour point.

Hydrocarbon oils which contain waxy constituents often lose their limpidity because of the separation of particles of solid wax. This separated wax appears either in the form of a cloud within the oil or as a more or less crystalline precipitate which may remain dispersed through-- out the oil. Frequently, the separated wax will collect on the walls of the container, especially near the surface of the oil, or will rise to the oil surface. Such separation of wax often occurs at temperatures which are substantially above the congealing temperature or pour point of the oil, with the result that small constrictions in a lubricating system may become obstructed. The lack of clarity is in itself undesirable, because of the unattractive appearance of the oil. This separation of solid wax is manifested both in the formation of clouds of dispersed more or less crystalline precipitates and in the formation of surface wax.

It is one object of our invention to provide a process for reducing, delaying or preventing the separation of such particles of wax by the addition of certain innocuous substances to the oil which are hereinafter referred to as wax suppressors. Other objects of the invention will be oil of small quantities of mixtures of certain natural non-paraflinic waxes with viscous SO: soluble mineral oil fractions. While it is already known that cloud, formation can be suppressed by the addition of natural waxes, it has been found that mixtures of these waxes with viscous S02 soluble mineral oil fractions are undoubtedly The amount of the mixture required to obtain a certain result is less than the amount of other compounds to obtain the same result. i

The waxes which fall within the scope of the present invention are at least in partsaponifiable and are characterized by the large content of high molecular weight fatty acids and/or esters of said fatty acids with monoor poly-hydroxy alcohols, said acid or acid radical generally containing between ten and thirty-five carbon atoms.

These waxes should preferably be of a relatively light color.

Natural waxes which may be mixed with viscous S02 soluble mineral oil fractions in accordance with the present invention are, in particular, white beeswax, yellow beeswax, spermaceti (cetaceum), wool wax, bayberry wax, candelilla wax, carnauba wax, Chinese wax, cocoa wax, cottonseed wax, Japan wax and montan wax. Other natural waxes may also be used, the specific waxes recited having been selected because of their availability at low-cost as commercial waxes.

The term viscous S02 soluble mineral oil fractions is used herein to designate S02 soluble mineral oil fractions having a viscosity above 250 seconds Saybolt Universal at 210 F., and materials contained therein. Such fractions may be produced by extraction of viscous mineral oil distillates or residues with a naphthenlc solvent such as furfural, phenol, liquidSOz, cresylic acid, beta-beta-dichlorethyl ether, etc.

A preferred form of our invention lies in the use of certain materials contained in viscous S02 soluble mineral oil fractions that are known as albino asphalts. r

The mostsatisfactory results have been obtained with mixtures of albino asphalt with beeswax or montan wax, or with mixtures of albino asphalts with beeswax and carnauba wax, and

with mixtures of beeswax and montan wax..

These constitute a preferred embodiment of the present invention.

The term albino asphalt is used to designate certain normally solid or semi-solid translucent petroleum plastics which have been-obtained by with a naphthenic solvent to produce a raflinate' and an extract, and redistilling the extract to produce a semi-solid or solid plastic.

when

Western (asphaltic base) oils are used, the rafllnate produced with a naphthenic solvent such as S: is re-extracted with a stronger naphthenic solvent such as furfurl to produce a secondary extract. This secondary extract contains the desired plastic and may be redistilled to the desired consistency. According to the Merrill patent, translucent petroleum plastics may be produced by extracting a Western petroleum asphalt-free oil with a naphthenic solvent and removing the lower boiling components from the extract by distillation. The albino asphalt need not be obtained from fractions produced by extraction. Thus, according to the Bray patent such plastics can be prepared by the distillation of high boiling cracked material free from asphaltenes.

Albino asphalts produced by the above processes fall into two general types, one of which is acetone soluble and has a lower penetration index than the other, which is substantially acetone insoluble in an equal volume of acetone at 77 F.

The waxes and the viscous S02 soluble mineral oil fractions may be dissolved in the oil either singly or in combination with one another. The effective quantity of the wax suppressor mixture required for inhibiting wax formation in different oils varies with the different wax suppressor mixtures and also depends upon the quantity and nature of the hydrocarbon wax in the oil and upon the temperature to which the oil is to be cooled.

It has been found that the efi'ective quantities usually lie between 0.005% and 1.0% though amounts up to about 1.5% may be used to reduce the cloud point.

It has also been found that the above-described mixtures are eifective in reducing the pour point of hydrocarbon oils. When used for this purpose, somewhat larger quantities of suppressor agent are generally desirable, generally not exceeding 2%.

Such quantities of wax suppressors as are used in this invention to suppress the separation of wax, may have no significant effect upon the pour point of the oil, but have a marked effect in preventing or retarding the separation of solid wax. However, when used in larger concentration, these suppressor mixtures do exhibit pour I point reducing properties. Many of these waxes may have their effectiveness increased by having their acid constituents, which are naturally present, saponified.

Thus, the beeswax may, for instance, be treat ed with lead carbonate, calcuim oxide, magneslum oxide, zinc oxide, cadmium. oxide, barium oxide or other bases to convert the acidic constituents into the corresponding metal soaps. The beeswax metal oxide or salt thus treated, when used in conjunction with viscous S02 soluble mineral oil fractions, often has a greater power for suppressing wax than when only plain beeswax is used with the viscous S02 soluble mineral oil fractions.

It is possible to use not only the ordinary vis-.

cous S02 soluble mineral oil fractions, but also the hydrogenated fractions such as albino asphalts described in ,the' copending application of Anderson, Serial -No. 293,339, filed September 5, 1939. i

The wax suppressor agents may be added to the oils at ordinary or at elevated temperatures.

If the oil beingtreated contains particles of separated solvent paraflin wax, it is generally desirable to warm the oil to dissolve this parrafl'inic wax prior to treatment. The time required for dissolving the suppressor agent can be decreased greatly by warming and agitating the mixtures.

In large scale operations it is often desirable to dissolve a large concentrated oil and suppressor agent solution to the main body of oil. A1- tematively, the suppressor agentscan be conveniently dissolvedin the oil by placing fragments of the mixture of agents in a perforated container which is suspended in the oil.

To illustrate the use and eilect of the present wax suppressor agents, the following examples are presented, it being understood that the present invention is not limited to the particular wax mixtures with viscous SO: solublemineral oil fractions, temperatures, concentrations, or details contained therein. While the mixtures of viscous S02 soluble mineral oil fractions and wax may contain these components in various proportions, it is preferable to use mixtures containing these components between the limits of 1:9 and 9:1 albino asphalts to wax. and still more preferable to set the limits between 3:1 and 1:3.

Examples A sample of a motor oil having a Saybolt Uni-- versal viscosity of 1000 seconds at F. and a viscosity index ofepproximately 55 was placed in a 4 oz. oil sample bottle and allowed to stand in an ice box for 48 hours. After standing a heavy crystalline deposition of wax was observed at the sides of the bottle (side wax) and a flocculent suspension of more amorphous wax was noted in the body of the oil (body wax).

The above test was repeated on the same oil under the same conditions with the exception that 0.1% of a blend of 33% beeswax and 67% 13 penetration albino asphalt was added. After 48 hours the oil so treated remained perfectly bright with no trace of wax precipate or surface wax.

A sample of'a motor oil having a Saybolt Universal viscosity of 100 seconds at 210 F. was placed in a 4 oz. sample bottle and allowed to stand in an ice box for 72 hours. After standing a heavy crystalline deposition of wax was observed at the sides of the bottle (side wax) and I a flocculent suspension of more amorphous wax was noted in the body of the oil (body wax).

The above test was repeated on the same oil and under the same conditions with the exception that .3% of a blend of 33% beeswax and 67% of an S02 extract of 500 S. S. U. viscosity at 210 F. from a heavy bulk distillate was added. After 72 hours the oil so treated remained bright with no wax precipitate or body wax, and but a slight trace of side wax.

Further tests were carried out with different motor oils using varying proportions of wax suppressor mixture. The samples were placed in a 4 oz. oil sample bottle and held at 45 F. for 72 hours. Commercially available beeswax and a 13 penetration albino asphalt was used in the tests. The lube oil extract used was an S0: extract of 500 S. S. U. viscosity at 210 F. from a heavy bulk distillate.

The appearance of the sample as to body wax and side wax was then visually observed and recorded on an arbitrary basis. 0 indicates no visible wax; 1 a small amount of visible wax; 2 a moderate amount of visible wax, and 3 a fairly heavy deposit of visible wax.

The results of these tests are tabulated below:

Percent added gg gg Oil treated M 3%;? Bees- Side Body asphalt wax wax wax None None 2 2 0.017 0.008 1 1- 0.033 0. 017 1 Motor oil Saybolt Universal vis- 8 cosltyoi 1,000 seconds at 100 F. 268 0:132 0+ 0 0.2 None 2 2+ None 0. 017 0+ 2 None 0.066 2 None None 3 3 0. 017 0. 008 0+ 0 0.033 0.017 0+ 0 0.067 0. 033 0 0 Motor 011 S. A. E. 40 0.025 None 0+ 2 0.05 None 0+ 2 0.10 None 1 2 None 0.05 0+ 2 None 0.10 0+ 0+ None N 011% 2+ 3 0. 067 0. 03 0 0 Motor 011 Saybolt Universal \lS- cosity of 100 seconds at 210 F (1)66 8 None 0.033 2 0 Heavy lube oil Beesextract wax Motor oil Saybolt Universal visgg 3 coslty of 100 seconds at 210 F 2 0+ 0 Lubricating oils containing our wax suppres- 'sors may contain in addition other wax suppressors such as chlorinated naphthalenes, oxidation inhibitors, blooming agents, extreme pressure agents, wedging agents, reducing agents, corrosion inhibitors, and other compounding ingredients. V

We claim as our invention:

1. A limpid normally liquid oil composition comprising a hydrocarbon oil containing paraffin wax in amount suflicient to impart an undesirably highcloud point to said oil in the abscence of a wax suppressor, and dissolved there-,

in a quantity of less than .1% of a mixture of albino asphalt together with a natural at least partly saponifiable wax, said quantity being sufiicient to suppress the separation of paraifin wax above the pour point of the hydrocarbon oil.

2. A limpid normally liquid oil composition comprising a'hydrocarbon oil containing paraffin wax in amount sufiicient to impart an undesirably high cloud point to said oil in the absence of a wax suppressor, and dissolved therein a quantity of less than .1% of a mixture of albino asphalt together with a natural at least partly saponifiable wax selected from the group consisting of beeswax, spermaceti, bayberrywax, candelilla wax, carnauba wax, cottonseed wax, Japan wax and montan wax, said quantity being suflicient to suppress the separation of paraffin wax above the pour point of the hydrocarbon oil.

3. .A limpid normally liquid oil composition comprising a hydrocarbon oil containing paraffin wax in amount suflicient to impart an undesirably high cloud point to said oil in the absence of a wax suppressor, and dissolvedtherein a quantity less than .1% of a mixture of albino asphalt with beeswax, said quantity being sulficient to suppress separation of parafiin wax above the pour point of the hydrocarbon oil.

4. A limpid normally liquid oil composition comprising a'hydrocarbon oil containing paraffin wax in amount suificient to impart an undesirably high cloud point to said oil in the absence of a wax suppressor, and dissolved therein a quantity less than .1% of a mixture of hydrogenated albino asphalt with beeswax, said quantity being sufiicient to suppress separation of parafiin wax above the pour point of the hydrocarbon oil.

5. A limpid normally liquid oil composition comprising a hydrocarbon oil containing paraffin wax in amount suificient to impart an unde-.

sirably high cloud point to said oil in theabsence of a wax suppressor, and dissolved therein a quantity less than .1% of a mixture of albino asphalt and beeswax and a substance from the group consisting of montan wax and carnauba wax, said quantity being sufi'icient to suppress separation of parafiin wax above the pour point of the hydrocarbon oil.

6. A limpid normally liquid oil composition