US2943990A - Process and composition for preparing sulfur-chlorinated cutting oils - Google Patents

Description

PROCESS AND COMPOSITION FOR PREPARING SULFUR-CHLORINATED CUTTING OILS Maurice K. Rausch, Harvey, and Thomas A. Francis, Chicago, Ill., assignors to Sinclair Refining Company, New York, N.Y., a corporation of Maine No Drawing. Filed Jan. 20, 1956, Ser. No. 560,293

4 Claims. (Cl. 208-18) This invention relates to the preparation of lubricating oils. More particularly, the invention is concerned with the use of extract oils in the preparation of lubricating oils having high chemical reactivity and low sludge forming tendencies. v

In the preparation of lubricating oils generally, and especially high viscosity index lubricating oils, from Mid- Continent, naphthenic and paraffinic crude oils, it is common procedure to subject the oil to an extraction step to obtain rafiinate oils of improved viscosity index, lower carbon content, resistance to sludging and oxidation and so on. Considering the yield of lubricating oil based on the feed, it is obvious that the extract oil constitutes a loss from a very valuable product, the lubricating oil, and the use of such extract for as valuable a purpose as possible is indicated.

The preparation of reactive lubricating oils for purposes such as cutting oils, for example, normally involves acid treating a parafiin distillate under conditions of severity calculated to produce the desired specification. Acid treatment is inherently expensive and is characterized by collateral problems of air and stream pollution and the necessity for disposing of the highly corrosive acid sludge resulting during the treatment. The present invention is particularly concerned with lubricating oils, especially lubricating oils of the type employed as cutting oils, produced from stocks including extract oils and in a manner avoiding the problems characterizing prior art production of such oils.

It has now been discovered that a reactive oil of low sludge forming tendencies can be produced in a manner which does not require an acid treating procedure. This is achieved by separating a select portion of an extract oil, advantageously where said extract oil is obtained in the production of a lubricating oil having a viscosity index of at least 85, to obtain a reactive oil as a rafiinate where the ralfinate includes about 20 to 40 volume percent of the original extract. By reacting these oils with a sulfur chloride, a cutting oil can be produced. The results achieved in accordance with this invention are considered to be entirely unexpected since it is generally thought that acid treating is essential to the production of a reactive oil.

Thus, the essence of the method of the present invention is the separation of a select portion of an extract oil in a manner whereby a reactive raifinate oil including about 20 to 40 volume percent of the extract is obtained. This can be accomplished by several methods. For example, where the extract o'il being" treated consists essentially of a blend of an extract oil and a paraflin distillate, the select portion desired can be separated by solvent extracting the blend with a solvent which is selective for aromatics to obtain a raffinate yield of about 20 to 90 volume percent based on the blend, the optimum yield of extraction of the blend depending primarily upon the quantity of extract present; A second general procedure for obtaining the select portion of extract oil involves phase separation. In this procedure the extract 2,943,990 Patented Juiy 5, 1960 is treated as a solution in a solvent selective for aromatics, either alone or with various amounts of paraffin distillate, for example up to about 0.75 part of distillate per part of extract and preferably from about zero to 0.25 part of distillate per part of extract. To separate the desired ralhnate fraction the solvent extract solution is subjected to conditions such that the solvency power of the solvent tor a portion of the solubilized oil is reduced and a phase separation occurs. This can be effected by the introduction of a non-solvent, or by lowering the temperature of the solution sutficieutly to effect a phase separation, or by a combination of injection of a nonsolvent and the lowering of temperature.

For the purposes of the present invention extract comprising at least about 25 volume percent of the material treated must be used. Thus, in general a blend consisting essentially of an extract and a paraffin distillate wherein the extract makes up at least 25 volume percent of the blend, and can comprise as much as 100 volume percent, is used as the starting material. Where it is desired to produce the oil by solvent extraction it is preferred to employ a blend containing about 25 to 60 volurne percent of extract and more particularly 30 to 60 volume percent. Optimum results are achieved with the phase separation procedure when the material approaches or is 100% extract. One of the significant reasons for this diversity of optimum extract concentrations can be attributed to how the invention is to be integrated with existing facilities. Thus where a supply of extract free of the solvent with which it is obtained is available, it usually is most desirable to blend the extract with a suitable distillate and solvent extract the resulting blend. On the other hand it may be more advantageous to process the extract immediately upon its production in order to avoid the necessity for providing storage facilities. In this event, it may be desirable to treat the solvent-extract solution as such and the described phase separation procedure is tailored for this alternative. While the parafiin distillate could be added to this solvent-extract solution, it can be seen that such procedure involves an additional step; thus 100 percent of the extract is optimum.

More specifically, where a solvent extraction of a blend containing the extract is to be carried out, about 50 to 600 volume percent of solvent at a temperature of about 90 to 150 F. when using phenol is employed while a. temperature of about 90 to 200 F. is used with furfural. Whatever solvent is employed tor the extraction to obtain the desired rafiinate conditions are adjusted so that about 20 to 40 volume percent of the rafiinate produced originates in the extract portion of the blend so that a sufliciently reactive oil in an adequate yield is obtained. This result is achieved generally simply by extracting the defined blend to a rafiinate yield of about 50 to 90 volnine percent based on blend. The optimum yield for any blend will depend upon its composition taking into consideration maximum reactivity of product and the economics of the process. Examples of optimum yield ranges are as follows: .for a blend containing about 45 to 60 percent of the extract, the optimum raflinate yield is about 50 to 70 percent; for blends containing 25 to 40 percent of the extract, a raflinate yield of about to percent appears to be best.

The phase separation method procedure of the invention can be accomplished by two general procedures or by a combination ofthe two procedures. For example the solvent extract solution as obtained in normal refinery practice can be cooled from its tower bottom temperature, that is from about 180 F. to a temperature Within the range from about to F. to produce a two phase separation; the upper phase is a rafiinate and comprises about 20 to 70 volume percent based on the volume of extract solution charged and preferably aboutj 25 to 60 volume percent and the lower phase is a solution of the solvent and the remaining portion of the extract. The lower phase is withdrawn and the solvent recovered, for example, by distillation or flashing. The upperphase is withdrawn from the settler, which can' be cfthe batch or continuous type, and distilled as 'by. vacuum distillation to remove any solvent present. The second general procedure of effecting phase separation, involves changing the solvents ability to hold the extract oil in solution by the introduction of a suitable material whioh 'is soluble in solvent at conditions met but is not a solvent for the extract oil. The preferred material for this procedure is water though, of course, other non-solvents can be used. By non-solven't is meant a material which, at the conditions of operation, does not solubilize extract oil yet is soluble in phenol and similar solvents employed to extract lubricating oils in the production of high viscosity index lube oils. :In accordance with the second general procedure a 'quantityof water is injected into the solvent-extract solution to separate out a rafiinate oil in a yield based on the volume of the extract charged of about 20 to 70 percent and preferably about 25 to 60 percent. As the effect of a non-solvent on the solvent present in the extractsolution varies with temperature, it will be apparent that the optimum quantity of non-solvent to be employed will be dependent upon the temperature. It is preferred to employ about 5 to 25 volume percent of water in conjunction with moderately low temperatures in order to minimize subsequent separatory problems though the phase separation can be effected merely by water injection alone at higher temperatures by using larger quantities of water. Temperatures of about 105 to 135 F. in conjunction with 5 to 25 percent Water produce satisfactory results.

Extract oils as employed in the present invention result upon the solvent extraction of lubricating oil fractions such as neutral oils, especially solvent extraction designed to improve viscosity index. Where the preferred Mid-Continent oils are involved the extract results upon' solvent extracting to produce a raifinate oil with a viscosity index of at least 85 and preferably at 'least.90. With paraflin base oils, such as Pennsylvania oils, the extract is usually obtained when an oil of a viscosity index of at least about 100 is the rafiinate product; With'naphthenic base oils, the extract is secured in the production of oils of lower viscosity index. 'Regardlessof the base oil used the extract is derived by treating a lubricating oil base stock with a solvent selective for aromatic constituents, for example, phenol, furfural,nitrobenzene or liquid sulfur dioxide or similar solvents. Phenol is preferred and generally about 10 to 1000 volume percent based on the lubricating oil treated is used and the extraction is carried out at a temperature of about 155 to 210 F. at atmospheric or elevated pressures. Employing furfural a temperature range such [as 150 to 250 F. is used while a lower temperature,

i.e. under 150 F. is used with sulfur dioxide. solvent is then recovered from the extract. For purposes of the phase separation step of the present invention, the solvent removal step is omitted and the extract as a solution in its solvent is used as such.

1 The other major component which may be present in the material treated in accordance with the invention is a paraflin distillate preferably having a viscosity of about 37 to 75 SUS at 210 F. obtained from any crude oil. :Raw paraflin distillate is intended to designatedistil- 'late fractions, for example any distillate lubricating oil, or other overhead or side stream from a vacuum or other type of a reduced crude, which need not have been jchemically or physically treated as'by acids, alkalies, earth contacted, solvent extracted or subjected to other similar treatment normally associated with commercial lubricant manufacturing. In addition to or in lieu of fisuch distillates, other materials such as deresined Penn- Normally, r

sylvania bright stock or deasphalted and deresined residuals can be present. The distillate and extract can be blended merely by pouring together at ambient temperatures.

5 The processing step in the present invention applied to the raflinate oil recovered in the select separation step can include dewaxing andearth contacting if necessary to meet specifications or if desired. Thesetwo.

processes are known in the art generally. Typical conditions for a dewaxing step, for example benzene-toluenemethylethyl ketone dewaxing, include employing about 100 to 600 volume percent solvent per volume. of oil treated at temperatures of about 0 to '20 =F;"-It is possibleto dewax the-extract or extract-containing blends prior to the select separation step; but in such instance, greater quantities'of oil heed 'be'handled since all of the oil is thus dewaxed rather than just the separated portion and additional dewaxing may be required to meet specifications and thus dewaxing as a first step frequently is uneconomic. The dewaxed material can be contacted .with clay such as fullers earth or bauxite or the like in an amount of about 2 to 15 pounds of clay per barrel of oil and at a temperature of about 200 to 400 F. to improve color and odor stability, if desired. Typical polishing or clean-upclay contacting can also be employed at the choice of the operator. The invention will be described further in conjunction with the following specific examples. It should be understood that the details disclosed are not to be considered as limiting.

EXAMPLE I e A raw paraifin distillate having a viscosity of 105 SUS at 100 F. and obtained as a side stream inthe vacuum distillation of a Mid-Continent reduced crude-oil was countercurrently extracted in a tower by passing about 2 volumes of technical grade phenol per volume of distillate into the tower to produce a 95 viscosity index lubricant as raffinate and a percent phenol extract 49 solution. The tower was maintained at an 'averagetem- 'perature of about 185 F. by controlling the temperature of the feed streams. The extract produced had the following properties as determined from a sample from which the phenol was removed: API gravity, 19.7; viscosityat 100 45 183.9 SUS; viscosity at 210 F., 42.31 SUS; viscosity in- .dex 11; carbon residue .032%; specific dispersion 180; and aniline point 56.7 C. The solution of phenol and extract was withdrawn from the bottom of the tower and then passed into a cooler and heat exchanged, by cold 50 water passing through a tube immersed in the solution, to a temperature of about 105 "F. The cooled extract was then passed to a settler and permitted to remainin an unagitated state for 1 hour during which a phase separation intoitwo phases occurred. The resulting upper phase, which amounted to a yield of 34.2% based on the volume of extract oil fed to the settler, was withdrawn from the settler, passed through a heating coil, and then into a stripper where phenol was removed. The oil was 'then dewaxed by adding 5 volumes of a mixture contain- 0 ing 25 volume percent benzene, 25 volume percent toluene and 50 volume percent methylethyl ketone and filtering at a filter temperature of 5 R; which resulted in a dewaxed oil yield 77.3% of +10 F. pour point. The filtrate was clay contacted at 225 F. by adding 10 pounds 5 of Attapulgus clay per barrel of oil and filtered. The filtrate was recovered as product. '1 v A sample of a lubricating oil produced according to substantially the same process under the same conditions and from similar charging stocks as about described-was sulfur-chlorinated by treating with an excess of sulfurmonochloride for 7 hours at a temperature maintained the range of about to 'F. Excess sulfurmonochloride was then removed by air blowing at a tem- Tperature maintained within the range of about 170 to 75 210 for 18 hours and at room temperature for an adthe sulfur-chlorination. Significant data on the sulfurchlorinated product and on the dewaxed oil obtained from the extract prior to sulfur-chlorination are contained in the following table.

Table 1 Dewaxed Sulfur- Oil Chlorinated Extract Product Gravity, API 27. 4 23.6 Flash, F 400 395 Fire, F 440 435 Viscosity, SUS at 100 F 135. 5 177. 2 Viscosity, SUS at 210 F 41. 04 43. 7 Vi r'n ity Index 59.8 Pour, F 10 10 Color, N PA 2- 2+ Specific Dispersion- 129. 7 Aniline Point, C- 83. 2 Sulfur, percent 0.47 3. 66 Chlorine, perc nt 0.76

From these data it is apparent that a highly reactive nonsludging oil has been produced. Reactivity is especially evidenced by the sulfur content which increased from about 0.47% to 3.66%. Sulfur-chlorinations with these reactive oils usually result in sulfur contents in excess of about 2.5%. The stability of the product is apparent from the small color change on the NPA color test 2 to 2+. Stability is also evidenced by a storage test of a sample of the sulfur-chlorinated oil for 40 days. At the end of this period the sample was bland and free of sludge.

Sulfur-chlorinated products can be made with the reactive oil of this invention by any of known procedures. In general it is desired to have as high a sulfur content as is possible and accordingly an excess of the sulfurchloride is used, though smaller amounts may be used if desired. The reaction generally is conducted at about atmospheric pressure and a temperature of about 125 to 250 F., preferably in the presence of an inert atmosphere if the reaction mix is stirred vigorously. Reaction generally is complete in about 1 to 10 hours or more. Standard purification procedures are then applied aud usually include air blowing for purposes of removing excess sulfur-chloride and odor stabilization.

EXAMPLE II Samples of the oil shown in Table I of Example I (before sulfur-chlorination) were reacted with sulphur under the following conditions:

I. For 6 hours at 250 to 260 F. with 1.07% sulfur.

H. For 6 hours at 300 to 310 F. with 1.07% sulfur.

III. For 6 hours at 300 to 310 F. with excess sulfur; the excess was removed by filtration after the product had cooled to room temperature.

The sulfurized oils were analyzed; significant data obtained are:

Table II I II III Temperature of Sulfurizatlon, F 250-260 300-310 300-310 Added Sulfur, percent 1.07 1.07 Excess Gravity, API 26. 6 26. 4 26.1 Flash, F 380 410 400 Fire, F 435 445 445 Viscosity, SUS at 100 F 135. 7 139. 4 141. 0 Viscosity, SUS at 210 41. 04 41. 24 41. 40 Pour, F 5 5 15 Color, N PA 3- 8- Dark Sulfur, percent 1. 52 1. 57 2. 19 Sulfur, percent After 30 Days at 32 F 1. 13 1. 47 1.74

'From Table I in Example I above it can be seen that the original sulfur content of the samples was about 0.47% Thus, the oil took up 1.05% sulfur in case I, 1.07% sulfur in case II and 1.72% sulfur in case III thus again emphasizing the reactivity of the oil. These data also make it apparent that the reactivity of the oil, as shown by sulfur take-up, is a property of the oil and is substantially independent of temperatures, length of treatment and quantity of reactant, for example quantity of sulfur, employed. The data obtained in the 30 day storage test at 32 F. demonstrate that the reactive oils of the present invention are fully equivalent in sulfur retention to reactive oils produced by prior art acid treating procedures. Sulfurized oil I, in the table, is marketable as is in view of its light color and bland odor while oils II and III can easily be commercialized by conventional odor and color correction treatments.

EXAMPLE III A raw paraflin distillate oil obtained as a side stream in the vacuum distillation of a Mid-Continent reduced crude and having an API gravity of 29.4", a flash point of 375 F., a viscosity of 100 SUS at 100 F. and a pour point of F. was blended with an extract obtained by phenol extraction of a raw Mid-Continent distillate designed to produce a finished dewaxed oil of viscosity index. In the extraction a solvent oil ratio of 1.7 to 1 was used, the tower temperature ranged from about to F., 3 percent of water was introduced with the phenol and an additional 1 percent was injected during the process. The extract had an API gravity of 20.5, a viscosity index of 11, a specific dispersion of 180, a flash point of 385 F. and a viscosity of 42 SUS at 210 F. and about 2256 barrels of the extract were blended with about 4558 barrels of the distillate, approximately a 1:2 ratio. The blend was fed to the lower portion of a phenol extraction tower at a rate of about 6,814 b./d. while technical grade phenol (containing about 9 percent water) was introduced into an upper portion of the tower at a rate of about 4,992 b./ d. The tower was maintained at top and bottom temperatures of about 130 F. by control of the inlet temperature of the feeds. About 1.3 percent of water based on the phenol used was injected into the bottom of the tower. A waxy raflinate in a yield of 84.9 percent based on the blend was obtained. The waxy rafiinate was then dewaxed by adding to it a solution containing 25 volume percent benzene, 25 volume percent toluene and 50 percent methylethyl ketone in an amount of about 5 volumes of the solvent mixture per volume of raflinate and the resulting mixture filtered at a filter temperature of 10 F. The dewaxed filtrate testing at +5 F. pour point and obtained in 86.5 percent yield based on the amount of rafiinate fed to the filter was then treated with Filtrol No. 70 in an amount of 6 pounds of the clay per barrel of filtrate and filtered at 300 F.

Merely as an auxiliary check on the process to determine what percentage of the raflinate originally was extract, the following calculation was made:

With 100% of the distillate in extracting with phenol at equivalent severity yield normally is 87.1% .'.0.871X4558=3970 b./d. of original distillate in raflinate 1815 barrels of raflinate from extract X 100%=31.4% of raflinate or g 'of hydrochloride, and the product filtered. No sludge resulted during the sulfur chlorination. Significant data on the reactive oil and on the sulfur-chlorinated product are: g g p M Table III Laboratory tests on reactive oil; p 7 I 7 Gravity n 2.: 27.2 7 Flash, F 370 Fire, F. 1 n a 43 Vis., SUS at 100 F. 125.4 -Vis., SUS at-210 F. n 40.37 Viscosity index 58.3 Pour, F. Color, NPA .2- Colorresidue v 0.002 Color stability 2-, 2+ Sulfur percent 0.39 'Specific dispersion 130.6

, Sulfur-chl0rinated product: 1 H Sulfur percent. g 2.58 Chlorinepercent 3, 7 0.63

The excellent color stabilityof the oil produced and good sulfur content of its reaction product are readily for a' commercial product and the take-up of sulfur (difference'between original sulfur and end product) is an indication of; reactivity. The high specific dispersion shown also is an indication that the'oil produced is reactive. The fact that no sludge formed during the sulfurchlorination is evidence of the low sludge forming tendencies of thereactive oil. a

From the foregoing it is apparent that the present invention discloses an advantageous method of producing lubricating oils which are characterized by high reactivity yet are stable and have low sludge forming tendencies. The process is further advantageous in that the described results are achieved without the expensive acid treatment characteristic of prior art processes forproducing reactiveoils. v w a What is claimed is: a v

1. A method for producing a reactive oil product of low sludge forming tendenciesfi'om an extract oil obtained in the extraction ofa lubricating oil stock with a solvent selective for aromatics to produce a primary raffinate oil and said-extract oil, the step comprising extracting with a solvent selective for aromatics a material consisting essentially of said extract oil and a paraflin distillate, said extract being present in an amount of at least 25 volume percent of the total, to produce a secondary raflinate oil in a yield of about 20 to 90 volume percent of the material treated containing about 20 to 40 volume percent of the extract. 3 v 7 12.,A sulfur-chlorinated mineral oil which comprises the reaction product of a sulfur-chloride and areactive 'oil of low sludge forming tendencies, said reactive oil being a secondary rafiinate oil separated from an extract oil and including about 20 to 40 volume percent of said extract oil, said extract oilbeing obtained in the extraction of a lubricating oil stock with a solvent selective for aromatics to produce a primary raffinate oil and said ex- .tract oil, said reactive oil being'further characterized by being less soluble in a solvent which is selective for aromatics than the unseparated portion of said extract. a 1 3. A method for producing a sulfur-chlorinated mineral "oil which ,comprises the steps of separating a secondary rafiinate oil from anext'ractjoilobtained inthe' extraction of a lubricating oil stock with a solvent selective for aromatics to produce'a primaryj rafiinateoil and said extract oil, said separated secondary raflinate oil. including'about 20 to 40 fvolur'ne percentofrthe, extract oil and being characterized by being less soluble in a solvent which is selective for aromatics than the unseparated portion, and reacting said separated secondary raflinate oil with a sulfur-chloride to obtain a sulfur-chlorinated mineral oil.

4. A method for producing a sulfur-chlorinated mineral oil which comprises the steps of extracting with a solvent selective for aromatics a material consisting essentially of an extract oil and a paraflin distillate to produce a secondary rafiinate oil in a yield of about 20 to volume percent of the material treated containing about 20 to 40 volume percent of the extract oil, and reacting said secondary rafiinate oil with a sulfur-chloride to obtain a sulfur-chlorinated product, said extract oil in said material being present in an amount of at least 25 volume percent of the total and being obtained in the extraction of a lubricationg oil stock with a solvent selective for aromatics to produce a' primary rafl'inate oil and said extract oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,024,476 Rutherford Dec. 17, 1935 2,178,312 Clarke Oct. 31, 1939 2,218,997 Wasson Oct. 22, 1940 2,220,016 Lyons Oct. 29, 1940 2,367,468 Mixon et al Ian. 16, 1945 2,374,102 Jahn et a1. Apr. 17, 1945 2,560,548 Bartleson July 17, 1951 2,695,865 Mills Nov. 30, 1954 2,773,005

Meyer et al Dec. 4, 1956

Claims (1)

1. A METHOD FOR PRODUCING A REACTIVE OIL PRODUCT OF LOW SLUDGE FORMING TENDENCIES FROM AN EXTRACT OIL OBTAINED IN THE EXTRACTION OF A LUBRICATING OIL STOCK WITH A SOLVENT SELECTIVE FOR AROMATICS TO PRODUCE A PRIMARY RAFFINTE OIL AND SAID EXTRACT OIL AND A PARAFFIN DISTRACTING WITH A SOLVENT SELECTIVE FOR AROMATICS A MATERIAL CONSISTING ESSENTIALLY OF SAID EXTRACT OIL AND A PARAFFIN DISTILLATE, SAID EXTRACT BEING PRESENT IN AN AMOUNT OF AT LEAST 25 VOLUME PERCENT OF THE TOTAL, TO PRODUCE A SECONDARY RAFFINATE OIL IN A YIELD OF ABOUT 20 TO 90 VOLUME PERCENT OF THE MATERIAL TREATED CONTAINING ABOUT 20 TO 40 VOLUME PERCENT OF THE EXTRACT.