US3553107A - Production of white oils from hydrotreated and acid contacted oil stocks - Google Patents

Abstract

WHITE OILS ARE PRODUCED FROM A LUBRICATING OIL STOCK CONTAINING 5-30% AROMATICS BY VOLUME. THE PROCESS SUBJECTS THE LUBRICATING OIL STOCK TO HYDRO-TREATMENT AT 650-725*F. AT A PRESSURE BETWEEN 2,500-3,000 P.S.I.G. AND LHSV OF 0.5-3 WITH A CATALYST CONTAINING A HYDROGENATING COMPONENT SELECTED FROM GROUP VI AND GROUP VIII METALS AND A CARRIER FOR SAID METAL COMPONENT HAVING AN ACTIVITY INDEX OF LESS THAN 25. THE HYDROTREATMENT STEP REDUCES THE AROMATIC CONTENT TO LESS THAN 4% BY VOLUME AND NO SUBSTANTIAL HYDROCRACKING OCCURS. THE HYDROTREATED MATERIAL IS CONTACTED WITH FUMING SULFURIC ACID, 0.02-0.06 VOL. OF ACID/VOLUME OF OIL, THE OIL IS NEUTRALIZED WITH CAUSTIC AND EXTRACTED WITH ALCOHOL TO REMOVE SULFONATES. THE ALCOHOL-EXTRACTED MATERIAL MAY BE FURTHER SUBJECTED TO DEHYDRATION AND THEN CONTACTED WITH CLAY. THE PROCESS PROVIDES A MINIMAL PRODUCTION OF ACID SLUDGE AND SULFONATE BY-PRODUCT WITH EXTREMELY HIGH YIELD OF FINAL WHITE OIL.

Description

R. E. DONALDSON ETAL 3,553,107 PRODUCTION OF WHITE OILS FROM HYDROTHEATED Jan. 5, 1971 AND ACID CONTACTED OIL STOCKS Filed June 5, 1968 "k502i 3 m :o FN mm 2.3; mozmeiwo vfl z mmn 105528 2 6 $35: 8 613 2 uz o 5m o 0%? m a $5; mm mm 8.632 g 3 I mm 3 255 v 2 1056.28 $5528 $5528 .1 I I I mm N 3 av N v 8 EnEEE vn 53 m-I OIoo 02 9 30 Q u o m3| 5m NI oz .55. 8 US$56 :6.

EFEEEQI o QHE Immmm E United States Patent US. or. 20s 271 8 Claims ABSTRACT OF THE DISCLOSURE White oils are produced from a lubricating oil stock containing -30% aromatics by volume. The process subjects the lubricating oil stock to hydro-treatement at 650-725 F, at a pressure between 2,5003,000 p.s.i.g. and LHSV of 0.5-3 with a catalyst containing a hydrogenating component selected from Group VI and Group VIII metals and a carrier for said metal component having an activity index of less than 25. The hydrotreatment step reduces the aromatic content to less than 4% by volume and no substantial hydrocracking occurs. The hydrotreated material is contacted with fuming sulfuric acid, 0.020.06 vol. of acid/ volume of oil, the oil is neutralized with caustic and extracted with alcohol to remove sulfonates. The alcohol-extracted material may be further subjected to dehydration and then contacted with clay. The process provides a minimal production of acid sludge and sulfonate by-product with extremely high yield of final white oil.

Our invention relates to an improved process for the production of white oils from an aromatic stock by subjecting the charge stock to hydrogenation followed by a single acid contacting step. Specifically, our process produces white oils in high yields while minimizing production of undesired acid sludge and sulfonates.

It has previously been suggested in the art that extremely high quality materials, called white oils, could be produced from hydrocarbons boiling generally in the lubricating oil range by subjecting such materials to a series of acid treatment operations. Such previously suggested technique, however, had several distinct disadvantages in that the chemical cost of the operation was comparatively high due to the consumption of substantial quantities of acid in each contracting operation and that with each subsequent acid contacting operation the quantity of white oil product potentially available was diminished. Furthermore, with the multiple acid contacting operations the total quantity of acid sludge and sulfonates produced increased resulting in an excessively high production of the undesired sulfonate by-product and the production of excessively large quantities of acid sludge which presents an ever-increasing disposal problem. It is believed that in connection with such previously suggested multiple acid contacting processes the problems and disadvantages of such techinique increase in proportion to the aromatic content of the initial charge stock being processed. Accordingly, the treatment of an initial charge stock containing more than but a few percent of aromatics resulted in the compounding of the undesirable side effects mentioned above. I

We have discovered a process for the production of white oil from a lubricating oil boiling range stock containing from about 5 to about 30 percent by volume of aromatics by subjecting such charge stock to a particular type of hydrogen treatment followed by a single contacting of such hydrogen treated material with sulfuric acid and then recovering white oil as product from the acid contacted material.

3,553,107 Patented Jan. 5, 1971 The feed stocks suitable for employment in our process include generally any lubricating oil stock, which stocks usually boil in the range from about 600 up to about 1100 F. As mentioned previously, the process of our invention is designed for the treatment of such stocks containing between about 5 and 30 percent by volume aromatics. Such materials can be either raw or solvent extracted lube oil stocks of either substantially parafiinic or naphthenic composition as well as stocks from single pass or recycle lubricating oil hydrotreating, provided such stocks contain between 5 and 30 percent by volume aromatics. The process of our invention is distinctly advantageous in the treatment of stocks containing more than about 10 percent aromatics. Generally, when treating lower boiling lubricating oil stocks, e.g. boiling from about 600 up to about 750 to 800 F., aromatic contents up to about 30 percent by volume, or slightly higher, are satisfactory. When treating higher boiling charge stocks, e.g. boiling up to about 1100 F., it is preferred to employ stocks having an aromatics content of less than about 20 percent by volume. The charge stock employed in our inventive process can also be a lubricating oil stock which has previously been subjected to dewaxing and, in fact, at times it may be desirable to employ dewaxing as a pretreatment step when dealing with paratfinic stocks.

The aromatic-containing charge stock treated in accordance with our invention is subjected to a particular type of hydrogen treatment which accomplishes substantial hydrogenation of aromatic materials to naphthenic materials, while efiecting substantially no cracking or hydrocracking, i.e. no substantial production of lOWer boiling materials. Of the three major types of hydrogen treating operations generally associated with the lubricating oil field, i.e. hydrocracking, hydrotreating and hydrofinishing, the hydrogen treating operation employed in our invention falls generally in the range of hydrotreating. Thus, hydrocracking is an extremely severe operation wherein comparatively high boiling hydrocarbons, e.g. stocks containing components boiling above about 1000 F., are treated so as to effect somewhat random severing of carbon-to-carbon bonds, thereby resulting in a substantial overall reduction in molecular Weight and boiling point of the treated material in order to produce substantially large quantities of materials boiling below about 600 F. and a somewhat lesser quantity of materials boiling in the lubricating oil range from about 600 to 1000 or 1100 F. In hydrocracking, at times, the production of lubricating oil can be merely incidental to the production of gasoline and furnace oil. Hydrofinishing on the other hand, is the least severe treatment of the three operations mentioned above and generally is conducted by employing a catalyst having substantially no cracking activity. Accordingly, this mildest hydrofinishing operation affects substantially only reduction of sulfur, oxygen and nitrogen content with a comparatively small amount of, if any, aromatic saturation.

The area of hydrotreating is generally considered to be intermediate hydrocracking and hydrofinishing in its severity and capable of producing somewhat more substantial molecular rearrangement than does hydrofinishing while not effecting the excessive and somewhat random breakdown of molecules effected in hydrocraoking. Hydrotreating can also be effective for the saturation of aromatic compounds. (Within this general area of hydrotreating it is essential to the operation of our process that a comparatively severe hydrotreating can be effected wherein there is substantial saturation of aromatics to naphthenes. Generally, it is necessary to effect saturation of at least 50 percent of the aromatic materials present in the initial feed stock and preferably a higher saturation of aromatics is effected, such as, for example, about to percent or more. Although the hydrotreatmg operation of our invention must be sufficiently severe to effect substantial saturation of aromatics, it must not be so severe as to result in hydrocracking or the production of any substantial quantity of lower boiling materials. It is believed that the comparatively severe hydrotreating of our operation effects reactions involving primarily saturation of aromatics to form the corresponding naphthenes together with the formation of single ring naphthenes either by the course of saturation and splitting of polyaro'rnatic structures bonded by sulfur or nitrogen, e.g. diberizothiophene," or by the course of saturationof condensed aromatics to condensed naphthenes followed by the selective s'cission of the condensed naphthenic rings to form single ring alkyl naphthenes wherein the alkyl side chains formed are not severed from the cyclic nucleus.- r

in conducting the comparatively severe hydrotreating step of our invention a temperature in the range from about 600 to about 750 F. and preferably from about 650 to 725 F. is employed. Other operating conditions include a pressure between about 2000 to about 3500 pl's.i.g.and preferably from 2500 to 3000 p.s.i.g., a liquid'hourly space velocity from about 0.5 to about 310 and preferably from about 0.5 to about 1.5 volumes of hydrocarbon per volume of catalyst per hour and a hydrogen feed rate from about 2000 to about 10,000 standard cubic feet per barrel and preferably from about 4000 to about 6000 standard cubic feet per barrel. While it is not necessary to employ 100 percent pure hydrogen in the hydrotreating step of our invention and while we have found that hydrogen rich streams of the type generally available in refinery operations, e.g. 70 percent plus hydrogen, are quite acceptable, we prefer to employ as high a hydrogen concentration as possible, e.g. 95 percent. The particular operating conditions to be employed in any specific operation will, of course, vary to a certain extent depending upon the properties of the charge stock being treated. Accordingly, the operating conditions to be employed in the hydrotreating step of our invention must be selected so as to produce a hydrotreated material having an aromatics content of less than about 4 percent by volume and preferably lower. Thus, hydrotreated materials having an aromatics content in the range from about 1 to about 2 percent by volume are usually satisfactory. Also, the hydrotreating operation of our invention is to be conducted so as to provide a hydrotreated material having an Iodine Number of less than about 6.0 and preferably less than about 4.0. Advantageously, the hydrotreated material should have an Iodine Number of less than about 2.0. We have found that in conducting our hydrotreating step to produce the low aromatics content material without hydrocracking to lower boiling materials, Iodine Numbers as low as 1.0 and even 0.5 can be achieved conveniently.

Furthermore, the operating conditions employed in our hydrotreating step must be selected, in conjunction with the catalyst, so as to preclude any substantial degree of the random carbon-to-carbon cleavage typical of hydrocracking and minimize production of substantial amounts of lower boiling materials from such cause. Of course a certain reduction in boiling range of the hydrotreated material versus the untreated charge stock will be noticed but this reduction in the boiling point of some components is the result of hydrogenating aromatics to naphthenes. Generally, the yield of lubricating oil boiling range materials, e.g. boiling above the initial boiling point of the lubricating oil charge from our hydrotreating step will be at least about 90 percent by volume based upon charge and preferably at least about 95 percent by volume or higher.

The catalyst to be employed in our hydrotreating step is comprised of a metalliferous hydrogenating component distended on a material of somewhat limited cracking activity generally a material having an activity index of less than about 25. Thus, for example, we can employ catalysts comprised of Group VI and Group VIII metals, their oxides or sulfides, distended on an alumina support. Preferred catalysts include combinations of nickel and tungsten as well as nickel, tungsten and fluorine on alumina, such as, for example, catalysts containing equimolar proportions of nickel and tungsten and containing 10 to 30 percent by weight metals Preferably about percent by weight metals, such as a 6 percent by weight nickel and 19 percent by weight tungsten on alumina catalyst. Advantageously, however, the catalyst to be employed in our hydrotreating step is comprised of equal weight proportions of nickel and tungsten with a total metals content ranging from about up to about 50 percent. by Weight based upon thetotal catalyst. Thus, for example, a particularly preferred catalyst is one composed of 20 percent'by .w'eight'nickel and 20 percent by weight tungsten on' alumina. Preferably, such catalyst can also contain about 2 percent by Weight fluorine. Additionally, we have found that when employing such 20 percent by weight nickel, 20 percent by weight tungsten and 2 percent by weight fluorine on an alumina catalyst, a small quantity of fluorine, such as, for example, from about 1 to about 10 ppm. and preferably about 4 p.p.m.,-can be added to the hydrotreating'operation along with the hydrocarbon feed stock.

The hydrotreated material of substantially reduced aromatic content is then subjected to a single acid treatmentor aciddump by contacting it with fuming sulfuric acid or oleum containing up to about 20 percent free S0 This acid contacting step of our invention can be conducted at a temperature in the range from about to about 250 F. and preferably from about 100 to about 200 F. Normally, atmospheric pressure will be employed. The acid to oil ratio employed can vary from about 0.01 up to about 0.10 volumes of acid per volume of oil'and preferably is in the range from about 0.02 up to about 0.06'volumes of acid per volume of oil. The acid contacting step of our invention can be conducted as either a continuous or batch operation. Generally, no more than 20 percent of the acid is consumed in the single acid dump of our invention. Usually acid consumption will be less than 15 percent and advantageously is most often less than about 10 percent.

Subsequent to the acid treatment step of our process the hydrocarbon product material is recovered from the total efliuent by separation of the hydrocarbon phase from the acidphase and isolation of the desired White oil from acid sludge and sulfonates. 'Again, this recovery of product can be conducted as either a continuous or batch operation in accordance with techniques well known in the art including, for example, neutralization, steaming,-stripping and clay contacting or percolation. We have found it advantageous to employ in the recovery operation of our-process first a caustic neutralization of I the eifluent from the acid contacting followed by an alcohol'or alcohol and water extraction and then a vacuum stripping or dehydrating treatment whereby the desired white oil'product can be removedfrom theacid sludge and sulfonate by-product.

Although it is not necessary, we have found that the white oil product of-our invention can be even further improved in quality by subjecting it to clay treatment after it has been recovered from the acid .contacting efiiuent.

We have found that the processof our invention is effective to provide extremely high yields of finished white oils with yields of acid treated materials ranging up to better. than percent and at times greater than 97 percent based upon charge to acid treatment while simulta'neous'ly effecting a large reduction in acid sludge produc- 'tionfthereby'minimizing disposal problems, and while simultaneously providing a very low or negligible yield of aromatic sulfonates.

"In order to describe our invention in greater detail, reference is made to the attached drawing showing a schematic flow diagram of the process of our inventionl A lubricating oil stock boiling generally above about 600 F. and containing more than about percent by volume aromatics is passed via line to hydrotreater 12. Hydrogen gas is added into line 10 by means of line 14 prior to introduction into hydrotreater 12. The combined hydrogen and lubricating oil stock are contacted in hydrotreater 12 with a catalyst comprising a metalliferous hydrogenating component distended on a carrier of limited cracking activity under appropriate hydrotreating conditions of temperature, pressure,' space velocity and hydrogen feed rate. These conditions are selected so as to effect substantial saturation of aromatic components in order to provide a hydrotreated material having an aromatics content less than about 4 percent by volume. The eflluent from hydrotreater 12 is removed by means of line 16 and passed to gas-liquid separator 18 wherein hydrogen and other gaseous materials such as hydrogen sulfide are separated. The gaseous materials are removed from separator 18 by means of line 20 and the hydrogen component from this gaseous stream can be recycled to hydrotreater 12 by means not shown. The liquid from separator 18 is then passed by means of line 22 to a vacuum stripper 24 wherein lighter materials boiling below about 600 F. are stripped therefrom and removed overhead by means of line 26. A suitable stripping medium such as steam is introduced into stripper 24 by means of line 28. The stripped, hydrotreated material comprising at least about 90 percent by volume and preferably 95 percent by volume or greater based upon the fresh feed is removed from stripper 24 by means of line 30 and passed to contactor 32.

Fuming sulfuric acid or oleum containing up to about 20 percent S0 is added to line 30 by means of line 34 prior to introduction of the hydrotreated material into contactor 32. The amount of fuming sulfuric acid added by means of line 34 to line 30 will generally be in the range from about 2 percent to about 6 percent by volume based on hydrotreated material. Acid sludge is taken from contactor 32 by means of line 36 and is removed from the system. This acid treating step constitutes the single acid contacting or single acid dump of our invention.

The acid contacted hydrocarbon in an amount of at least about 95 percent by volume based upon hydrocarbon charge to the acid contactor is removed therefrom by means of line 38 and passed to contactor 40. A caustic stream, such as, for example, an aqueous sodium hydroxide stream with a sodium hydroxide concentration from about 5 to 20 percent, is introduced by means of line 42 into line 38 prior to its introduction into contactor 40. A spent caustic and water stream is taken from contactor by means of line 44 and is removed from the system. The now caustic neutralized material is removed from contactor 40 by means of line 46 and passed to contactor 48. An alcohol stream is added to line 46 by means of line 50 prior to introduction of the caustic neutralized material into contactor 48. Usually the alcohol stream of line 50 can be a mixture of a lower alkyl alcohol, such as, for example, isopropyl alcohol, and water with the alcohol comprising 25 to 80 percent by volume of the mixture and preferably greater than 50 percent by volume of the mixture.

The alcohol stream of line 50 is effective to extract sulfonates from the acid contacted and neutralized hydrocarbon so as to provide a substantially sulfonate-free raffinate. The alcoholic extract is removed from contactor 48 by means of line 52 and passed to separator 54 wherein an alcohol and water stream can be separated and removed therefrom by means of line 56 for recovery of alcohol values. The separated sulfonate is then removed from separator 54 by means of line 58.

The contactors 32, 40 and 48 can comprise any of the contacting apparatus well known in the art, such as, for example, Podbielniak contactors.

The rafliniate phase from contactor 48 is removed therefrom by means of line 60 and passed to a vacuum stripper-dehydrator 62 wherein it is stripped with an appropriate stripping medium, such as nitrogen, introduced via line 64 while being maintained at an elevated temperature generally somewhat above the boiling point of water or the particular alcohol employed in contactor 48 so as to remove the final traces of water and alcohol from the hydrocarbon stream. The trace alcohol mixture is removed from stripper-dehydrator 62 by means of line 66. The dehydrated hydrocarbon from stripper-dehydrator 62 is removed therefrom by means of line 68 and passed to clay contactor 70 wherein it is contacted or percolated through a bed of any of the well known clay adsorbents in order to remove any final traces of contaminants remaining from the acid treatment and recovery operations. The white oil product is removed from clay contactor 70 by means of line 72.

In order to describe our invention in further detail, reference is made to the following examples.

EXAMPLE I In this example portions of two solvent extracted and dewaxed feed stocks boiling above about 600 F. and containing more than 5 percent by volume of aromatics were treated in accordance with two different techniques so as to provide a material passing the Carbonizable Substances Test (ASTM D 565), a requirement of white oils. One portion of each of these two stocks was subjected to conventional acid contacting following the Sherwood procedure to provide a material passing the Carbonizable Substances Test. The other portion of each of these stocks was subjected to comparatively severe hydrotreating, as required by our invention, prior to the first acid contacting of the Sherwood procedure.

In accordance with the Sherwood procedure 2000 grams of the oil to be treated were added to a three-necked, round bottom flask equipped with a motor-driven stirrer, a thermometer and a dropping funnel. Vigorous stirring was commenced and 200 grams of fuming sulfuric acid (20 percent free S0 were slowly added through the dropping funnel during a period of about five minutes. The initial temperature of the oil was about 25 C. and no heating or cooling were applied during acid addition. After the 200 grams of acid had been added, the stirring of the mixture was continued for an additional ten minutes.

The acid sludge was separated from the sour oil either by centrifuging at above 2000 rpm. or by settling in a large separatory funnel overnight. The sour oil was then passed to a second three-necked flask equipped with a stirrer and a thermometer. A quantity of isopropyl alcohol constituting 12.5 percent by volume based upon the sour oil was added to the flask. Next, a 20 percent aqueous sodium hydroxide solution was slowly added to the flask with vigorous stirring until the mixture was neutralized to a pH of 8 as shown by moist pH indicator paper. At this time additional water was added to the mixture so that the final strength of the alcohol-water mixture in the system was 50 percent. This neutralized mixture was then heated to 158 F. and stirred for fifteen minutes.

The heated and neutralized mixture was then transferred to a separatory funnel and settled until a clean separation of layers was obtained (usually three layers are obtained-a lower aqueous brine layer, a middle alcohol-sulfonate extract layer and a top oil layer). The brine layer was drawn off and discarded and the alcohol sulfonate extract layer was drawn off and saved for calculation of sulfonate content.

The remaining oil layer was then placed in a flask and heated to a temperature in the range from 230 to 248 F. and blown with nitrogen for thirty minutes to remove all traces of alcohol and water. The oil layer was then cooled to room temperature. This procedure constitutes one acid dump.

The above described procedure was then repeated until a product material passing the Carbonizable Substances Test was obtained.

The inspectiondata for each of the raw charge stocks is shown in Table I below. One portion of each of these charge stocks was then subjected to severe hydrotreating in the presence of a catalyst comprising 20 percent nickel, 20 percent tungsten and 2 percent fluorinesupported on 8 EXAMPLE 11 In this example the two. solvent extracted and dewaxed feed stocks identified in Example I as well. as a third solvent extracted and dewaxed feed stock were subjected an alumina'having an activity index of less than about 20 to treatment in accordance with our invention for the and C Y from the HaFShaW Qhwllcal production of white oils employing the techniques de- C P Y designated as The {p scribed in conjunction with the drawing. The Raw Charges dltlons 1n eachl of h v f operaggns mcluded I and II were subjected to hydrotreating employing the an z g g f f g i 7O catalyst and operating conditions described in Example'i l sure 0 an a lqul our y space V6 061 y 0 so as to produce respectively, Hydrotreated Stocks. Iand Livoluriles of charge per Volume of catalyst per hour II' having the ins ections shown in Table I of Exam 1e-"I The yield from each of the hydrotreating operations is The and f d f k h d th h also shown in Table I. Inorder to illustrate the advan- H b 1 l ,5; 3 F m-spec Ions? oWn,n i ta geous eife ct of our invention, eachvof the ra-wcharge e 15 W arge III was Sublected i f stocks and. each..of the hydrotreated stocks were then hydrotreatment m x the a a y as subjected to treatment in accordance with the Sherwood x m I and p y p COIldltlOBS l ng procedure to provide a material passing the Carbonizable an average Outlet temperature of about 7 1 1 Substances Test. The results of such treatment are shown u f about 3000 p.s.i.g. and a liquid hourly space velocin Table I below. ity of about 1.0 to provide HydrotreatedStock III.

TABLE I Hydro- Hydro- Raw treated Raw treated Charge I Stock I Charge II Stock II Yield from hydrotreatment, percent by vol.:

Overhead 5. 0 7. 6 Bottoms 96. 3 94. 8 Inspections, Grav y: 33.1 34.8 31. 8 34.9 Viscosity, SUS: sec.:

100 F 92.6 83.1 76. 3 69.3 210 F 38.7 37. 9 37. 0 36. 4 Color, Saybolt 30 Cloud Point, F 4 0 4 Pour Point, F 0 0 5 0 Flash Point, 00, F 380 385 360 350 Sulfur 0. 22 2 1 0.17 2 1 Iodine Number. 4. 8 1. 6 8. 5 1. 2 UV Absorptivity, D

At 260 Mu 0. 56 0. 01 2.68 0.15 At 290 Mm 0.24 0. 01 1. 32 0.06 Characteristic Groups, D2007:

Saturates 89.9 98.7 83.7 98. 5 Aromatics 9. 9 1. 2 16. 0 1. 5 Polar compounds 0.2 0. 1 0.3 0. 1 Asphaltenes 0. 01 0. 1 0. 1 0. 1

Sherwood procedure Number of acid dumps required to pass carbonizable sub. test 3 1 4 1 White oil yield, percent by voL. 88. 6 97. 3 80. 2 97. 5 Sulionate yield, percent by vol 6. 5 0. 2 5. 2 0.1

1 Percent. 2 I.p.m.

It will be noted from the data presented in Table I above that each of the portions which had been hydrotreated in accordance with our invention yielded a product which passed the Carbonizable Substances Test after only one acid dump, while the raw charge stocks from which the hydrotreated materials were obtained required three or four acid dumps in order to produce a material passing the Carbonizable Substances Test. Further, it will be noted that the white oil yields obtained by acid treatment of the hydrotreated stocks in'accordance with our invention were well above 95 percent, i.e. 97.3 percent and 97.5 percent, as opposed to the white oil yields of only 80 percent and 88 percent obtained when acid treating the raw stocks. Moreover, it will be noticed that acid treatment of the hydrotreated stocks provided extremely low yields of sulfonates in the range from 0.1 to 0.2 percent as opposed to the 5 to 6 percent yields when acid treating the raw stocks.

A comparison of .the inspection data for each of the hydrotreated stocks relative to the raw charge from which it was obtained indicates that the hydrotreating in accordance with our invention results in a minimal production of lower boiling materials while effecting saturation of most of the aromatics, both polynuclear and mononuclear, present inthe raw charge stocks. It is believed that this reduction of aromatics in the material to be acid treated is effective not only to increase the yield of white oil but also to reduce the production of sulfonates.

TABLE II Hydro- Raw treated ChargeIlI Stock III Yield from hydrotreatment, percent by vol.:

Overhead 1. 7 100. 0 28. 4 30. 6

708 113 1 F 72 59.3 Color, Saybolt 30 Cloud Point, F 1 1 22 Pour Point, F 10 20 Flash, 00 F 510 395 Sulfur 1 0. 29 2 2 Iodine Number 6. 8 l. 9 UV Absorptivity, D200 A 2 0 M 0. 84 0. O4. 0 46 0. O2 Characteristic groups, D2007 Saturates 80. 5 96. 2 Aromatics 18. 5 3. 7 Polar Compounds. 1. 0 0. 1 Asphaltenes 0. 1 0. 1

1 Percent. 2 P.p.m.

From the data in Table II it will'be seen that the severe hydrotreatment of Raw Charge III in accordance with our invention was efifective to provide a substantial reduc tion in aromatics content of the treated material along with a reduction in Iodine Number while producing a minimal amount of lower boiling materials. The data in Table II indicate that the results of our severe hydrotreatment of Raw Charge III were substantially similar to the results achieved with the severe hydrotreatment of Raw Charges I and II shown in Example I.

Each of the Hydrotreated Stocks I, II and III was then subjected to contacting with fuming sulfuric acid followed bycaustic neutralization, alcohol extraction, vacuum stripping-dehydration and clay contacting in substantially the manner indicated in the attached drawing.

Due to the different composition of Hydrotreated Stocks 1, II and -II[ and the desire to produce diifering types of white oil products, slight variations in the acid contacting, caustic neutralization and alcohol extraction, such as quantity of reactants employed, were utilized in the treatment of each of the three hydrotreated stocks. The three contacting units employed for the acid treatment, caustic neutralization and alcohol extraction for each of the three stocks was a Podbielniak contactor Model D l8. In the processing of each of the three stocks the following reagents were employed:

(1) Acid Treatment-Furning Sulfuric Acid (20% free (2) Caustic Neutralizationl0% NaOH Solution (3) Alcohol Extraction60% by weight Isopropyl Alcohol, 40% by weight Water In the treatment of Hydrotreated Stock I the amount of fuming sulfuric acid employed in the single acid dump was 6.5 percent by weight based upon hydrotreated stock, the amount of NaOH solution employed in neutralization was 6.25 percent by volume based on sludgefree hydrocarbon and the amount of alcohol mixture employed was 10.0 percent by volume based upon neutralized hydrocarbon.

In the treatment of Hydrotreated Stock II the acid dosage employed was 8.5 percent by weight based on hydrotreated stock, the caustic dosage was 6.25 percent by volume based upon sludge-free hydrocarbon and the alcohol mixture was employed in an amount of 12.5 percent by volume based upon neutralized hydrocarbon.

In the treatment of Hydrotreated Stock III the acid dosage employed was 11.0 percent by weight based on hydrotreated stock, the caustic dosage was 15.0 percent by volume based on sludge-free hydrocarbon and the dosage of the alcohol mixture was 14.0 percent by volume based on neutralized hydrocarbon.

In the treatment of each of the three stocks an alcohol and water mixture as well as sulfonates were removed from the alcohol extracted product and such product was then subjected to vacuum stripping followed by clay percolation. The particular operating conditions employed for the vacuum stripping and clay filtering as well as the inspection data for the final white oil products are shown in Table HI below.

TABLE III Vacuum stripping Stock I Stock II Stock III Operating conditions:

Vacuum, mm. Hg 77 97 82 Charge Rate. gaL/hr 5. 0 4. 7 4. 2 Temperature, F.:

Overhead. 245 241 224 Flash 414 390 417 Bottom 437 421 451 Reboiler 457 448 454 Stripping medium Stripping rate, s.e.f./hr 5 5 5 Yields, percent by weight:

Overhead 0. 6 1. 5 3. 0 Bottoms 99. 4 98. 5 97. 0 Clay Filtering:

Clay description Amount charged, lbs 53 53 53 Operating conditions:

Average rate, bbl./hr./ton clay 1. 1 1. 1 0. 69 Average temperature. F 130 133 139 Clay age at end of run, bbl. of oil/ton clay 76. 7 53. 0 42. 1 Clay soakage, bbL/oil/ton clay 4. 50 4. 92 4. 83 Yield of clay filtered oil, percent by wt. (corr. to 100% recovery) 93. 9 92. 5 90. 6 Inspections:

Gravity, API 35. 2 34. 9 30. 8 Viscosity, SUS: sec., 100 F 83. 0 70. 5 434 Color, Saybolt D-130 +30 +30 Vacuum stripping Inspections:

Cloud Point, F 4 0 24 Pour Point, F 0 5 20 lash Point, 00, F 380 355 470 Taste Odor D1833 0 0 0 White mineral oil evaL, by C FR 121.1146, carbonizable substances,

D565 Solid Parafiin Sulfur Compounds FDA UV Absorp./Om M 260-269 I 0. 03 0. 09 0. 05 270279 0. 02 0.08 0.03 280-289, 0. 02 0. 08 0. 03 290299 0. 02 0. 07 0.03 300329 0. 02 0. 046 0. 01 330350 0. 005 0. 015 0. 001 Iodine Number 0. 10 0. 10 0. 10

l Prepurified nitrogen.

11 N0. 1 Floridin 15-30 mesh elutriated for three hours at 500600 F. to remove water and fines.

3 None.

4 Pass.

From the data of this example it can be seen that the process of our invention not only results in a minimal production of acid sludge and sulfonate by-product but also results in an extremely high yield of final white oil products. Particularly, the data shown in Table III clearly illustrate that the various White oil products obtained in accordance with our invention are of extremely high quality meeting USP and FDA specifications. Thus, for example, it will be noted that each of the products has a Saybolt color of at least 30 and passes the tests for carbonizable substances, solid parafiins and sulfur compounds. It will also be noted from the data shown for the ultraviolet absorptivity in the range of 270 to 279 and that each of the oils easily meets the FDA requirement of a maximum of 0.1 at 275 mp. It should also be noted that each of the white oils produced quite obviously then meets the less stringent specification for technical grade white oil.

In addition to meeting the USP and FDA specifications it will also be seen from the data in Table III that the three white oil products are each of an extremely high quality having properties which should be generally satisfactory to meet the additional requirements of individual white oil users, such as, for example, a maximum flash point of 300 F., a cloud point no greater than the freezing point of water and a pour point substantially below the freezing point of Water.

We claim:

1. A process for the production of white oils from a lubricating oil stock containing from about 5 to 30 percent by volume of aromatics which process comprises 1) subjecting lubricating oil stock to hydrotreatment by contacting it with hydrogen and a catalyst at a temperature from about 650 to about 725 F., a pressure from about 2500 to about 3000 p.s.i.g. while employing a hydrogen rich gas stream having a hydrogen concentration of at least 70 percent, a liquid hourly space velocity from about 0.5 to about 3.0 volumes of lubricating oil stock per volume of catalyst per hour and a hydrogen feed rate from about 2000 to about 10,000 standard cubic feet of hydrogen per barrel of lubricating oil stock, the catalyst being comprised of a hydrogenating component selected from the group consisting of Group VI and Group VIII metals, their oxides and sulfides, composited with a carrier having an activity index of less than about 25 whereby aromatics are hydrogenated and no substantial cracking occurs to produce a hydrotreated material containing less than about 4 percent by volume aromatics, (2) subjecting the hydrotreated material to a single contacting with fuming sulfuric acid at an acid to oil ratio from about 0.02 to about 0.06 volumes of acid per volume of oil, (3) subjecting the acid contacted material to caustic neutralization, (4) subjecting the caustic neutralized material to alcohol extraction thereby re- 1 1v moving sulfonates and (5) recovering white oil as product from -thealcohol extracted material.

2. The process of claim 1 wherein the hydrogenating component of thecatalyst consists essentially of nickel and tungsten and the carrier .is alumina.

3. The process of claim 2 wherein the nickel and tungsten are present in equal. weight proportions, the total metals content of .the catalyst is from about 30 to about 50. percent by weight'based upon-the total catalyst, the carrier is an, alumina having an activity index of less than about 20v and the catalyst also contains fluorine.

4. The, process of claim .1 wherein the hydrotreating conditions are-selected so as to provide a yield of hydrotreated material, boiling'in the same range as the lubricating oil stock of at least 90 percent by volume based upon lubricating oil charge.

5, The process-of claim 1 wherein the acid contacting is conducted ,at a temperature from about 80 to about 250 F. .and acidconsumption is less than 2 0 percent based upon the acid charge.v

6. The process of claim 5 wherein the acidconsumption is --less than about '15 percent.

7. The process of claim 1 wherein the yield of acid 12 treated oil from the acid contacting step is at least about 95 percent by volume based upon charge to the acid contacting step., I I I 4 8. The process of claim 1 whereinv .the alcohol extracted material is further subjected to dehydration and 5 is then clay contacted. 1

References Cited I i UNITED STATESPATENTS DELBERT E. GANTZ, Primary Examiner 20 G. I. CRASA NAKIS AssiStant Examiner I us. 01. X.R. 20s 144, 264, 274, 301

2% I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,553,107 Dated January 5, 1971 Invent0r(s) R. E. Donaldson, H. C. Murphy, Jr. and H. C. Stauf It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 16, "hydro-treatement" should be --hydrotreatment- Column 1, line 48, "contracting" should be -contacting-. Column 1, line 59, "techinique" should be -technique-.

Column 2, line 66, "can" should be deleted.

Column 5, line 73, "raffiniate" should be -raffinate-.

Signed and sealed this 8th day of June 1971.

'(SEAL') Attest:

EDWARD M.FIETGHER,JR. I WILLIAM E. SCHUYLER Attesting Officer Commissioner of Pat

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