US3080313A - Method of producing a medicinal mineral oil - Google Patents

Description

United States Patent 3,980,313 METHOD OF PRODUCDIG A MEDICINAL MINERAL OliL Kenneth M. Beals and William A. Home, 0ai rn0nt,-Pa., assignors to Gulf Research & Development Company,

Pittsburgh, Pa., a corporation of Delaware No Drawing. Filed Nov. 24, 1959, Ser. No. 855,014

1 Claim. (Cl. 2438-168) This invention relates to a method for making high purity, light colored petroleum oils and to the novel products of the method. More particularly, it relates to a method comprising hydrocracking of a residual crude oil fraction and to the novel'ligh't colored or colorless oil compositions consisting essentially of naphthenic hydrocarbons that are obtained thereby.

It is known in the art to prepare light colored or colorless lubricating oil fractions by severely acid treating a straight run or partially refined lubricating oil fraction. The light'col'ored or white oil products of conventional treatments have a low or negligible content of aromatics;

They consist essentially of mixtures of paraffin and naphthenic hydrocarbons and have about the same molecular weight range or boiling range as the charge stock.

We have now developed a new method for producing light colored or colorless lubricating oils of low viscosity from heavy residual petroleum oil fractions. Our method unexpectedly producesoils of novel composition, specifically, oils that consist entirely or almost entirely of naphthenic'hy'droc'arbons. These oils are substantially entirelylight colored, low viscosity lubricating oils which have excellent viscosity index-*an'd high specific gravity relating to-conven'tional highly refined white oils. They consist almost entirely of naphthenes, being free of or substantially free of aliphatic parafiins and having no more than a low content of aromatics, e.g., less than 5 mol percent. By distillation and other refining treatments that characterize the preferred form of our process they can be freed completely of aliphatic parafii'ns and arimatics and rendered colorless, tasteless and odorless.

Because of their unique composition and numerous valuable qualities, the oils of our invention are valuable for many uses and are uniquely adapted for certain purposes. They are suitable'for pharmaceutical and cosmetic purposeswherein"the'oils are solvents or carrier media for active pharamaceutical' or cosmetic ingredients. They are also useful assolveuts or carriers for insecticides, their colorless quality making them free from harmful staining effects. Being colorless or light colored, the'light lubricating oils of the invention are'valuable as lubricants for textile and food machinery because they will not stain-the textile or food products. In these lubricating uses our products are especially valuable because of their high viscosity indices.

Being almost entirely naphthenic, the oils of our inven- "ice tion have higher'specific gravity than conventional white oils of similar molecular weight range that contain large proportions of aliphatic parafiins. The higher specific gravity makes our oils superior for forming emulsions because, as recognized in the art,-the closer the density of an oil is to that of Water the more readily it forms a stable emulsion with water. To obtain satisfactory emulsions with conventional white oils having a high content of open chain parafiins it has sometimes been necessary to include aromatics in the oil to raise the specific gravity or to use an undesirably large amount of emulsifying agent. However, aromatic are undesirable in cosmetic and pharmaceutical products. Aromatics may be carcinogenic and also are generally more reactive than naphthenes and paraffin's. Thus, because of the high specific gravity of the naphthenic oils of our invention, they are'especially valuable for forming with Water stable emulsions to be used as cosmetic or pharmaceutical lotions, ointments or the like, that are essentially free of carcinogenic or reactive aromatics.

Even when physiological eifects are not a problem, our

oils are especially valuable in forming emulsion lubricants because, being'naphthenic and thus of higher density than parafiinic oilsof the same molecular weight range, they require smaller amounts of emulsifying agents or othercontaminant's forforming a stable emulsion than lower density paraffinic oils. In comparison to oils that are readily emul-sifiable because of high density resulting from aromatics content, our oils are less subject to chemical deterioration. In 'fact, in all'of'the mentioned uses, stability against deterioration or chemical change is a valuable property of our naphthenic oils. This characteristic is especiall'yimpo'rtan't for'lubricants such as textile machinerylubricantswhich must not develop excessive colo'r'or acidity.

In general the method of our invention, by which our new products are made, comprises subjecting to severe hydrocracking' a heavy residual crude petroleum fraction by contacting the hydrocarbon charge with a catalyst comprising one 'or'm'or'e' sulfides of metals of group Via of the periodic table at a temperature from 700 to 800 F., a pressure above 1,500- pounds per square inch gauge, a hydrogen to hydrocarbon'feed ratio from 2,500 to 10,000 standard cubic feet per barrel of hydrocarbon and at a liquid-hourly space velocity from 01410 1.5 volumes per volume per hour. 'Ih'e'hyd'rocracked' product is distilled to recover alight lubricating oil of which the initial boiling'point is"above400 F. and of which the end point, or at least the'95 percent point, is lower than the initial boiling point, or at least lower than the 5 percent point, of the hydrocracking charge, said oil containing less than about 5 mol percenta'liphatic paraffins and less than about 5 mol percent aromatics: In a preferred embodimentthe light lubricating oil'is distilled to an initial boiling point that is sufiiciently high'that'theoikis free of aliphatic parafrlns and the oil is clay contacted and acid-treated to obtain an oil that is also colorless and free of aromatics. In another preferred embodiment, dewaxing'is used to obtain a product of low pour point.

The product of our invention'is the naphthenic light lubricating'oil obtained by the above method which is free of or substantially-free 0f aliphatieparaffins, (i.e., contains less than about 5 mol percent aliphatic parafiius), contains less than 5 mol percent aromatics, has a'viscosity index of at least 90, and preferably at least 100, and an ASTM Union color lighter than 1.

The method and product of our invention are illustrated by the following example.

EXAMPLE 1 The charge stock was a deasphalted residual fraction of Ordovician crude oil having the following characteristics:

Gravity, API 23.6

This heavy oil was charged to a hydrocracking reactor containing a fixed bed of pelleted catalyst composed of nickel and tungsten sulfides in a mol ratio of 4:1. Reaction conditions included temperature of 745 to 775 F., pressure of 3,530 pounds per square inch gauge, hydrogen rate of 5,000 standard cubic feet per barrel of hydrocarbon and liquid-hourly space velocity of 0.5 volume of hydrocarbon per volui .e of catalyst per hour. The normally liquid product from the hydrocracking operation was subjected to atmospheric distillation to remove light furnace oil, gasoline and lighter material. The remaining product was distilled in a continuous vacuum column to obtain a fraction boiling between furnace oil and 725 F. (corrected to atmospheric pressure). This fraction was re-run in a true-boiling point still to remove light ends and an oil was obtained having a viscosity at 100 F. of about 70 Saybolt Universal seconds. The oil was treated with fullers earth and filtered. Inspections of the product are as follows:

Table I Inspection data:

Gravity, APT 34.5 Specific gravity 0.8524 Viscosity, SUS:

100 F 69.6 210 F 36.6 Viscosity index 110 Color, Union: ASTM D155-45 1- Flash point, 0.C., F.: ASTM D92-52 390 Fire point, 0.0., F.: ASTM D92-52 420 Pour point, F.: ASTM D97-47 30 Refractory index, 70 C. 1.4512 Sulfur, percent 0.04 Nitrogen, percent 0.003 Carbon residue, Conradson, percent: ASTM D18952 0.01 Copper strip test, 212 F., 3 hrs.: ASTM D130-55T 1 Neutralization value, ASTM D974-54T: total acid No. 0.02 Iodine No., mod. Hanus 3.5 Distillation, vacuum, corrected to 760 mm.

Over point F.) 455 at F.) 685 at F.) 696 50% at F.) 707 70% at F.) 719 90% at F.) 733 Hydrocarbon type analysis by high temperature mass spectrometer, rnol percent:

Alkanes 0.0 Non-condensed cyclo-alkanes 63.8 Condensed cyclo-alkanes 33.1 Mono-nuclear aromatics 2.8 Naphthalenes 0.3

Table I shows that our product is an almost water-white, lubricating oil. It is a light lubricating oil, having a Saybolt Universal viscosity at 100 F. in the range of 55 to seconds, and specifically of 69.6 seconds in the example. It has a high viscosity index, i.e., above 90, and specifically the product of the example had a viscosity index of 110. The distillation indicates that the oil is substantially entirely a synthetic, hydrocracked product since its distillation point is substantially lower than the 10% distillation point of the residual charge stock. The analysis shows that the oil is completely free of paraffins and has a very low content of aromatics, namely, 2.8 percent mono-nuclear aromatics and 0.3 percent naphthalenes. The inspection data show various valuable prcperties that are characteristic of the high purity naphthenic product, the high specific gravity being especially notable.

The yields of different fractions of Example 1 give an indication of the relationship of our product of the residuum charged to hydrocracking. In the hydrocracking stage the yield of liquid product based on the hydrocracking residual charge stock was 104.6 volume percent. After removal of light furnace oil and gasoline, the hydrocracked product amounted to 72.3 volume percent of the hydrocracking charge stock. Vacuum distillation of the latter product produced our product as defined in Table I in a yield of 10.8 volume percent of the vacuum tower charge. In Example 1 there was also obtained from the heavy residual hydrocracking charge stock a good yield of furnace oil and of a highly naphthenic gasoline that is an excellent reforming charge stock.

We have indicated that the starting material for our process is an asphalt-free or deasphalted crude oil residuum. The starting material can be any residuum obtained by vacuum or like distillation of any crude petroleum or residual fraction thereof which, after (leas phalting, has a viscosity at 210 F. of 90 to 200 Saybolt Universal seconds. For instance, the residuum can be prepared by vacuum distillation of a Pennsylvania, Mid- Continent, West Texas, Kuwait, etc., crude. Any convcntional deasphalting procedure can be used. Preferably, the residuum is deasphalted by contact with a low boiling hydrocarbon such as propane, propylene or butane to precipitate asphalt which is then separated from the oil.

To hydrocrack the deasphalted residuum we employ a solid catalyst which not only has high activity for saturation of aromatics but also high activity and selectivity for carbon-carbon bond scission. Such hydrocracking catalysts are known in the art. They comprise the sulfides of metals of group We of the periodic table mixed with a sulfide of an iron group metal. The sulfide catalysts can initially be in the oxide form and converted to sulfides in the reaction zone by reaction with sulfur in the charge stock or with a sulfur compound such as hydrogen sulfide that is introduced into the reactor to sulfide the catalyst. Specific catalysts can consist of molybdenum sulfide, tungsten sulfide or chromium sulfide mixed with a sulfide of iron, cobalt and/ or nickel. A particularly desirable catalyst is a mixture of nickel sulfide and tungsten sulfide. Such a catalyst containing from 1 to 4 mole of nickel per mol of tungsten (calculated as metals) has especially high activity and selectivity for hydrocracking. Other satisfactory sulfide mixtures are cobalt sulfide-tungsten sulfide and nickel sulfide-molybdenum sulfide mixtures. The catalysts can be supported or unsupported.

The hydrocracking reaction conditions for our process are of such severity as to produce an entirely synthetic light lubricating oil product. The temperature can range from 700 to 800 F. and temperatures of 725 to 775 F. are preferred. The pressure should be above 1,500 pounds per square inch gauge. There is no upper limit on pressure but a pressure in the range of 2,000 to 4,000 pounds per square inch gauge is preferred because of the excessive cost of equipment required for higher pressures. A relatively low liquid-hourly space velocity is employed sons to obtain severe hydrocracking. A suitable range,

for the space velocity is 0.4 to 1.5 volumes of liquid hydrocarbon per volume of catalyst per hour.

The hydrogen employed in the process can be pure hydrogen but hydrogen of lower purity such as a reformer hydrogen stream containing about 80 mol percent hydrogen works very well. If an impure hydrogen stream is used, it is recommended that part ofthe recycle hydro gen be bled from the recyclestream or that a recyclehydrogen clean-up procedure be used. The hydrogen-tohydrocarbon ratio of the reactor charge, including recycle and fresh hydrogen, should be from about 2,500 to 10,000 standard cubic feet per barrel'of hydrocarbon charge.

The efiiuent from thehydrocracker is normally subjected to cooling and gas-liquid separation to separate hydrogen and other light gases from the normally liquid hydrocarbons. The hydrogen-rich stream recovered in this manner can be recycled to the hydrocracking reaction.

The next step in the process, namely, dis-tillation of normally liquid hydrocarbons of the hydrocracking efiiuent, is of critical importance in our process. The liquidef fluent from the hydrocracking stage has afull boiling range from gasoline to heavy lubricating oil and contains paraflin wax. The product'of our invention is recovered from this liquid by distillation. The gasoline and light furnace oil can be distilled off at atmospheric pressure but, in order to prevent decomposition of the heavier fractions, our light'lub'ricating oil fraction is-recovered by vacuum distillation. The product of the invention is recovered as a distillate fraction having an initial boiling point above 400 F. and a 95% point below 950 F., all temperatures being corrected to atmospheric pressure. Our preferred product, as shown in the example, is the distillate fraction of the liquid hydrocracking efiiuent having an initial boiling point above 450 F. and a 90% point below 750 F.

Although our procedure of severe hydrocracking of selected stocks and selective distillation of the product thereof will produce a novel and valuable light colored light lubricating oil without further treatment, we prefer, as indicated in the example, to subject the light lubricating oil distillate to clay contacting. This can be carried out in accordance with known procedure wherein the oil is mixed with powdered filter clay such as fullers earth. The oil-clay slurry is held at elevated temperature, e.g., 200 to 600 F. for several minutes and is then pumped through a filter press to separate the clay from the oil. The main result of this procedure is further to decolorize the oil, although even without the clay contacting step our product is substantially colorless or of very light color.

As shown in Table I the product of our process, although free of paraiiins, may have a small content of aromatics, i.e., less than about mol percent. To obtain a completely naphthenic white oil that is completely colorless, tasteless and odorless, we can subject the hydrocracked light lubricating oil of the invention to conventional acid treating. A suitable acid treating procedure involves contacting the oil in a series of batch treatments with small amounts of sulfuric acid (e.g., 5 Weight percent of the oil) using 20 percent oleum (104-105 percent H 80 for each treating shot. After contaeting with the acid the sulfonate sludge is settled, the oil is decanted and the procedure is repeated several times. Preferably, the oil is then neutralized by washing with a solution of a basic substance, e.g., sodium carbonate solution, The washed neutral oil is air dried and is then filtered with adsorbent clay. Our product of Table I has been subjected to sulfuric acid treatment substantially in the manner described with the following results.

Acid Treatment: I Acid cdnsumemwr. percent 2,0.0 Whiteoil yield',vo1.percent 94,0 Sulffonate yield, v01; percent; 1:0

Table: II shows-that'sulfuric acid treatment of 1 the productof Table I-resulted in-a'white oil yield of 94' volume percent with a rather lowacid consumption. The prod-' uct istastele'ss, odorless, colorless: and-is substantially-en tirely naphthenic, the small content of aromaticshaving' been removed by the acid'treatment; The cloud and pour; points'of the acid treatedoil are entirely: satisfactory. for' many'purposes'but are rather high for some purposes; The rather high values are probably the result of certain high meltingpoint naphthenic hydrocarbons being present intheoil. The cloudandpour points can be lowered by subjecting the oil to conventional dewaxing. procedures; For certain lubricatingspurposes for which low. pour pointis desired the pour point can also"bereduce'd by adding a small amount of any conventional pour point de-' pressant such as Acryloid 618 which is a" polymethacrylate.

' EXAMPLES 2 AND 3 In other operations in which the deasphalted Ordovician residual fraction described in Example 1 was hydrocracked substantially in the manner of Example 1 we have used dewaxing in the product recovery procedure to obtain products of low pour point. In these runs the hydrocracking efiluent was subjected to gas separation and the liquid hydrocracking product was subjected to atmospheric distillation with steam stripping to remove light furnace oil, gasoline and lighter products. The remaining product was then subjected to solvent dewaxing with methy-l ethyl ketone and employing a rotary filter, the dewaxing conditions being such as to produce the desired pour point for the ultimate product. In Example 2 the dewaxed product was subjected to continuous vacuum distillation and in Example 3 was subjected to precise, batch, vacuum distillation, in each instance to recover a light lubricating oil having substantially the composition of the products of the invention. The properties of the light lubricating oil fractions obtained as products of these two runs are listed in Table III.

Table III Inspection Date Example Example Gravity, API 30.4 35.7 Specific Gravity..- 0. 8428 5 viscpggy, SUS- O 8 63 58. 9 62.0 210 35. 0 35. 6 Viscosity Index 104 113 Pour Points, F.; AS'IM D9747 -30 5 Sulfur, percent 0.04 0. 04 Iodine No., Mod. Hauus 4.1 Color, Union, ASTM D155-4 1- Carbon Residue, Conradson, percent ASTM D189 52 0.01 Neutralization Value, ASTM D974-54Tz Total Acid l To 0.01 Distillation, Vacuum, Corrected to 760 mm. Hg:

Over Point (F.) 441 at (F.) 714 Hydrocarbon Type Analysis by High Tempereture Mass Spectrometer, M01 percent:

Alkanes 3. 2 1. 3 Non-condensed cyclosalkaues 08. 8 70.1 Condensed cyclo-alkanes 25.6 25. 3 Mono-nuclear aromatics..- 2. 2 3. 1 Naphthalenes 0. 2 0. 2

The above table shows that conventional dewaxing can be used to produce products of the invention of low pour point, for example, 30 F. in Example 2 and F. in Example 3. The products of these examples had a small content of alkanes but can be rendered essentially free of alkanes if distilled to a somewhat higher initial boiling point or percent point, the reason being that the alkanes are in the light end of the product. The preferred products of our invention are essentially free of open chain parafins, as in Example 1, but products such as Examples 2 and 3 which have a small content of alkanes, e.g., less than about 5 mol percent, have many of the valuable properties that characterize the products of the invention. Thus, the products of Examples 2 and 3 have high specific gravity, high viscosity, index, light color and are composed almost entirely of naphthenic hydrocarbons. They also have good stability. The product of Example 3 was maintained at 210 F. for 48 hours and no color change was observed. The product did form a small precipitate when exposed to light for 4 days, but a similar product which had been clay treated did not change after 30 days exposure to light.

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

We claim:

A method for producing light colored medicinal mineral oil which comprises contacting a deasphaltcd residual petroleum crude oil fraction having a viscosity at 210 F. or at least 90 SUS with a hydrocracking catalyst comprising a sulfide of a group VIa metal and a sulfide of an iron group metal in the presence of hydrogen under severe hydrocracking conditions, said conditions including a temperature from 700 to 800 F., a pressure above 1,500 pounds per square inch gauge, a hydrogen concentration from 2,500 to 10,000 standard cubic feet per barrel of hydrocarbon and a liquid-hourly space velocity from 0.4 to 1.5 volumes of liquid hydrocarbon per volume of catalyst per hour, fractionally distilling the liquid hydrocarbon product from this hydrocracking operation, separating a distillate fraction which consists essentially of naphthenic hydrocarbons and less than 5 mol percent each of aliphatic and aromatic hydrocarbons, which fraction has a viscosity at 100 F. of between about and SUS, which fraction has a viscosity index of at least 90, which fraction has an initial boiling point above about 450 F., and which fraction has a percent boiling point below about 750 F. and subjecting said fraction to acid and clay treatment.

References Cited in the file of this patent UNITED STATES PATENTS 2,554,282 Voorhies May 22, 1951 2,882,220 Mikeska et al. Apr. 14, 1959 2,899,380 Lanning Aug. 11, 1959 2,934,492 Hemminger et al Apr. 26, 1960 2,967,204 Beuther et a1. Jan. 3, 1961 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3 Patent No, 3,080,313 March 5, 1963 Kenneth M, Beals et a1,

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 48, for "arima'tics" read aromatics column 2, line 12, for "aromatic" read aromatics column 3, line 51, for "Refractory" read Refractive column 4, line 18, for ."of", third occurrence, read to column 6, Table III, third column, line 2 thereof, for

O,856,8" read 0,8463 column 7, line 15, after "viscosity" strike out the comma;

Signed and sealed this 8th day of October 1963.,

(SEAL) Attest:

EDWlN L, REYNOLDS ERNEST w. SWIDER Attesting Officer Act ing Commissioner of Patents