US3436334A

US3436334A - Stable hydrocarbon lubricating oils and process for forming same

Info

Publication number: US3436334A
Application number: US630207A
Authority: US
Inventors: Bernard A Orkin; Milton Braid
Original assignee: Mobil Oil AS
Current assignee: Mobil Oil AS; ExxonMobil Oil Corp
Priority date: 1967-04-12
Filing date: 1967-04-12
Publication date: 1969-04-01
Anticipated expiration: 1986-04-01

Description

United States Patent US. Cl. 208-18 Claims ABSTRACT OF THE DISCLOSURE Hydrocarbon lubricating oil resistant to deterioration upon exposure to light and air is formed by contacting high boiling hydrocarbons with hydrogenation/dehydrm genation catalysts and hydrogen with hydrogen consumption, and thereafter dehydrogenating the resulting product on contact with a metal oxide or with a metal and oxygen.

FIELD OF INVENTION This invention has to do with stable hydrocarbon lubricating oils which are resistant to deterioration upon exposure to light and air, and to a process and means for obtaining the same.

DESCRIPTION OF THE PRIOR ART For many years, lubricating oils have been obtained from hydrocarbon oils of various character by fractional distillation. In order to obtain lubricants of relatively high viscosity index (V.I.), it has been the practice to subject the oils to solvent extraction to remove components serving to lower the VI. The solvent extracted lubricants are resistant to light and air; however, they are generally fortified with one or more additives in order to improve their resistance to oxidation during use and the like.

More recently, hydrocarbon lubricating oils of somewhat different character have been obtained by a variety of processes in which high boiling fractions are contacted with hydrogen in the presence of hydrogenation/dehydrogenation catalysts at elevated temperatures and pressures. In such processes, there is a consumption of hydrogen. Lubricating oil fractions are separated from the resulting products. Such lubricating oil fractions differ from those obtained by fractional distillation of crude oils and the like, since they have such relatively high V.I. values that solvent extraction treatments are generally not required to enhance their V.I. values. However, such lubricating oil fractions suffer from the shortcoming that they are unstable when exposed to light (particularly, actinic rays) and air. When so exposed, sediment and lacquer formation occurs, thus lessening the commercial value of such lubricants. The present invention is directed to a process and means for overcoming such a shortcoming.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a process and means for forming lubricating oils resistant to deterioration upon exposure to light and air. There are also provided the stable oils so formed.

The process of the present invention comprises contacting a high boiling hydrocarbon fraction with a catalyst having hydrogenation and dehydrogenation properties in the presence of hydrogen at elevated temperature and at elevated pressure, whereupon there is a net consumption of hydrogen, to form a plurality of fractions including a lubricating oil fraction boiling above about 650 F. The lubricating oil fraction is separated from said plurality of fractions. The lubricating oil fraction is then contacted with a metal of Group VIII and oxygen or with a metal oxide wherein the metal is selected from Groups IIB, VI-B and VIII of Mendeleetfs Periodic Table at an elevated temperature.

DESCRIPTION OF SPECIFIC EMBODIMENTS Hydrocarbon feed fractions The hydrocarbon feed material or fractions which can be contacted with hydrogen as described herein, can be substantially any hydrocarbon feed material susceptible to treatment with hydrogen. Generally, however, it is preferred to use high boiling range materials boiling above about 650 F. Such materials include heavy gas oils, residual stocks, cycle stocks, topped crudes, reduced crudes and relatively high boiling hydrocarbon fractions derived from coal, tars, pitches, asphalts and shale oils. These materials can be obtained by fractionation, as by vacuum distillation, of crude oils identified by their source, viz.: Pennsylvania, Mid-Continent, Gulf Coast, West Texas, Amal, Kuwait and Barco.

Hydrogenation/ dehydrogenation catalysts The catalysts employed herein can include any type of catalyst having hydrogenation and dehydrogenation properties. Such catalysts are well known in the art. The catalysts include oxides and sulfides of any metal of Group VI-B of Mendeleetfs Periodic Table or mixture thereof, typical of which are: chromium sulfide, molybdenum sulfide and tungsten sulfide. Others include oxides and sulfides of Group VIII of said Periodic Table or mixture thereof, as illustrated by: the sulfides of iron, cobalt, nickel, palladium, platinum, rhodium, osmium and iridium. Still other catalysts include mixtures of the above oxides and sulfides of the metals of Groups VI-B and VIII of said Periodic Table typified by mixtures of nickel sulfide and tungsten sulfide; cobalt sulfide and molybdenum sulfide; and nickel sulfide and molybdenum sulfide. These metals can be deposited upon adsorbent carriers such as alumina, silica-alumina and silica-zirconia.

Preferred catalysts include those comprising at least one of the metals mentioned above, deposited upon a composite-like oxide of at least 2 of the elements of Groups II-A, III-B, IV-A and IV-B of said Periodic Table. Additional preferred catalysts include a sulfided or unsulfided 1-8 weight percent cobalt oxide and 3-20 weight percent molybdenum trioxide on a silica-alumina or silica-zirconia base containing silica in amounts of from about 5 to about weight percent.

Catalysts comprised of such metals associated with molecular sieves can also be employed. Such catalysts are typified by those described in US. Patent No. 3,173,854.

The catalyst loses some of its activity during use and, therefore, is regenerated. The spent catalyst is contacted with a free oxygen-containing atmosphere at an elevated temperature sufficient to burn carbonaceous deposits from the catalyst. Conditions for regenerating the catalyst include a temperature between about 600 F. and about 1,000 E, a pressure of from atmospheric to about 500 pounds per square inch, a total gas flow rate of from about 1 to about 20 volumes per volume of catalyst per minute and an oxygen concentration of from about 0.1 percent to percent. The oxygen can be diluted with steam, nitrogen or other inert gas.

Hydrogen Pure hydrogen can be used. However, hydrogen of low purity obtained by recycle or other hydrogenating process can be used, but it is recommended that the recycle hydrogen be subjected to purification to remove some of the undesirable impurities such as water, sulfur compounds, methane and the like. The hydrogen can be circulated at a rate in the range of from about 1,000 to about 20,000 standard cubic feet (s.c.f.) per barrel of hydrocarbon 3 charge, and preferably 5,000-10,000 s.c.f. per barrel of charge. Hydrogen consumption can be less than about 40 s.c.f. per barrel of charge and greater. However, it is preferred to have a hydrogen consumption of 100 or more s.c.f. per barrel of charge.

Hydrogen contact operation Hydrocarbon charge is contacted with hydrogen and a catalyst of the character described above, at a temperature ranging from about 500 F. to about 1,000 E, preferably 600850 F. Hydrogen pressure is of the order of from about 100 to 10,000 pounds per square inch gauge (p.s.i.g.). Liquid hourly space velocity (L.H.S.V.) of charge normally falls within the range of 0.1 to 10, preferable 0.2-2, volumes of charge (as 60 F. liquid) per volume of catalyst per hour.

The hydrogen contact can be carried out in any suitable equipment for catalytic Operations. The contact can be operated batchwise. It is preferable, however, and generally more feasible to operate continuously. Accordingly, the process is adapted for operations using a fixed bed of catalyst. The process can be operated using a moving bed of catalyst wherein the hydrocarbon blow can be concurrent or countercurrent to the catalyst flow. A fluid type of operation wherein the catalyst is carried in suspension in the hydrocarbon charge can be employed.

In the contact with hydrogen, reaction conditions of temperature, pressure, space velocity and type of catalyst can be controlled such that there is substantially no conversion of the hydrocarbon charge. Generally preferred however are conversions varying between about percent and about 75 percent by volume to products boiling lower than about 650 F.

Hydrogenated product fractionation Following hydrogen contact, products are withdrawn from a suitable reactor and are then passed through a heat exchanger or other suitable cooling device, wherein they are' cooled to temperatures at which hydrogen gas can be separated. The cooled effluent is then passed into a high pressure gas separator. Gases are removed and liquid product is passed to a fractionator from which several fractions are removed. A lubricating oil fraction boiling above about 650 F. constitutes one of such fractions.

The lubricating oil fraction may contain some wax products. Removal of wax, if present, can be accomplished by any treatment conventionally used for dewaxing oils to provide an oil having a pour point below about F. or lower. Such dewaxing can be completed at this stage of the process or following subsequent contact with a metal and oxygen or with a metal oxide catalyst.

Metals and metal oxide catalysts The metal catalysts used herein are those having dehydrogenating properties and are members of .Group VIII of Mendeleeffs Periodic Table. Such metals include iron, cobalt, nickel, platinum and palladium. Platinum is preferred.

These metals can be deposited upon adsorbent carriers including alumina, silica-alumina, silica-zirconia, and charcoal, or can be associated with molecular sieves as described in US. Patent No. 3,173,854.

Metal catalyst concentration can vary considerably, as from about 0.25 to about percent by weight of metal on a suitable base such as alumina.

The catalysts lose activity during use. Activity can be restored by discontinuing hydrogen and charge flow to the catalyst. At elevated temperature, as about 970 F., flue gas or other inert gas such as nitrogen is circulated through the catalyst. Then, air is injected into the circulaing gas in increasing concentration to a maximum of about 2 percent (volume), such care being taken to avoid formation of an explosive mixture. Deposits on the cata- 4 lyst are so burned off. The efiluent gas is analyzed to determine the carbon dioxide content thereof; when the CO value decreases to a minimal level, the reactivation operation is discontinued.

Suitable metal oxide catalysts for use with or without oxygen are oxides or oxide mixtures of metals of Groups II-B, VI-B and VIII. Typical oxides include: ferric oxide; cobalt (II) oxide; zinc oxide and chromic oxide.

Here again, such oxides can be deposited upon carriers such as mentioned above.

The metal oxide catalysts are generally used in quantitles of from about 5 to about volumes of lubricating oil fraction per volume of catalyst.

Regeneration of the metal oxide or metal oxides can be accomplished conventionally by heating the same at elevated temperature, as at 9001,200 F. with free-oxygen containing gas.

Metal or metal oxide contact Group VIII metal catalysts used in contact with the lubricating oil fractions are employed at elevated temperatures. Generally, temperatures ranging from about 200 F. to about 400 F. are employed.

When a metal catalyst is employed an oxygen-free containing gas is also employed. Thus, air or various mixtures of oxygen and nitrogen are suitable. In general, from about 0.01 to about 0.3, and preferably 0.03-0.l, volume of oxygen is used per volume of lubricating oil fraction with which it is contacted.

Oxygen in the form of a free-oxygen containing gas can also be used with one or more of the metal oxides contacted with the lubricating oil fractions. In such event, from about 0.01 to about 0.3, and preferably 0.030.1, volume of the gas is used per volume of the oil fraction.

Metal oxide catalysts are employed at temperatures from about 650 F. to about 800 F., with temperatures of approximately 750 F. being particularly advantageous.

Liquid hourly space velocity of lubricating oil fraction ranges from about 0.1 to 6, particularly 0.3-3, volumes of charge (as 60 F. liquid) per volume of catalyst per hour.

The lubricating oil fractions and the metal or metal oxide catalysts can be contacted in any of the procedures referred to above under the subheading Hydrogen contact operation.

Illustrative examples The following examples illustrate, and in no sense, limit the invention.

EXAMPLE 1 A Kuwait-Barco propane deasphalted rafiinate was treated with hydrogen as described below. The charge stock had the following properties:

Viscosity at 210 F.:

Kinematic viscosity, cs. 34.34

Saybolt seconds universal 162 Pour point, F Flash point, F. 606 Carbon residue, weight percent 1.09 Nitrogen, weight percent 0.08 Sulfur, weight percent 1.93

The catalyst comprised a silica-zirconia support containing approximately 11 percent by weight of ZrO The support was then spray impregnated with 10 percent M as a water solution of ammonium molybdate drying at 220 F. for 16 hours and calcining 3 hours at 1,000 in air. The resulting composite was then impregnated with 3 percent CoO as a water-solution of cobalt nitrate, Co(NO .6H O, dried at 230 F. for 3 hours and calcined 10 hours at 1,000 F. in air. The resulting catalyst was sulfided with a 50% H 50% H mixture employing 2 volumes per volume of catalyst per minute for 5 hours at 800 F. Further details of the preparation and character of this catalyst are available in US. Patent 3,182,012, issued May 4, 1965.

The liquid product obtained by contact with hydrogen and the catalyst under the conditions described below was fractionated, thereby providing approximately 57 percent by volume of a lubricating oil fraction having a boiling point above about 650 F.

Temperature, F. 772 Pressure, p.s.i.g 2,000 L.H.S.V. 0.8 H circulation, s.c.f./bbl. 8,000 Conversion (100-products boiling above 650 F., in

volume percent) 43 1 0.4 fresh charge and 0.4 liquid recycle. 100-650 F. fraction.

The lubricating fraction was then dewaxed at about 0 F., with 3 volumes of 50/50 (volume) methyl ethyl ketone (MEK) toluene.

A variety of dewaxed lubricating oil fractions were so Portions of the dewaxed lubricating oil fractions were contacted with a catalyst (A) comprising 0.5 percent (weight of platinum on activated alumina containing 0.55 percent of chloride iron. This is a commercial catalyst, RD150 of Baker Sinclair. Included in this operation were oxygen-nitrogen gas mixtures. Each run was conducted in a continuous flow reactor in which the liquid charge rate, gas rate, temperature and pressure were controlled. The resulting products were fractionated in order to obtain lubricating oil fractions having boiling points above about 600 F.

The lubricating oil fractions were exposed to air and ultraviolet light source and rated at 24 and 48 hours. Equipment utilized in the ultraviolet light test was such as described in ASTM Test Method D529. The operating temperature was approximately 115120 F. The light source was a lamp (6,000 watts). Samples of the oil fractions were contained in 4 dram glass vials during the test.

The dewaxed lubricating oil fraction before contact with a metal catalyst, formed a heavy precipitate in the test in less than 24 hours.

In the test, precipitates formed are rated visually in the following order:

None

Very slight Slight Medium Heavy Very heavy m-P-wN O TABLE I.OXIDATIVE DEHYDROGENATION METAL CATALYST, ATMOSPHERIC OOMPA RATIVE EXAMPLES 2 N2 0. 6 400 O2 N2. 0.6 300 20% 02 80% N; 0.6 200 2, 98% Ni... 0.6 200 02 98% N2... 0. e 400 1 Viscosity and Viscosity Index (V .I.) of product boiling above about 600 F. 1 Gas rate 100 ccJmin. for 100 cc. of catalyst. 3 Gas rate 50 cc./min. for 50 cc. of catalyst.

4 Continuous run for 8 hours.

obtained, as illustrated by the fraction identified by the properties given below:

Other fractions employed had viscosity indices ranging from about 100 to 125.

As indicated by the results presented in Table I, the lubricating oil fraction is stabilized by direct oxidation with oxygen at ZOO-400 F. over the platinum-on-alumina catalyst (Runs -103). An excess of oxygen with the same catalyst is undesirable as revealed by Runs 104-106, and is detrimental to the catalyst when it is used thereafter with suitable quantities of oxygen (Runs 107-108). With fresh catalyst at 400 F., 0.6 L.H.S.V., and 100 cc./ minute of 2% 0 -98% N the resulting product was stable even after several hours on-stream time. Longer time intervals, as 24 hours, are to be voided, since the resulting products are not light stable.

EXAMPLE 2 Additional portions of the dewaxed lubricating oil fraction described above in Example 1, were contacted with metal oxide catalysts. Each run was conducted in the manner indicated by Eaxmple 1.

Catalyst B comprises 10 percent (weight) of ferric oxide deposited upon activated alumina. This is Catalyst Fe-030l of Harshaw Chemical.

Catalyst C comprises 10 percent (weight) cobalt (II) fraction occurs to form said stabilized lubricating oil fraction.

2. The process of claim 1 wherein said high boiling hydrocarbon fraction boils above about 650 F.

3. The process of claim 1 wherein said high boiling hydrocarbon fraction is converted to a product containing from about to about 75 volume percent boiling below about 650 F.

4. The process of claim 1 wherein the high boiling TABLE IL-OXIDATIVE DEHYDRO GENATION, METAL OXIDE CATALYST, ATMOS PHERIG PRESSURE Total Liquid Precipitate Product; Catalyst Inert Oil, Temp., Arom, Wt.

Gas 1 LHSV F. Percent 0.11. Wt. K.V.,

Percent 2 210 F V1. 24 48 72 5 N2 0.6 650 2 N2 0. 6 750 0 N2 0. 6 650 3 Na 0. 6 750 0 N2 0. 6 650 3 N2 0. 6 700 1 Na 0. 6 725 4 N2 0. 6 750 1 N2 0. 6 675 2 N2 0. 6 700 4 N2 0. 6 725 3 N2 0. 6 750 3 N2 0.6 675 3 N2 0. 6 700 3 N2 0. 6 725 3 N1 0. 6 750 2 1 Gas rate 50 cc./minute for 50 cc. of catalyst. 2 O.H.=Overhead or product boiling 600 F Results provided in Table II above, demonstrate that the iron oxide (Catalyst B) and cobalt oxide (Catalyst C) catalysts are highly effective at 750 F.

Comparative Example A Conventional antioxidants for lubricating oils have .proven to be ineffective for stabilizing the foregoing oils which had not been contacted with a metal catalyst and oxygen, or with a metal oxide catalyst. This is illustrated with an oil of the character of that described in Example 1, before treatment with a metal catalyst and oxygen or with metal oxide. One-tenth percent (0.1%) of 2,6-ditertiary butyl-4-methyl phenol was incorporated in the oil. The resulting product was tested in the ultraviolet light test. There was no appreciable improvement as shown by a comparative test with the oil alone in the ultraviolet light test.

Having thus given a general description of the process and means of this invention and provided by way of example specific embodiments thereof, it is to be understood that no undue restrictions are to be imposed by reason thereof, and minor modifications may be made thereto without departing from the scope thereof.

What we claim is:

1. A process for forming a stabilized lubricating oil fraction resistant to deterioration upon exposure to light and air which comprises contacting a high boiling hydrocarbon fraction with a conversion catalyst having hydrogenation and dehydrogenation properties in the presence of hydrogen at elevated temperature and pressure conditions selected to consume hydrogen and convert said high boiling hydrocarbon fraction to form a plurality of fractions including a lubricating oil fraction boiling above about 650 F., separating said lubricating oil fraction from said plurality of fractions, contacting said lubricating oil fraction after dewaxing with a catalyst system selected from the group comprising a metal of Group VIII of Mendeleeffs Periodic Table in combination with a selected amount of free-oxygen containing gas or with a metal oxide of a metal selected from Groups H-B, VI-B and VIII of said table at a temperature selected from within the range of about 200 F. to about 800 F. depending upon the metal employed so that a desired selective oxidative dehydrogenation of the lubricating oil hydrocarbon fraction boils above about 650 F.; the hydrogenation/dehydrogenation catalyst contact temperature is from about 600 F. to about 850 F.; hydrogen is circulated at a rate of from about 5,000 to about 1,000 s.c.f. per barrel of charge of the high boiling hydrocarbon fraction; and the high boiling hydrocarbon fraction is converted to a product containing from about 10 to about 75 volume percent boiling below about 650 F.

5. The process of claim 1 wherein the metal of Group VIII is platinum.

6. The process of claim 1 wherein the metal of the metal oxide is a metal of Group II-B.

7. The process of claim 1 wherein the metal of the metal oxide is a metal of Group VI-B.

8. The process of claim 1 wherein the metal of the metal oxide is a metal of Group VIH.

9. The process of claim 8 wherein the metal oxide is ferric oxide.

10. The process of claim 8 wherein the metal oxide is cobalt oxide.

11. The process of claim 1 wherein said lubricating oil fraction is so contacted with a Group VIII metal at a temperature of from about 200 F. to about 400 F.

12. The process of claim 1 wherein said lubricating oil fraction is so contacted with said metal oxide at a temperature of from about 650 F. to about 750 F.

13. The process of claim 1 wherein said lubricating oil fraction is so contacted with said metal oxide in the presence of a free oxygen-containing gas.

14. In a process for forming lubricating oils resistant to oxidation upon exposure to light and air, from a lubricating oil fraction formed by contacting a high boiling hydrocarbon fraction with hydrogen in the presence of a hydrogenation/dehydrogenation catalyst at hydrogen consumption temperatures and pressures, the improvement which comprises further contacting said lubricating oil fractions with a catalyst system selected from the group comprising a metal of Group VIII of Mendeleeffs Periodic Table and a selected amount of free-oxygen containing gas or with a metal oxide of a metal selected from Group IIB, VI-B or VIII of said table, under conditions of oxidative dehydrogenation to form a lubricating oil fraction more resistant to deterioration by air and light.

15. A hydrocarbon lubricating oil fraction resistant to 9 1 0 deterioration upon exposure to light and air, obtained "by 2,904,505 9/1959 Cole 208-144 the process of claim 1. 3,242,068 3/1966 Paterson 2081l1 References Cited HERBERT LEVINE, Primary Examiner. UNITED STATES PATENTS 5 US. Cl. X.R. 2,915,452 12/1959 Fear 208-48 208-43, 57

2,726,194 12/1955 Van Beest et a1 208255 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,436,334 April 1, 1969 Bernard A. Orkin et a1.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

, Columns 5 and 6, TABLE I, third column, before the first five entries, insert as a footnote 2 Signed and sealed this 14th day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. E. JR

Attesting Officer Commissioner of Patents