US2921025A - Hydrocatalytic refining of lubricating oils and catalyst therefor - Google Patents

Description

HYDROCATALYTIC REFINING F LUBRICATING OILS AND CATALYST THEREFOR No Drawing. Application May 14, 1957 Serial No. 658,958

5 Claims. (Cl. 208264) This invention relates to a process for refining or finishtreating lubricating oils or their fractions by hydrogenation under specific, mild conditions, in the presence of a catalyst consisting of moylbdenum oxide on an alumina support containing small amounts of silica, whereby improvements in physical properties of the products are obtained without impairment of the inherent good qualities of the'feed. More particularly, the process is one in which, through mild hydrogenation at temperatures no greater than about 600 F. using a particular catalyst composition, the neutralization number of a lubricating oil can be reduced substantially to zero without affecting the natural oxidation resistance, viscosity and other properties of the feed, and over extended periods of time with no appreciable reduction incatalyst activity.

Recent developments in the hydrogenation 'of petroleum show that hydrogenation is adaptable for converting heavier oils to gasoline andgas oil, increasing the paraffinicity of kerosenes, burning oils and lubricating oils, and converting all types of asphalts to distillate fuels. Until the last few years, commercial hydrogenation has been restricted to the use of highly purified hydrogen at pressures greater than atmospheric, temperatures below the decomposition temperature of the feed, and in the presence of powerful but sensitive catalysts of the type of reduced nickel. These processes were generally applicable to sulfur-free and arsenic-free materials and accordingly related primarily to the treatment of vegetable fats and oils. By using hydrogen alone andemploying greatly increased pressures, both coal and petroleum oils can be liquefied to a high degree, but because of their high contents of sulfur and oxygen compounds, the resulting products are diflicult to crack or further refine. With the advent of 1 catalytic desulfurization, hydrogenation and reforming processes as applied to lighter stocks and the development of sulfur-resistanct catalysts, the art has seen many developments in the field of flexible methods of treating and refining by the use of hydrogen.

In the' application of hydrogenation as a refining,

United States Patent '0 2,921,025 Patented Jan. 12, 1960 ished oil by the use of addends to offset deficiencies in oxidation stability, demulsibility, acid number, sludge resistance and the tendency to corrode metal parts which are directly or indirectly a result of the refining process.

Within the vast amount of art available on hydrogenation, hydrodesulfurization, destructive hydrogenation, hydrogenolysis and related refining processes employing hydrogen to treat a wide variety of feed stocks, attention is generallp directed to such matters and problems as the method of catalyst preparation or pretreatment, catalyst composition, removal or destruction of sulfur, oxygen and nitrogen compounds, removal or destruction of asphaltic or resinous compounds, the use of promoters, obtaining fluidizable catalysts, color stability in the product, removal of unsaturates and maintaining catalyst life or activity. Hydrogen processing is generally conducted at temperatures above 750 F., employing pressures well above 500 lbs. per square "inch, and such processes inherently remove or transform both undesirable and desirable constituents. The art has now come to recognize thatcertain of thenaturally-occurring sulfur, oxygen and nitrogen compounds that are destroyed or removed during these refining operations have a decided elfect upon the oxidation stability and sludge-forming propensities of the refinedlubricating oils. Although it is recognized that the stability of the lubricating oil in service, wherein it is subjected to highly complicated oxidation atmospheres catalyzed by the presence of metallic surfaces, which oxidation progresses as the extent of use is prolonged, may be reduced by removing certain of the more unstable naphthenes or aromatics or diphenyls, it is the organic sulfur compounds that are responsible for any remaining resistance to oxidation theoil may have after such refining methods have been applied.

Attempts have been made to isolate the sulfur compounds naturally present in lubricating oil fractions, as

by the formation of mercuric chloride addition comp pounds, or by selective adsorption on fullers earth, but

. oils. Differences in the activity 'of various sulfur compounds in reacting with peroxides, which are apparently present under oxidative conditions, is explainable on the basis of structure of the sulfur compounds and their ability to inhibit peroxide formation. However, such reaction products are also deleterious and contribute to sludge formation during use. The refiner, therefore, is faced with the dilemma of refining lubricating oils to improve their flow characteristics, while still trying to retain a sufficient concentration of natural sulfur compounds to prevent the development of appreciable concentrations of peroxides and consequent high oxidation rates, and at the same time vmaintaining the content of sulfur compounds sufliciently low so that upon oxidation poses. It is'also recognized in the art that only through judicious application of refining methods canthe inherent stability, color properties, or viscosity-temperature characteristics of a lubricating oil or wax be preserved, since many refining operations, including acid treatment, hy-

the concentration of deleterious oxidation innocuous.

In accordance with the present invention, it has been discovered that lubricating oils, their fractions, and base stocks may be refined by mild hydrogenation using a molybdenum oxide-alumina-silica catalyst under particular conditions of temperature and pressure to effect the greatest possible reduction in neutralization number of naphthenic acid content without adversely affecting the viscosity, viscosity index, steam emulsion number, or causing the destruction of the naturally-occurring, oxidatiominhibiting sulfur compounds, While at'the same time maintaining prolonged catalyst life even though the catalyst is sensitive to the presence of sulfur compounds.

V Accordingly, a first object of this invention is to provide products is a process for refining or finishing lubricating oil fractions and lubricating oil base stocks.

Another object of this invention is to provide a superior catalyst composition and method of its utilization for The data further show that the catalyst composition is a critical factor with respect to cycle life. The results show that the combination of about 9 percent molybdenum oxide on a support consisting of 99 percent l P the Propertiesflf lubricating stocks y mild 5 alumina and 1 percent silica is a very efiective catalyst in hydrogenation. reducing acid number when used at temperatures in the Athird object of the invention is to providea catalyst range of 550600 F., and that its activity is still at a for mild hydrotreating of lubricating oils, which catalyst maximum after 161 hours of continuous processing. A contains a minor amount of an oxide of molybdenum similar composition, containing 9 percent molybdenum incorporated in an alumina-silica support contain g a 10 oxide on alumina alone, showed poorer acid reduction predominate amount of alumina. activity and had an active cycle life of only 7 hours.

These and other objects of the invention will become Similarly, catalysts composed of lesser amounts of apparent as the description th'ere'o'f proceeds molybdenum oxide maintain high activity for acid re- In order to demonstrate the invention, a series of eX- moval for a much longer time when the alumina support periments were conducted in which a 241 viscosity neutral contains minor amounts of silica. lubricating oil stock was treated 'to mild hydrogenation at The results of Table II show further the specificity of diff r nt temp r re. l s at a liq id VO'IilIhe ho rly our catalyst composition for acid removal and long cycle space velocity of 1.5, and. a hydrogeh-to-oil mol ratio life. A composition of 9% M00 and 3% C00 on a of 6.5to.7.5, under a pressure 01500 'p.s.i.g. and-employsupport consisting of activated alumina containing 5% ing various molybdenum oxide'containing catalysts; The silica was evaluated for comparative purposes, and, at lubricatingoil stock before treatment hadthe following the same operating conditions as used for our preferred characteristics: 7 catalyst, showed poor activity, selectivity, and catalyst API 5 gravity h 242 llfe. .The cobalt molybdate catalyst reduced theacid 20 number of a heavy residual lube oilto only about 0.5., Refractive lndex n /D 1.4863

V and at thesame time reduced the sulfur content by an Molecular welght 370 appreciable amount. The results in Table 11 show the Neutralization number (1948) 3.03 Vis 3 F SUS p p 241 3 detrimental effect of th s type of catalyst and emphas ze 8 SUS the superiority of the specific'catalyst compositions of our invention for the refining of lubricating oils. Viscosity index 76 imilarly, the use of Porocel (an activated bauxite Sulfur content, wt. percent 1.13

- containing about 84% alumina, 15% silica, and minor Steam emulsion No. 145 I Boflh-l ran 6 a F 72O 930 amounts of iron) as the catalyst for acid removal showed g g again the marked superiority of our catalyst for this par- The results of these experiments are shown in Table I. ticular purpose. The results in Table IIobtained with Results with a catalyst of this invention are compared Porocel also demonstrate its short'active life compared to results with two well-known commercial catalysts in to the catalysts of our invention. Table II. 5

TABLE I Hydrotreating lubricating oil Catalyst Comp. Characteristics of Product Tenflp.

Run Base Comp. treat- Vis., SUS Wt. Steam .Vol. Catalyst Life 1 N0. Perment, M01. Neut Per- .Emul- P er- V I cent F. API Color C.R. 1WD Wt. No VI cent sion cent Lube M005 5102 Also: 100 F. 210 -F. No. ']7?1 Stock hrs. bbl./t0n

1 Length of service before Neut. N 0. reached 0.1 at which time regeneration was necessary.

2 Neut. N0. at end of 12 hours of operation.

silica supports are eifective catalysts for the neutralization of lubncating'oil stocks and that the greatest effectiveness is obtained at temperatures of 600 F. or lower. It should 'be noted also that the, greatest eificiency in .acid neutralization is obtained over those catalyst compositions wherem the molybdenum oxide is incorporated into porous plied where the mainobje'ctof the treatment is a reduction in the neutralizationnumber of the lubricating oil a pp a ning minor proportions of silica. without appreciably afiecting the sulfur content and vis- Yields Length I of Run,

without affecting said mineral Reactor What is claimed is: 1. The process of refining mineral lubricating oils, hav- Pressure, Temp p.s.i.g.

5 to weight percent of molybdenum oxide must be present and the alumina support must contain from between about 90 to 99.95% alumina, which means that the silica content can vary between 0.05 to 10%.

ing natural resistance to oxidation and deterioration due to the content of naturally-occurring sulfur compounds therein and containing acidic compounds whereby said the content of manually-occurring sulfur compounds and without deleteriously affecting the viscosity, viscosity index and steam emulsion number of said mineral lubricating oils which consists in subjecting Hydrogen Reactor Rate 8.0.12] bbl.

' API TABLE II LHVSV Product Specifications Charge 011 Table III.

Hydrogenation of distillate and residual lube oil stocks Catalyst Same as Run 12 Table I.

cobalt molybdate.

(In 6...- Poroeel. No. 4,

Vis., SUS

Run No.

Run No.

TABLE IV within the conditions set forth in Table IV content of acidic compoundsis reduced tmdm n m mm m x m mrm e O w am um m mml m n u tr mmmmmwm s mnqme .1 mt HT n c .WLWOIW Bi C at he CO6 n w s: $5 a .mm m 1 71507 0 25 2 w w 6 n t 810 .owm .OOZW wmmev Rn ...2....2....l raw 0 Emu- 100 02 21 0000 m h m w 6.1 0mm. hu c t WS 6 e a t 50305334 25 55 a e m m m a m was EUMHLMMWMM e 0 .mwv MWH m w ma m m SP t M19 5 mmma mt m nausea? 0 2. 1 m m w A nmmflmmmm ufiumn a .rfi an m m ohvtmu pa t t S C S 09953631450555 mun nm N 5 0 mo m mm mmmmmmmm LLL 01 a 3 4 MN .0

n d S W .m.0 m w 64 63576 00 0 0 m w $y w e I 9779787 "QQWMQ LL 0. 0 N nm g V n 2. n ma a u I m m ad w F sfiasmaasjnmnn as... 5 n E n w w euemn uwnwmnam D 000845 R m mh y.O L .0 d 2 1 1 11 M 0 0 0 0 ou d w n w n w n T m flmm m s S P W t6 T e V F 21 803 H mm A .m rnew g S s azaf "WW3 m 0dw mn w W m Zmuaflfi 2 3 W 4 w sue s.m d 1 n n 1 79 9 mhfl y u n V m m om H 11. m tg flvb n. 0 81 2 d m an- M 1 6 15 6 n ur. .m r umnmunmu 2 4.88 6 .m m u1.S. 11 1 a o n otwoumumn a W b m dvmudmduduu w e mm a alumlmamum 6 tma .1 .1 mau a m mm W m w m a nmnmm m 1 mad 3 w hd hm a a nn w wum m pTO D e e ew me mm mu m un U0 v. on m m m m mmnmdwmw w o mtwbow nm mmnmm m u s r an I m w m mmuwm mn m m am a m :2" 1 N 6 wvnmmww L anaamnmnn In general, the operating conditions used in treating lubricating oils to obtain the desired results are as follows:

Temperature 450-600 F. LVHSV 0.5-2.0. Hydrogen/HG mol. ratio 5.0-10.

Pressure 100-500 p.s.i.g

H rate 1000-4000 s.c.f./bbl. By operating using the catalyst compositions of this invention, lubricating oil distillates, bright stocks, and residual oils can be improved with respect to their VI, color, neutralization number, demulsibility, and reduction in the carbon residue, resins and oxygenated compounds, without imlubricating oils to contact with hydrogen at a temperature percent alumina and about 1.0 wt. percent silica with about 9.0 wt. percent molybdenum oxide and an alumina base containing about 95.0 wt. percent alumina and about 5.0 wt. percent silica with about 3.0 wt. percent molyhdenum oxide, and recovering a hydrogenated lubricating oil characterized by having a neutralization number (1948 method) of below about 0.03, the original content of naturally-occurring sulfur compounds, without impairment of the physical properties thereof.

2. The process in accordance with claim 1 in which said catalyst is an alumina base containing about 94.2 wt. percent alumina and about 5.8 wt. percent silica with about 3.0 Wt. percent molybdenum oxide. 7

3. The process in accordance with claim 1 in which said catalyst is an alumina base containing about 99.0

wt. percent alumina and about 1.0 wt. percent silica with abou 90mpe q n zmq yb n mox 4. The process in accordance with claim 1 in which said catalyst is an alumina base containing about 95.0

'wt. percent alumina andabout 5.0 wt. percent silica with about 3.0 wt. percent molybdenurmoxide.

5. The process in accordance with claim 1 in which the lubricating oil is a neutral oil having a viscosity at 100 F. of about 240, a viscosity at 210 F. of about 47, a steam emulsion number of about 145, a neutralization number of about 2.88, and a sulfur content of abou 1.13 weight percent.

References Cited in the file ofthis patent ZUNITED ST ATES PATENTS 2,437,532 Huffman Mar. 9, 1948 2,486,361 Nahin e,t a1. "Oct. 25, 1949 2,654,696 La Porte Oct. 6, 1953 2,706,167 Harper et al Apr. 12, 1955

Claims (1)

1. THE PROCESS OF REFINING MINERAL LUBRICATING OILS, HAVING NATURAL RESISTANCE TO OXIDATION AND DETERIORATION DUE TO THE CONTENT OF NATURALLY-OCCURRING SULFUR COMPOUNDS THEREIN AND CONTAINING ACIDIC COMPOUNDS WHEREBY SAID CONTENT OF ACIDIC COMPOUNDS IS REDUCED WITHOUT AFFECTING THE CONTENT OF NATURALLY-OCCURRING SULFUR COMPOUNDS AND WITHOUT DELETERIOUSLY AFFECTING THE VISCOSITY, VISCOSITY INDEX AND STEAM EMULSION NUMBER OF SAID MINERAL LUBRICATING OILS WHICH CONSISTS IN SUBJECTING SAID MINERAL LUBRICATING OILS TO CONTACT WITH HYDROGEN AT A TEMPERATURE OF BETWEEN ABOUT 550* AND 600*F. IN PRESENCE OF A CATALYST SELECTED FROM THE GROUP CONSISTING OF AN ALUMINA BASE CONTAINING ABOUT 94.2 WT. PERCENT ALUMINA AND ABOUT 5.8 WT. PERCENT SILICA WITH ABOUT 3.0 WT. PERCENT MOLYBDENUM OXIDE, AN ALUMINA BASE CONTAINING ABOUT 99.0 WT. PERCENT ALUMINA AND ABOUT 1.0 WT. PERCENT SILICA WITH ABOUT 9.0 WT. PERCENT MOLYBDENUM OXIDE AND AN ALUMINA BASE CONTAINING ABOUT 95.0 WST. PERCENT ALUMINA AND ABOUT 5.0 WT. PERCENT SILICA WITH ABOUT 3.0 WT. PERCENT MOLYBDENUM OXIDE, AND RECOVERING A HYDROGENATED LUBRICATING OIL CHARACTERIZED BY HAVING A NEUTRALIZATION NUMBER OIL CHARACTERIZED BY HAVING A NEUTRALIZATION NUMBER (1948 METHOD) OF BELOW ABOUT 0.03, THE ORIGINAL CONTENT OF NATURALLY-OCCURRING SULFUR COMPOUNDS, WITHOUT IMPAIRMENT OF THE PHYSICAL PROPERTIES THEREOF.