US2915448A - Hydro-refining method for lubricating oils and wax using nickel molybdate or silver molybdate on alumina - Google Patents

Description

United States Patent HYDRO-REFINING METHOD FOR LUBRICATING OILS AND WAX USING NICKEL MOLYBDATE OR SILVER MOLYBDATE 0N ALUlVIINA Weldon G. Annable, Crystal Lake, and William Jacobs, Mundelein, Ill., assignors to The Pure Oil Company, Chicago, 111., a corporation of Ohio No Drawing. Application May 25, 1956 Serial No. 587,221

6 Claims. (Cl. 20827) This invention relates to a method of refining or finish-treating lubricating oils, waxes and their fractions by hydrogenation. under specific mild conditions in the presence of a catalyst comprising silver molybdate and/ or nickel molybdate. More particularly, this invention relates to a method of decolor'izing and stabilizing lubricating oils and waxes and their semi-finished fractions without affecting the other properties thereof by treatment with hydrogen at 450 to 650 F., 150 to 1000 lbs. per square inch pressure, using hydrogen circulation rates of 800 to 4000 s.c.f./bbl. in the presence of a catalyst comprising 2 to 30 weight percent of silver molybdate or nickel molybdate or mixtures thereof supported on alumina. H I

It is known in the art that the heavier fractions of crude 'oil, such,a's lubricating oils and waxes and their fractions are enhanced in utility and stability by refining through both chemical and physical means. Lubricating oils and waxes are commonly subjected to various treatments for the purpose of increasing their stability during I portant, producing good yields of finished products which have acceptable color, odor and general appearance. It is essential that these refined products retain their enhanced and augmented properties after they leave the which is applicable to lubricating oilsandwaxes and their fractions wherein the above objectives may be accomplished.

The art teaches that various addends may be incorporated in refined petroleum products to overcome shortcomings in inherent properties, further augment desirable physical and chemical properties, and bring about new properties. Because of their cost, the necessity of close control of their use, differences in effectiveness and the desirability of attaining a stable and uniform level of good oxidation resistance, or color, or viscosity or other properties in the product, it is equally desirable that the use of additives be minimized or eliminated. Another object of this invention is to provide a process for finishing lubricating oils and waxes and their fractions which; in whole or in part, eliminates the necessity of further fortification by the use of additives.

It is also recognized in the art that only through judicious application of refining methods can the inherent stability, color properties, or viscosity temperature properties of a lubricating oil or wax be maintained, since many refining operations, including acid treatment, hydrogenation, solvent extraction, adsorption, thermal diffusion, extractive distillation, chemical and clay treatice ments, remove desirable constituents as well as undesirable constituents. The higher fractions of petroleum contain the more complex hydrocarbons along with various significant amounts of oxygen, sulfur and nitrogen compounds. This means that removal or transformation of one or more of these types of compounds may bring about a desirable change in the finished product for one purpose and a highly undesirable change for another purpose. The oxidation-inhibiting properties of the naturally occurring sulfur compounds is a good example of this phenomenon, for which there is ample evidence and considerable discussion in the prior art. A lubricating oil which has been severely refined to a very low sulfur content is not as stable to oxidation, nor as resistant to wear, as the same oil which has not been as severely refined and which contains small amounts of residual, naturally occurring sulfur compounds. Nitrogen and oxygen compounds have similar but lesser effects, although certain natural acidic or phenolic bodies have been shown to be exceptions to this rule. The natural sulfur compounds seem to be the principal agents responsible for the stability of straight mineral lubricating resistance to oxidation, 'or resistance ,to emulsification,

that may b'e'p'rese'rit in a refined oil or wax ready for finishing oi" 'd'ecolorization, this invention provides a finishing step which does not deleteriously effect any inherent stability or other desirable property. A further object of the invention is to provide a refining or finishing process for lubricating oils and waxes involving mild hydrogenation under certain conditions using a particular catalyst;

it is well known in the art that oils and waxes may be beneficiated by treatment at elevated temperatures withhydrogen using catalysts known to promote thehydrogenation reaction. For this purpose the art lists a large number of metal compounds, particularly the oxides and sulfides of group VI and group VIII metals, paying particular attention to chromium,.molybdenum, tungsten, iron, cobalt, and nickel. Many references are made to the use of oxides of molybdenum, either alone or admixed with other components, such as alkali metals, alkaline earth metals, oxides and sulfides; these are promoted with iron, cobalt or nickel for the purpose of hydrogenating organic materials. Mixtures of oxides and molybdenum oxide are used to promote the hydrogenation of glyceride oils. In the prior art investigations molybdate salts of various metals are designated as superior hydrogenation catalysts. The present invention is based upon the finding that for the purpose of decolorizing and stabilizing lubricating oils and waxes without deleteriously affecting the other properties thereof, silver molybdate and nickel molybdate are outstanding in their properties and are not the equivalent of the large group of catalytic materials disclosed in the prior art.

Accordingly, it becomes a primary object of this invention to provide a process for the refining of lubricating oils, waxes and their fractions under certain mild conditions of hydrogenation using silver molybdate and/or nickel molybdate as the promoting material.

A second object of this invention is to provide a process for decolorizing lubricating oils and waxes by hydrogenation at 450 to 650 F. in the presence of a silver molybdate-alumina catalyst and/ or a nickel molybdate-alumina catalyst.

A third object of this invention is to provide a process for decolorizing lubricating oils and waxes in high yields without deleteriously affecting such properties as viscosity, viscosity index, gravity, emulsibility, penetration and general stability during use and during storage.

A further object of this invention is to provide a process for decolorizing and finish-treating lubricating oils and waxes possessing natural resistance to oxidation and deterioration under conditions such that these inherent stability properties of the oils and waxes, or fractions of temperatures, on the other hand is an efiective decolorizing agent and silver molybdate carries the ASTM color down to +3. Furthermore, it is apparent that the other product characteristics of the finished oil, such as VI, gravity, steam emulsion number are equivalent to, if not better than, those produced by the commercial catalyst or cobalt molybdate. In finishing lubricating oils the color of the hydrogenated product will vary somewhat with the grade of neutral oil. Light neutrals should have an ASTM color of about 1, while bright stocks should have an ASTM color of about 5, with the other neutrals having colors between these two extremes.

The problem of improving the color of waxes, particularly microcrystalline wax, is more difiicult than improving the color of lubricating oils. Clay contacting or other contacting methods are capable of producing ASTM colors slightly darker than 1 to meet a color specification of 2. Careful control of the contacting method may bring about a product color of about 1 /z+. Percolation methods SAE 30 oil: are not capable of yielding products which meet these C n COHTadSOH, Welght Pcfcellt 0- color specifications. The invention is further illustrated Color, ASTM (NPA) 4% by reference to the data in Table II showing the results Flash, C.O.C., F 445 obtainable in hydrogenating microcrystalline wax having Fire, C,O.C., F. 95 the following characteristics:

Flash, f; 435 Color, ASTM (NPA) +4 /2 VlS. SUS at 100 F., secs 604 M I o etmg point, P 179 vlS, at F-, Se s P t t 770 F 1 Vis sus at 210 F. secs 67.9 ene fa 3 a 7 d 93 Penetration at 100 F 27 9 ex Penetration at l20 F 84 Gravlty: 6 30 Total sulfur weight percent 014 Refractlve Index, N /D 1-4 Bromine number 1.6 This microcrystalline wax was obtalned fr m a Mid.c Total lfu weight percent 0.67 tinent residuum having the following characteristics: boils Steam emulsion number 792 a ove a o SUS t 2 39 1,

TABLE I Hydrotreating SAE 30 base oil Reaction Conditions Product Characterlstles Exp.

No. Catalyst H Car- Vie. Vls. Vls. Steam Temp., Press, LVHSV Rate, bon Color Flash, Fire, at at at V.L. Grav., RJI. Br. Tot. Emu]. F. p.s.l.g. ftJ/bbl. Res. 000 000 210 API .010. $1111. No.

(STP) F. F. F.

11" 550 250 1.0 5,700 4 400 510 1.4020 2 0 llzeylgglt 000 250 1.8 2,300 0.55 14% 445 510 662 247.2 66.1 94 27.5 1.4910 1 7 8.2g 1% obalt mol bdate la 3-.--. 15.8 weight 450 250 1.0 5, 700 314+ 27 1 1 4910 0 55 86 percent nickel molybdate on alum 4 do 550 250 1.0 5,700 a 27.4 1.4 .42 5.-.- .do 600 250 1.1 5,500 13% 27.3 1.4902 3.34 g 15 7 1 11: 000 250 1.2 5,100 0.48 +3 450 500 555 248.7 66.2 94 27.3 1 4010 1 0 0.52 51 silver molybdate onalum- From the results of Table I, it is apparent that a commercial catalytic hydrogenation catalyst (catalyst A) when used under mild conditions of 550 F. and 250 p.s.1.g. gives a product which is fair as far as physical +90 F.; and S, 2.1%; by treating same by propane deasphalting, phenol extracting and methyl ethyl ketone dewaxing.

In carrying out the hydrogenation experiments in Table properties are concerned but is ineffective in removing 70 H, the following conditions Were sed color bodies. Similarly, cobalt molybdate ordinarily used in hydrotreating of lubricating oils, althrough being equal to commercial catalyst A in other respects, only reduces the color to +4 /2 as determined by ASTM Method D-45T. Nickel molybdate, at even lower 15 Temperature 550 F. Pressure 500 p.s.i.g. LVHSV 1.1. Hydrogen charge rate 2,500 ftfi/bbl. Rec ery 00 TABLE II Hydrogenation of a mtcrocrystallme wax Product Characteristics,

Yield, Color, M.P. Penetration at- Total S,

Run Catalyst bb./ton ASTM .F weight (N PA) percent 7--.- 15.8 tWetight percent nickel molybdate on alumina, prepared from aluminum 44. 1+ 178 17 29 97 0.08

8- 12.2 weight percent of cobalt molybdate on alumina 4+ 179 16 27 9 16.7 weight percent silver molybdate on alumina 180 20 10- Catalyst B. (+219 (179) (12) (30) 11 Catalyst "8 +2 181 12 12- Alumina (alone)- +2% 181 12 30 13 Activated carbon 3 180 16 29 14--. Fullers earth +2 179 12 30 15 Equilibrium bauxite +2 179 19 30 16- 15.3 weight percent silver molybdate on silica 4 177 14 27 17 25.0 weight percent copper molybdate on alumina +156 177 12 26 18 10.0 weight percent copper dichromate on pumice 4+ 177 14 24 1 Conducted at 550 F., 500 p.s.i.g., LVHSV of 1.4, Hz charge rate 2,000 ftfi/bbl. (STP), recovery 100%.

In accordance with the results of Table H, it is seen that under the conditions specified, nickel molybdate and silver molybdate are outstanding in their ability to decolorize microcrystalline waxes. A comparison of experiments 7 and 9 with experiment 16 shows that alumina is the best carrier for silver molybdate and nickel molybdate. Those products which have ASTM colors of +2 or 2 /z+ are not commercially desirable. The process of hydrogenation at low temperatures in accordance with this invention is capable of continuous commercial production of 1+ color microcrystalline waxes, which is not possible using contacting or percolation methods.

The process of hydrogenation in accordance with this invention may be conducted on a batch or continuous basis using any type of reactor or series of reactors known to the art. A mixture of melted wax (or the lubricating oil) and hydrogen gas is fed to the hydrogenation reactor containing the catalyst. This mixture is preferably preheated to the reaction temperature of 450 to 650 F. and the reactor is maintained at 150 to 1000 lbs. per square inch pressure during the passage of the melted wax or lube oil therethrough. Unconsumed hydrogen is separated from the products and may be recycled through the hydrogenation reactor. Hydrogen circulation rates of 800 to 4000 s.c.f/bbl. are used.

In preparing a catalystto be used in accordance with this invention, the alumina carrier may be prepared by precipitating the oxide of aluminum from an aqueous solution of a water-soluble aluminum salt such as the chloride, nitrate, sulfate, etc. This aqueous solution is treated with ammonia, carbon dioxide or acid to precipitate an aluminum compound. The precipitate is washed several times with water to remove any watersoluble impurities and then dried. The water-washing may be carried out both before and after the drying process which is carried out at 100 to 500 F. After thorough drying the prepared carrier is calcined at higher temperatures in the order of 700 to 1200 F. and may then be extruded, piiled, pelleted or otherwise shaped, granulated, or powdered. The alumina carrier is next impregnated with nickel and/ or silver molybdate by immersing the carrier in a suitably concentrated aqueous solution of the nickel and silver salts and ammonium molybdate. Excess unabsorbed aqueous solution is removed by decantation, filtration or by centrifuging, and the impregnated carrier is dried at temperatures of from 100 to 1200 F. This drying is preferably carried out in stages, as is taught in the prior art, that is, by heating to 100 to 500 F. in the first stage and 750 to 1200 F. in the second stage. The heating or calcining may be accompanied by the use of an oxidizing atmosphere suitable to maintain the nickel and silver in the form of oxides associated or combined with the molybdena in the form known as molybdate salts.

The catalysts may be prepared by suspension of a hydrous alumina gel in distilled water, adding aqueous solutions of water-soluble salts of nickel and/or silver, as above mentioned, and ammonium molybdate, and precipitating these metals from the suspension in the form of combined oxides by adjusting the pH through the addition of a suitable base to a value above about 7.0. The suspension is agitated during the precipitation to bring about dispersion of the precipitated oxides in the alumina gel. The resulting mixture is gelatinous and is waterwashed and dried, as above, to complete the catalyst preparation.

The catalysts may also be prepared by powdering an alumina carrier, calcining the powder and impregnating with water-soluble salts of nickel or silver or mixtures of same, under conditions to form nickel molybdate and/ or solver molybdate. The alumina may be activated prior to impregnation. By each of these methods of preparation, the amount of silver molybdate or nickel molybdate is maintained within about 2 to 30 weight percent based on the total catalyst weight. Catalysts containing about 15.8 weight percent of nickel molybdate or about 16.7 weight percent of silver molybdate are superior for decolorizing waxes and lubricating oils.

The foregoing complete disclosure of this invention is not to be considered as limiting since many variations may be made by those skilled in the art without departing materially from the scope or spirit of the claims:

What is claimed is:

1. The method of decolorizing a mineral lubricating oil without impairing the natural resistance to oxidation and deterioration due to naturally-occurring sulfur compounds contained therein and simultaneously improving the steam emulsion characteristics thereof which consists in contacting said mineral lubricating oil with hydrogen at a temperature of about 450 to 600 F. in the presence of a catalyst selected from the group of an alumina base containing about 15.8 weight percent of nickel molybdate and an alumina base containing about 16.7 weight percent of silver molybdate, and recovering a hydrogenerated lubricating oil characterized by improved color and reduced steam emulsion number.

2. The method in accordance with claim 1 in which the temperature is about450" F., the catalyst is an alumina base containing about 15.8 weight percent of nickel molybdate.

3. The method in accordance with claim 1 in which the temperature is about 550 F. and the catalyst is an alumina base containing about 15.8 weight percent of nickel molybdate.

4. The method in accordance with claim 1 in which the temperature is about 600 F. and the catalyst is an alumina base containing about 15.8 weight percent of nickel molybdate.

5. The method in accordance with claim 1 in which the temperature is about 600 F. and the catalyst is an alumina base containing about 16.7 weight percent of silver molybdate.

, 6. The method of decolorizing a microcrystalline wax without impairing the penetration, melting point, and natural resistance to oxidation and deterioration due to naturally-occurring sulfur compounds contained therein which consists in contacting said microcrystalline wax with hydrogen at a temperature of about 550 F. in the presence of a catalyst selected from the group of an alumina base containing about 15.8 weight percent of nickel molybdate and an alumina base containing about 16.7 weight percent of silver molybdate, and recovering 8 a hydrogenated microcrystalline wax of improved color, and having substantially the same melting point, penetration, and content of said sulfur compounds.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2,915,448 December 1, 1959 Weldon G. Annable et al,

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

Column 3 and 4, Table I, fourteenth column thereof, in the sub heading under Product Characteristics", for "V,L. read VJ, column 6,

line 37', for "solver" read silver line 61, for hydrogenerated read hydrogenated Signed and sealed this 14th day of June 1960.

( SEAL) Attest:

KARL H. AXLINE Attesting Officer ROBERT C. WATSON Commissioner of Patents

Claims (1)

1. 6. THE METHOD OF DECOLORIZING A MICROCRYSTALLINE WAX WITHOUT IMPAIRING THE PENETRATION MELTING POINT, AND NATURAL RESISTANCE OF OXIDATION AND DETERIORATION DUE TO NATURALLY-OCCURING SULFUR COMPOUNDS CONTAINED THEREIN WHICH CONSISTS IN CONTACTING SAID MICROCRYSTALLINE WAX WITH HYDROGEN AT A TEMPERATURE OF ABOUT 550*F. IN THE PRESENCE OF A CATALYST SELECTED FROM THE GROUP OF AN ALUMINA BASE CONTAINING ABOUT 15.8 WEIGHT PERCENT OF NICKEL MOLYBDATE AND AN ALUMINA BASE CONTAINING ABOUT 16.7 WEIGHT PERCENT OF SILVER MOLYBDATE, AND RECOVERING A HYDROGENATED MICROCRYSTALLINE WAX OF IMPROVED COLOR, AND HAVING SUBSTANTIALLY THE SAME MELTING POINT, PENETRATION, AND CONTENT OF SAID SULFUR COMPOUNDS.