United States Patent Office Patented Oct

3,281,355 United States Patent Office Patented Oct. 25, 1966 2 MoC)Br2, MoaOCls, MoOCls, MoOF. It is also pos 3,281,355 sible to employ aqueous sulfuric acid solutions of MoC3, STABLE COLLOIDAL DESPERSONS OF or H2MoC) or molybdenum blue. Other suitable start MOLYBDENUM SULFIDE ing materials include solutions of molybdenum naph Elmer B. Cyphers, Cranford, and Max W. Hill, Westfield, N.J., assignors to Esso Research and Engineering Com thenates or sulfonates in one or more of the lower alco pany, a corporation of Delaware hols. By lower alcohol is meant a C to Caliphatic al No Drawing. Filed Nov. 15, 1963, Ser. No. 323,887 cohol, i.e., methanol, ethanol, isopropyl alcohol or butyl 14 Claims. (Cl. 252-18) alcohol. The formation of the molybdenum sulfide can be car The present application is a continuation-in-part of ap O ried out in the presence of the detergent additive per se. plication Serial No. 99,688, filed March 31, 1961, and It is usually more convenient, however, to carry out the abandoned subsequent to the filing of the present appli formation in an oil concentrate of the detergent additive. cation. These concentrates usually contain about 10 to 80 wt. This invention relates to the preparation of composi percent of the detergent additive, with the remainder be tions containing stably dispersed molybdenum sulfide of 5 ing lubricating oil. colloidal particle size and to the use of such compositions The lubricating oil may be either a mineral oil or a in lubricating oil formulations. Particularly, the inven synthetic oil. Examples of synthetic oils include syn tion relates to the formation of molybdenum sulfide in thetic hydrocarbon oils, polysilicones, polyglycols, dibasic situ by the reaction of a molybdenum-containing com acid esters such as di-2-ethyl hexyl sebacate, carbonate pound with a sulfur-containing compound in the presence 20 esters, glycol esters such as C3 oxo acid diesters of tetra of a protective colloid or a dispersant-detergent. ethylene glycol, and complex esters, as for example the Molybdenum sulfide has been recognized as an excel complex ester formed by the reaction of 1 mole of sebacic lent lubricating material because of its outstanding reduc acid with 2 moles of tetraethylene glycol and 2 moles tion of wear and friction. This material has been widely of 2-ethyl hexanoic acid. The mineral lubricating oils used in the formulation of solid grease compositions. 25 may be of any suitable type including those derived from However, its insolubility in lubricating oil and its black the ordinary paraffinic, naphthenic, asphaltic or mixed color have militated against its use in liquid lubricant base mineral crude oils by suitable refining methods. compositions such as crankcase oils for internal combus The detergent additives which are operable as dis tion engines. Many attempts to incorporate molybdenum persants for the present invention include the petroleum sulfide into fluid oil have been made by grinding the 30 sulfonates, synthetic alkyl aryl sulfonates, various alkyl molybdenum sulfide to an exceedingly fine particle size phenates, alkyl phenate sulfides, phosphosulfurized olefin and then dispersing it in oil. Such dispersions still have polymers, and various combinations of these additives. a dark color and the solid particles tend to settle out of Following are specific descriptions of several of the above the oil during storage. types of detergent additives. It has now been found that by preparing molybdenum 35 Petroleum sulfonates generally used as lubricating oil Sulfide in situ in the presence of certain protective col detergents are the oil-soluble alkaline earth metal salts loidal materials it is possible to obtain stable dispersions of high molecular weight sulfonic acids. These sulfonic which avoid the black color normally associated with acids are produced by the treatment of petroleum oils of molybdenum sulfide. While the molybdenum sulfide is the lubricating oil range with fuming sulfuric acid and preferably prepared by the reaction of a molybdenum salt 40 generally have molecular weights of about 300 to 700. and hydrogen sulfide, it is within the scope of the in Petroleum sulfonates are well known in the art and have vention to employ other sources of the sulfide ion such been described in numerous patents, e.g., U.S. 2,467,176. as ammonium hydrosulfide, or ammonium polysulfide, Detergent sulfonates can also be derived synthetically or the corresponding alkali metal derivatives, e.g. sodium from relatively pure alkyl aryl sulfonic acids having from or potassium hydrosulfide or polysulfide. The protective 45 about 10 to 33 carbon atoms per molecule. For exam colloidal materials are those materials which are known ple, sulfonated products of alkylated aromatics such as in the lubricating art as detergent additives. Since such benzene, toluene, Xylene, and naphthalene, alkylated with detergent additives are normally added to automotive olefins or olefin polymers of the type of polypropylene, crankcase oils they can now be made to serve the addi polyisobutylene, etc., can be used. tional function of stably suspending the molybdenum sul 50 Specific examples of the above two types of sulfonates fide. The resulting compositions containing molybdenum include calcium petroleum sulfonate of about 880 molec Sulfide show a marked tendency in reducing wear and ular weight, barium petroleum sulfonate of about 980 friction as will be later demonstrated. molecular weight, calcium C alkyl benzene sulfonate, Stated more explicitly the process of this invention is barium C alkyl benzene sulfonate and calcium C alkyl conducted by reacting a water-soluble or a lower-alcohol 55 benzene sulfonate; wherein said C alkyl group is derived Soluble salt of a compound of molybdenum in which from diisobutylene; said C alkyl group is obtained from compound the valence of molybdenum is at least four, tripropylene and said C alkyl group is obtained from with a reagent effective to furnish sulfide ions and there tetraisobutylene. by form molybdenum sulfide, the reaction being con The above sulfonates may be either neutral sulfonates, ducted in the presence of a lubricating oil detergent addi 60 i.e. where the sulfonic acid is neutralized with an equal tive that is capable of stably suspending molybdenum sul mole equivalent amount of metal base, or the sulfonates fide in the lubricating oil. may be of the so-called "high alkalinity' type. In the lat Particularly useful molybdenum salts for forming the ter case, additional metal base, in excess of that required for simple neutralization, is reacted with the sulfonic sulfide are those of the formula: XMoO, wherein X rep 65 acid to form an alkaline product which can then be resents a metal or an ammonium radical, and n is either blown with carbon dioxide to reduce its alkalinity and 1 or 2, depending upon the valence of X. Specific exam form a substantially neutral final product. The term sul ples of such molybdates include ammonium molybdate fonate as used herein and in the appended claims in and alkali metal molybdates such as those of sodium or cludes both neutral sulfonates and so-called high alkalinity potassium. 70 (or high metal content) sulfonates. Other molybdenum salts that may be used in aqueous Metal salts of alkyl phenols and of alkyl phenol sulfides solution include MoCl4, MoBra, MoCaCl2, Mo.OCl, are also well known in the art. Metal salts of alky1 3,281,355 3 4 phenols having straight chain or branched chain alkyl . The molybdenum-sulfide-containing compositions of groups of from 5 to 20 carbon atoms are usually preferred, the invention are prepared by any number of methods, and the metal used to form the phenate is preferably an several of which follow: alkaline earth metal, e.g., calcium, barium, strontium, or A molybdenum salt such as ammonium molybdate is magnesium, although other salts such as those of alumi dissolved in water and the resulting solution is slowly num, sodium, cobalt, lead, chromium or tin are some added to heated detergent while bubbling hydrogen Sul times used. A specific example is the barium salt of the fide through the detergent. The temperature of the de alkylation product of phenol with tripropylene. Metal tergent during this addition is maintained in the range salts of the corresponding alkyl phenol sulfides may also of about 250° to 600 F., preferably 275 to 425 F. be used. The latter are the thioethers and polysulfides of O Alternatively, all the aqueous solution of molybdenum alkyl phenols, i.e. compounds in which the alkyl groups salt is first added to the hot detergent, and then hydrogen are joined by one or more divalent sulfur atoms. The sulfide is bubbled through the mixture. In either case, alkyl phenols can be converted to phenol sulfides by re molybdenum sulfide is formed in situ and sufficient heat action with sulfur dichloride. If sulfur monochloride is is applied to boil off the water and to help promote the used, the resulting products are primarily alkyl phenol 5 reaction between the hydrogen sulfide and the salt. For disulfides. Specific examples of the phenate sulfides in purposes of economy, it is preferred that the water solu clude barium tertiary octyl phenol sulfide, calcium tertiary tion of the molybdenum salt be saturated so as to min octyl phenol sulfide, barium-calcium nonyl phenol Sul imize the amount of water to be later evaporated. Such fide, barium tertiary amyl phenol sulfide, calcium dodecyl a saturated solution will usually contain about 15 wt. per phenol sulfide, and barium nonyl phenol sulfide. High 20 cent of the salt in the use of ammonium molybdate. It alkalinity (i.e. high metal content) phenates and phenate is more preferred to add a small amount of a volatile acid sulfides are also included in the above description.

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