US2958590A - Stabilized hydrocarbon fuel oil composition - Google Patents

Description

,4 STABIIJIZIEDHYDROCARBON FUEL OIL COMPOSITION Joel R. Siege], Irvington, N.J., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Filed Oct. 15, 1957, Ser. No. 690,184

Claims. (Cl. 44-62) The present invention is directed to the stabilization of hydrocarbon oils, and particularly of petroleum middle distillates, against discoloration and the formation of sediment during storage. More particularly, the invention concerns the stabilization of hydrocarbon fuel oils during storage by incorporating into those oils addition agents that inhibit degradation of the fuel oils and which at the same time serve to disperse any sediment-producing materials that may have formed in the fuel oil. The addition agents of this invention are of particular value because they do not form ash or residues when the fuel oils are burned.

The hydrocarbon fuel oils with which this invention is particularly concerned broadly comprise petroleum distillates that are commonly employed in various burner systems, as fuels for diesel engines, as jet fuels and as domestic or industrial heating oils. Such fuel oils may be gene'ra'lly characterized as those that consist of a major proportion of hydrocarbons boiling'in the range of from about 350 F. to about 900 F. Fuel oils tend to deteriorate on storage, particularly'when they contain cracked hydrocarbon stocks, as they now commonly do. It has been found that if percent or more of the fuel oil composition comprises cracked stocks, the formation of sludge or sediment during storage may be markedly increased, leadingto the plugging or fouling of oil lines, filters and burner nozzles.

Attempts have been made in the past to overcome the sediment-forming problem by incorporating addition agents in the fuel oils. Many of these additives, however, particularly metal salts such as metal naphthenates, metal sulfonates and metal salts of alkyl phenol sulfides, have been objectionable in that they leave an ash residue on combustion.

' It is a primary object of this invention to improve the stability of petroleum hydrocarbon fuel oils against the formation and precipitation of sediment while at the same time minimizing the formation of ash when such fuels are burned. It is an additional object of the invention to improve the color stability of such fuel oils.

. It is still a further object of this invention to provide improved addition agents, and improved methods of preparation of the same, for accomplishing the objects stated above.

. In accordance with the present invention, the sedimentforming tendencies of petroleum hydrocarbon oils, and particularly of fuel oils, can be markedly reduced by incorporating therein minor proportions, of the order of from about 0.001%to' about 0.2%, of a polymeric material containing an amidine group. The polymeric materials of this invention are preferably prepared by co- 'polymerizinga mixture of three types of monomeric materials, namely, a long chainalcohol ester of a conjugated unsaturated dibasic acid, a vinyl ester of a short chain fatty acid and an N-vinyl amide, and then reacting the resulting copolymer with a primary amine, preferably a tertiary alkyl primary amine. Suitable vinyl esters include vinyl acetate and vinyl propionate. The dibaic mat-o vinyl ester.

"ice

acid ester may be a maleate, fumarate, itaconate, aconitate, or the like. 7 p

The dibasic acid ester component of the copolymer is preferably an ester of fumaric acid or of mixed fumaric and maleic acids and a long chain alcohol of from about 8 to 24 carbon atoms such as octyl (C laury1 (C tridecyl (C arachidyl (C behenyl (C or tallow (C alcohols produced by the hydrogenation of tallow acids. J

The N-vinyl amide component of the copolymer is characterized by the general structures:

and

H?==CH where, in the first formula, R is selected from the group consisting of hydrogen and alkyl groups of 1 to. 18 carbon atoms and R is'an alkyl group of from 1 to 18 carbon atoms, and, in the second formula, 11 is an integer from 2 to 4. Preferably R and R are alkyl groups of 1 to 8 carbon atoms. a The second formula given above represents compounds of the first formula wherein R and R have been replaced by a single divalent hydrocarbon radical of from 2 to 5 carbon atoms to give an internal or cyclic amide. e

Among the N-vinyl. amides that may be employed in practicing this invention are included N-vinyl-N-methyl acetamide, N-vinyl oleamide, N-vinyl pyrrolidone, N- vinyl-N-isopropyl-Z-ethyl hexoic amide, N-vinyl piperidone, -N-vinyl-fi-methyl pyrrolidone, and 'N-vinyl-evalerolactam; i

Preferably the copolymers are prepared from mixtures of the monomers in the proportion of about 1 to 1.5 moles of vinyl ester, about 0.5 to'0.7 mole of dibasic acid ester and about 0.5 to 0.3 mole of the N-vinyl amide. Preferably the amounts of the latter two components should add up to about 1 mole for the l to 1.5 moles of The'polymerization is conducted in a solution of benzene or other solvent, e.g., xylene, toluene, etc. (50 percent by weight) at temperatures of 60 to 212 F. and may be promoted by gamma radiation or by use of a peroxide type catalyst such as benzoyl peroxide, a hydroperoxide or an azo catalyst such asalpha-alphaiazo-bis-iso-butyronitrile. 'The polymerization is corn, ducted until a product of -0 to 100,000 but preferably 2000 to 20,000 Staudinger molecular-weight is produced. The copolymer product after boiling off the solvent is then reacted with a tertiary alkyl primary amine. The amines employed in this invention are preferably those having from about 4 to about 20 carbon atoms. Among the amines that may be used are tertiary octyl primary amine, tertiary dodecyl primary amine, and a commercial mixture of tertiary alkyl primary amines of 12 to 15 carbon atoms, marketed under the name Primene 81R.

The copolymer product is reacted with the amine by mixing the product withfrom 1 to 3 moles, preferably 1.25-2.5 moles, of amine per mole of amide group in the copolymer, the mixture being dissolved in somesuitable non aqueous solvent boilin'g'in the range of about 212 F. toabout 350 F., e.g. toluene, xylene. The mix is then refluxed at a temperature of 212-350" F., preferably 230300 F., for a period of 110 hours, preferably 2-6 hours, in a nitrogen atmosphere in the presence of a dehydrating agent such as 110% (based on the polymet) of fused zinc chloride or aluminum chloride for example. Alternatively, or in conjunction with the dehydrating agent, the refluxing can be conducted in an apparatus provided with a water separator. The product is filtered, the solvent and; excess amine are-removed-by evaporation in a vacuum and the polymer isaredissolved in the desired solvent. In the; reaction, the; amine group reacts with the amidegroup of the polymer, forming water. and an azomethine group C=NR. The water is removed by distillation orby; absorption: by the de hydrating agent.

The following, examples will serve to'illustrate: this invention.

EXAMPLE: 1

Vinyl acetate, tallow fumarate and N-vinyl pyrrol idone in the mole ratio of 1-.4/.635/ .365 were dissolved in sufiicient benzene to make a 50 percent solution by weight. 1.0 percent of benzoyl peroxide was added and polymerization was conducted at 110 F. for 20 hours in the presence of gamma radiation at a dose rate of 1 mr./hr. Then 0.7 mole of tertiary octyl amine (which was an excess) was added along with a quantity of xylene equal in weight to the? polymer mix. The blend was refluxed for 4.5 hours in a nitrogen atmosphere in the presence of 8.8 percent anhydrous zinc chloride, based on the polymer. This solution was then filtered, the solvent and excess amine were removed under reduced pressure, and the polymer was dissolved in 50'per cent of. its weight of benzene. It was established'byinfrared spectroscope thatthe amidine groupingwas'present in the polymer.

EXAMPLE 2 a A commercial fuel oil was selected for stability tests using the oil itself as well as a blend of the oil containing the additive described in the foregoing example. The oil was a blend of 50 percent virgin distillateand 50 percent cracked stock. Typical inspections for this type of oil are as follows:

The base fuel and the additive-blend were subjected to a stability test which consisted in storing thefuel oil for a period of 16 hours while maintaining the temperature at 210 F. At the end of the 1.6 hours the fuel oil was filtered and the amount of sediment that had been formed during the storage period was quantitatively determined.

Table I sets forth the data obtained in these tests:

Table l AOOELERA'IED STORAGE STABILITY TEST Insoluble Sediment Formed After 16 Hours 210 F., tug/600 g. Oil

Additive 1 None. "0.01% of Product of Example 1 It will be noted from the data in Table 1 that the 1 polymer was very effective in reducing the sedimentforming tendency of the fuel oil.

It is not intended that this invention be limited to the specific examples presented by way of illustration. The scope of the invention is limited only by the appended claims.

What is claimed is:

1. A stabilized hydrocarbon fuel oil composition consisting of a major proportion of hydrocarbons boiling in the range of from about 350 F. to about 900 F., and a minor proportion of a reaction product of a tertiaryalkyl primary amine with a copolymer of a vinyl'ester of a short chain fatty acid, a long chain alcohol'ester of a conjugated unsaturated dibasic acid, and an N-vinyl amide selected from the structural formulas consisting of:

wherein R is selected from the group consisting of hydrogen and alkyl groups of 1 to 18 carbon atoms and R is an alkyl group of from-1 to 18 carbon atoms, and wherein n is an integer from 2 to 4, wherein the amount of vinyl ester utilized is in the range from about 1 to 1.5 moles, wherein the amount of dibasic acid present is in the range from about 0.5 to 0.7 mole and wherein the amount of N-vinyl amide is present in a concentration from about 0.5 to 0.3 mole, said reaction product being present in said hydrocarbon oil composition in an amount suflicient to inhibit the formation of sediment in the said oil.

2. The composition as defined by claim 1 wherein the concentration of the reaction product in the hydrocarbon oil composition is within the range of about 0.001% and about 0.2%.

3. The composition as defined by claim 1 wherein the amine has from 4 to about 20 carbon atoms.

4. The composition as defined by claim 1 wherein the reaction product is obtained from the reaction. of from 1 to 3 moles of amine per mole of amido group in the copolymer.

5. The composition as defined by claim 1 wherein said reaction product is prepared from tertiary octyl amine and a copolymer of vinyl acetate, tallow. furnarate and N-vinyl pyrrolidone.

References Cited in the file of this patent UNITED STATES PATENTS- 2,387,501 Dietrich Oct. 23, 1945 2,469,737 McNab et al May 10, 1949 2,553,325 Loritisch May 15, 1951 2,597,202 Lawney May 20, 1952 2,626,945 Carlin Jan. 27, 1953 2,737,452 Catlin et a1 Mar. 6, 1956 2,771,348 Meguerian Nov. 20, 1956 2,793,943 Moore May, 18', 1957 2,800,401 Lusebrink et al July 23, 1957 2,800,452 Bondi et a1. July 23, 1957 FOREIGN PATENTS 523,748 Belgium Nov. 14', 1953