US2936224A - Gasoline composition - Google Patents

Description

United States Patent F GASOLINE COMPOSITION No Drawing. Application September 6, 1957 Serial No. 682,322

1 Claim. (Cl. 44-69) This invention is directed to rust-inhibited motor fuel compositions; in particular, gasolines having a combination of additives which act synergistically to inhibit rust formation.

After the necessary refinery operations and subsequent blending leading to their formation, gasoline compositions are transmitted into storage tanks. Such storage tanks may be immediately adjacent to the area wherein the refining and blending operations took place or they may be in an area hundreds of miles away from the refining operations. Regardless of the proximity of these storage tanks to the refining operations, the gasoline compositions must be transported in pipe lines over short distances or long distances.

It is the usual practice, before gasolines are transmitted through pipe lines over long distances, that they are stored in huge tanks until they are necessarily piped into other areas. For the most part, the storage vessels and the pipes are prepared from ferrous metals. In the final refining steps, gasolines are usually treated with aqueous solutions of basic substances and water-washed. Thus, water is suspended in the gasolines as they are placed in the storage vessels. Also, there is always a significant amount of water that gets into .the gasoline because of variations in temperatures and relative humidity resulting in air being sucked into the storage vessels and the pipe lines, with the result that such water from the air becomes carried into the containing vessels. Thus, the storage vessels and the pipe lines, because they are commonly made of ferrous metals, rust.

Over a period of time, this rusting is sufficient to result in the formation of rust particles which flake from the metal surfaces. Not only is the life of the storage vessel and the piping equipment reduced by'such a rusting process, but the rust particles often become carried into the gasoline tanks of service stations. Such particles can then be transmitted to the gasoline tanks of automobiles and possibly cause plugging of fuel lines and filters. Furthermore, the rusting in pipe lines results in increased frictionbetween the pipeline arid the gasolines, reducing the amount of gasoline which can thus flow through the lines.

It is well known that for many years the petroleum I industry as a whole-has spent large sums of money in trying to find'a solutionto-this-problein ofrusting of storage vessels and piping equipment. However, such efiforts have notbeen wholly successful in retardin g rusting. Also,many of the rust inhibitors are not entirely a compatible with the numerous gasoline additives currently being used. 1

Therefore, it is an object of this invention to provide gasoline compositions useful in internal combustion engines, which gasoline compositions have rust inhibiting properties such that the usual rusting of ferrous metal containers for gasolines is appreciably reduced in the presence of water and oxygen.

In accordance with this invention, it has been discovered that rust-inhibited gasoline compositions are obtained by incorporating therein lead sulfonates and polyglycols. Thus, the gasoline compositions of this invention comprise a major proportion Of a hydrocarbon (or mixture of hydrocarbons) suitable as gasolines for internal combustion engines, and a minor amount, suflicient to inhibit rusting of said fuel in the presence of water and oxygen, of a combination of lead sulfonates and polyglycols.

The base fuels used herein as gasoline compositions are the hydrocarbon distillates (e.g., petroleum distillates) currently produced for commercial use as gasolines for use in internal combustion engines. Such gasolines may be derived from cracked or straight-run stocks, or a blend of such stocks, and include the hydrocarbons derived from shales and like bituminous materials, or produced by reacting carbon monoxide and hydrogen as in the Fischer-Tropsch synthesis. It is particularly preferred that the gasoline compositions used herein comprise a hydrocarbon or a mixture of hydrocarbons boiling substantially within the gasoline boiling range; that is, in the ASTM D-86 boiling range of about 50 F. to about 435 F.

The particular lead sulfonates which are contemplated herein in combination with polyglycols as rust inhibiting ingredients in gasoline compositions are the lead salts of synthetic alkylbenzene produced by alkylating benzene with propylene polymers or other parafiinic group. The resulting .sulfonic acids have average molecular weights of about 400 and are characterized by an alkyl side chain of about 18 carbon atoms in length. It is of particular importance for the use of the lead sulfonates according to this invention that the molecular weights of the sulfonic acids are in the range of about 350 to 500, which corresponds to an alkylbenzene hydrocarbon having an alkyl side chain of about 14 to 20 carbon atoms in length as the starting material. Lead sulfonates of sulfonic acids of higher molecular weights are less effective in inhibiting rust formation in combination with the polyglycols herein, while, on the other hand, the lead sulfonates of sulfonic acids of lower molecular weights are more readily removed from the fuels by the water therein.

Included herein are the petroleum sulfonic acids (i.e., sulfonic acids derived from petroleum fractions) in the molecular weight range set forth hereinabove.

The following example illustrates the preparation of a lead sulfonate useful in the composition herein.

EXAMPLE I.-PREPARATION OF LEAD SULFONATE A lead sulfonate may be prepared from a synthetic alkyl aromatic hydrocarbon in the following manner: An alkyl aromatic hydrocarbon was produced by alkylating benzene with propylene polymers in the presence of a hydrofluoric acid catalyst. 25% fuming sulfuric acid was added slowly and the temperature was maintained between and F. The addition of the sulfuric acid was completed in 4 to 6 hours, after which the spent acid was allowed to settle and was withdrawn for disposal. The' sulfonicacid layer was slowly transferred to a neutralization vessel containing sufiicient caustic soda to neutralize the sulfonic acid. L

The crude sodium sulfonate thus obtained was dissolved in a hydrocarbon solvent consisting of one part of a light mineral oil of naphthenic character and low Wax content, and two-thirds of a petroleum thinner, such as Stoddard solvent. The resulting solution was washed with two 10% sodium chloride aqueous solutions to remove the sodium sulfate formed. The sulfate-free solution was then converted to lead sulfonate by treating twice with 20% lead nitrate aqueous solution, with the temperature being maintained at about to F.

The lead salt was subjected to two hot water washes,

filtered, and heated to remove the hydrocarbon solvent. The resulting lead alkylbenzene sulfonate had a molecular weight of about 1000.

The polyglycols which are used herein in combination with lead sulfonate as rust inhibitors in gasoline compositions are those exemplified by the formula:

wherein R is hydrogen or a hydrocarbon radical having no more than 8 carbon atoms, x and y are numbers from 25 to 75 and represent the mole percent of the total moles of ethylene oxide and propylene oxide in the polyglycol. The total of x and y (i.e., x-l-y) equals 100. Preferred are polymers containing equal molar amounts of ethylene oxide and propylene oxide units; that is, x=50 and y=50. More particularly preferred are the polymers containing from 7 to 14 ethylene oxide units and from 7 to 14 propylene oxide units, and wherein R in the above formula is a butyl radical.

Where R is not hydrogen, it is an aliphatic hydrocarbon radical containing no more than 8 carbon atoms, exemplified by the following radicals: methyl, ethyl, propyl, isopropyl, butyl, pentyl, hexyl, heptyl, n-octyl, isooctyl, Z-ethylhexyl, etc.

As is seen from the formula hereinabove for the polyglycols used herein in combination with lead sulfonates, the polyglycols are derived from the combination of ethylene and propylene oxides. The polyglycols which are effective herein are those having molecular weights ranging from about 300 to about 10,000. However, because of the greater effectiveness thereof, it is preferred that the molecular weights range from about 500 to about 4000.

The lead sulfonates may be used herein in amounts of about '1 p.p.m. to about 100 p.p.m.; preferably 10 p.p.m. to 75 p.p.m., and the polyglycols may be used in amounts of 1 p.p.m. to 50 p.p.m.; preferably, 1 p.p.m. to 10 p.p.m.

The weight ratio of lead sulfonate to polyglycol employed in the fuel composition is from about 10:1 to about 0.2:1. Preferred are ratios from about :1 to about 1:1. The concentration of the combination added to the fuel may vary from about 2 p.p.m. to about 75 p.p.m. The preferred concentration of the combination of lead sulfonate and polyglycol varies from about 2 p.p.m. to 30 p.p.m.

Table I hereinbelow present data showing the effectiveness of the combination of lead sulfonate and polyalkylene glycols as rust inhibitors in motor fuel compositions.

The rust ratings were obtained by the ASTM procedure D-665 modified to a test duration of 17 hours and carried out at 70 F. The test metal specimen was immersed in the test fuel. Synthetic sea water was used. The resultant specimens were visually rated as to the amount of corrosion. A rating of 7 means that the specimen was fully rusted and a rating of 1 indicates no rust on the specimen.

The test gasoline used was an aviation gasoline hav- 4 ing the following ASTM D-86 distillation characteristics:

The lead sulfonate was a 20% solution of a lead alkyl benzene sulfonate having a molecular weight of about 1000 in a mixture consisting of 37.5% paraffinic base oil having a viscosity of 450 SSU at F., and 62.5% of a petroeum thinner having a 50% distillation point (ASTM D-86) of about 350 F. This lead sulfonate solution contained 4.12% lead. The concentration of this 20% solution used in obtaining the data of Table I hereinbelow is set forth at 5 p.p.m. and 10 p.p.m. Thus, the concentration of the undiluted lead alkyl benzene sulfonate is actually 1 p.p.m. and 2 p.p.m.

This polyglycol was a butyl other of a mixed ethylene-propylene polyglycol having a molecular Weight of about 880. The ethylene oxide and propylene oxide groups were present in equal molar amounts.

This polyglycol was a butyl ether of a mixed ethylene-propylene polyglycol having a molecular weight of about 2240. The ethylene oxide and propylene oxide groups were present in equal molar amounts.

I claim:

A rust-inhibited gasoline composition consisting essentially of an internal combustion engine gasoline having incorporated therein from 1 p.p.m. to 2 p.p.m. of a lead alkyl benzene sulfonate having a molecular weight of about 1,000, and from 1 to 50 p.p.m. of a polyglycol of the formula:

(3H5 041190(CH1OH=O)=(CH:CHO),H wherein x and y represent the mol percent of the total mols of alkylene oxides present in the polyglycol and are numbers, each having a value of 50, said polyglycol having a molecular weight of 880, and wherein the weight ratio of said lead sulfonate to said polyglycol in the gasoline composition is from about 5:1 to about 1:1.

References Cited in the file of this patent UNITED STATES PATENTS 2,533,303 Watkins Dec. 12, 1950 2,575,003 Caron et a1 Nov. 13, 1951 2,799,649 Caldwell et a1. July 16, 1957