US2000283A - Motor fuel - Google Patents

Description

use.

Patented May 7, 1935 UNITED STATES PATENT OFFICE MOTOR FUEL No Drawing. Application August 8, 1934, Serial No. 738,927

13 Claims.

This invention relates to improvements in compositions, especially motor fuels, and more particularly to the prevention of the formation of gummy products in gasoline during storage or Crude motor fuels or gasoline as commercially produced are extremely complicated mixtures comprising saturated and unsaturated hydrocarbons of the aliphatic series as well as some aromatic compounds. On standing and in use in the presence of air, some of these compounds have a tendency to become colored and form resinous, gummy nonvolatile and insoluble products which render the fuel objectionable in color and destroy its usefulness. The presence of these resinous, gummy nonvolatile and insoluble products in a motor fuel tend to form a coating on the containers, cause sticking of the valves, clog the v jets and decrease the efiiciency of the fuel. However, because of the high value of the fuels containing these compounds in their natural state, it is very desirable to maintain them in the motor fuel in such state or condition. Likewise, crude benzol or blends of cracked gasoline and benzol form gums on storage.

Up to the present time, it generally has been necessary to remove the constituents which behave objectionably in order to prevent discolorae tion of the gasoline or the formation of gums or the like therein, thereby also losing the advan tageous efiects of such constituents. Such constituents are usually removed by treatment of the crude gasoline with sulfuric acid or fullers earth in a vapor phase process. However, even at best, such treatment fails to completely remove all of the desired constituents.

This state of the art has given rise to the development and use of so-called stabilizers or gum inhibitors with such gasoline having objectionable tendencies. The known gum inhibitors have been generally inefiicient, requiring the use of relatively large amounts thereof, the addition of which to gasoline has been limited by their relative insolubility in the gasoline. Furthermore, some of these gum inhibitors color the gasoline and are therefore objectionable. For example, 4-amino phenol precipitates badly from gasoline and colors it an intense red.

My invention has for an object the inhibition of discoloration and gum formation in motor fuels and the stabilization of the constituents thereof. A further object is to make it possible to use, as a fuel for internal combustion engines, liquid hydrocarbon fuels, such as gasoline, that contain larger amountsv of unsaturated hydrocarbons than is now commercially possible. A still further object is to produce such fuels at a lower cost than the present fuels. Still further objects are to produce a new composition of matter and to advance the art. Other objects will 5 appear in the following description of my invention.

My invention is based upon the discovery that the replacement of one of the hydrogens on the nitrogen of amino hydroxy aryl compounds with 10 a. cyclohexyl radical markedly increases the solubility of these compounds in solvents of low dielectric constant such as benzol or cracked gasoline, removes the rapid tendency to discolor on storage and exposure to light possessed by free 15 amino phenols, and yields compounds which possess excellent gum inhibiting properties for cracked hydrocarbon distillates such as cracked gasoline and benzol.

My present invention comprises the use of 20 amino hydroxy aromatic compounds in which one hydrogen of the amino group is substituted by a cyclohexyl group or substituted cyclohexyl group. I prefer to use the amino phenols or amino cresols wherein an amino hydrogen has 25 been replaced by a cyclohexyl radical. These latter classes of compounds may be represented by the formula:

wherein R. represents a benzene nucleus which may be substituted with other radicals for example the hydrocarbon radicals such as alkyl radicals and R represents a cyclohexyl radical which may be substituted by hydrocarbon radicals such 35 as alkyl radicals. Among the members of this group of compounds which are particularly suitable as gum inhibitors for cracked hydrocarbon distillates are the ortho, meta, and para cyclohexyl aminophenols; ortho and para (Z-methyl cyclohexyl) aminophenols; ortho, meta and para (i-methyl cyclohexyl) aminophenols; ortho and para (i-ethyl cyclohexyl) aminophenols; cyclohexylamino alkyl phenols such as 4-cyclohexylamino 2-methyl phenol, 4-cyclohexylamino 3- methyl phenol, 3-cyclohexylamino 5-methyl phenol, 4-cyclohexylamino 2-ethyl phenol, 3-cyclohexylamino 2,4-dimethyl phenol and 4-cyclohexylamino 2,5-dimethyl phenol. I may also use an admixture of cyclohexyl aminophenols or cyclo- 50 hexylamino cresols. Other aromatic hydroxy compounds containing cyclohexylamino groups may be used, for example, cyclohexylamino 2- naphthol, 4-cyclohexylamino naphthol and 2-cyclohexylamino naphtho l. Thesecompounds may be prepared by any of the well-known methods of preparing N-substituted aminophenols. For example, p-cyclohexylamino phenol and cyclohexylamino cresols may be prepared by condensing hydroquinone or an alkyl substituted hydroquinone with cyclohexylamine. The ingredients are reacted in a closed vessel at a temperature of about 200 C. Pressure is developed in the vessel during the reaction. If desired, a trace of anhydrous aluminum chloride may be employed as a catalyst.

In most motor fuels, only very minute quantitles on the order of 0.001 to 0.006% of these compounds need be added. However, more or less than these amounts may be added depending on the nature and amount of unsaturated compounds and preformed gum present in the motor fuel to which they are added. Fuels containing preformed gum generally require the addition of larger amounts of the stabilizer due to the accelerating action of the gum already present.

The method of adding the inhibitor or stabilizer is immaterial. The inhibitor may be added by first dissolving it in a solvent such as methanol or benzol and the solution then dissolved in the motor fuel or the motor fuel may be allowed to percolate through a mass of the agent to directly dissolve the desired amount therefrom.

The inhibitors forming the subject matter of this invention were tested in motor fuels in accordance with the oxygen absorption test proposed by Voorhees and Eisinger in their paper "Importance and Significance of Gum in Gasoline, Proc. Am. Pet. Inst. 10 Sec. II (1929). In these tests, a sample of cracked gasoline is heated under an oxygen atmosphere to 210 F. in a glass rubber stoppered flask on a boiling water bath. The heating is continued until completion of what is known as the induction period at which point oxygen is absorbed at the rate of 1 cc. per minute. The number of minutes required to reach the induction period bears direct relation to the stability of the fuel during storage. This characteristic is possessed by cracked hydrocarbon distillates such as cracked gasoline and benzol. Gasoline, when heated beyond this point, rapidly forms large quantities of gum.

An inhibitor extends the induction period and decreases the amount of gum formed by the cracked hydrocarbon distillate. The data set forth in the following table show the effectiveness of the cyclohexyl amino phenols in a sample of sweetened cracked gasoline which tends to deteriorate and develop gummy substances on storage.

Induction period Mmeml in minutes Sweetened cracked gasoline (control 265 Control +0.00l5% p-cyclohexylamino phenol 525 C0ntrol+0.0015% p-(2-mcthyl cyclohexyl)-amino phenol 465 Control+0.00l5% i-cyclohexylamino Z-meihyl phenol 505 From the above data it is apparent that the amino phenols containing a cyclohexyl group in the place of one amino hydrogen are very eifec-- than the aralkyl substituted amino phenols,

The compounds forming the subject matter of my invention are powerful stabilizers and gum inhibitors even in the small amounts specified and hence permit the use of gasoline containing larger amounts of compounds objectionable because of their gumming tendencies thereby requiring lesser refining which decreases the cost of producing the gasoline. These compounds are readily soluble in motor fuels such as gasolines, do not precipitate readily from the gasoline and do not objectionably color the same.

While I have disclosed several specific embodlments of my invention, it is to be understood that the same are given merely by way of illustration and various modifications thereof will readily appear to those skilled in the art within the scope of my invention. Accordingly my invention is to be limited solely by the appended claims construed as broadly as permissible in view of the prior art.

This application is a continuation in part of my o-pending application 591,238, filed February 5, 932.

I claim:

1. A motor fuel comprising cracked hydrocar- "con distillates normally tending to form gum on storage having incorporated therein, in an amount sufficient to inhibit gum formation, a hydroxy aromatic amine having one hydrogen of the amino group replaced by a cyclohexyl radical.

2. Amotor fuel comprising cracked hydrocarbon distillates normally tending to deteriorate and form gum on storage having incorporated therein, in an amount sufiicient to inhibit such deterioration and gum formation, a para hydroxy phenyl amine having one hydrogen of the amino group replaced by a cyclohexyl radical.

3. Cracked gasoline normally tending to form gum on storage having incorporated therein, in an amount sufficient to inhibit gum formation, a para hydroxy aromatic amine having one hydrogen of the amino group replaced by a cyclohexyl nucleus. 4. A motor fuel comprising cracked gasoline normallytending to deteriorate and form gum on storage having incorporated therein in an amount not exceeding about 0.005% of a cyclohexyl amino phenol to inhibit such deterioration and gum formation.

5. A motor fuel comprising cracked gasoline normally tending to deteriorate and develop gum on storage having incorporated therein, in an amount sufficient to inhibit such deterioration and gum formation, 4-cyclohexyl amino phenol.

6. A motor fuel comprising cracked hydrocarbon distillates which normally tend to deteriorate and develop gums on storage having incorporated therein, in an amount suflicient to inhibit such deterioration and gum formation, a compound having the formula:

wherein R represents an alkyl substituted benzene nucleus and R represents a cyclohexyl radical.

7. A motor fuel comprising cracked gasoline normally tending to deteriorate and develop gum on storage having incorporated therein, in an amount sufficient to inhibit such deterioration and gum formation, a cyclohexylamino methyl phenol.

8. A cracked gasoline normally tending to de teriorate and develop gum on storage having incor'porated therein, in an amount sumcient to inhibit such deterioration and gum formation, 4- cyclo-hexylamino 2-methy1 phenol.

9. Motor benzol normally tending to form gum on storage having incorporated therein, in an amount sufiicient to inhibit gum formation, a hydroxy aromatic amine having one hydrogen of the amino group replaced by a cyclohexyl nucleus.

10. Motor benzol normally tending to form gum on storage having incorporated therein, in an amount sufiicient to inhibit gum formation, a cyclohexyl amino phenol.

11. Motor benzol normally tending to form gum on storage having incorporated therein, in an amount sufficient to inhibit gum formation, 4- cyclohexyl amino phenol.

12. Motor benzol normally tending to form gum on storage having incorporated therein, in an amount sufficient to inhibit gum formation, a compound having the formula:

wherein R represents an alkyl substituted benzene nucleus and R represents a cyclohexyl radical.

13. Motor benzol normally tending to deteriorate and form gum on storage having incorporated therein, in an amount suificient to inhibit such deterioration and gum formation, a cyclohexylamino methyl phenol.

CHESTER W. HANNUM.