USRE23239E

USRE23239E - Inhibitor for gasoline

Info

Publication number: USRE23239E
Authority: US
Publication date: 1950-06-06

Description

Reiuued June 1950 INHIBITOR FOR GASOLINE Robert H. Rcsenwald, Western Springs, and Joseph A. Ohenicek, Bensenville, Ill., assignors to Universal Oil Products Company,

Chicago,

111., a corporation of Delaware No Drawing. Original No. 2,310,710, dated February 9, 1943, Serial No. 295,476, September 18, 1939. Application for reissue December 7, 1948,

Serial No. 64,028

19 Claims.

Matter enclosed in heavy brackets reissue specification; matter printed in This invention relates to a method for stabilizing olefin-containing hydrocarbon oils, and more particularly, cracked gasolines of the petroleum origin. However, gasolines from other sources, such as coal tar, shale oil, etc., may be also treated according to the present invention, as may those made by polymerization of olefins, reforming of naphthas, etc.

More specifically, the invention concerns a method for stabilizing olefin-containing gasolines during storage in respect to their valuable properties such as color and anti-knock value and low gum content which tend to depreciate because of the action of oxygen upon the olefins in said gasollnes.

The cracking and reforming processes which are employed to produce additional yields of gasoline from heavy hydrocarbonaceous oils, or to increase the anti-knock properties of naphthas and straight run gasolines, produce motor fuels having substantial concentrations of unsaturated hydrocarbons. particularly mono-olefins and diolefins. These olefinic hydrocarbons tend to form peroxides and gums when stored in the presence of oxygen. The use of inhibitors to prevent such reactions has been practiced, and many types of compounds have been suggested for this purpose, including aminophenols, wood tar fractions, polyhydroxy phenols, etc.

In one specific embodiment, the present invention comprises the treatment of unstable olefincontaining gasolines to preserve their valuable properties in respect to gum content, color and anti-knock value by adding thereto minor quantitles of 2-alkyl-i-alkoxyphenols of the general structure wherein R comprises any alkyl group and OR is an alkoxy group wherein R is of the same or different molecular weight and structure than R.

The properties desirable in a gasoline gum inhibitor are as follows:

[ appears in the original patent but forms no part of this italics indicates the additions made by reissue a. Solubility in the gasoline to a degree in excess of the maximum concentration in which it is likely to be used.

b. High degree of potency so that relatively small concentrations can be used.

c. Insolubility or relatively low solubility in water or aqueous alkaline or acidic solutions with which the gasoline is likely to come in contact.

d. Either normally liquid or having a high degree of solubility in a non-aqueous, gasolinemiscible solvent thus increasing the ease of handling and addition to thegasoline.

e. Non-reactive with tanks, fittings, lines, engine parts, etc, with which the gasoline is likely to come in contact.

1. Of light color, and imparting or developing no objectionable color or odor to the gasoline when added, or during storage.

The inhibitors of the present invention too. large extent fulfil these requirements.

The degree of insolubility of an inhibitor in water or caustic solutions is of particular importance since gasoline storage tanks generally contain water which is alkaline in reaction. Ii the inhibitor is soluble in the water layer, it is partially removed from the gasoline and thus its effect is greatly reduced. The present type of compound has been found to be practically insoluble in water and in most cases to be but slightly removable from gasoline by contact with dilute alkaline solutions.

The compounds of the present invention are useful for preventing the deterioration of gasoline, but different individual compounds of the same type are not necessarily exact equivalents.

The alkyl groups substituted in the ring may comprise any alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, t-butyl, amyl, isoamyl, secondary amyl, etc. 01'

these groups the t-alkyl groups appear to be more effective in contributing to the inhibitor potency of the resultant compound than do those groups of lower molecular weight, for example methyl and ethyl groups. Likewise, the groups of higher molecular weight contribute to other desirable properties of the inhibitor such as decreasing the solubility of the resulting compound in aqueous solutions. The substituent group is preferably in the position ortho to the hydroxyl group.

aaasa Some compounds having alkyl groups in the meta position may also have inhibiting value.

We have found that when the alkoxy or ether group is in the 4-position, compounds having greater inhibitor potency are available than when this group is in any other position in the substituted phenol. The alkyl group oi this alkoxy substituent may comprise for example ethyl. methyl, propyl, isopropyl, butyl, isobutyi, secondary butyl, t-butyl, amyl, isoamyl, secondary amyl. t-amyl, etc. groups. Oi these, the groups or relatively low molecular weight, comprising methyl or ethyl groups appear to have the strongest influence, although other groups have considerable value. Straight-chain alkyl substituents or greater length than two carbon atoms tend to produce inhibitors of lower potencies than when methyl or ethyl groups are substituted. An example of the improved eii'ectiveness of the present type of inhibitor is illustrated as fol- B r uinone Hvdwim mmrl ether-1.69 noQon mco- :?on

:HI iHl i-ethylhydroquinone fl-ethyl-Mnethoxyphenol potency as compared with a widely used commercial gum inhibitor. From the illustration it quinone have little or no inhibitor value compared with the commercial inhibitor. The monomethyl ether of hydroquinone has a considerable potency, being 1.69 times as eflective as the commercial inhibitor. The substitution of an ethyl group in the position ortho to the hydroxyl group (2- ethyl-4-methoxyphenol) increases the inhibitor ratio to an even greater extent, so that the resulting 2-ethyl-4-methoxyphenol is 2.39 times as eii'ective as the commercial inhibitor.

The alkyl substituents may be introduced into the aromatic nucleus in a number of ways. One oi these consists in alkylating a hydroq'uinone ether by contacting it at a temperature 01' -80" C. with the alcohol corresponding to the group to be substituted, using phosphoric acid as the catalyst. The reaction mixture is stirred continuously until the reaction is complete. The mixture is then washed with water to remove remaining acid and is extracted with 10% sodium hydroxide solution to remove the unreacted hydroquinone ether. The insoluble portion is distilled under reduced pressure and the resulting compound may be further purified by recrystallization.

The term stabilizing" gasoline as used herein is intended to mean the prevention of deterioration of the gasoline in-so-i'ar as its desirable properties of storage stability, color, anti-knock value, etc., are concerned.

The following example still further illustrates the benefits and usefulness of the present type of inhibitor. This example is given to demonstrate the usefulness and practicability of our invention, but should not be construed as limiting it to the exact compounds illustrated therein. As in the foregoing, the inhibiting value inso-i'ar as the stabilization of gasoline is concerned is reported in terms 01' inhibitor ratio compared with a commercially used gum inhibitor.

In the following table are shown a number of representative compounds 01' the present invention together with their inhibitor ratios:

TABLEI Irrmrros Rs'rros or 2-Anm-4-Arxommons nr 0.05% Concsmsrron The results show that the compounds listed are specially eflectlve inhibitors as compared to a commercial gum inhibitor when used in equal 2 weights. They are not, however, exactly equivalent since the specific efiects of different groups in the alkoxy or in the ortho ring substituted positions may be quite different. Thus it will be seen that an ethyl or methyl group in the alkoxy group is more effective than other alkyl groups 'tried. On the other hand, the substitution of a t-butyl group in the aromatic ring greatly increases the inhibitor potency of the resultant 'noted also that the t-butyl group as the ring substituent reduces the alkali solubility oi the compounds to a greater extent than does an ethyl group in the same position. It will also be observed that the compounds of the present invention have practically no detrimental effect on the color or color stability of the gasoline when added in these quantities. In all cases, the color 01 the resulting gasoline was equal to or better than that oi. the gasoline inhibited with a commercial inhibitor.

It has been our observation in the laboratory The inhibitor potency as measured by the oxygen bomb induction period and copper dish gum both before and after washing the inhibited gasoline with water and 5%--by volume of 1% sodium hydroxide solution is illustrated. In this case the gasoline was inhibited with a sufflcient quantity of each inhibitor to produce approximately the same induction period. Hydroquinone monoethylether and monoiso-propylether are included in the list for purposes of comparison. The percentage of inhibitor removed by water or caustic is calculated from the per cent decrease in induction period after the sample has been washed with water or with caustic solution. It will be noted that the compounds of the present invention are less soluble in water thanthe commercial inhibitor or hydroquinone monoethylether. Moreover, these compounds are less soluble in dilute caustic solution than the monoalkylethers or the commercial gum inhibitor. It will be compound. that the inhibitors of this invention are compara- The efiectiveness is further illustrated by the tively stable insofar as color is concerned when data presented in Table II. exposed to air. One 01' the disadvantages of many TABLE II Oxygen Bomb Induction Per Cent Ra- MgCu Dish Gum Period moved Inhibitor ofl Water Caustic Ori Water Caustic Water Caustic 5 Wash Wash Wash Wash Wash Wash Blank gasoline 127 138 134 80 75 Commercial inhibitor 4 24 180 310 260 18 89 2-tert-butyl-4-methoxyphen 8 7 9 305 310 295 D 0 2-tort-butyl-4-ethoxyphenol- 7 9 10 310 335 330 0 0 2-tert-butyl-4-1so ropoxy henol 15 15 17 290 295 280 0 0 Z-tert-butyH-iso utoxy enol 16 24 19 310 300 295 0 0 2-ethyl-4- inrynhenn 37 64 19 300 300 0 67 HthyIA-ethoxy 13 19 28 290 300 0 47 Hydroqu none monoethyl ether 32 38 104 310 $0 100 9 89 Hydroqumone mono-isopropyl ether 27 44 115 280 270 90 0 92 commercial inhibitors is that they develop color rapidly when exposed to air. The stable character of the present inhibitors may therefore be considered an advantage.

We claim as our invention: 7

1. A process for stabilizing olefin-containing hydrocarbon oils in regard to their desirable properties which comprises adding to said 0115 a minor portion of a compound having the general structure wherein R and R are alkyl groups.

2. A process for stabilizing olefin-containing gasoline in regard to its valuable properties which comprises adding to said gasoline a minor portion of a compound having the general structure wherein R and R comprise alkyl groups.

3. A process for stabilizing cracked gasoline against deterioration of its valuable properties which comprises adding to said gasoline a minor portion of a compound of the following general formula:

wherein R is a t-alkyl group and R is an alkyl group.

4. A process for stabilizing olefin-containing gasoline against deterioration of its valuable properties which comprises adding to said gasoline a minor portion of a compound of the following general formula:

wherein R is a t-butyl group and R is an alkyl r up. a a

I 5. A process for stabilizing olefin-containing gasoline against deterioration of its valuable properties which comprises adding to said gasoline a minor portion of a compound of the-following general formula:

wherein R and R' are t-alkyl groups.

6. A process for stabilizing olefin-containing gasoline against deterioration of its valuable properties which comprises adding to saidgasoline a minor portion of a 2-alkyl-4-a1koxyphenol.

[7. An inhibitor for cracked gasoline which comprises essentially a compound having the general formula:

wherein R and R are alkyl groups] [8. An inhibitor for olefin-containing gasoline which comprises essentially a compound having the general formula:

wherein R is an alkyl group and R is different aikyl mun-II 9. An inhibitor [for olefin-containing gasoline] which comprises essentially a compound having the general formula:

wherein R comprises a t-alkyl group and R an alkyl group having a smaller number of carbon atoms than said t-alkyl group.

10. An inhibitor for olefin-containing gasoline which comprises essentially a compound having the general formula:

wherein R is a t-butyl and R is an alkyl group.

11. An inhibitor for olefin-containing gasoline which comprises essentially a compound having the general formula:

wherein R and R are t-alkyl groups.

[12. An inhibitor for olefin-containing gasoline which'comprises essentially a compound having the general formula:

wherein R is an alkyl group and R is a t-alkyl r up-II 13. An inhibitor for olefin-containing gasoline which comprises essentially a compound having the general formula:

wherein R is a t-alkyl group and R is a t-butyl group.

14. Motor fuel comprising olefinic gasoline and a relatively small amount or a 2-alkyl-4-alkoxyphenol.

15. Motor fuel comprising olefinic gasoline and a relatively small amount a: a z-t-alkyl-i-alkoxyphenol.

18. Motor fuel comprising oleflnic gasoline and a relatively small amount or a compound having the general formula:

wherein R is an alkyl group 01' at least 3 carbon atoms and R. is an alkyl group 01' less than 3 carbon atoms.

[17. An inhibitor comprising a 2-alkyl-4-alkoxyphenol] [18. An inhibitor comprising a compound having the general formula wherein R is an alkyl group oi at least 3 carbon atomsandR' isanalkylgroupoi'lessthan3 carbon atoms] 19. An inhibitor comprising a Z-tertiargaikul-laikoruphenol.

20. An inhibitor comprising Z-tertimbutul-lmethomhenol.

21. An inhibitor comprising Z-tertiarubutul-lethomhenol.

22. Aainhibitor compriging acompouna having the general formula:

wherein R is a tertiarpallcpl group and R is an alkul group of less than 3 carbon atoms.

23. An inhibitor comprising a Z-tertiarualkul- 4-alk0xuphenol in which the alley! and alkoxy groups each contain not more than 5 carbon atoms. 4

24. An inhibitor comprising a compound having the general formula:

wherein R is a tertiarualkul group of not more than 5 carbon atoms and R is an alley! group of less than 3 carbon atoms.

ROBERT H. ROSENWALD. JOSEPH A. CHENICEK.

REFERENCES man The following references are ol' record in the flle of this patent or the original patent:

UNITED STATES PATENTS Number Name Date 1,884,559 Calcott et al. Oct. 25, 1932 1,942,827 Mills et al. Jan. 9, 1934 1,987,2 28 Bruson Jan. 8, 1935 OTHER REFERENCE oraanische Chemie, 4th edulrstea Beilstein:

:l'. 114;" vol. VI. m M m