US2373631A - Stabilized aviation gasoline - Google Patents

Description

hPa'tcnted Apr. 10, 19 45 STABILIZED AVIATION GASOLIN John E. Mltal, Alton, EL, asslgnor to Shell Development Company san Francisco, Calif., a

corporation of Delaware No Drawing. Application'April 27, rats,

' Serial No. assass- (ores-s9) This invention relates to inhibitors for aviation gasoline containing tetra-alkyl lead, which inhibitors increase the storage stability of said gasolines.

It is an object of the invention to produce motor fuel compositions of enhanced storage stability, particularly aviation fuels. Another purpose is to provide new and improved inhibitors for leaded aviation gasoline. Other objects will be apparent from the following description' I have found that the addition of hydrobromic or hydriodic acid to an oxidation inhibitor comprising an amino phenol greatly increases the stability of an initially stable gasoline containing tetra-alkyl lead and the inhibitor. Gasolines which are susceptible to this treatment for retarding their decomposition are relatively stable compositions such as straight run or casing head gasoline, allwlated fractions such as iso-octane, and the. like. Although such hydrocarbons have a comparatively long life when stored alone, their age decomposition is tremendously accelerated whenthe conventional quantity (up to about 8 ccJsal.) of tetra-alkyl lead is added to the fuel to increase its mock rating. In such a gasoline, both the initially stable hydrocarbons and the upon standing so that the natural life of the gasoline is greatly shortened byth'e occurrence of both lead precipitate and organic gum formation.

$19 I Inhibit .tetra-alkyl lead disintegrate at a fairly rapid rate On the other hand,;for some undetermined reason, hydrobromic' or hydriodic acid does not exhibit this enhancing efiect in' the presence of amino phenolic inhibitors when the inhibitors are used to stabilize a cracked (i e. unsaturated) or originally unstable gasoline. My inhibitors thus exhibit their principal stabilizing power in preventing the decomposition of tetra-alkyl lead which is dissolved in gasoline or other motor fuel.

' The hydrobromic or hydriodic acid may advantageously' be present in any amount up to the stoichiometric quantity necessary to neutralize the basic amino phenolic inhibitor. Less than this equivalent amount will have an eflect proportionate to the quantity present, while any amount in excess of the stoichioinetrical quantity will have no additional inhibiting eflect and on the contrary'may possess the disadvantage of being corrosive. I

This enhancing eflect maybeiilustrated by the the following examples in which straight run gas- Inhibitor A bad the following composition:

- The amount of hydrogen bromide used in inhibitor A in trials 2 and 4 was only the amount necessary to neutralize the inhibitor.

Induction Inhibitor A ibitor -I InhibitorBhydrobz-omlde The improvement in induction periods obtained in these tests on the basis of equal weights oiv inhibitors was even greater than the simple nu-- merical diflerence between the figures in the last column above, since the amount of amino phenol itself in the quantity of amino phenol hydrobromide used is obviously considerably less than the equal weight or unneutralized amino phenol taken for comparison.

This enhancing eifect is observed only when amino phenols are employed with hydrobromic acid or hydriodic acid. Inhibitors containing only the amino group or only the phenolic group do not exhibit such increased anti-oxidant ability. Indeed, hydrobromic acid exhibits an adverse-effect' in the presence of non-amino phenolic inhibitors.

The amino group of the phenolic inhibitor be a primary amine, or one hydrogen may be substituted (to produce a secondary amine) by such groups asmethyl, ethyl, nand iso-propyl,

normal tertiaryand iso-butyl, amyl, hexyl,

cyclohexyl, acetyl, acetonitrile, butylidene, heptylidene, benzylidene (as well as'chloror nltrobenzylldene), cinnamylidene, furfuryl, and the like, their analogues, homologues and suitable substituted derivatives.

oline containing 4'cc. tetra-ethyl lead per gallon or diflerent inhibitors or their hydrobromidcs.

The amino phenolic inhibitor maybe mononucleaisuch as the above or they may be polynuclear, as well as monoor poly hydroxy, as in amino naphthol, phenyl or benzyl .mino mph- Inhibitor B consisted of benzyl p-amino phenol.

thol, amino anthranol, amino phenanthrol, ami- A -no 61- or tri-hydroxy naphthalene, etc.

When more than one =NH cr -NH: group is found in the phenolic compound, sufl'ioient hydrobromic or nydriodic acid may be employed tounstable on storage and a stabilizing simulate! a compound selected'irom the. group or primary and secondary ar'nino phenol hydroneutralize all primary or secondary amines presout.

In general, concentrations of my amino phe-." nolhydrobromide or amino phenolhydriodic inhibitors between about 0.0005% and 0.1% and more preferably between about 0.0005% and .004% are adequate to stabilize a typical aviation or saturate type gasoline.

The hydrobromic or hydriodic acid and the amino phenol may be added to the asoline sepa rately, together, or they may be first mixed in the desired proportion and incorporated: in the gasoline as needed.

I claim as'my invention:

1. A stable motor fuel comprising a predomi-.

nant amount of a normally stable gasoline type motor fuel containing an amount of tetra=a1kyl leadsumcient to render the mixture relatively iodides andhydrobromides.

2. The composition of claiml, wherein the tetv. ra-alkyl lead is tetra-ethyl lead.

-3.'-The composition oi claim 1, wherein there is substantially no unneutralized amino phenol. 4. The composition of claim '1, wherein the stabilizer is derived from a secondary amino phe 5. The composition of claim 1, whereinthe stabilizer is-present in about 0.0005% w. to about.

Q 8. The composition of claim 1, wherein the amino phenol is benzyl para amino phenol.

- JOHN E.

wherein the amino phenol is N butyl para amino phenol.