US2728645A - Anticorrosive gasoline - Google Patents

Description

2,728,645 ANTICORROSIVEVGASOLINE Samuel Clyde Vaughn, Berkeley, Calif., ass'ignor to Tide Water Associated Oil Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application April 1, 1952, Serial No. 279,924

6 Claims. (Cl. 44-450) The present invention relates to corrosion inhibitors for gasolines having high octane ratings, and especially those gasolines designed for use in aircraft type internal combustion engines. More particularly, it relates to corrosion inhibitors formed as reaction products from alkyl acid phosphates and certain amines, and, which are compatible with other desirable additives. It further relates to anti-corrosive gasoline and means for producing the same. It also relates to the means for manufacturing corrosion inhibitors.

Recently, corrosion inhibitors for gasoline have attained importance as a result of research designed to inhibit corrosion in fuel systems and storage-tanks, particularly where moist gasoline may come in contact .with' such metals as iron, copper, brass or the like. This type of corrosion is caused usually'by the presence of water, and occurs generally at the water-gasoline,interface. Further: more, various components used in leaded gasolines are thought to be active promoters of corrosion.

The appearance of water as a separate phase in aviation gasolinemay be caused either by entrained water from the fueling pumps used in fueling aircraft, since these use water displacement to pump the gasoline; or,'by moisture in the air above the gasoline in the fuel tank,- since, at temperatures prevalent in high altitude flying, the moisture condenses and precipitates.

, Another class of important additives often used in aviation gasoline is composed of certain anti-knock agents designed praticularly for rich mixture operation. Foremost among these additives are aniline and its homologs, such as for example, ethyl aniline, methyl aniline, amyl aniline, diamyl aniline, cumidine, and xylidine. These aromatic amines are very effective for this particular purpose when used in proportions of about one to three percent of the gasoline, and function as cumene substitutes in aviation gasoline blends.

Although corrosion inhibitors and the above mentioned anti-knockagents function excellently when each is used in, the absence of the other, many of the common corro sion inhibitors are not compatiblej therewith. Conse: quently, when many ofthe alkyl acid phosphate-amine neutralization'products conventionally used for anti-corrosion purposes are added to a gasoline containing aniline or a homolog of aniline, an; undesirable .precipitateor haze forms, The deleterious effects of precipitates in liquid'fuels are well'recognized, and in this instance they may form a stoppagein carburetor jets or otherfine orifices as well as remove a substantial portion ofthe corrosionrinhibitor from the gasoline solution. It will also be appreciated that gasoline. homogeneity is one of the accepted requisites of marketability.

In accordance with the invention, it has been: found that when alkyl acid phosphates are reacted, or neutralized, with branched chain dialkyl aliphatic amines having 4-15 carbon atoms per alkyl group and in which each branchis a methyl group attached to a carbon atom positioned at least two carbon atoms from the terminal carbon excellent gasoline soluble corrosion inhibitorsare produced which "ice do not form precipitates or haze in gasoline solutions containing aniline or its homologs. Some examples of the aforesaid branched chain dialkyl aliphatic amines which are satisfactory for use in the present invention are suggested as follows:

Di secondary butylamine Di secondary amylamine Di 3-methyl pentylamine Di 2,4-dimethyl hexylamine Di 2,5,8 tri methyl dodecylamine The need for methyl side chains in lieu of longer chains Cir such as ethyl or propyl, for example, is confirmed by the fact that longer side chains do form precipitates when the reaction product therefrom is in the presence of aniline or its homologs. In this connection di Z-ethyl hexylamine is unsatisfactory for the reason stated above. Likewise, if the methyl group is attached to the next to the last carbon atom (i. e. in the so-called iso position) the compounds thus formed produce precipitates.

While certain variations and deviations from the teachings of the present invention are encompassed within its scope and spirit, it is nevertheless recommended that the process of manufacturing the finished gasolines containing desired additives be carried out in specified steps. For example, the order of addition of materials as well as the method of mixing the components must follow definit patterns.

The amine and alkyl acid phosphate may be reacted, or neutralized, by mixing the theoretical neutralizing quantities of the two components, heating above room temperature, care being taken not to exceed temperature at which decomposition takes place, and then thoroughly mixing until reaction is complete. The reaction product is tested to determine the degree of neutralization, and after neutralization is confirmed as complete, said reaction product is then blended into gasoline as desired,

or may be blended into a small amount of gasoline to be used as a gasoline concentrate. The aniline or homolog thereof may be added in whatever order desired. However, the amine-alkyl acid phosphate neutralization product is insoluble in aniline and its homologs and as a consequence thereof a one package additive is not practical.

Another procedure for manufacturing the novel reaction products which inhibit corrosion comprises dissolving the amine or gasoline concentrate of amine in the gasoline to be treated, and then adding a predetermined amount of alkyl acid phosphate. Alternately, the alkyl acid phosphate may be added to the gasoline and then the requiredamount of amine added. The blend is-then mixed thoroughly for about a half-hour to insure.com-' plete reaction. A similar procedure may be followed for the preparation of a gasoline concentrate, should this be desired. The blend or concentrate is then tested for degree of neutralization, and when found to be satisfactory as evidenced by its non-precipitation or non-haze formation, the aniline or its homolog, or a gasoline concentrate thereof, may then be added and the gasoline thoroughly mixed for ultimate use. I

It is an important qualification of the present process that the aniline or homolog thereof never be mixed with a blend containing the alkyl acid phosphate until all of the acidity of the alkyl acid phosphate has been neutralized by the amine; To test the degree of neutralization, the following procedure has been found to be effective. A drop of the reaction mixture is added to a 1% solution of aniline in aviation gasoline. If precepitation occurs on mixing then a small additional quantity of the amine is added to the reaction mixture with continued heating and agitation. This procedure is followed until a non-precipitating reaction product is finally formed from s mmers the alkyl acid phosphate and the branched chain dialkyl aliphatic amine.

The alkyl acid phosphates which may be used in the neutralization stepof the presenhprocess arewthose'having from 8 to 16 carbonatoms per alleyl group. 'Mainly :for commercial reasons, the preferred 'alkyl tacidqahosphate is .Lorol 'acid;phospha-te, which isia mixture of the phosphoric esters of Lorol alcohol. 'lzhe'tterm "lrorol alcohol is used in the .trade todenote a mixture of primary normal aliphatic alcohols-of 8 to 12 carbon atoms which are obtained by fractionation of the alcohols resulting from the reduction of cocoanut and/or palm kernel oils. Lorol acid phosphate mixtures are readily obtainable on the market and for'this reason are preferred to the more :purified esters of 'greater scarcity and higher price. 'Gne Lorol acid phosphate is sld underthetrade name Ortholeum 1'62 and is-understood to be mainly a'mixture of mono and di acid phosphates of *Izorol alcohol. Though for the reasons stated above -Lorol" acidpho'sphates are preferred;other'alkyl' acid'phosphates containing "from8 to 16carbon'a'toms peralkyl'group' are satisfactory. For *example, a commercial grade at n-octyl acid phosphate was found"to produce an'excllent reaction; product.

'Toform the desired neutralization *productfthe proper proportions of branched chain "dialkyl aliphatic'amineand alkyl acid phosphate "may readily be determined by an electrometric titration of a sample "of the alkyl "acid phosphate withaqueousKOH' solution to 'a'pHofabout"9. From'the "amount of KOH used the quantity of amine required to neutralize the acid radicals .of thephosphate may 'easily'be calculated. 'It is always desirable to have a's'light excess .of'amine present, and good results have been obtained with 'asmuch as 50% excess of branched chain dialkyl aliphatic amine.

In order to prevent corrosion effectively, the lower concentration'limit of the reaction product with respect'to thefinished gasoline should'be about 0.002% by weight. This was determined by means of ASTMTD66'5"47T corrosion test modified to a bath temperature of'80--8'2"F. The upper concentration limit is determined by that amount .ofneutralization product which would cause engine deterioration due to the excessive quantity of phosphates thenpresent. Theupper limit is about'0.05'% by weight.

Certain embodiments of the present invention are more fully illustrated by the following examples:

Example I lntoa suitable vesselequipped-with meansifor heating, agitating, and cooling the-charge, there .are introduced 110 ,parts of di (secondary butyl) amine followedgra'duallyby 150.parts of a mixture of mono and-di .Lorol acid-phosphates.(Ortholeum .162). .Themixture is za'gitatedivigorouslyandcooled as required to keep the temperature :below 200 F. The'reaction is =vigorous=and exothermic, consequently'the rate of addition ofthe-phosphate is controlled to avoid 'exeeeding'the above temperature limit. The'resulting mixture is stirred for aboutl hour at 140 F. 'Thereactionproductis aviscous,'*oily liquid, yellow "in color.

The reaction product is then tested for neutrality :by means "of the aforementioned neutralization-test, and, if found to'be acid, additional branched chain dialkyl :aliphatic amine is added.

Finally, fivepounds of the finished additive=are added to 17,000 gallons of aviation gasoline in a blender and agitatedrfor about '15 minutes. Then 1020pounds of mixed xylidiues are added and the mixture resulting therefromis agitated for about .a halfrhour. 'Ther'final gasoline is completely homogeneous; free from haze, corrosionfresistant, and has a rich mixture anti-knockratiug commensurate with the amount of xylidines *used.

Cir

4 Example II A 10% by weight solution in gasoline of the finished additive from Example I is prepared by dissolving pounds of the reaction product in 900 pounds of gasoline in a mixer. The gasoline additive concentrate is thoroughly mixed for about onehour, and 50 pounds of this concentrate then blended into 111,000 gallons of aviation gasoline. The resulting mixture is agitated for about 15 minutes. Finally, '1'020'.pounds of mixed xylidines are added and mixing continuedforan additional 30.niinutes. This finished product is comparable to that obtained in Example'I.

"Example *II] To 17,000 gallons of "aviation "gasoline in a blender are added 7.10 lbs. of di (2,5,8-trimethyl dodecyl) amine. The resulting mixture is thoroughly agitated for about 10minutes, and then 2.68 pounds of a mixture of mono and di Lorol acid phosphate (Ortholeum 162) are added with-continued mixing for about one-half hour. After'the "neutralization tests indicate the productionof a satisfactoryreact-ion product, 1020 pounds of mono methyl aniline are added and agitation continued for another half-hour. As in the former examples, tests indicate the "production of 'excellent quality "finished gasoline.

Example IV Alkylatepercent '70-88 Aromatics do '5-16 Isopentane do.. 5-14 Tetra.ethyl.lead.. -cc. per gallon 4 nevertheless, th'elinvention in its broadest scope-comprehends the treatment of-anymotor.fuel. Similarly, it willhe -appreciated that the-reaction: product of the present invention may be blended in proper proportions any desired gasoline with the advantage .that 'the purchaser or user may add any suitable amount of auilineor homologs thereoflfor the purpose of=obtaining rich mixture anti-'knoekmroperties', without difiiculties iarisingfrom preeipitation ofrhaze formation which is generallyencountered*=when 'le'ss*satisfactory-corrosion inhibitors areiuse'd.

It will now betapparent that l havetdevised'a 'novel -and useful process'an'd composition of matter which embodies the features I of advantageenumerated as desirable. in' the statementof the-invention and the abovedescr'iptionand while"in"'the-' present "instance "there are described the preferred embodiments 't'l'iereot' *whi'c'h *h'ave been found 'in practice to give-satisfactory and-reliable results, it'is toT'be understood that "t'hc same is susceptible of modification in various particulars without departing from the spirit or scope of 'the i'nvention-or sacrificing any of its =advantages.

1.. Acompletelyhomogeneous, corrosion-resistant avi-ation' ful having aliigh "rich mixture anti-knock rating, comprisinggasoline"containing-'sufiicient aromatic amine from the "group consisting of aniline and-'homologs of aniline tosubstantially increase the *rich mixture antikno'k properties (it the'gas'oline-andbetween-0002922 and 0.05% by weight of the finished gasoline of the addition product resulting from contacting an alkyl acid phosphate having from 8 to 16 carbon atoms per alkyl group with between 100% and 150% of the quantity theoretically required to neutralize said phosphate of a branched chain dialkyl aliphatic amine having 4-15 carbon atoms per alkyl group and in which each branch is a methyl group attached to a carbon atom positioned at least two carbon atoms from the terminal carbon.

2. An anti-corrosive gasoline as in claim 1 wherein the branched chain dialkyl aliphatic amine is di (secondary butyl) amine.

3. An anti-corrosive gasoline as in claim 1 wherein the branched chain dialkyl aliphatic amine is di (2,5,8- trimethyl dodecyl) amine.

4. An anti-corrosive gasoline as in claim 1 wherein the branched chain dialkyl aliphatic amine is di (3-methyl pentyl) amine.

5. The method of simultaneously improving the anticorrosive and the rich mixture anti-knock properties of a gasoline, which comprises forming in said gasoline a corrosion inhibiting amount of the addition product of an alkyl acid phosphate having 8 to 16 carbon atoms per alkyl group and a branched chain dialkyl aliphatic amine having 415 carbon atoms per alkyl group and in which each branch is a methyl group attached to a carbon atom positioned at least two carbon atoms from the terminal carbon and in which all the acid hydrogen of said phosphate is neutralized by said amine, then adding suflicient aromatic amine from the group consisting of aniline and homologs of aniline to substantially increase the rich mixture anti-knock properties.

6. The method of inhibiting the formation of an insoluble precipitate when an amine-phosphate corrosion inhibitor is added to a gasoline containing an aniline octane booster, which comprises adding to a gasoline an alkyl acid phosphate having 8 to 16 carbon atoms per alkyl group, adding between and about of the quantity theoretically required to neutralize all the acid hydrogen of said phosphate of a branched chain dialkyl aliphatic amine having 4-l5 carbon atoms per alkyl group and in which each branch is a methyl group attached to a carbon atom positioned at least two carbon atoms from the terminal carbon thereby forming in said gasoline an addition product of said amine with said phosphate, then adding sufiicient aromatic amine from the group consisting of aniline and homologs of aniline to substantially increase the rich mixture anti-knock properties of the gasoline, the amounts of the amine and the phosphate being such as to produce an addition product of between 0.002% and 0.05 by weight of the finished gasoline.

References Cited in the file of this patent UNETED STATES PATENTS 2,297,114 Thompson Sept. 29, 1942 2,413,262 Stirton Dec. 24, 1946 2,413,852 Turner Ian. 7, 1947 2,550,982 Eberz May 1, 1951 FOREIGN PATENTS 225,547 Germany Nov. 2, 1942

Claims (1)

1. A COMPLETELY HOMOGENEOUS, CORROSION-RESISTANT AVIATION FUEL HAVING A HIGH RICH MIXTURE ANTI-KNOCK RATING, COMPRISING GASOLINE CONTAINING SUFFICIENT AROMATIC AMINE FROM THE GROUP CONSISTING OF ANILINE AND HOMOLOGS OF ANILINE TO SUBSTANTIALLY INCREASE THE RICH MIXTURE ANTIKNOCK PROPERTIES OF THE GASOLINE AND BETWEEN 0.002% AND 0.05% BY WEIGHT OF THE FINISHED GASOLINE OF THE ADDITION PRODUCT RESULTING FROM CONTACTING AN ALKYL ACID PHOSPHATE HAVING FROM 8 TO 16 CARBON ATOMS PER ALKYL GROUP WITH BETWEEN 100% AND 150% OF THE QUANTITY THEORETICALLY REQUIRED TO NEUTRALIZED SAID PHOSPHATE OF A BRANCHED CHAIN DIALKYL ALIPHATIC AMINE HAVING 4-15 CARBON ATOMS PER ALKYL GROUP AND IN WHICH EACH BRANCH IS A METHYL GROUP ATTACHED TO A CARBON ATOM POSITIONED AT LEAST TWO CARBON ATOMS FROM THE TERMINAL CARBON.