EP0299119A1

EP0299119A1 - Corrosion inhibited oxgenated fuel systems

Info

Publication number: EP0299119A1
Application number: EP87306222A
Authority: EP
Inventors: Irvine J. Knepper; Robert J. Garrecht
Original assignee: Petrolite Corp
Current assignee: Baker Petrolite LLC
Priority date: 1986-06-23
Filing date: 1987-07-14
Publication date: 1989-01-18
Also published as: BR8703124A; JPS6436691A

Abstract

This invention relates to a corrosion inhibited system comprising I An oxygenated fuel and II the reaction products of

(1) an alkenyl or alkyl succinic acid or anhydride or the polymer thereof; and
(2) an amine.

Description

In U.S.P. 3,703,587, there is described and claimed:

"1. The process of inhibiting corrosion of metals and alloys in contact with corrosive media which comprises contacting said metals and alloys with a poly-ester-amide-acid composition formed by reacting (1) an alkyl or an alkenyl succinic acid or the anhydride thereof with (2) a polyol, the product of which is reacted with an alkanol amine to form an ester-amide and then reacting said so formed ester-amide with an alkyl or an alkenyl succinic acid or the anhydride thereof.
S.N. 124,031 filed February 25, 1980 relates to the reaction products of an alkyl or alkenyl succinic acid or the anhydride thereof (AASA) and an alkylether diamine (EDA) and the use thereof as corrosion inhibitors.

Alkenyl succinic acid anhydrides of the corresponding acids are utilizable in S.N. 124,031. The general structural formulae of these compounds are:

wherein R is an alkenyl radical. The alkenyl radical can be straight-chain or branched-chain; and it can be saturated at the point of unsaturation by the addition of a substance which adds to olefinic double bonds, such as hydorgen, sulfur, bromine, chlorine, or iodine. It is obvious, of course, that there must be at least two carbon atoms in the alkenyl radical, but there is no real upper limit to the number of carbon atoms therein. However, it is preferred to use an alkenyl succinic acid anhydride reactant having between about 8 and about 18 carbon atoms per alkenyl radical. In order to produce the reaction products of this invention, however, an alkenyl succinic acid anhydride or the corresponding acid must be used. Succinic acid anhydride and succinic acid are not utilizable herein. For example, the reaction product produced by reacting with succinic acid anhydride is unsatisfactory. Although their use is less desirable, the alkenyl succinic acids also react, in accordance with this invention, to produce satisfactory reaction products. It has been found, however, that their use necessitates the remaval of water formed during the reaction and also often causes undesirable side reactions to occur to some extent. Nevertheless, the alkenyl succinic acid anhydrides and the alkenyl succinic acids are interchangeable for the purposes of the present invention. Accordingly, when the term "alkenyl succinic acid anhydride" is used herein, it must be clearly understood that it embraces the alkenyl succinic acids as well as their anhydrides, and the derivatives thereof in which the olefinic double bond has been saturated as set forth hereinbefore. Non-limiting examples of the alkenyl succinic acid anhydride reactant are ethenyl succinic acid anhydrides; ethenyl succinic acid; ethyl succinic acid anhydride; propenyl succinic acid anhydride; sulfurized propenyl succinic acid anhydride; butenyl succinic acid, 2-methyl-butenyl succinic acid anhydride; 1,2-dichioropentyi succinic acid anhydride; hexenyl succinic acid anhydride; hexyl succinic acid; sulfurized 3-methylpentenyl succinic acid anhydride; 2,3-dimethylbutenyl succinic acid anhydride; 3,3-dimethylbutenyl succinic acid; 1,2-dibromo-2-ethylbutyl succinic acid; heptenyl succinic acid anhydride; 1,2-dioctyl succinic acid; octenyl succinic acid anhydride; 2-methylheptenyl succinic acid anhydride; 4-ethylhexenyl succinic acid; 2-isopropylpentyl succinic acid anhydride; nonenyl succinic acid anhydride; 2-propylhexenyl succinic acid anhydride; decenyl succinic acid; decenyl succinic acid anhydride; 5-methyl-2-isopropylhexenyl succinic acid anhydride; 1,2-dibromo-2-ethyloctenyl succinic acid anhydride; decyl succinic acid anhydride; undecenyl succinic acid anhydride; 1,2-dichloro-undecyl succinic acid; 3-ethyl-2-t-butylpentenyl succinic acid anhydride; dodecenyl succinic acid anhydride; dodecenyl succinic acid; 2-propylnonenyl succinic acid anhydride; 3-butyloctenyl succinic acid anhydride; tridecenyl succinic acid anhydride; tetradecenyl succinic acid anhydride; hexadecenyl succinic acid anhydride; sulfurized octadecenyl succinic acid; octadecyl succinic acid anhydride; 1,2 dibromo-2-methylpentadecenyl succinic acid anhydride; 8-propylpendadecyl succinic ac°d anhydride: eicosenyl succinic acid anhydride; 1,2-dichtoro-2-methyinona decenyl succinic acid anhydride; 2-octyl- dodecenyl succinic acid; 1,2-diiodotetracosenyl succinic acid anhydride; hexacosenyl succinic acid, hexacosenyl succinic acid anhydride; and hentriacontenyl succinic acid anhydride.
The methods of preparing the alkenyl succinic acid anhydrides of S.M. 124,031 are well known to those familiar with the art. The most feasible method is by the reaction of an olefin with maleic acid anhydride. Since relatively pure olefins are difficult to obtain, and when thus obtainable, are often too expensive for commercial use, alkenyl succinic acid anhydrides are usually prepared as mixtures by reacting mixtures of olefins with maleic acid anhydride. Such mixtures, as well as relating pure anhydrides, are utilizable herein. Corresponding alkyl succinic anhydrides can also be employed, i.e., where the alkenyl group is saturated in any of the above instances, the preparation of alkyl succinic acids and anhydrides thereof is well known to the art.
The etherdiamine of S.N. 124,031 has the general formula ROANH A'NH₂ where R is an alkyl group having about 1 to 18 carbons, such as from about 5 to 13 carbons, for example from about 8 to 10 carbons. but preferably about 8-9 carbons.
A and A', which may be the same or different alkylene group, having about 2 to 10 carbons such as about 2 to 5 carbons, but preferably 3 carbons.
The preferred etherdiamine is CH₃(CH₂)₇-_SO(CH₂)₃NH(CH₂)₃NH₂
The reaction products are prepared by mixing the components together at ambient temperature. Since the reaction is exothermic, cooling may be desirable in larger batches.
The molecular weight of tetrapropenyl succinic acid is 284 and CH₃(CH₂)₇CH₂0(CH₂)₃NH(CH₂)₃NH₂ is 258. Thus, the stoichiometrical weight ratio of AASA to EDA is about 1.1 to 1. As a corrosion inhibitor the most effective AASA to EDA weight ratio is in excess of 1.1 to 1, with an optimum of about 3 to 1 or greater.
Thus, the AASA to EDA weight ratio can be for example from about 10 to 1, such as from about 8 to 1, but preferably from about 6 to 1, with an optimum of about 3 to 1.
Stated another way, the reaction product contains an excess of AASA.
Because of the energy crises, oxygenated fuels such as alcohol have been employed as fuels, either alone, or in combination with petroleum products. Non-limiting examples of oxygenated fuels include ethanol, methanol, tertiary butyl alochol (TBA), methyl tertiary butyl ether (MTBE) or mixtures thereof, which are incorporated into the fuel as fuel extenders, octane boosters or both.
We have now discovered that the compositions of S.N. 124,031 are excellent corrosion inhibitors for oxygenated fuel systems.
Gasohol (and other oxygenated fuels) present at least one special problem. That is if water is mixed with gasohol a clear solution results up to about 0.5 to 0.7% (depends upon fuel temperature and aromatic content of the gasoline.) When the critical amount of water is exceeded a phase separation occurs. The separate phase contains both water and ethanol. In addition to the obvious potential problem of poor operability should this aqueous phase enter the fuel systems of vehicles is the concern (supported by some evidence) that this water/ethanol phase is quite corrosive. The compositions of the present invention are useful in solving this problem.
The compositions of S.N. 124,031 have been widely tested to prove their usefulness. These tests are summarized as follows:

1. Dynamic rust test data which show that AASA and EDA perform synergistically to prevent rust formation as measured by this procedure when gasohol (90% gasoline, 10% ethanol) is the test fuel.
2. Dynamic rust test data which shows the compositions of the present invention (AASA + EDA) perform well when the test fuel is gasoline containing MTBE.
3. Dynamic rust test data which shows that when the compositions of this invention are blended with a multifunctional gasloine additive the resulting anti-rust performance is significantly improved. Test fuels include base unleaded gasoline and unleaded gasoline containing the appropriate amounts of ethanol, MeOH + TBA, MTBE, and TBA.
4. Carburetor cleanliness tests which show that the inclusion of the compositions of this invention in a multifunctional gasoline additive package does not interfere with the performance of the additive as a carburetor detergent.
5. Static corrosion tests which show that the compositions of this invention when added to a gasoline will provide corrosion protection in the aqueous phase which develops when the gasoline is mixed with water. Gasolines included in this evaluation include in addition to base gasoline, gasoline containing ethanol and MeOH + TBA. Metals tested included mild steel and zinc. Test waters included pH-4 and pH-10 water as well as deionized water.

The following examples are presented by way of illustration to prove the effectiveness of the present compositions in oxygenated fuels.

Additive Compositions

Composition B (ether diamine) EDA (7-9)

CH₃-(CH₂)_7-9 -0-(CH₂)₃- NH - (CH₂)₃- NH2

Composition C (ether diamine) EDA (13)

CH₃- (CH₂)₁₃- 0 - (CH₂)₃- NH (CH₂)₃- NH₂

Composition D

86.8% Composition A
13.2% Composition B

.Composition E (MFGA)

Commercial multifunctional gasoline additive (carburetor detergent, rust inhibitor, anti-icing agent):

Composition F (MFGA)

Commercial multifunctional gasoline additive. (Different additive supplier than composition E above).

Gasoline Identification

Gasoline 1-A Unleaded regular gasoline Gasoline 1-B 90% gasoline 1-A, 10% Fuel grade ethanol (gasohol) Gasoline 1-C 95% gasoline 1-A, 2.5% methanol 2.5% Tertiary butylalcohol (i.e. 5% OxinolTM) Gasoline 1-D 90% gasoline 1-A, 10% Methyl tertiary butyl ether (i.e. 10% MTBE) Gasoline 1-E 93% gasoline 1-A, 7% Tertiary butyl alcohol (i.e. 7% TBA) Gasoline 2-A No lead regular gasoline Gasoline 2-B 90% gasoline 2-A, 10% Fuel grade ethanol (gasohol) Gasoline 3 Leaded regular gasoline
National Association of Corrosion Engineers N.A.C.E. TM-01-72

Apparatus:

As specified in ASTM method D-665.
Procedure:

1. Insert polished spindle into 300 ml of test fuel.
2. Allow spindle 10 minute static and 20 minute dynamic wetting time at 100° F.
3. Add 30 ml of distilled H₂0 and stir for 3t hrs.
4. Remove spindle, wash with isopropyl alcohol, then isooctane, air dry and grade immediately.

Rating Index:

A 100% rust free
B + + 0.1 % or less of total surface area rusted
B + 0.1 % - 5% total surface area rusted
B 5% - 25% total surface area rusted
C 25% - 50% total surface area rusted
D 50% - 75% total surface area rusted
E 75% - 100% total surface area rusted

CARBURETOR CLEANLINESS TEST

Purpose:

This test was developed to evaluate the ability of gasoline additives to keep clean the throttle body area of carburetors. Deposits, induced by blowby contamination of the intake air, EGR, and by the engine operating conditions selected, tend to form in the throttle body area. Deposits in this area can affect the idle and low speed metering characteristics of the carburetor thereby influencing exhaust emissions, fuel consumption, and performance.

General Test Description:

A six-cylinder 300 CID engine is operated for a total of 20 hours in a test stand. Power is absorbed by a momentum exchange water brake dynamometer. During the test period the engine is cycled between idle and cruise speed. The cycle is a ten-minute cycle with the idle and cruise phases being three minutes and seven minutes in duration respectively. Idle conditions of 700 RPM and 1.5% CO in the emissions under no load are set at the start of the test. Cruise conditions are maintained at 2000 RPM with 10BHP load throughout the test. A controlled amount of blowby is returned to the carburetor at all times and full EGR is applied during the cruise phase. Exhaust emissions are recorded. Temperatures and other parameters which affect or indicate eingine operation are measured and in some cases controlled. The weight of deposits formed on a removable throttle body sleeve is used to judge additive performance.

Objective

This test is used to determine the corrosive effects of a water/ethanol phase on various metals that are in direct contact with this mixture.

Summary

A polished metal coupon is totally immersed in a water/ethanol phase obtained by adding water to gasohol in an amount sufficient to extract ethanol into the aqueous phase. The sample is stored in the dark at room temperature. The coupon is visually inspected for evidence of corrosion and weight changes are also recorded.

Procedure

A one inch square metal coupon with a ₇ inch centered hole is polished, rinsed in heptane then acetone, and dried. Initial coupon weight is then obtained. Two hundred (200) mls of gasohol are placed in an 8-ounce acid-cleaned jar. Twenty (20) mls of water are added to the gasohol and shaken thoroughly to effect the separation of a lower water/ethanol phase. The metal coupon is then suspended in the lower phase using a ¼ inch glass rod with an enlarged and flattened end so that the coupon surface is totally immersed in the lower phase but off the bottom of the jar. The jar lid is sealed and the jar is placed in a dark environment. Visual inspections for evidence of corrosion are made periodically and a coupon weight change is recorded at the end of the test. The corrosion products, if any, are removed using a camel's hair bruch prior to obtaining a final weight.
Other amines besides those disclosed and claimed in S.N. 124,031 can also be employed.
In addition other alkenyl succinic acids can also be employed such as by way of illustration and not of limitation polymeric alkenyl succinic acids such as those containing the following repetitive unit.
where R is a hydrocarbon group having at least about 8 carbons such as about 8 to 48 carbons, for example from about 12 to 42 carbons, but preferably from about 20 to 28 carbons. Preferably the hydrocarbon group is alkyl.
The following examples are illustrative.

Additive Compositions

Composition G 50%
where R = CH₃(CH₂) ₁₁-50% Aromatic hydrocarbon solvent Composition H 66°.
X=OC(CH₃)₃ Y=H where n=1-10 34% Aromatic hydrocarbon solvent
X=-OC(CH₃)₃ Y=H where n = 1-10 Composition J
Composition K
Composition L
Composition I Composition M
Composition N
Thus, a wide variety of amines can be employed in this invention. These include primary, secondary and tertiary monoamines, diamines, and polyamines. Preferably, the amines have a total of about 6-40 carbons, for example from about 8 to 30 carbons, but preferably from about 10 to 18 carbons. The optimum number of carbons in the amine will depend upon the particular amine employed. In general, the optimum number of carbons is from about 8 to 30, but preferably from about 10 to 20. In the preferred embodiment the amine has a hydrocarbon group which has a continuous carbon chain of at least about 6 carbons such as from about 6 to 34, for example from about 6 to 20, but preferably from about 6 to 14.
The hydrocarbon group may be a straight, branched chain, or both. In addition to hydrocarbon and amine group, the amine may also have other elements present such as oxygen, etc.
Thus, the amine employed may be represented by the following formula
R Ⓝ where R is the hydrocarbon group having at least about 6 carbon atoms and Ⓝ is the rest of the amine. Ⓝ may be a mono amine, a diamine or a polyamine or may contain other elements such as oxygen, etc. such as -(
A)_nNH₂ where A is alkylene, preferably -(CH)_2-3 and n is a zero or number such as 0-6, but preferably 1-3. R may be attached to an intermediate oxygen containing group such as -(OA)_m- where A is alkylene, preferably -(CH₂)_2-3 where n is a number preferably 1 such as
where m = 1 and n = 0, the compound is ROANH₂ where m and n are 1, the compound is ROAN ANH₂, etc.
The following are non-limiting examples of suitable amines:

n-Butyl amine, Furfurylamine
Dibutyl amine, Dodecylamine
2-ethylhexyl amine, Monoethanolamine
Di(2-ethylhexyl)amine, Diethanolamine
Monoisopropanolamine, N-methyl ethanolamine
Diisopropanolamine, N-ethyl ethanolamine
Methyl isopropanolamine, N-Amylamine
Butyl isopropanolamine, Di-n-amylamine
Hexylamine, Sec-amylamine
Dihexylamine, N-ethylbutylamine
Heptylamine, 2-amino-4-methylpentane
Octylamine, 4-amino-2-butanol
Dioctylamine, 5-isopropylamino-1-pentanol
Decylamine, N-butylaniline

Similarly, secondary high molecular weight aliphatic amines known as Armeen 2C can be used.
Also, high molecular weight aliphatic amines known as Armeen 8D, Armeen 12D, Armeen 16D, Armeen C, Armeen 18D, Armeen CD, Armeen HTD, Armeen T, Armeen O.
Suitable amines having an aromatic ring include alpha-methylbenzylamine and alpha-methylbenzyl- monoethanolamine.
Other amines include:

2-amino-2-methyl-1-propanol
2-amino-2-methyl-1,3-propanediol
2-amino-2-ethyl-1,3-propanediol
3-amino-2-methyl-1-propanol
2-amino-1-butanol
3-amino-2,2-dimethyl-1-propanol
2-amino-2.3-dimethyl-1-propanol
2,2-diethyl-2-amino ethanol
2,2-dimethyl-2-amino ethanol
3-amino-1,2-butanediol
4-amino-1,2-butanediol
2-amino-1,3-butanediol
4-amino-1,3-butanediol
2-amino-1,4-butanediol
3-amino-1,4-butanediol
1-amino-2,3-butanediol
Tris-(hydroxy methyl) amino methane

Amines having ring structures include aniline, diphenylamine, cyclohexylamine, dicyclohexylamine, and various comparable amines with alkyl substitutents in the ring.
A monoamine compound can be cyclic or non-cyclic. Those which are cyclic may be heterocyclic as in the case of morpholine and its derivatives or oxazolines which may be regarded as derivatives of N-acyl-2-amino-ethanols. This would apply where instead of being a derivative of monoethanolamine the oxazoline was a derivative of a low molal acid or a high molal acid and 2-amine-2-methyl-1,3-propanediol.
One may use polyamines corresponding to the formula
?C=0, or greater (for example 1-10 or greater) in which R" is hydrogen, alkyl, cycloalkyl, aryl, or aralkyl and R' is a divalent radical such as

Examples of suitable amines include: Ethylenediamine, Diethylenetriamine, Triethylenetetramine, Tetraethylenepentamine, Propylenediamine, Dipropylenetriamine, Tripropylenetetramine, Butylenediamine, Aminoethylpropylenediamine, Aminoethylbutylenediamine
Other polyamines in which the nitrogen atoms are separated by a carbon atom chain having 4 or more carbon atoms include the following: Tetramethylenediamine, pentamethylenediamine, and especially hexamethylenediamine.
and derivatives obtained by treating ethylenebisoxypropylamine with 1,2,3, or 4 moles of ethylene oxide, propylene oxide, butylene oxide, or the like.
Other compounds including those having cyclic structures include piperazine, and the corresponding derivatives obtained by treating piperazines with alkylene oxides. The same applies to substituted piperazine such as the 2,5-dimethylpiperazine.
As to mono-substituted dialkanol piperazine see U.S. Pat. No. 2,421,707, dated June 3, 1947, to Malkemus.
Another example of polyamine which may be employed as a reactant is the kind described as "Duomeens."
Duomeen is a trademark designation for certain diamines. Duomeens have the following general formula:
R is an alkyl group derived from a fatty acid or from the mixed fatty acids as obtained from certain oils. The specific Duomeen and the source of the radical R are as follows:

Duomeen 0; R = oleic acid
Duomeen T; R = Tallow oil fatty acid
Duomeen C; R = Coconut oil fatty acid
Duomeen S; R=soya oil fatty acid

N-octyl ethylenediamine
N-tetradecyl ethylenediamine
N-hexadecylethylenediamine
N-dodecyl triethylenetetramine
N-dodecyl propylenediamine
N-decyl butylenediamine
It is to be noted that all the above examples show high molal groups, i.e., eight carbon atoms or more. The same derivatives in which methyl, ethyl, propyl, butyl, amyl, acryl groups, or the like, appear instead of octyl, decyl, etc., are equally satisfactory.
The compositions of this invention may be employed in any amount capable of inhibiting rust or corrosion, such as in minor amounts of at least 1 p.p.m., such as at least 5 p.p.m., for example 15 to 200 p.p.m., or more, but preferably 25-50 p.p.m.
In certain instances, it may be desirable to add larger amounts of the compositions of the invention, such as up to about 100,000 p.p.m. or greater, for example from about 20 to 1,000 p.p.m.
In addition, it is clearly understood that the claims of this invention include the presence of water therein as a dissolved, suspended, and/or separate phase. This is described as item 5 on page 6. The compositions of this invention inhibit corrosion in those systems where water is in the dissolved, suspended, or separate phase, including inhibition in the gasohol phase, as well as the separate water phase or separate water-alcohol phase.

Claims

1 A corrosion inhibited system comprising

I. an oxygenated fuel, and

II. A composition comprising the reaction product of

(1) an alkenyl or alkyl succinic acid or the anhydride, or polymer thereof; and

(2) an amine.

2 The system of claim 1 where the amine is an aliphatic mono- or polyamine.

3 The system of claim 2 where the amine has the formula ROANHA'NH₂ where R is alkyl and A and A' are alkylene.

4 The system of claim 3 where the alkylether diamine is CH₃(CH₂)_nO(CH₂)₃NH(CH₂)₃NH₂ where n = ₇-13.

5 The system of claim 1 where a stoichometric excess of alkenyl or alkyl succinic acid or anhydride or the polymer thereof is reacted.

6 The system of claim 2 where a stoichiometric excess of alkenyl or alkyl succinic acid or anhydride or the polymer thereof is reacted.

7 The system of claim 3 where a stoichiometric excess of alkenyl or alkyl succinic acid or anhydride or the polymer thereof is reacted.

8 The system of claim 4 where a stoichiometric excess of alkenyl or alkyl succinic acid or anhydride or the polymer thereof is reacted.

9 The system of claim 1 where the 'alkenyl group is tetrapropenyl.

10 The system of claim 2 where the alkenyl group is tetrapropenyl.

11 The system of claim 3 where the alkenyl group is tetrapropenyl.

12 The system of claim 4 where the alkenyl group is tetrapropenyl.

13 The system of claim 5 where the alkenyl group is tetrapropenyl.

14 The system of claim 6 where the alkenyl group is tetrapropenyl.

15 The system of claim 7 where the alkenyl group is tetrapropenyl.

16 The system of claim 8 where the alkenyl group is tetrapropenyl.

17 The system of claim 1 when oxygenated fuel is gasohol.

18 The system of claim 2 when oxygenated fuel is gasohol.

19 The system of claim 3 when oxygenated fuel is gasohol.

20 The system of claim 4 when oxygenated fuel is gasohol.

21 The system of claim 5 when oxygenated fuel is gasohol.

22 The system of claim 6 when oxygenated fuel is gasohol.

23 The system of claim 7 when oxygenated fuel is gasohol.

24 The system of claim 8 when oxygenated fuel is gasohol.

25 The system of claim 9 when oxygenated fuel is gasohol.

26 The system of claim 10 when oxygenated fuel is gasohol.

27 The system of claim 11 when oxygenated fuel is gasohol.

28 The system of claim 12 when oxygenated fuel is gasohol.

29 The system of claim 13 when oxygenated fuel is gasohol.

30 The system of claim 14 when oxygenated fuel is gasohol.

31 The system of claim 15 when oxygenated fuel is gasohol.

32 The system of claim 16 when oxygenated fuel is gasohol.