JPH0153996B2 - - Google Patents

Description

[Detailed description of the invention]

Metal corrosion caused by conventional motor vehicle fuels such as conventional gasoline has been less of a problem because such hydrocarbon fuels are inherently non-corrosive. However, with the advent of alcohol-containing or linear alcohol fuels such as gasohol, corrosion has become a serious problem due to the corrosive nature of such fuels. This corrosion has been reported to be due to the presence of acidic contaminants such as formic acid in such fuels. Avoiding these contaminants is almost impossible as they are present in fuel quality alcohol and are formed as natural alcohol oxidation products during storage. It is known from US Pat. No. 4,305,730 that polymerized linoleic acid, especially the trimer, is an effective corrosion inhibitor for alcoholic motor fuels. Here,
It has been discovered that the corrosion protection properties of such polymerized polyunsaturated aliphatic monocarboxylic acids are improved by the use of co-additives according to the invention. According to the present invention, metal corrosion caused by alcohol-based motor vehicle fuels is prevented by adding to the fuel a combination of (A) a polymerized polyunsaturated aliphatic monocarboxylic acid and (B) a sterically hindered phenol. Therefore, the present invention provides a liquid fuel suitable for use in internal combustion engines, comprising 5 to 100% by weight of one or more alcohols and 0 to 95% by weight of gasoline.
(A) a polymer of one or more C16 _{- C18} polyunsaturated aliphatic monocarboxylic acids; and (B) an anti-corrosion amount of a combination of at least one sterically hindered phenol. provide. The additive combinations of the present invention are useful in any engine fuel containing or consisting of oxygenates. Such fuels include gasoline-alcohol mixtures called "gasohol" and linear alcohol fuels. Useful alcohols include methanol, ethanol, n-propanol, isopropanol, isobutanol, and the like. Gasohol typically contains about 2-30% alcohol by volume. The most widely used alcohols are methanol and ethanol. At a concentration of about 10% by volume, the phase separation problem is
This occurs especially when water is present. Phase separation can be minimized by adding cosolvents such as ethers, ketones, esters, etc. to the gasohol. A particularly useful cosolvent is methyl tert-butyl ether, which also helps increase octane number. The additive combination according to the invention can be used in concentrations that provide the required corrosion protection. A useful range is about 1 to 5000 parts per million (ppm). A particularly preferred range is about 5 to 2000 ppm, with concentrations of 10 to 500 ppm most preferred. Component A is one or more carbon atoms 16 to 18
It is a polymer of polyunsaturated aliphatic monocarboxylic acids having Examples of such acids are linoleic and linolenic acids and mixtures thereof. The polymer consists primarily of dimers and trimers of the polyunsaturated acid. Suitable polymers of linoleic acid are commercially available. Mixtures with high trimer content are most preferred. Component B of the combination according to the invention is a hindered phenol. This includes fuel (eg gasohol or alcohol fuel) soluble phenols having at least one bulky substituent substituted ortho to the phenolic hydroxy group. Representative bulky substituents are secondary and tertiary alkyl [including cycloalkyl and alkyl (cycloalkyl)] or aralkyl groups. The most preferred hindered phenols are those substituted with secondary or tertiary alkyl or aralkyl groups at both positions ortho to the phenolic hydroxy group. Such phenols include: 2,6-di-sec-butylphenol 2,6-diisopropylphenol 2,6-di-tert-butylphenol 2,6-di-sec-octylphenol 2-tert-butyl-6 -(α-methylbenzyl)
Phenol 2-isopropyl-6-(α,α-dimethylbenzyl)phenol 2,6-di-(α-methylbenzyl)phenol 2,6-di-(α,α-dimethylbenzyl)phenol and the like are included. In particularly preferred embodiments, the hindered phenol is also substituted in the para position with an alkyl group containing from 1 to about 20 carbon atoms. Examples of such hindered phenols include: 2,6-di-tert-butyl-4-methyl-phenol 2,6-di-tert-butyl-4-ethyl-phenol 2,6-di-tert-butyl -4-(n-butyl)-
Phenol 2,4,6-tri-tert-butyl-phenol 2,6-di-tert-butyl-4-(sec-octyl)
Examples include phenol, 2,6-di-tert-butyl-4-(sec-eicosyl)phenol, 2,6-diisopropyl-4-methylphenol, 2,4,6-tri-sec-butyl-phenol, and the like. In a particularly preferred embodiment, the hindered phenol is 2,6-di-(α-methylbenzyl)-4
_-C1-20 -alkyl-phenol. Examples of these include: 2,6-di-(α-methylbenzyl)-4-methyl-phenol 2,6-di-(α-methylbenzyl)-4-ethyl-phenol 2,6-di-(α-methylbenzyl)-4-ethyl-phenol -methylbenzyl)-4-3rd
Butyl-phenol 2,6-di-(α-methylbenzyl)-4-(n
-butyl)-phenol 2,6-di-(α-methylbenzyl)-4-(sec-octyl)-phenol 2,6-di-(α-methylbenzyl)-4-nonyl-phenol 2,6-di-(α-methylbenzyl)-4-nonyl-phenol -(α-Methylbenzyl)-4-dodecylphenol 2,6-di-(α-methylbenzyl)-4-octadecylphenol 2,6-di-(α-methylbenzyl)-4-eicosylphenol, etc. It will be done. Sterically hindered methylene bisphenols are also useful. These include 2,2'-methylenebis-(4
-alkyl-6-tertiary alkyl-phenol) and 4,4'-methylenebis-(2-alkyl-6
-tertiary alkyl-phenol). Typical examples of these include 2,2'-methylenebis-(4-methyl-6-tert-butyl-phenol), 2,2'-methylenebis-(4,6-di-tert-butyl-phenol),
butyl-phenol), 4,4'-methylenebis-
(2,6-di-tert-butyl-phenol), 4,
Included are 4'-methylenebis-(2-methyl-6-tert-butyl-phenol) and mixtures thereof. The most preferred hindered phenol is 2,6-
Bis-(α-methylbenzyl)-4-nonyl-phenol. Nonyl groups can be easily utilized by alkylation with propylene trimer. The weight ratio of component A to component B in the combination according to the invention can vary over wide ranges, such as from 1 to 10 parts of A to 1 to 10 parts of B. In particularly preferred embodiments, from about 0.5 to 5 parts of component A to one part of component B
parts by weight. In a more particularly preferred embodiment
0.6 to 4.0 parts by weight of component A are used per part of component B. The most preferred ratio is 1:1. Components A and B can be added separately to the fuel. It is particularly preferred if components A and B are premixed to form a package and this package is added to the fuel in an amount sufficient to achieve the required degree of corrosion protection. Most preferably, components A and B are premixed with a solvent to facilitate handling and formulation. Suitable solvents include alcohols (eg methanol, ethanol, isopropanol), ketones (eg acetone, methyl ethyl ketone), esters (eg tert-butyl acetate) and ethers (eg methyl tert-butyl ether). Aromatic hydrocarbons are very useful solvents. These include benzene, toluene, xylene, and the like. Excellent results are obtained using xylene. The concentrations of active ingredients A and B in the package can vary widely. For example, the active ingredient content can range from about 5% by weight to the solubility limit of A or B in solvent. When using xylene, a total active ingredient content of about 5 to 25% by weight is generally used, especially a total active ingredient content of about 10% by weight. Tests were conducted to determine the anti-corrosion properties of the additive combinations of the present invention. This test measures the corrosion of metal coupons immersed in a test liquid under different test conditions. Uses aluminum, brass, zinc, lead and copper coupons. The coupons were first cleaned with Carborundum 40, washed with petroleum ether,
It is then dried in an oven at 40° C. for 10 minutes. Each coupon is weighed and then immersed in 130 g of test liquid in a sealed bottle at a specified temperature for a specified time. At the end of the test period, the coupons are removed from the fuel and, after light brushing to remove any loosely adhering liquid, the coupons are washed, dried, and weighed again as at the beginning of the test. Record any changes in coupon weight. Both weight gain and loss indicate corrosion. Corrosion is characterized by two modalities, either weight loss due to loss of metal or weight gain due to deposition of corrosion products, and visual inspection of the coupons after the test in the tests described below indicates that these two modalities are are mutually exclusive. The first series of tests tested linoleic acid polymers (mainly trimers) and 2,6-di-(α-methylbenzyl).
- Equal weight combination with 4-nonylphenol
The experiments were carried out in various alcohol-type fuels containing 100 ppm. In this series of tests, the temperature is room temperature and the soaking time is 6 weeks. The results are shown in the table below for weight gain or loss in mg. The numbers in the box are the results when no inhibitor was used.

[Table] Nium brass 〓0.4(〓0.5) 〓0.3(〓0.9) 〓0.1(〓1.
0)

[Table] In the next series of tests, coupons were tested with 100 ppm formic acid and 10 ppm methyl formate to increase the test severity.
into a bottle containing methanol.
The additive tested was a mixture of equal amounts of linoleic acid trimer and various hindered phenols listed in Table 2. Additive concentration is 100ppm. Bottles containing test coupons were stored at 40°C for two weeks. Weight changes due to corrosion are shown in Table 2 below.

Table: Y ¹ is a mixture of tert-butyl-phenols containing primarily 2,6-di-tert-butyl-phenol. Y ² is 2,6-di-(α-methylbenzyl)-4
-nonyl-phenol. Another test was conducted demonstrating the synergistic results obtained with this combination of additives. These tests were conducted in methanol with 100 ppm formic acid and 10 ppm methyl formate. The metal coupons were immersed in fuel and stored at 40°C for 2 weeks. Additive D is 2,6-di-(α-methylbenzyl)-4-nonyl-phenol. Additive E is a linoleic acid trimer. Additive D+E is an equal weight mixture of D and E. The total inhibitor concentration in each test was
It is 300ppm.

Table: These results show that the combination gives better results than would be expected from the results obtained with each component alone. The next series of tests used 100 ppm of formic acid as fuel.
and methanol with 10 ppm of methyl formate added. The metal coupon was only partially immersed (approximately 50%) and the bottle was stored at 40° C. for 2 weeks. The additive is a 50/50 mixture of linoleic acid trimer and 2,6-di-(α-methylbenzyl)phenol. The additive concentration in each example is 300 ppm. The test results are shown in Table 4.

[Table] Contains 15% methanol by volume and also contains formic acid.
The following tests were conducted in gasohol with 100 ppm and 10 ppm of methyl formate. The entire metal coupon was immersed and stored at 40°C for 2 weeks. The additive concentration is
It is 100ppm. The results with and without the test additive are shown in Table 5. The test additive was an equal weight mixture of linoleic acid trimer and various hindered phenols listed in Table 5.

[Table] M ¹ is linoleic acid trimer + 2,6-di-(α-methylbenzyl)phenol. ^N2 is linoleic acid trimer + methylene bridge 2,6
It is a mixture of -di-tert-butyl-phenol and ortho-tert-butyl-phenol. ^O3 is linoleic acid trimer+2,6-di-tert-butyl-4-n-butyl-phenol. Although the test results are not equally effective for all metals in all fuels, they show that the additive combination of the present invention provides very good corrosion protection on average.

Claims (1)

[Scope of Claims] 1. A liquid fuel suitable for use in an internal combustion engine, which contains one or more types of alcohol with a concentration of 5 to 100%.
% by weight, 0-95% by weight of gasoline and a combination of (A) one or more polymers of _C16 - _C18 polyunsaturated aliphatic monocarboxylic acids and (B) at least one sterically hindered phenol. A liquid fuel characterized by containing an amount that prevents corrosion of substances. 2. According to claim 1, the polymer of one or more _C16 to _C18 polyunsaturated aliphatic monocarboxylic acids mainly comprises a dimer, trimer or a mixture thereof of linoleic acid. Liquid fuels listed. 3. Liquid fuel according to claim 1, wherein the or each hindered phenol is substituted in both positions ortho to the phenolic hydroxyl group by secondary or tertiary alkyl or aralkyl groups. 4. The liquid fuel according to claim 1, wherein the phenol is 2,6-di-(α-methylbenzyl)-4-C _1-20 -alkyl-phenol. 5. The liquid fuel according to claim 4, wherein the phenol is 2,6-di-(α-methylbenzyl)-4-nonylphenol. 6 The phenol is 2,6-di-tert-butyl-
The liquid fuel according to claim 3, which is 4- _C1-20 -alkylphenol. 7 The phenol is 2,6-di-tert-butyl-
Claim 6 which is 4-butylphenol
Liquid fuels listed in section. 8 The phenol is 2,6-di-tert-butyl-
Claim 6 which is 4-methylphenol
Liquid fuels listed in section. 9 The phenol is 4,4'-methylenebis-
The liquid fuel according to claim 3, which is 2,6-di-tert-butylphenol. 10 (A) one or more C ₁₆ - _{C 18} polyunsaturated aliphatic monocarboxylic acid polymers and (B) at least one
A corrosion inhibitor concentrate as a corrosion inhibitor for alcohol-type fuels, comprising a solvent containing a combination of sterically hindered phenols in an amount of at least 5% by weight.