KR940005200B1 - Method of improving cetane number of fuel oil and compositions - Google Patents

Abstract

This relates to improving the cetane no. of fuel and the new fuel composition. The method adds aliphatic amine or nitrogen-containing heterocyclic compound salt of nitroalkyl carboxylic acid of formula (1) in a conventional fuel such as diesel. In formula, R1 is C4-C17 alkyl and A is the compound of formula (2) or (3). And the addition quantity is 200-1000 ppm.

Description

Cetane number improved fuel oil production method and fuel oil composition

The present invention relates to a method for preparing a fuel oil having improved cetane number and a fuel oil composition prepared by the method, and more particularly, by adding an aliphatic amine salt or a nitrogen-containing heterocycline compound salt of nitro alkyl carboxylic acid to fuel oil. The present invention relates to a method for producing fuel oil capable of improving cetane number and a fuel oil composition produced by the method.

In general, the cetane number 50 of the direct current diesel oil obtained by distilling from crude oil is high, so there is no problem in the use of a high-speed diesel engine.

However, in the case of diesel oil produced by high-octane gasoline by contact distribution of diesel oil, the cetane number is low as 30-40 and the ignition is poor. Therefore, the use of a cetane number improver is required to improve the combustion performance of the fuel.

Cetane number improvers are decomposed during fuel combustion to produce free radicals, prevent ignition delays, make diesel engines easier to start, and reduce exhaust emissions. Conventional cetane number improvers include aliphatic nitrate compounds, aliphatic peroxides, aldehydes, ketones, ethers, esters, metal oxides, aliphatic hydrocarbons and the like.

Among them, peroxides are rarely used because they may have an adverse effect on explosion risk and fuel. In addition, except for aliphatic nitrate compounds, there is a disadvantage in that the degree of improvement in cetane number is low and the amount used is high. As a result, cetane number improvers, which are currently commercially used and widely used, are aliphatic nitrate compounds, especially octyl nitrate.

The present inventors conducted extensive research to develop a cetane number improving agent having a high cetane number improving effect and a low explosion risk in addition to the cetane number improving agent. As a result, an aliphatic amine salt or a nitrogen-containing heterocyclic compound of a night alkyl carboxylic acid It was found that the salt has an excellent cetane number improving effect, and the present invention was completed based on this finding.

Accordingly, an object of the present invention is to provide a method for preparing fuel oil capable of improving cetane number, and another object of the present invention is to prepare a fuel oil composition containing an amine salt of nitroalkyl carboxylic acid. In order to achieve the above object, the method of the present invention is an aliphatic amine salt of a nitro alkyl carboxylic acid or a nitrogen-containing heterocyclic compound represented by the following structural formula (1) to a conventional fuel oil, preferably diesel, thereby improving cetane number. It consists of making oil.

In Formula (1), R ₁ is a saturated or unsaturated substituted or unsubstituted alkyl group having 4 to 17 carbon atoms, which forms R ₁ COO, and general functional groups such as hydroxyl group, chlorine, and fluorine may be present. Preferred carboxyl groups include valeric acid groups, hexanoic acid groups, 2-ethylhexanoic acid groups, tecanoic acid groups, lauric acid groups, stearic acid groups, and hydroxy stearic acid groups. In the above structural formula, it is preferable that NO ₂ is introduced into the terminal of the carboxylic acid or in the middle of the carbon chain so as to form free radicals when the fuel oil is burned to increase the flammability.

In addition, A is an aliphatic amine of formula (2) or a nitrogen-containing heterocyclic compound of formula (3).

R ₂ , R ₃ and R ₄ in Formula (2) may be the same or different from each other except when all are hydrogen and each is hydrogen and a saturated or unsubstituted alkyl group having 1 to 4 carbon atoms. The aliphatic amines constituted as described above are monoethylamine, monopropylamine and monobutylamine as primary amines, and diethylamine, dipropylamine, diisopropylamine and dibutylamine as secondary amines. Examples of the amines include triethylamine, tripropylamine, tributylamine, and diisopropylethylamine.

R ₅ , R ₆ , R ₇ , R ₈ , and R ₉ bonded to each carbon atom constituting the pyridine in the formula (3) may be the same or different from each other, and each of hydrogen and C 1 to 4 saturated substituted or It is an unsubstituted alkyl group and a general functional group such as hydroxyl group, chlorine and fluorine may be present. Preferred compounds of the above structural formula (3) include pyridine, 2-methylpyridine, 4-methylpyridine, 2-tert-butylpyridine, 2,6-semi-butylpyridine, 2,4,6-trimethylpyridine (collidine) Can be.

Carboxylic acids of the above formulas are already known and are described in Org. Syn. Coll Vol. V, 445 describes the preparation thereof, and the method for preparing the amine salt is described in Org. Syn. Coll Vol. I. Well shown in 3. For example, 4-methyl-4-nitrovaleric acid triethylamine salt is prepared by reacting 2-nitropropane with acrylic acid methyl ester to prepare 4-methyl-4 nitro valeric acid methyl ester. Decomposition yields 4-methyl-4-nitrovaleric acid and is prepared by reacting triethylamine with the same molar number.

As described above, the carboxylic acid amine salt of the above structural formula is preferably appropriate concentration of the additive necessary to obtain the desired cetane number improving effect used in diesel fuel, but may vary depending on the type of diesel fuel used. For fuels, 200 to 1000 ppm is suitable, where the cetane number improving effect is reduced at 1000 ppm or more, and less than 200 ppm is difficult to achieve the desired effect.

The carboxylic acid amine salt of the above structural formula may be added to the fuel as it is, but may be added in a concentrated form using an inert stable organic solvent at 80-370 ° C. At this time, light oil having 10 to 30 carbon atoms is preferable, and oxygen-containing compounds such as diethyl ether, terahydrofuran, and methyl tert-butyl ether are preferably used together with the hydrocarbon solvent. Small amounts of surfactants such as 2- (2-butoxyethoxy) -ethanol may also be used to enhance solubility.

A fuel composition for attaining another object of the present invention is a nitroalkyl carboxylic acid of formula (1) of 200-1000 ppm with respect to conventional fuel oil, preferably diesel fuel oil and a small amount, preferably fuel oil. It consists of an amine salt.

Hereinafter, the configuration and effects of the present invention will be described in detail with reference to the following examples. However, this example does not limit the scope of the present invention.

Example 1

The CFR single-cylinder engine was used to measure the cetane number of the diesel fuel mixture.

16.1 g of 4-methyl-4-nitrovaleric acid and 10.1 g of triethanalamine were mixed to obtain 26.2 g of liquid 4-methyl-4-nitrovaleric acid triethylamine salt at room temperature, and then mixed with 80 g of diesel. 106 g of a solution (containing 24.7 wt% of amine salt) were prepared.

The test solution is prepared by adding the above-mentioned mixed solution to 2 liters of diesel such that the carboxylic acid amine salt content is 200, 400, 600, 800, and 1000 ppm. The engine is operated for at least 10 minutes using a reference fuel without cetane (cetane number 45), and after the steady state is reached, the selector switch of the ignition delay measuring instrument is positioned. Adjust the handwheel so that the reading on the ignition delay meter exceeds 15 and then reads the handwheel reading when it is set to 13.

The previous procedure is carried out on the reference fuel (the cetane number 50.5) and on the fuel.

The cetane number of the test fuel is measured by the following method.

Where Cs is the cetane number of the test fuel.

A is the handwheel reading of the test fuel

B is the cetane number of the reference fuel

C indicates the handwheel reading of the reference fuel.)

At this time, the relationship between the amount of 4-methyl-4-nitrovalic acid triethylamine salt used and cetane number is shown in Table 1 below.

TABLE 1

Example 2

16.1 g of 4-methyl-4-nitrovaleric acid and 7.3 g of diethylamine were mixed to obtain 23.4 g of 4-methyl-4-nitrovaleric acid diethylamine salt as a solid at room temperature, followed by solid with 15 g of tetrahydrofuran. Dissolve and add 60 g of diesel to prepare 98 g of a mixed solution (containing 23.9 wt% of amine salt).

The test solution is prepared by adding the above-mentioned mixed solution to 2 liters of diesel such that the carboxylic acid amine salt content is 200, 400, 600, 800, and 1000 ppm. Its method was carried out in the same manner as in Example 1, wherein the change relationship between 4-methyl-4-nitro valeric acid diethylamine salt usage and the cetane number is shown in Table 2.

TABLE 2

Example 3

16.1 g of 4-methyl-4-nitrovaleric acid and 7.9 g of pyridine were mixed to obtain 24.0 g of liquid 4-methyl-4-nitrovaleric acid pyridine salt at room temperature, followed by 15 g of tetrahydrofuran and 2- (2- 5 g of butoxyethoxy) ethanol and 60 g of diesel were added to prepare 104 g of a mixed solution (containing 23.0 wt% of an amine salt).

The test solution is prepared by adding the above-mentioned mixed solution to 2 liters of diesel such that the carboxylic acid amine salt content is 200, 400, 600, 800, and 1000 ppm. Other methods were carried out in the same manner as in Example 1, wherein the change relationship between 4-methyl-4-nitrovaleric acid pyridine salt used amount and cetane number is shown in Table 3 below.

TABLE 3

Example 4

A mixture of 16.1 g of 4-methyl-4-nitrovaleric acid and 12.1 g of 2,4,6-trimethylpyridine (collidine) was mixed, and 4-methyl-4-nitrovaleric acid 2,4,6- liquid at room temperature. After obtaining 28.2 g of trimethylpyridine salt, 15 g of tetrahydrofuram, 5 g of 2- (2-butoxyethoxy) ethanol and 60 g of diesel were added to prepare 108 g of a mixed solution (containing 26.1 wt% of amine salt).

The test solution is prepared by adding the above-mentioned mixed solution to 2 liters of diesel such that the carboxylic acid amine salt content is 200, 400, 600, 800, and 1000 ppm. Other methods were carried out in the same manner as in Example 1, wherein the change relationship between 4-methyl-4-nitrovaleric acid 2,4,6-trimethylpyridine salt used amount and cetane number is shown in Table 4 below.

TABLE 4

As described above, the fuel oil of the present invention may have a significantly improved cetane number than the nitro alkyl carboxylic acid amine salt is not added.

Claims (12)

A process for producing cetane number-enhanced fuel oil, comprising adding an aliphatic amine salt or a nitrogen-containing heterocyclic compound salt of nitro alkyl carboxylic acid of the following structural formula (1) to a conventional fuel. In formula (1), R ₁ is a saturated or unsaturated substituted or unsubstituted alkyl group having 4 to 17 carbon atoms, and A is an aliphatic amine of formula (2) or a nitrogen-containing heterocyclic compound of formula (3) to be. R ₂ , R ₃ and R ₄ in the above formula (2) may be the same or different from each other except when all are hydrogen, and each is hydrogen and an embedded substituted or unsubstituted alkyl group having 1 to 4 carbon atoms. R ₅ , R ₆ , R ₇ , R ₈ , and R ₉ bonded to each carbon atom constituting the pyridine in the formula (3) may be the same or different from each other, and each of hydrogen and C 1 to 4 saturated substituted or Unsubstituted alkyl group. The method for producing cetane number-enhanced fuel oil according to claim 1, wherein a general functional group such as a hydroxyl group, chlorine, and fluorine is present in R ₁ of the formula (1). According to claim 1, wherein R ₁ in the formula (1) is represented by a carboxyl group of R ₁ COO, wherein the carboxyl group of R ₁ COO valeric acid group, hexanoic acid group, 2-ethylhexanoic acid group, A method for producing cetane number-enhanced fuel oil, characterized in that it is a tecanoic acid group, lauric acid group, stearic acid group or hydroxy stearic acid group. The method for producing a cetane number-enhanced fuel oil according to claim 1, wherein the NO ₂ of the formula (1) is present in the terminal or the middle of the R ₁ . A compound according to claim 1, wherein A in formula (1) is an aliphatic amine of formula (2), which is monoethylamine, monopropylamine or monobutylamine for primary amine, diethylamine for secondary amine, Dipropylamine, diisopropylamine or dibutylamine, and the tertiary amine is triethylamine, triproamine, tributylamine or diisopropylethylamine. A compound according to claim 1, wherein A in formula (1) is pyridine, 2-methylpyridine, 2-tert-butylpyridine, 2,6-tert-butylpyridine or 2, A method for producing a cetane number-enhanced fuel oil, characterized in that 4,6-trimethylpyridine (collidine). The method for producing cetane number-enhanced fuel oil according to claim 1, wherein the nitro alkyl carboxylic acid amine salt is added in a concentrated form using an inert, stable organic solvent at 80 to 370 ° C. . 8. The method for producing cetane number improved fuel oil according to claim 7, wherein the organic solvent is light oil having 10 to 30 carbon atoms. The compound according to claim 1 or 8, wherein when the carboxylic acid amine salt is added, an oxygen-containing compound such as diethyl ether, tetrahydrofuran, methyl tert-butyl ether and 2- (2-butoxy ethoxy) ethanol Method for producing a cetane number-enhanced fuel oil, characterized in that the same surfactant is used in combination with the hydrocarbon solvent. The method according to claim 1, wherein the carboxylic acid aliphatic amine salt or the nitrogen-containing heterocyclic compound salt is added in an amount of 200 to 1000 ppm with respect to the fuel oil. A fuel oil composition comprising a common fuel oil and a carboxylic acid aliphatic amine salt or a heterocyclic compound salt of structural formula (1) of 200 to 1000 ppm relative to the fuel oil. 12. The fuel oil composition according to claim 11, wherein the fuel oil is diesel.