RU2659221C2 - Antidetonating additive on the basis of mixture of methylated toluidines and method of selective receiving of mixture of n-methyl-toluidines - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a novel process for the preparation of a mixture of N-methyl-toluidine isomers with a concentration of at least 98 % and to the use of a mixture of N-methyl-toluidine isomers with a concentration of at least 98 % of the amines, obtained by this method, as an octane-raising additive to gasoline. Method consists in the reaction of a mixture of toluidines, without their preliminary separation into individual isomers, with methanol at a molar ratio of a mixture of toluidines and methanol of 1: 1.70–1.75 in the vapor phase at atmospheric pressure in the presence of a copper-containing catalyst at a temperature ranging from 200 °C to a temperature not exceeding 350 °C in a layer of copper-containing catalyst. As the copper-containing catalyst, a catalyst is used comprising: CuO 12–19 %; MnO 2–9 %; Cr₂O₃ 1.0–5.0 %; Fe₂O₃ 1.0–5.0 %; Co₃O₄ 0.5–1.5 %; Al₂O₃ – remainder or CuO 37.5–55.0; ZnO 9.0–25.5; Al₂O₃ – remainder or CuO 25.0–41.0; ZnO 25.0–30.0; NiO 4.5–5.5; Al₂O₃ – remainder. Isolation of reaction products is carried out by partial condensation. Preparation of a mixture of N-methyl-toluidine isomers can be carried out in a hydrogen stream at a molar ratio of a mixture of isomers of N-methyl-toluidines and hydrogen of 1:1.0:1.1.

EFFECT: additive obtained by the proposed method has a higher octane number (not less than 96.7%) in comparison with the previously known additive based on aromatic amines (at least 92.1%) at the same concentration.

3 cl, 2 tbl, 9 ex

Description

The invention relates to additives that increase the anti-knock resistance of hydrocarbon fuels (fuels, gasolines), and can be used in the field of oil refining, gas processing to create high-octane fuels.

With the advent of internal combustion engines operating at high compression ratios, the problem of increasing the octane number of hydrocarbon fuels (fuels) arose.

It is known that the octane number of fuels increases with an increase in the content of branched and unsaturated hydrocarbons and aromatic hydrocarbons in the fuel. Continuous development and improvement of aviation and automotive technology requires the creation of new high-octane fuels.

This problem can be solved by creating new chemical processes for reforming direct gasoline, catalytic cracking and catalytic reforming or adding special antiknock additives (additives) and high-octane components to hydrocarbon fuels (fuels). In this case, a synergy effect may occur.

The most technologically and economically advantageous is the use of high-octane hydrocarbon combustible antiknock additives.

It is known that to increase the octane number of fuels, both ash and ashless antiknock additives (additives) and oxygenates are used (used).

The well-known ash antiknock additives (additives) used to date are organic compounds of manganese, iron, copper, chromium, cobalt, nickel, rare earth elements, lead, etc.

However, they all have high toxicity, especially organic lead compounds, both themselves and their combustion products, and have a negative effect on the operation of internal combustion engines, accumulating on the electrodes of spark plugs, pistons and walls of the combustion chamber, significantly reducing its life (RU patent No. 2078118, CL C10L 1/18, 04/27/1997).

Ashless antiknock additives (additives), although less effective than ash ones, are more widely used and used, especially in combination with other components.

The most famous and common ashless antiknock additives (additives) are: low molecular weight aromatic amines (N-methylaniline (MMA), xylidine, toluidine).

Known adopted as a prototype method for producing N-methyl substituted aromatic amines by reducing the corresponding nitro compounds with methanol in the vapor phase at elevated temperature, in the presence of an industrial copper-containing catalyst brand "Virgon", or "S-40", or "NTK-10-7F" modified with nickel or palladium or platinum, taken in an amount of 0.3-10 wt. % The process is usually carried out at a temperature of 200-260 ° C, atmospheric pressure and the feed rate of the liquid initial mixture of methanol with an aromatic nitro compound from 0.5 to 2.5 h ^-1 , maintaining the ratio of methanol / aromatic nitro compound in the initial mixture from 1: 1 to 5 :one. The total yield of aromatic amines up to 99.5%, product productivity up to 0.4-1.3 g / g /h. The method allows you to change the ratio of the resulting N-methyl substituted and unsubstituted aromatic amines (US Pat. RU 2207335, IPC C07C 211/48, C07C 211/46, C07C 209/36, 2003).

This method has a significant drawback - high thermal loads in the frontal layer of the catalyst lead to destruction of the catalyst, which significantly narrows the range of possible catalysts for the process, as well as an increased content of tertiary amine impurities, especially in the initial contact period. Another disadvantage of this method is the use of an expensive catalyst modified with platinum group metals, which can be justified only by its increased service life, which is not indicated in the patent.

The objective of the invention is to provide an additive to gasoline and the technology of producing an anti-knock additive to motor gasolines as an effective alternative to the traditionally known and used in the production of motor gasoline traditional amine antidetonators: N-methylaniline, N-methyl-para-anisidine.

The technical result of the invention is the provision of the possibility of obtaining a mixture of N-methyl-toluidines with a purity of not less than 98% by weight, (by the sum of amines) and a high yield of about 95%, which makes it possible to organize highly profitable industrial production of anti-knock additives for gasoline.

The problem is solved by creating an additive to gasoline containing an octane-increasing component based on a nitrogen-containing compound in the form of a mixture of N-methyl-toluidines of the general formula (1),

where R ₃ is a CH ₃ radical, with a concentration of at least 98% by the sum of amines.

The problem is solved by creating a method for producing aromatic amines by reacting the corresponding nitro compounds with methanol in the vapor phase at elevated temperature and atmospheric pressure in the presence of a copper-containing catalyst, according to which a mixture of toluidines (without preliminary separation into separate isomers) is used at a temperature of 180-240 ° C in a stream hydrogen at a molar ratio of a mixture of toluidines: hydrogen - 1: 3, followed by separation of products by partial condensation.

The copper-containing catalyst may be promoted with oxides of iron, chromium, cobalt, nickel and zinc and may contain:

CuO 12-19%; MnO 2-9%; Cr ₂ O ₃ 1.0-5.0%; Fe ₂ O ₃ 1.0-5.0%; With ₃ O ₄ 0.5-1.5%; Al ₂ O ₃ - the rest.

A copper-containing catalyst may contain:

CuO 37.5-55.0; ZnO 9.0-25.5; Al ₂ O ₃ - the rest.

A copper-containing catalyst may contain:

CuO 25.0-41.0; ZnO 25.0-30.0; NiO 4.5-5.5; Al ₂ O ₃ .

The combination of the above components and their ratio is new and provides an additive with higher properties compared to known additives. Considering the properties of a mixture of N-methyl-toluidines, which are aromatic amines and are not derivatives of aniline (since they are toliamines), their use as anti-knock additives to motor gasolines is very promising and is limited only by the lack of industrial large-tonnage production. In this regard, the development of an economical industrial method for producing a mixture of N-methyl-toluidines is an urgent production task.

A mixture of N-methyl-toluidines is obtained by vapor-phase alkylation of a mixture of tolyl amines with methanol in the presence of a granular copper-containing catalyst.

The alkylation of tolyl amines with methanol consists of the following reactions successively occurring on the surface of the catalyst:

A) dehydrogenation of methanol to formaldehyde: CH ₃ OH → CH ₂ O + H ₂ ;

B) the condensation of tolylamines with formaldehyde to form an intermediate synthesis product and water: CH ₂ O + C ₇ H ₉ N → C ₇ H ₉ NCH ₂ + H ₂ O;

B) hydrogenation of the intermediate with hydrogen to N-methyl-toluidines: C ₇ H ₉ NCH ₂ + H ₂ → C ₇ H ₉ NHCH ₃

The conditions for obtaining a mixture of N-methyl-toluidines are illustrated by the following examples.

Example 1. In a stainless tubular reactor with an inner diameter of 51 mm, 30 ml of inert material (Rashig ceramic rings) and 100 ml of copper-containing catalyst No. 1 were charged. The free volume of the reactor above the catalyst was also filled with 30 ml of inert material. The inert material above the catalyst acts as an evaporator of the reactants. Nitrogen was passed through the reactor at a rate of 200 ml / min and heated with an electric heater to a temperature of 200 ° C. At this temperature, catalyst recovery was started by supplying pure methanol to it at such a rate that the temperature in the catalyst bed did not rise above 300 ° C. After completion of the recovery (the cessation of heat generation and a drop in temperature in the catalyst bed to 200 ° C) for another 1 hour, pure methanol vapors were passed through the reactor. Then, methanol was replaced with a mixture consisting of 1 molar part of a mixture of toluidines and 1.7 molar parts of methanol, which was supplied at a rate of 0.06 L / h and the synthesis of N-methyl-toluidines was carried out. Contact gases were cooled in a glass ball cooler and collected in a collector. The condensate was divided into aqueous and organic layers in a separatory funnel. The organic layer was analyzed by gas chromatography on a Crystal 5000.2 chromatograph. The contacting process was carried out continuously until the appearance of an unreacted mixture of toluidines in the amount of 5% in the organic layer of the catalyst. After which the flow of the reaction mixture was stopped and the installation was switched to the catalyst regeneration mode. To do this, water vapor was supplied to the catalyst, then water vapor was diluted with air, gradually increasing its concentration, but so that the temperature in the catalyst layer did not exceed 350 ° C. After the regeneration (cessation of heat generation in the catalyst bed), the installation was transferred to the recovery mode and then to the contacting mode (described above). The average yield for 1 contact period (3500 h) was at least 85-95%.

The organic layer (target product) during the process was continuously separated from the aqueous layer by partial condensation, the intermediate products and methanol were returned to contacting. A partial mixture of N-methyl-toluidines with partial condensation came out with a concentration of not less than 98% (by the sum of amines).

Tests of the additive samples for antiknock efficiency were carried out in a “mixture of 70” (a mixture of isooctane and normal heptane in a ratio of 70:30 by volume) according to the motor method according to the method of GOST 511-82. The higher the octane gain, the higher the antiknock effectiveness of the additive. The test results are shown in table 1.

Example 2. As in example 1, but the process was conducted in a stream of hydrogen at a molar ratio of a mixture of toluidines: hydrogen - 1: 3. However, when applying such a molar ratio, the yield of the target product is reduced by 5-7%.

Example 3. As in example 2, but the process was conducted in a stream of hydrogen, with a ratio of 1 molar part of a mixture of toluidines, 2 molar parts of methanol and 3 hydrogen. However, this reduces the concentration of the target product by 2-3%.

Example 4. As in example 1, but catalyst No. 2 was used.

Example 5. As in example 2, but catalyst No. 2 was used.

Example 6. As in example 3, but catalyst No. 2 was used.

Example 7. As in example 1, but catalyst No. 3 was used.

Example 8. As in example 2, but used catalyst No. 3.

Example 9. As in example 3, but catalyst No. 3 was used.

Examples No. 1, 2, 3, 4, 5, 6, 7, 8, 9 were carried out on catalysts of the following compositions:

CuO 12-19%; MnO 2-9%; Cr ₂ O ₃ 1.0-5.0%; Fe ₂ O ₃ 1.0-5.0%; With ₃ O ₄ 0.5-1.5%; Al ₂ O ₃ - the rest (catalyst No. 1);

CuO 37.5-55.0; ZnO 9.0-25.5; Al ₂ O ₃ - the rest (catalyst No. 2);

CuO 25.0-41.0; ZnO 25.0-30.0; NiO 4.5-5.5; Al ₂ O ₃ - the rest (catalyst No. 3).

The results of the experiments in examples 1-9 are shown in Table. 2.

The resource of the catalysts before their replacement was 7000 hours with one intermediate regeneration .. The proposed method allows the use of existing industrial plants used to obtain aniline and N-methylaniline.

The technical result of the invention is the provision of the possibility of obtaining a mixture of N-methyl-toluidines with a purity of not less than 98% of the mass. (by the sum of amines) and a high yield of about 95% of theory.

Claims (3)

1. A method of obtaining a mixture of isomers of N-methyl-toluidines with a concentration of at least 98% of the amines by reacting a mixture of toluidines with methanol in the vapor phase at elevated temperature and atmospheric pressure in the presence of a copper-containing catalyst, characterized in that they use a mixture of toluidines without them preliminary separation into individual isomers at a molar ratio of a mixture of toluidines and methanol 1: 1.70-1.75 at a temperature in the range from 200 ° C to a temperature not exceeding 350 ° C in a layer of a copper-containing catalyst, while using a copper-containing catalyst containing: CuO 12-19%; MnO 2-9%; Cr ₂ O ₃ 1.0-5.0%; Fe ₂ O ₃ 1.0-5.0%; Co ₃ O ₄ 0.5-1.5%; Al ₂ O ₃ - the rest or CuO 37.5-55.0; ZnO 9.0-25.5; Al ₂ O ₃ - the rest or CuO 25.0-41.0; ZnO 25.0-30.0; NiO 4.5-5.5; Al ₂ O ₃ - the rest, followed by the isolation of reaction products by the method of partial condensation. 2. The method according to claim 1, characterized in that the mixture of isomers of N-methyl-toluidines is carried out in a stream of hydrogen at a molar ratio of a mixture of isomers of N-methyl-toluidines and hydrogen of 1: 1.0: 1.1. 3. The use of a mixture of isomers of N-methyl-toluidines with a concentration of at least 98% of the amines obtained by the method of claim 1 as an octane-enhancing additive to gasoline.