RU2620083C1 - Method of obtaining antidetonation additives to automobile gasolines and fuel composition containing antidetonation additive received by the developed method - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention discloses a process for the production of an anti-knock additive based on alkyl tertiary alkyl ethers carried out by reacting an alcohol with an isoalkylene-containing fraction, characterized in that methanol is used as an alcohol, as an isoalkylene-containing fraction, an isobutylene-containing or isoamylene-containing fraction derived from the reaction mixture of methyl t-butyl or methyl-t-amyl ether is mixed with unreacted and water-separated methanol in the following ratio, wt %: methanol 4-30; methyl t-butyl or methyl-t-amyl ether up to 100. A fuel composition of automobile gasoline from hydrocarbon fractions containing an antiknock additive obtained by the developed method at a concentration of 3.0-22.0 wt %.

EFFECT: improvement of the operational properties of fuels, a significant increase in the detonation resistance of base fuels, other physical-chemical and operational properties are unchanged or within acceptable limits.

3 cl, 4 tbl

Description

The invention relates to the field of oil refining and petrochemicals, specifically to a method for producing an anti-knock additive for gasoline based on methyl tert-butyl ether (MTBE) or methyl tert-amyl ether (MTAE) and methanol, as well as to a fuel composition containing an anti-knock additive obtained by the developed method.

It is known that MTBE and MTAE are used as high-octane gasoline components. MTBE is the main oxygenate in our country (AM Danilov. “The use of additives in fuels: a Handbook”, St. Petersburg, “HIMIZDAT”, 2010, p. 98) and one of the most common abroad. Unlike MTBE, MTAE is less used due to less isoamylene resources.

Methyl alcohol also has experience in the use of motor gasolines and alcohol fuels from small additives (1-3%) to a very high content of 85% (V. M. Kapustin et al. “Oxygenates in gasoline”, M., “KolosS ", 2011, p. 186-187).

Several inventions are known where a process for preparing pure alkyl tert-alkyl esters is provided. In particular, these are copyright certificates of the USSR: SU 1793683, 1995; SU 1815954, 1995; SU 1805652, 1995 and patent RU 1814281, 1995. The production technology of these esters does not allow to obtain a complex methanol-containing high-octane additive.

Also known patent RU 2209811, 2003, which proposes a method for producing a complex product containing ethanol or methanol and alkyl tert-alkyl esters of C ₄ -C ₇ . In addition to esters and alcohol, it contains unreacted C ₅₊ hydrocarbons. The presence of the latter increases the instability of the product during storage, as well as in the composition of gasolines. The specific effectiveness of the product as a high-octane additive decreases, which entails the difficulty of adjusting the antiknock properties of gasolines.

Closest to the claimed solution is patent RU 2168490, 2001. The patent describes a method for producing a mixture of ethyl tert-butyl ether (from 50 to 97%) and ethanol (from 3 to 50%) on a sulfoionite catalyst. This is achieved by introducing an excess of ethyl alcohol into the feed stream, which allows ethanol to be left in the bottom product. The disadvantage of this process is the need to modernize the production lines and equipment of the installation to ensure the possibility of supplying a large amount of ethanol to the process.

The objective of the present invention is to develop a method for producing antiknock additives to gasoline, which allows to obtain additives in existing plants for MTBE or MTAE, and a fuel composition containing an additive obtained by the developed method.

The problem is solved by the development of a method of producing an antiknock additive to motor gasolines based on MTBE or MTAE, carried out by reacting methanol with an isobutylene-containing or isoamylene-containing fraction, which is characterized in that MTBE or MTAE extracted from the reaction mass is mixed with unreacted and separated methanol from the following ratio in water ,% mass .:

Methanol 4-30 Methyl tert-butyl or methyl tert-amyl ether up to 100

Additionally, an anti-corrosion additive in a concentration of up to 0.002% of the mass can be added to the mixture. and / or as a stabilizer of low temperature properties isopropyl or isobutyl alcohol up to 30% of the mass.

Also claimed is a fuel composition of motor gasoline from hydrocarbon fractions containing an anti-knock additive obtained by the developed method in a concentration of 3.0-22.0% by weight.

It should be noted that in order to reduce the cost of the proposed antiknock additive, the authors developed a method that allows you to transfer existing installations focused on the production of pure ether to the production of finished high-octane additives.

It is known that in the synthesis of pure MTBE or MTAE esters, methyl alcohol in excess of 2: 1 with respect to olefin is used as a reagent (V. M. Kapustin, M. G. Rudin. “Chemistry and technology of oil refining”, M., Chemistry, 2013, p. 445). Unreacted amounts of alcohol come from the ester synthesis zone, together with the spent butane (isopentane-isoamylene) fraction, to the block where the hydrocarbon fraction is separated from the alcohol by absorption of the latter with water. Next, methanol enters the rectification unit for separation from water and returns to the process.

The fundamental difference between the proposed technical solution and the technology for the production of ethyl tert-butyl ether according to the patent RU 2168490 is the involvement of a part of unreacted methanol in the composition of the antiknock additive. To achieve this goal, an additional unit for mixing ether, methanol and, if necessary, an anti-corrosion additive and isopropanol or isobutanol is installed. Ether is supplied to the mixing unit from the reaction unit for the synthesis of ethers, alcohol is taken from the methanol separation unit, and additional components are supplied from the commodity and raw materials park. The main objective of the mixing unit is to provide the required ratio of the components of the additive.

Another important advantage of this solution is the reduction in operating costs for pumping unreacted methanol to return to the process. Thus, at the exit from the installation, a finished high-octane additive is obtained.

It should be noted that a twofold amount of methanol supplied to the installation allows the manufacture of the additive without introducing an additional amount of alcohol (the methanol in the composition of the additive is always less than the esters). Moreover, part of the methyl alcohol will also be sent for recycling, which will facilitate the reorientation of existing ether production plants to the production of high-octane additives. At the same time, it is obvious that this technology allows you to get the installation with a flexible release of products, as it remains possible to produce pure ether.

The composition of the samples of the proposed additives obtained by the developed method, and examples of the effectiveness of its use in gasoline are presented in table 1.

Pure MTBE was used as the sample number 1.0, and pure MTAE number 2.0.

As a corrosion inhibitor, two samples were used:

- a prototype based on isoalkenyl succinic acid;

- industrial design DCI-11.

The quality of anticorrosion additive samples is presented in Table 2. The presence of an anticorrosion additive in the composition of the additive obtained by the proposed method minimizes the effect of alcohol on metal surfaces that the additive or fuel composition will come into contact with at all stages of its life cycle. The anticorrosive additive is specially selected to improve the operational properties of this additive.

Additionally, the additive may contain a stabilizer of low temperature properties - isopropyl or isobutyl alcohols in an amount up to 30% of the mass.

Evaluation of the antiknock efficiency of the additive obtained by the proposed method (Table 1) was carried out by introducing it at a concentration of 15% of the mass into the base fuel with an octane number according to the research method 90. The detonation resistance of the samples was determined according to GOST R 52947 by the research method and according to GOST R 52946 motor method.

As can be seen, compared with pure MTBE, the proposed additive has a higher antiknock efficiency. When using an additive based on MTAE, the results of measurements of octane numbers also exceed the detonation resistance for pure MTAE.

Evaluation of the anti-corrosion properties was carried out according to the modified ASTM D 665 method in the presence of distilled water at a temperature of 38 ° C for 4 hours. In accordance with the recommendations of this method, to determine the degree of corrosion of the rod surface after testing, visual assessment criteria were adopted, according to which the maximum degree of corrosion (more than 5% of the surface of the rod is covered with corrosion products) is estimated at 3 points (this indicator was obtained for base fuel and gasoline with MTBE) ; the surface of the rod, free from traces of corrosion (clean rod), is rated at 0 points. 1 point is also a satisfactory result, since it implies no more than six dark dots and spots with a diameter of 1 mm each.

As follows from the data in table 1, the additive obtained by the proposed method can improve the operational properties of fuels, in contrast to gasoline with MTBE (0-1 points versus 3 points).

Assessment of the low-temperature properties of the additive samples obtained by the proposed method with base fuels was carried out according to GOST 5066 at the cloud point. The norm for this indicator was adopted according to GOST R 52201 “Ethanol motor fuel for automotive engines with positive ignition. Benzanols ", not higher than minus 30 ° С. The second point of the invention is a method for producing high-octane additives, optionally containing a stabilizer of low-temperature properties - isopropyl or isobutyl alcohols. Adding the latter makes it possible to lower the cloud point of fuels and to ensure the possibility of operation in various climatic conditions, as well as maintaining the commercial quality of gasolines when moisture enters them. Depending on the amount of additive in the fuel, it is recommended to introduce a stabilizer up to 30% of the mass. The introduction of a stabilizer significantly reduces the cloud point of fuels (below -60 ° C), or allows you to save the value of this indicator with an increase in water content up to 0.125% of the mass. in gasoline. An example of the effectiveness of the phase stabilizer is shown in table 1.

The chromaticity of the resulting fuels was evaluated according to the ASTM D 1500 method on an automatic apparatus PFXi-195/2 from Lovibond, which automatically determines the color of transparent samples according to one-dimensional scales accepted as industrial standards. A value of <0.5 means that the fuel is virtually colorless.

It is also proposed a fuel composition of motor gasoline containing an additive obtained by the claimed method, in an amount of from 3.0 to 22.0% of the mass. The maximum concentration of use of the proposed additives is adopted in accordance with the European Standard for the Quality of Motor Gasoline (European Standard EN 228: 2012), according to which the content of esters with five or more carbon atoms in gasolines is allowed at 22 vol.%.

The composition, physico-chemical and operational characteristics of the basic mixtures of hydrocarbons are given in table. 3.

The composition of the samples of the fuel composition of gasoline containing the additive obtained by the proposed method, and the results of its tests are given in table. four.

To confirm the effectiveness of the claimed fuel composition were prepared 10 samples of gasoline by introducing samples of the inventive additives in the base mixture of hydrocarbon fractions. The basic mixtures of hydrocarbon fractions were: a mixture of reforming gasoline (70% wt.) And isomerizate (30% wt.), As well as a mixture of catalytic cracking gasoline (60% wt.), Isomerizate (30% wt.) And alkylate (10 % mass.).

Physico-chemical characteristics and composition of the basic mixtures of hydrocarbon fractions are presented in table 4. The use of mixtures of hydrocarbon fractions and additives obtained by the proposed method in an amount of 3.0-22.0% by mass leads to the preparation of the proposed fuel composition. The test results shown in table 4 showed that the introduction into the base mixture of hydrocarbon fractions of an antiknock additive obtained by the developed method significantly increases the detonation resistance of base fuels, while other physicochemical and operational properties do not change or are within acceptable limits. Samples numbered 2, 5 and 7 meet the requirements of GOST 32513-2013, the remaining samples satisfy the requirements of EN 228-2012. The results of the assessment of corrosion exposure showed that the introduction of the proposed additives can improve the anticorrosive properties of fuels.

It should be noted that the resulting fuel composition can be used in standard internal combustion engines with forced ignition of the air-fuel mixture without adaptation due to the low methanol content.

Thus, a method has been developed for the production of anti-knock additives to motor gasolines, which makes it possible to obtain additives at existing MTBE or MTAE production plants, i.e. transfer existing installations focused on the production of pure ether to the production of finished high-octane additives.

The additive obtained by the proposed method in the stated ratios of the components can improve the operational properties of fuels, significantly increases the detonation resistance of base fuels, while other physico-chemical and operational properties do not change or are within acceptable limits.

Claims (4)

1. A method of producing an anti-knock additive to automobile gasolines based on alkyl tert-alkyl ethers, carried out by reacting an alcohol with an isoalkylene-containing fraction, characterized in that methanol is used as the alcohol, an isobutylene-containing or isoamylene-containing fraction isolated from the iso-containing fraction is isolated from the reaction mixture methyl tert-butyl or methyl tert-amyl ether is mixed with unreacted and separated from water methanol in the following ratio, wt.%: Methanol 4-30 Methyl tert-butyl or methyl tert-amyl ether up to 100 2. A method of producing an antiknock additive according to claim 1, characterized in that the anticorrosion additive is additionally added in a concentration of up to 0.002 wt.% And / or isopropyl or isobutyl alcohol up to 30 wt.%. 3. A fuel composition of motor gasoline from hydrocarbon fractions containing an antiknock additive obtained by the method according to any one of claims. 1, 2, at a concentration of 3.0-22.0 wt.%.