For a selection of n-hexane from hexasticha gasoline fractions

 

(57) Abstract:

The invention relates to the field of chemical technology, and more specifically to a method for allocation of n-hexane from hexasticha gasoline fractions containing the addition of n-hexane blastocytosis to him hydrocarbons: 2.2-Dimethylbutane, 2,3-Dimethylbutane, 2-methylpentane, C-methylpentan, Methylcyclopentane and other paraffin and cycloparaffin Uglevodorody composition C5-C6. Proposed allocation method n-hexane (from the specified raw materials) finishing above 99 wt.%, all indicators meet the specifications for n-hexane brand "pure" rectification method with a separating agent, in which a mixture of benzene and n-heptane, in two columns. In the first column at atmospheric pressure allocate on top of the fraction of light hydrocarbons, in the second column of the cubic product of the first column at a pressure 800-7000 mm RT. Art. on top secrete n-hexane, which douchemat from benzene adsorption on zeolites or by treatment with oleum.

The invention relates to the chemical industry, more specifically to a method for allocation of n-hexane from hexane fractions, representing narrow benzylideneamino fractions containing paraffin and cycloparaffin hydrocarbon is 30% n-hexane, allocate, for example, from refined, which are obtained during the extraction of aromatic hydrocarbons from catalization reforming of straight-run gasoline fractions 62 - 105oC, 62 - 85oC selective solvents (Nadutkina S. I. and other Chemistry and technology of fuels and oils, 1976, No. 7, S. 3 - 5). According to the requirements of THE 6-09-3375-78 on n-hexane brand "pure" concentration of the basic substance, there must be not less than 99,0% by weight, the indicator color is not more than 0.5 mg of iodine per 100 ml of product bromine number of not more than 0.02 g of bromine in 100 ml of product, final boiling point within 68,5 - 68,9oC (Hexane solvents (nefras) THE 38.1011228 - 90).

Hexane brand "pure" is widely used as a reagent in the laboratory of organic synthesis, as well as in the textile, perfume, food industry. The market price of n-hexane of this brand is currently 12 million rubles per ton, while 1 ton of nefras - expected raw material for separation of n-hexane - costs only 700 thousand rubles. Feasibility analysis conducted by the applicants have shown that the method clear rectification using the techniques suggested below how the allocation of n-hexane from nefras is economically feasible.

The sharp increase in energy prices in recent years has made the process unprofitable, which led to the closure of all facilities for the production of individual paraffin hydrocarbons on the basis of this method.

A known method of purification of n-hexane from Methylcyclopentane method of extraction distillation (A. C. 177863 from 3.10.1964,, publ. BI N 2, 1966) (prototype method). As a separating agent in this way it is proposed to use dimethylformamide or a mixture of propylene carbonate.

According to the method, a mixture of n-hexane and Methylcyclopentane introduced as food by 1/3 from the top of the distillation column efficiency 50 so so In the upper part of the column serves a separating agent in a ratio of 10 wt. H. separating agent 1 wt. including shared with the quality of the distillate selected n-hexane, containing 99 wt.% the basic substance and 1 wt.% Methylcyclopentane. From the cube column allocate the mixture separating agent Methylcyclopentane and n-hexane in a ratio of 98 wt.% Methylcyclopentane, 2 wt.% n-hexane.

The disadvantage of this method is the high thermolability and reactivity proposed separating agent, its high cost and corrosive, which requires for the manufacture of equipment expensive grades of alloy steels.

As shown by our research, selected by the method prototype n-hexane contains trace amounts of formic acid, a product of hydrolytic decomposition of dimethylformamide in the presence of water, traces of which always have a place in the commodity dimethylformamide, what makes this product unsuitable for a number of applications, in particular in the pharmaceutical industry and as extractants natural fats. Adding to the separating agent is propylene carbonate as the decomposition products detected admixture of unsaturated compounds, which causes an increase in the bromine number of the target product ( example 12 of the present application).

The purpose of the present invention is the extension of the resource cost, improving quality. The essence of the method consists in the following. Narrow hexane fraction, isolated by distillation or from the raffinate of the extraction of aromatic hydrocarbons by selective solvents, or from the faction MK-85oC gasoline hydrocracking of vacuum distillates or from pyrolysis resin after its two-stage hydrogenation and other industries, is sent to the power of the first distillation column efficiency is not less than 100 - 150 so so together with a separating agent, in which a mixture of benzene and n-heptane containing up to 20 wt.% benzene, at mass ratio in the power of the column Methylcyclopentane : a separating agent equal to (5 - 30):1. On the top of the column operating at atmospheric pressure and the temperature of the top 61 - 64oC, bottom 75 - 82oC, allocate the fraction of light hydrocarbons, i.e., having a boiling point below n-hexane containing 8 to 12 wt.% n-hexane, which can be used as high-octane component of motor fuel, as it consists mostly of hydrocarbons from the structure. On bottom of the column allocate n-hexane, Methylcyclopentane separating agent. The bottom product of the first column refer to the power of the second column efficiency, the temperature of the top and bottom are parameters, derived from the values of the selected pressure and composition of the raw material).

On top of the second column secrete a mixture of n-hexane and benzene, on the bottom is a mixture of Methylcyclopentane and n-heptane. Distillate product of the second column is directed to the purification of n-hexane from impurities benzene. This cleaning is performed one described in the literature methods: processing product oleum followed by rinsing with a solution of sodium carbonate (Refining and petrochemicals, vol. 1, 1996, S. 10) or by adsorption on zeolites of type NaX (Alpatova L. A. Chemical industry abroad, N 8, niitekhim, 1964). After such cleaning, the content of benzene in n-hexane does not exceed 0.01 wt.%, what makes one fit the selected n-hexane in all areas of its application (example 1 of this application). The method of purification of n-hexane from benzene adsorption on the zeolite is preferred over the method oleum treatment, because in this way it is possible is quite simple regeneration of benzene by purging the adsorber hot nitrogen. In the case of oleum purification of benzene in the end turns into a sodium salt of benzosulfimide, i.e., we have the loss of benzene. However, given the large capacity and relatively low price of benzene, and the small is about n-hexane.

The second component separating agent is n-heptane, quite simply regenerated from the cubic product of the second column by distillation (example 1).

The process of selection of n-hexane is carried out at a mass ratio Methylcyclopentane : a separating agent (5 - 30):1. The specified value set in relation to Methylcyclopentane as the most difficult to separate from the desired product impurities.

Salient features of the proposed method are

the organization scheme of allocation of n-hexane from a narrow hexane fractions, including the extraction boiling impurities by distillation for the first column and the selection of the cubic product from this column of the target n-hexane on top of the second column operating at an elevated pressure in the range 800 - 7000 mm RT. Art.;

the selection of the target product in the presence of a separating agent, which is used as a mixture of benzene and n-heptane containing up to 20 wt.% benzene at mass ratio in the raw material process Methylcyclopentane : a separating agent (5 - 30) : 1.

Studies conducted by the applicants in the pilot installation of continuous rectification, showed that the pressure in the first distillation colonize target n-hexane is essential. When the pressure in the column below the proposed limit allocation of n-hexane purity rate of 99.0 wt.% (THE requirements) is not possible (example 8). The pressure increase above 7000 mm RT. senior economically impractical because of the additional energy consumption for separation are not compensated by improving the quality and yield of the target product.

Similarly, the increase in the concentration of benzene in the separating agent, the flow separating agent on phase separation in comparison with the claimed values is not economically compensated by increasing yield and quality of the secreted n-hexane.

The increased pressure in the distillation separation bizcochada hydrocarbons known, but usually this technique is used to ensure conditions for the condensation of the top product, i.e., to increase the allowable temperature of the cooling agent and the lower surface of the capacitor. In the proposed method, the higher pressure rectification in the second column are used solely to enhance the relative volatility of n-hexane and Methylcyclopentane, resulting in improved quality and yield of the target product. The effect of increasing the relative volatility in the system n-hexane - metaltitlepane the allocation of n-hexane from Netrusov.

The effect of pressure on the purity and yield secreted by rectification from nefras n-hexane and separating action of a mixture of n-heptane and benzene is non-obvious fact and cannot be predicted theoretically, because in the literature there are no data on the phase equilibria in the system n-hexane - Methylcyclopentane - benzene - n-heptane under a pressure of 800 to 7000 mm RT. Art. that it is not possible to simulate the considered separation on the computer.

All data following examples obtained from tests on pilot plant continuous operation. This indicates compliance of the distinctive features of the way the criteria of novelty and non-obviousness.

It must be emphasized that the above effect of the proposed method is achieved only when the total use of distinctive signs. When separate them using the required purity of the target product is a 99.0 wt.% - not achieved, and the yield of the target product is significantly lower (examples).

The advantage of the proposed method is that the components used therein separating agent, in contrast to the proposed method is the prototype, are products of oil refineries those whom Pat. The proposed method allows to significantly expand the raw material base for production of n-hexane, to simplify the technology of its allocation due to the exclusion from the process of nitrogen - and oxygen-containing thermolabile and corrosive compounds, to improve the quality of the target product by reducing the content of trace unsaturated compounds and acids.

The quality of the secreted n-hexane meets all the requirements of TU, its output capacity ranges from 76 to 89 wt.% depending on the applied pressure on the second stage of the process.

The method is illustrated by the following examples.

Example 1 (average values of the requested parameters)

Narrow hexane fraction, separated from the raffinate of the extraction of aromatic hydrocarbons by method a clear rectification column efficiency 50 so so with the multiplicity of the 17 irrigation, composition, wt.%: 2.2-dimethylbutan - 0,82; 2,3-dimethylbutan - 2,53; 2 - methylpentan - 7,93; 3-methylpentan - 12,08; n-hexane - 56.78 has; Methylcyclopentane - of 12.33; other hydrocarbon composition C5- C6- 7,53, with a flow rate of 100 kg/hour send in the power of the first distillation column, filled spiral prismatic nozzle 7 x 7 x 0.5 mm efficiency 150 so so You is significant. The pressure in the top of the column - 760 mm RT. Art. in the bottom of the column - 915 mm RT. century, the temperature in the top of the column 63oC, in the bottom - 76oC, the temperature of the input raw materials - 69oC, irrigation - 35oC, the ratio of irrigation - 25. Together with the flow of raw materials in the food column enter 1,03 kg/h separating agent composition, wt.%: benzene - 10, n-heptane - 90. The mass ratio of Methylcyclopentane : a separating agent is equal to 12 : 1.

On top of the first column allocate 35,20 kg/h of distillate product composition, wt.%: 2.2-dimethylbutan - 2,33; 2,3-dimethylbutan - 7,19; 2-methylpentan - 22,53; 3-methylpentan - 34,23; n-hexane - 11,98; Methylcyclopentane - 0,35; other hydrocarbon composition C5-C6- 21,39. The specified product is used as a component of gasoline AI-93.

On bottom of the column allocate 65,83 kg/hour cubic product composition, wt.%: 3-methylpentan - 0,05; n-hexane - 79,85; Methylcyclopentane - 18,54; benzene - 0,16; n-heptane - 1,40.

VAT product of the first column refer to the power of the second distillation column, the dimensions, and the efficiency is similar to the first working when the pressure in the top of the column 3500 mm RT. Art. in the bottom - 3698 mm RT. century, the temperature in the top of the column - 124oC, in the bottom - 136oC, with the multiplicity of the irrigation 33, the temperature of the irrigation 33oC.

Distillate product of the second column was fed to the adsorber filled with type zeolite NaX, where the adsorption of impurities benzene in zeolite. After treatment, get 47,47 kg/hour target n-hexane containing 99,40 wt. % of the basic substance, to 0.60 wt.% Methylcyclopentane (concentration of benzene in it within the accuracy of the analysis is less than 0.01 wt.%), hue 0.25 mg of iodine per 100 ml, bromine number 0,012 g of bromine in 100 ml. yield of the target product - 83,1 wt.% from the potential content in raw materials.

Adsorbed on the zeolite emit benzene by purging the adsorber hot nitrogen. Desorbed benzene recycle in the process.

Purification of n-hexane from impurities benzene can be accomplished by treating the distillate product of the second column of oleum. For this distillate product of the second column is treated sequentially with oleum in a mass ratio of distillate product: oleum equal to 1 : 0.5, and then the resulting mixture was washed with 5% sodium carbonate solution. The result is n-hexane to benzene content less than 0.01 wt.%, condom from potential content in raw materials 83,1 wt.%.

CBM product of the second column of composition, % wt: n-hexane - 24,59; methyl-cyclopentane - 69,99; n-heptane - 5,42 sent in the power of the distillation column efficiency 30 so t, operating at atmospheric pressure, the temperature of the top 70,6oC, bottom 102,4oC, ratio of irrigation of 2.5. On the top of the column allocate 16,11 kg/h of distillate product composition, wt.%: n-hexane - 26,0; Methylcyclopentane - 74,0; used as a component of gasoline PHI-93, on the bottom of the column to 0.92 kg/h of n-heptane, recycled as a component of the separating agent in the feeding of the first column.

Example 2 (lower pressure value in the second column)

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the pressure in the second column corresponds to the lower claimed the border, namely 800 mm RT.article.

In the process obtain the target n-hexane containing a 99.0 wt.% the main substance of 1.0 wt.% Methylcyclopentane, the chromaticity of 0.48 mg of iodine per 100 ml, bromine number of 0.017 g of bromine in 100, the Yield of the target product is 75.6 wt.% from the potential content in raw materials.

Example 3 (upper pressure value in the second column)

Raw materials of the composition shown in example 1, p is implemented border namely 7000 mm RT.article.

In the process obtain the target n-hexane containing a 99.6 wt.% the basic substance, 0.4 wt.% Methylcyclopentane, the chromaticity of 0.21 mg of iodine per 100 ml, bromine number 0,010 g of bromine in 100, the Yield of the target product to 88.7 wt.% from the potential content in raw materials.

Example 4 (lower bound ratio Methylcyclopentane: a separating agent).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1 with the difference that the ratio of Methylcyclopentane: a separating agent meets the bottom of the claimed boundary, namely 5:1.

In the process obtain the target n-hexane, containing of 99.5 wt.% the basic substance, 0.5 wt.% Methylcyclopentane, color, 0.22 mg of iodine per 100 ml, bromine number of 0.017 g of bromine in 100, the Yield of the target product is 84.8 wt.% from the potential content in raw materials.

Example 5 (the upper limit of the ratio of Methylcyclopentane: a separating agent)

Raw materials of the composition shown in example 1, is subjected to separation as in example 1 with the difference that the ratio of Methylcyclopentane : separating agent claimed the top border, namely 30 : 1.

As a result of PR is th 0,42 mg of iodine per 100 ml, bromine number 0,019 g of bromine in 100 g of the target product Yield of 76.3 wt.% from the potential content in raw materials.

Example 6 (upper limit of the concentration of benzene in the separating agent)

Raw materials of the composition shown in example 1, is subjected to separation as in example 1 with the difference that the concentration of benzene in the separating agent claimed the top border, and 20 wt.%.

In the process obtain the target n-hexane containing a 99.6 wt.% the basic substance, 0.4 wt.% Methylcyclopentane, color 0.19 mg of iodine per 100 ml, bromine number 0,015 g of bromine in 100, the Yield of the target product to 84.6 wt.% from the potential content in raw materials.

Example 7 (comparative without separating agent)

Raw materials of the composition shown in example 1, is subjected to separation as in example 1 with the difference that the separation is carried out without the use of a separating agent.

In the process obtain the target n-hexane, containing by 98.7 wt.% the main substance of 1.3 wt.% Methylcyclopentane, color 0,41 mg of iodine per 100 ml, bromine number 0,016 g of bromine in 100, the Yield of the target product to 67.3 wt.% from the potential content in raw materials.

Example 8 (sravniteljnoe 1, subjected to separation as in example 1 with the difference that the separation is carried out without application of the separating agent and at atmospheric pressure in the second column.

In the process obtain the target n-hexane containing 98,1 wt.% the main substance of 1.9 wt.% Methylcyclopentane, color 0.43 mg of iodine per 100 ml, bromine number of 0.014 g of bromine in 100, the Yield of the target product is 48.6 wt.% from the potential content in raw materials.

Example 9 (comparative, with a separating agent at atmospheric pressure in the second column)

Raw materials of the composition shown in example 1, is subjected to separation as in example 1 with the difference that the separation is carried out at atmospheric pressure in the second column.

In the process obtain the target n-hexane containing 98,8 wt.% the main substance of 1.2 wt.% Methylcyclopentane, color 0,39 mg of iodine per 100 ml, bromine number to 0.011 g of bromine in 100, the Yield of the target product - 68,9 wt.% from the potential content in raw materials.

Example 10 (no benzene in the separating agent)

Raw materials of the composition shown in example 1, is subjected to separation as in example 1 with the difference that the separation is carried out without using the AC.% the basic substance, 1.0 wt.% Methylcyclopentane, color 0,42 mg of iodine per 100 ml, bromine number 0,016 g of bromine in 100, the Yield of the target product - 73,1 wt.% from the potential content in raw materials.

Example 11 (a different composition of incoming raw materials for separation)

Narrow hexane fraction, separated from the raffinate of the extraction of aromatic hydrocarbons by method a clear rectification column efficiency 50 so so with the multiplicity of the 17 irrigation, composition, wt.%: 2.2-dimethylbutan 1,12; 2,3-dimethylbutan 1,66; 2-methylpentan 5,72; 3-methylpentan 16,07; n-hexane - 54,35; Methylcyclopentane - 16,33; other hydrocarbon composition C5- C6- 4,75 with a flow rate of 100 kg/hour send in the power of the first distillation column, filled spiral prismatic nozzle HH,5 mm efficiency 150 so so the Height of the Packed section of the column is 15 m, the height of the column - 20,7 m the Point of entry of raw materials - 55 so so from the top of the Packed section of the column. The pressure in the top of the column - 760 mm RT.art., in the bottom of the column 915 mm RT.art., the temperature in the top of the column to 62.8oC, in the bottom - 76,8oC, the temperature of the input raw materials 69,7oC, irrigation - 35oC, the ratio of irrigation - 28. Together with the flow of raw materials in the food column enter 2,04 kg/h separating agent composition, wt. %: benzene - 13,0, n-heptane - 87,0. Massowah/h of distillate product composition, wt. %: 2.2-dimethylbutan - 3,47; 2,3-dimethylbutan - 5,14; 2-methylpentan - 17,73; 3-methylpentan 49,67; n-hexane - 11,98; Methylcyclopentane - 0,51; and other hydrocarbon composition C5- C6- 14,72. The specified product is used as a component of gasoline AI-93.

At the bottom of the columns distinguish 69,77 kg/hour cubic product composition, wt.%: 3-methylpentan - 0,06; n-hexane - 73,84; Methylcyclopentane - 23,17; benzene - 0,38; n-heptane is 2.55.

VAT product of the first column refer to the power of the second distillation column, the dimensions, and the efficiency is similar to the first working when the pressure in the top of the column 3500 mm RT.art., in the bottom - 3698 mm RT.art., the temperature in the top of the column - 124,2oC, in the bottom - 138oC, with the multiplicity of the irrigation 35, the temperature of the irrigation 32oC.

On the top of the column allocate 48,16 kg/h of distillate product composition, wt.%: 3-methylpentan - 0,09; n-hexane - 99,58; Methylcyclopentane - 0,78; benzene - 0,55; bottom - 21,62 kg/hour cubic composition, wt.%: n-hexane - 18,73; Methylcyclopentane - 73,06; n-heptane - 8,21.

Distillate product of the second column was fed to the adsorber filled with type zeolite NaX with the size of the input Windows 8 , where adsorption of impurities benzene in zeolite. In the treatment of 46.68 get kg/h televosorom number - 0,012 g of bromine in 100 ml. yield of the target product is an 85.2 wt.% from the potential content in raw materials.

CBM product of the second column of the composition, wt.%: n-hexane - 18,73; Methylcyclopentane - 73,06; n-heptane - 8,21 sent in the power of the distillation column efficiency 30 so t, operating at atmospheric pressure, the temperature of the top 70,8oC, bottom 102,9oC, ratio of irrigation to 2.7. On the top of the column allocate 19,84 kg/h of distillate product composition, wt.%: n-gexcon - 20,4; Methylcyclopentane - 79,6; used as a component of gasoline AI-93, on the bottom of the column - 1,78 kg/HR of n-hexane, recycled as a component of the separating agent in the feeding of the first column.

Example 12 (method prototype)

Raw materials of the composition shown in example 1, with a flow rate of 100 kg/h are referred to as power supply 16 so-so from the top of the distillation column efficiency 50 so so-3 so-so from the top of the column as a separating agent serves 1000 kg/h of mixture composition, wt.%: 90 wt.% of dimethylformamide and 10 wt. % of propylene carbonate. The process of rectification is carried out at a temperature of the top of the column 68,5oC, bottom 120oC, at atmospheric pressure. From the top of the column as distillate allocate 43,6 kg/h of the target product so, bromine number 0.04 g of bromine in 100 ml, i.e., the last two indicators target product does not meet the requirements of TU. Output n-hexane - of 76.8 wt.% from the potential content in raw materials.

Example 13 (raw - hexane fraction isolated from gasoline hydrocracking)

Hexane fraction, isolated by distillation of the fraction of NC - 85oC gasoline obtained by hydrocracking of a vacuum distillate composition, wt.%: 2.2-dimethylbutan - 3,16; 2,3-dimethylbutan - 6,17; 2-methylpentan - 1,94; 3-methylpentan - 5,20; n-hexane - 62,34; Methylcyclopentane - 4,82; other hydrocarbon composition C5- C6- 16,37, is subjected to separation as in example 1 with the difference that for rectification use the column efficiency 100 so so

In the process obtain the target n-hexane containing at 99.1 wt.% the main substance of 0.9 wt.% Methylcyclopentane, the chromaticity of 0.44 mg of iodine per 100 ml, with a bromine number of 0.015 g of bromine in 100 g

The yield of the target product of 76.8 wt.% from the potential content in raw materials.

For a selection of n-hexane from hexasticha gasoline fractions containing n-hexane and blastocytosis to him hydrocarbons: Methylcyclopentane, 3-methylpentane, 2,2-Dimethylbutane, 2,3-Dimethylbutane, 2-methylpentane with a separating agent, followed by purification of the target product from the separating agent, characterized in that, as a separating agent, a mixture of benzene and n-heptane containing up to 20 wt.% benzene at mass ratio in raw Methylcyclopentane: a separating agent (5-30) : 1, and the rectification of the original gasoline fraction together with the separating agent is carried out in two columns emitting boiling hydrocarbons mixed with n-hexane on top of the first column with the efficiency of 100-150 tons tons, followed by distillation of the obtained cubic product in the second column operating at a pressure of 800 to 7000 mm RT.art., emitting a mixture of n-hexane and benzene on the top of the column and a mixture of Methylcyclopentane and n-heptane on the bottom of the column.

 

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21 cl, 1 dwg

FIELD: petroleum processing and petrochemistry.

SUBSTANCE: in particular, invention aims at producing extraction dearomatized component from reformat of gasoline fraction, which component may be used in production of petroleum solvents such as hexane solvents. Process comprising countercurrent extraction of aromatic hydrocarbons with liquid selective extractant to separate dearomatized component (raffinate) and subsequent extractive rectification of resulting extract phase by distilling off aromatic hydrocarbons is characterized by that liquid selective extractant is diethylene glycol or triethylene glycol, countercurrent extraction is carried out at 125-140°C, extractive rectification is carried out using process steam in presence of saturated selective extractant wherein evaporation of water is performed with the aid of energetic steam, unsaturated selective extractant after extractive rectification and recycled gasoline are sent to extraction stage preliminarily using unsaturated selective extractant as heat carrier to generate process steam, and energetic steam condensate is used to heat recycled gasoline to 80-130°C.

EFFECT: enhanced process efficiency.

3 cl, 1 dwg, 1 tbl, 3 ex

FIELD: petrochemical processes.

SUBSTANCE: hydrocarbon mixture obtained by extractive distillation of C4-fraction using selective solvent, which mixture contains those C4-hydrocarbons, which are better soluble in selective solvent than butanes and butenes, is subjected to continuous separation. Mixture is supplied to first distillation column, wherein it is separated into top stream, containing 1,3-butadiene, propine, and, if necessary, other low-boiling components and, if necessary, water, and bottom stream containing 1,3-butadiene, 1,2-butadiene, acetylenes, and, if necessary, other high-boiling components. Proportion of 1,3-butadiene in bottom stream of the first distillation column is controlled in such a way as to be high enough to dilute acetylenes beyond the range wherein acetylenes can spontaneously decompose. Top stream from the first distillation column is passed to second distillation column, wherein it is separated into top stream, containing propine, and, if necessary, other low-boiling components and, if necessary, water, and bottom stream containing pure 1,3-butadiene.

EFFECT: simplified process and reduced power consumption.

4 cl

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