SU1065402A1 - Process for recovering mixtures of formic and muriatic acids - Google Patents

Abstract

A method for isolating a mixture of mu-scale and salt acid from abdominal forms (Hxcfl by chlorofuction of furfural in the production of mucochloric acid, characterized in that, in order to improve the quality of the mixture of formic and hydrochloric acids and the degree of extraction of murine & marine, and in the form of morphine and hydrochloric acid; impurities of organochlorine compounds with hydrochloric acid and the absorber obtained is returned to the production of mucochloric acid, and then purified waste gases are subjected to the second stage of absorption with hydrochloric acid, with the separation of the aqueous phase of the mixture target acids.

Description

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The invention relates to methods for extracting a mixture of formic and hydrochloric acid from gases, which are formed during the chlorination of furfural in the production of mucochloric acid.

A mixture of formic and hydrochloric acids can be used as an intermediate in the process of isolating formic acid, as well as an intermediate in the synthesis of other compounds.

The closest technical solution to the proposed is a method for separating a mixture of formic and hydrochloric acids from a multicomponent mixture of the products of the reaction of chlorination of furfural in an aqueous medium by condensation of a vapor-gas mixture (gases) l.

However, upon condensation of the vapor – gas mixture of the process of chlorination of furfural, a mixture of formic and hydrochloric acids is obtained with an impurity of up to 1% of organochlorine compounds and with a low content of formic acid. The average composition of the condensate, weight,%:

Formic acid 35

Hydrogen chloride 20

Organochlorine.

Compounds 1.0 including mucochloric acid 0.6

waterReal

In connection with this, the cooler-condenser is gradually forgotten by solid organochlorine substances, which necessitates periodic cleaning of the apparatuses and requires the installation of parallel refrigeration-condensers to ensure continuous process. This complicates the process for the production of mucochloric acid.

In addition, the use of a known method of extracting a mixture of acids in the production of mucochloric acid does not provide a satisfactory purification of gases from organic impurities; therefore, only second grade hydrochloric acid is obtained as a waste from the production of purified carbon dioxide, and therefore is not used in traditional households. It is unrealistic to waste production.

Due to these drawbacks, the known method has not been applied in the production of crooked production, and the mixture of formic and hydrochloric acids, which is formed in the production of mucochloric acid, is sent to neutralization.

The aim of the invention is to improve the quality of the mixture of formic and hydrochloric acids, as well as the emitted gases, and the degree of extraction of formic acid from the abgas. The goal is achieved

According to the method for isolating a mixture of formic and hydrochloric acids from gases, the extraction of furfural in the production of mucochloric acid during the chlorination of furfural, organochlorine compounds are absorbed from the gases using hydrochloric acid. acids and absorber obtained are returned to the production of mucochloric

5 acids, and then purified exhaust gases are subjected to the second stage of absorption with hydrochloric acid with separation of the aqueous phase of the mixture of the target acids. Carrying out the process in such a way improves the quality and degree of evolution of the mixture of formic and hydrochloric acids.

The implementation of the method lies in the fact that the exhaust gases from the furfural polychlorinating reactors of the following composition, wt.%:

Chlorine 14-17

Chloride water- 65-68 years

 Carbon dioxide 1.4-1.6 Inert gases0.5-1.0 Water2.0-9.0 Formic acid, 5 lots6-10 Organochlorine compounds 0.5-1.0 first enter the packed column irrigated with hydrochloric acid, 0 where is the complete purification of gases from organochlorine compounds. The resulting absorbent of the following composition, wt.%: Organochlorine compounds 2.0-10.0 Formic acid 30, 0-44.0 Hydrogen chloride 15, 0-30.0 Q Water Remaining

return to the process of obtaining mucochloric acid, where it is used as an additive to the medium in which the furfural is chlorinated.

Organochlorine-free

substances, exhaust gases are sent to the second absorption column, also irrigated with hydrochloric acid, which absorbs formic acid from 0 gases of the following composition, wt.%: Chlorine 15.0-18.0

Hydrogen chloride65, 0-75.0 Carbon dioxide 1.5-3.0 Inert gases 0.5-1.5

Formic acid2,0-10,0

WaterEverything

As a result of absorption of gases, a liquid phase is obtained, consisting of a mixture of formic and hydrochloric acids of composition, wt.%: Formic acid. 48-52 Hydrogen chloride 18-22 Water Else In addition, along with the proposed method, along with obtaining this mixture of acids, a high degree of purification of gases is achieved, making it possible to produce hydrochloric acid from them with an organic impurity content (formic acid) of not more than 1.0 weight ( if necessary, this value can be reduced to 0.02 wt.%). This low content of impurities allows the use of hydrochloric acid, which is the main waste product of mucochloric acid, for electrolysis. A small part of this hydrochloric acid is used for irrigation of absorbers.

Using the proposed method for separating a mixture of acids from mucochloric acid production gases also ensures uninterrupted carrying out a continuous process and greatly simplifies it by replacing the system of refrigerator-condensers, which must be periodically cleaned of accumulated organochlorine substances with packed columns (2-3 pieces).

The yield of the mixture of formic and hydrochloric acids should be considered separately for each component. This is due to the fact that in the process of isolating this mixture, a partial (about 10% of stoichiometry) oxidation of formic acid to CO2 and HC according to the scheme

nsoon + 2nse;

nsoon + nose- co2 + not +.

five

The same amount of formic acid is oxidized in the main process and about 5% of its stoichiometry accumulates in the mother liquor. Therefore, formic acid can be obtained with a yield of about 60% of stoichiometry

0 BASIC reaction - the process of obtaining mucochloric acid.

When extracting formic acid from the mother liquor in the strained process, i.e. in chlorination of furfural and dehydration of the mother liquor, the yield of formic acid can be increased up to 75%, since only in this case is it possible

0 obtaining a mixture of acids with a high content of formic acid.

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The table shows the material balance of the process of separation of formic and c, olic acids.

Cleaning organochlorines from organochlorine compounds

125.6 18, 4 15.6 81, 7 65.1 0, 3 0.2

CBS

115.9 18, 3 15.8 79, 2 68.2 GS

8,17,0

1,81,6

t

0.90,8

7,66,6

including 3.6

HCOOH-0,1

, 233.0 Water2, 466.9 EU: BGO129, 2,

Isolation of a mixture of formic and hydrochloric acids (or condensate) Abgas, incl. 115.9 - 122.4 - Abgas, incl. 109.3 - 103.0 18, 315,818,515.1С “2

79,268,282,167,3HCe

OO0,30,2 HOS

8,17,08,06,4 UNH

Table continuation

Cun

zana

13.3

0.3

2.34, 2

31,628, 63, 8

5.0

37,5t

129.2

16,718,518,0

72,678,075,7

O0,10,1

0,091,41,4

1.71.71.6

0,81,01,0

8,12,32,2

O O 0.2 1.0 7.9 49.4 6.6 34.0

122.4 TOTAL 125.3 CBS - organochlorine compound The yield of formic acid is equal to the known - 53%. From these data it can be seen that the gas compositions in the optimum mode are almost the same for the proposed known methods. In the process of obtaining mucochloric acid, g-mol furfural is used, which corresponds to a stoichiolutric amount of formic acid 12.4. g / h According to the proposed method, a mixture of formic and hydrochloric acids obtained by purifying exhaust gases from organochlorine compounds at the first stage and contaminated with chlorine with organic substances is continuously returned to the main process for the chlorination of furfural, thereby enriching the reaction mass with organo-chlorine substances and formic acid, which leads to an increase in the yields of the mucochlorine and formic acid lots and provides for the complete purification of the gases from organochlorine organisms in a known way when extracting Avinic acid from the mother liquor produces condensate containing 24.6% formic acid, 20% hydrogen chloride, and 3.8 organochlorine compounds. In this case, in a mixture of acids, the molar ratio of formic acid to hydrogen chloride is 24.6 20 0.98: 1.0. ; Зб75 According to the proposed method, this value is equal to °, which is 1.6 times greater.

Table continuation

HCt; 3.0 18.7 4.1 21.2 Water 5.1 31.9 8.5 43.8 TOTAL 125.3 122.4 to the proposed method 64%. In preparing the target mixture of acids using the proposed method, the degree of extraction of formic acid is equal to 97.5%, while in a known way only 82.5%. The yield of hydrochloric acid (ie, hydrogen chloride) is higher than stoichiometric. This is due to the occurrence of side reactions of oxidation of formic acid and hydrolysis of chlorine under the conditions of chlorination of furfural, with the help of which the oxidation of the initial aldehyde occurs. Example. The exhaust gases formed in the process of chlorination of furfural in the amount of 70 l / h are fed to the first absorption column irrigated with hydrochloric acid. The composition of the gases, wt.%: Chloride 65-69 prenatal 1.3-1.7 Carbon dioxide 0.5-1.0 Nitrogen Formic acid Chlororganic, 01-0.1 kie substances Water Irrigation of the absorption column is supplied 3.6 g / hydrochloric acid, the irrigation density in terms of water is 1-2 cMVcM — h. The liquid fraction leaving the column has the following composition, wt.%: Organochlorine substances2-3 Formic acid 30-34 Hydrogen chloride 27-30 WaterOther This mixture in the amount of 13.3 g is returned to the process as a reference to the medium in which the furfural is chlorinated. Purified from organochlorine compounds, the gases are sent to a third-party absorption column, their tav, wt.% 1 Chlor15-17 Hydrogen chloride, "67-70 U; where; kislot 1.2-1.6 Nitrogen 0.6-1.0 Muravina Acid 6-8 Into the Other Absorption Tower, 10 mm in diameter, has a nozzle height from a Fensk stake of 0.54.5 mm to 1100 mm. The columns are irrigated with 33% hydrochloric acid, the irrigation density in terms of water is 2 / 5-3.5 cm, the process is carried out at room temperature. From the column continuously output of formic and hydrochloric acids in the amount of 16 g / h with the content, wt.%: Formic acid 48-52 Hydrogen chloride 18-20 Water, Recycling Exhaust gases of the second absorber are directed to the absorption of hydrogen chloride with water, their composition, wt.%: Chlorine 16-18 Hydrogen chloride. 72-76 Carbonic acid 1.4-1.8 Nitrogen 0.8-1.2 Formic acid 0.05-0.1 Water Else - Thus, the proposed method produces a mixture of formic and hydrochloric acids that does not contain organochlorine impurities and suitable for the production of formic acid from it, which meets the requirements of the highest grade according to GOST 1706-78. The resulting mixture of formic and hydrochloric acids can be used as an intermediate product in the process of isolating formic acid, as well as an intermediate in the synthesis of other compounds. In addition, the proposed method, in addition to obtaining this mixture of acids, achieves a high degree of purification of exhaust gases, ensuring the possibility of obtaining from them hydrochloric acid, suitable for electrolysis.

Claims (1)

METHOD FOR ISOLATING MIXTURE OF FORMIC AND HYDROCHLORIC ACID from abgases formed during the chlorination of fur furoles in the production of mucochloric acid, characterized in that, in order to improve the quality of the mixture of formic and hydrochloric acids and the degree of extraction of formic acid, the impurities are absorbed using organochlorine compounds from the gases. and the resulting absorbate is returned to the production of mucochloric acid, and then the purified abgases are subjected to the second stage of absorption with hydrochloric acid with the release of the aqueous phase of the target mixture slot. " I