SU513963A1 - The method of producing difluorochloromethane - Google Patents

Description

(54) METHOD OF OBTAINING DIFFLUORLORL ETHANE

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The invention relates to a method for producing freons, more specifically, to a method for producing difluorochloromethane (freon-22), which has been used as a coolant and raw material for the production of fluorine-containing monomers.

A known method of producing difluorochloromethane by the interaction of chloroform and hydrogen fluoride in the presence of antimony chloride, which is carried out by co-contacting chloroform and hydrogen fluoride in a liquid state under a pressure of 7-9 bar and a temperature of 50-80 ° C.

However, the productivity of the difluorochloromethane production process by a known method is relatively low, since no more than 550 kg / h of hydrogen fluoride can be supplied to the difluorochloromethane synthesis reactor with a capacity of 6 m. This is due to the extraction of antimony chloride with liquid hydrogen fluoride with the formation of the second phase, consisting of hexachlorofluorostric acid and hydrogen fluoride, i.e., passivation of the catalyst, which leads to a decrease in the production of the process.

To intensify the process according to the proposed method, it is recommended to use hydrogen fluoride in a gaseous state.

Carrying out the process in this way allows you to completely eliminate the formation

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phases of liquid hydrogen fluoride and liquid chloroform, and thereby extraction of antimony pentachloride with liquid fluoride water (d:.:, .. s. pgi.h-igiorych-ie catalyst. P;). :: T () craKii iige significant value reactor performance and intensification of the process as a whole. The method was tested under laboratory conditions.

Example. The synthesis of freon-22 is carried out in a cylindrical apparatus with a capacity of 2 liters (diameter 106 mm, height 230 mm), equipped with a column (diameter 25 mm, height 400 mm), filled with a nozzle pz nichrome wire 2x3 mm. The top of the column is equipped with a refrigerator with the temperature of the coolant minus 30 ° C. Chloroform is fed to the upper part of the column, hydrogen fluoride is siphoned to the lower part of the reactor (bubbling height is 150 mm). The fluorination process is carried out at atmospheric pressure and those: Sherature in the apparatus 15-25C. 700 ml of chloroform and 210 ml of antimony tichloride are preloaded into the apparatus.

When hydrogen fluoride is supplied in the liquid state (i.e., by a known method), when the hydrogen fluoride feed rate is increased for some time, fluorination reaction is stopped, which corresponds to the fluorine feed rate; 1 total hydrogen is 1.9-2 mol / h. When hydrogen fluoride is supplied in a liquid state at a rate not exceeding 1.9 mol / h, the degree of conversion of hydrogen fluoride is 80% and the formation of the desired product takes place, which is released in a gaseous state; the total freon content is 21 and 22.9%, while when hydrogen fluoride is fed in excess of 2 mol / h, any outgassing almost completely stops and the volume of the reaction mass increases.

When hydrogen fluoride is supplied under the same conditions, no fluorination reaction is observed in the gaseous state. The supply of hydrogen fluoride can

increase to 3.5 moles / h, then the degree of conversion of hydrogen fluoride is 84.6%, and the composition of the resulting organic products is as follows:%: 22.75; F 21 49.6; СНС1з4,7%.

Fore | Mula Invention

1. A method of producing difluorochloromethane by reacting chloroform with hydrogen fluoride in the presence of antimony chloride as a catalyst, followed by separation of the target product, characterized in that, in order to intensify the process, hydrogen fluoride is used in a gaseous state.