SU1150919A1 - Method of producing difluormethane - Google Patents

Abstract

A method for producing diphlorochloromethane by treating chloroform with hydrogen fluoride in the presence of an antimony pentachloride catalyst, previously dissolved in the starting reagent, at a temperature of 60–10 ° C and a pressure of 7–13 atm, using antimony pentachloride to simplify the process and increase its performance , pre-dissolved in chloroform at a concentration of 20-30 vol.%, and the process is conducted by bubbling hydrogen fluoride through the reaction mass in the presence of chlorine, introduced in an amount of 0, 05-0.2% by weight of chloroform.

Description

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(; O The invention relates to a method for producing difterchloromethane, used under the name refrigerant-22 as a refrigerant and as a raw material for producing fluorine-containing polymers. A method is known for producing difluorochloromethane (DFCA) by treating chloroform with hydrogen fluoride in the presence of an antimony pentachloride catalyst. temperature of 53-85 ° C, pressure of 19.5-39 atm and concentration of catalyst 12, 7-22, 7 vol. The disadvantage of this method is low (53-66%) yield of DFCM and low equipment productivity.-Output of DFCM per 1 m re The effective mass is from 0.19 to 0.82 kmol / h. The closest to this technical result and the achieved result is a method for producing DFCM by treating chloroform with fluoride hydrogen and hydrogen in the presence of orally catalysis — a mixture of pentachloride and antimony trichloride, 1: 0.05-0.8, at a temperature of 40-120 ° C and a pressure of 7-13 atm. The catalyst is pre-dissolved in liquid hydrogen fluoride, and the treatment of chloroform is carried out by feeding liquid hydrogen fluoride into the resulting solution. and chloroform. The concentration of the catalyst in the reaction mass is 60-80% by volume. The method provides a yield of the target product in the range of 79.6-98.6%. The disadvantages of this method are large corrosion, which complicates the whole process and low productivity of the process. The corrosion of the equipment is due to the high activity of the mixture of catalyst with hydrogen fluoride used in the known method. Specially conducted comparative experiments showed that the corrosion rate of steel 12X18H10T in the presence of such a mixture containing 30-80% by volume of catalyst is 20-32. The productivity of the equipment in the known method is 1.09-2.08 kmol / h per 1 reaction mass. The purpose of the invention is to simplify the process, in particular, to reduce corrosion and improve its performance. The objective is achieved by the method of producing DFCM by treating chloroform with hydrogen fluoride in the presence of 192 antimony pentachloride catalyst, previously dissolved in chloroform at 60-11 o C and a pressure of 7-13 atm, moreover, the catalyst concentration is 20-30 vol.%, the treatment with chloroform with hydrogen fluoride is carried out by bubbling hydrogen fluoride through the reaction mass, and the process is carried out in the presence of chlorine introduced in the amount of 0.05-0.2% by weight of chloroform. Distinctive features of the invention are the use of antimony pentachloride, previously dissolved in chloroform, in a concentration of 20-30 vol.%, Bubbling of hydrogen fluoride through the reaction mass, carrying out the process in the presence of chlorine, introduced in an amount of 0.05-0.2% by weight of chloroform . The use of antimony pentachloride as a catalyst, previously dissolved in chloroform at a relatively low (20–30%) concentration, and the bubbling of hydrogen fluoride together with its introduction in liquid form prevent the formation of highly corrosive mixtures of catalyst with hydrogen fluoride. At the same time, the introduction of chlorine prevents the transition of the catalyst to the less active halides of trivalent antimony and, thus, prevents an increase in the productivity of the equipment. In general, the use of a new set of techniques allows an increase in the productivity of equipment while reducing corrosion. Tests carried out for 5 months in a reactor made of 12X18H10T steel showed that the corrosion rate averaged 0.03. The invention is illustrated by examples 1-7. Comparative Example 8 shows the inexpediency of decreasing the concentration of the catalyst, since this decreases the degree of use of hydrogen fluoride. Increasing the catalyst concentration above 30% is corrosive to the equipment and therefore impractical. Comparative examples 9 and 10 show the optimal choice of chlorine concentrations. The decrease in chlorine (example 9) leads to a drop in product yield, an increase (example 10) - to

chlorine contamination of products and unproductive consumption of the latter.

Example 1-10. The treatment of chloroform with hydrogen fluoride is carried out in an industrial reactor with a volume of 6 m from nickel-chromium-nickel steel of 12X18H10T. The reactor is equipped with two series-installed reverse coolers cooled with brine with a temperature of minus 15 C. The unit is equipped with a pressure gauge and thermometers for measuring the temperature in the liquid phase of the reactor and in the gas phase after the second refrigerator.

Chloroform and catalyst - mineral chloride antimony are preloaded into the reactor at a predetermined ratio. The contents of the reactor are heated to 60110 ° C and the catalyst is dissolved in chloroform. Hydrogen fluoride gas is continuously fed from the feed tank to the resulting solution, bubbling it through the layer of the solution at a speed of 340-700 kg / h. At the same time, chloroform is added to the reaction mass at a rate of 1280– 2500 kg / h. The feed rate of chloroform is chosen so as to maintain a constant level of the reaction mass in the reactor and thus a constant concentration of catalyst in the reaction mass. In addition, chlorine gas is additionally bubbled through the layer of the reaction mass at a rate of 1.27-2.22 kg / h.

When the pressure in the reactor reaches 7–13 abs. Atm. begin the selection of the reaction products after the second cooler by reducing the gaseous products to atmospheric pressure. The temperature of the gases after the second refrigerator is maintained in the range from 0 to -5 ° C, regulating the supply of refrigeration brine. Selected products are treated with Consecutive hydrochloric acid to extract unreacted hydrogen fluoride, then with water and sodium carbonate solution. Her-. The trapped gases are subjected to two-stage mixing, dried with a cooled solution of calcium chloride and condensed. Condensed raw analyze. The target product and the under-fluorinated product fluoride-fluoromethane are isolated from the raw material by multi-stage distillation. The latter is used as a raw material by adding chloroform to the starting material.

The specific conditions of the experiments and the results of these experiments are presented in the table.

From the table it can be seen that the method of obtaining DFZM in accordance with the present invention provides an increase in the productivity of equipment while reducing corrosion and maintaining a high (83-96.5%) yield of DFCM.

76 8.8 0.32 0.18 95.0 105-110 10.5-130.33 60-67 7-8.80.35 78 8.80.30 76 8.60.30 0.18 94, 1 2.1 2.5

8,8

25.0

80 74 78 72

0.30

. 0.34 8.8 11.3 8.6 24.9 0.31 8.6 0.29 25.0 Note:

87.9

0.18

3.2 94.3 2.8 81.4

2.7

0.06 85.8 0.86

3.1 The degree of use of hydrogen fluoride is 95%; in other experiments, the degree of use of hydrogen fluoride is 98-100%.

Claims (1)

METHOD FOR PRODUCING DIFLUOROCHLOROMETHANE by treating chloroform with hydrogen fluoride in the presence of a catalyst - antimony pentachloride, previously dissolved in the initial reagent, at a temperature of 60 110 C and pressure 7-13 atm, characterized in that, in order to simplify the process and increase its productivity, use antimony pentachloride previously dissolved in chloroform at a concentration of 20-30 vol. assy chloroform. ΐ