KR0184381B1 - Process for producing 1-chloro-1,1-difluoro ethane and 1,1,1-trifluoroethane - Google Patents

Abstract

The present invention provides a continuous liquid phase of 1,1,1-trichloroethane or 1,1, -dichloroethylene and anhydrous hydrofluoric acid at a reaction pressure of 15 to 50 bar and a reaction temperature of 110 to 180 ° C. in a molar ratio of 1: 10 or more. A method of simultaneously producing 1-chloro-1,1-difluoroethane and 1,1,1-trifluoroethane comprising reacting.

Description

Continuous preparation of 1-chloro-1,1-difluoroethane and 1,1,1-trifluoroethane

1 is a process flowchart showing a process for continuously preparing 1-chloro-1,1-difluoroethane and 1,1,1-trifluoroethane according to the present invention of FIG.

* Explanation of symbols for main parts of the drawings

1 reactor 6 reflux tower

10, 12: condenser 11: HCI distillation column

13: grower

The present invention relates to 1,1,1-dichloroethane and 1,1,1-dichloroethane, consisting of reacting 1,1,1-trichloroethane or 1,1, -dichloroethylene with anhydrous hydrofluoric acid in a liquid phase. A method for continuously producing trifluoroethane.

1-chloro-1,1-difluoroethane (hereinafter referred to as HCFC-142b) is used as a raw material for the production of 1,1-difluoroethylene, an aerosol propellant, etc., and 1,1,1-trifluoroethane HFC-143a (hereinafter referred to as HFC-143a) is known as one of the promising new alternative refrigerants by mixing with difluoromethane, 1,1,1,2-tetrafluoroethane because it has no effect on ozone layer destruction.

HCFC-142b and HFC-143a are known compounds prepared mainly by the reaction of 1,1,1-trichloroethane (or 1,1-dichloroethylene) with hydrofluoric anhydride (hereinafter referred to as AHF). It is known that the reaction proceeds in several stages as shown below.

However, in the reaction for producing HCFC-142b or HFC-143a by the fluorination reaction, side reactions in which unsaturated organic substances such as vinylidene chloride and 1,1-chlorofluoroethylene are polymerized occur as well as the desired product. 1,1,3,3-pentafluorobutane, oligomers, tars, etc. may be produced.

Numerous methods are known in the art that can produce HCFC-142b or HFC-143a.

For example, Japanese Patent Publication No. 59-46211 describes a method for producing HCFC-142b and HFC-143a by reacting HCC-140a and AHF in the presence of an inert solvent and an anticontaminated catalyst. According to this method, the preparation of HCFC-142b and HFC-143a is very strict under the conditions of the inert solvent which can be used, so that the reaction temperature and pressure are only possible under the appropriate conditions, and catalyst deterioration, separation of the formed tar and high boiling point catalyst This can cause various problems. Furthermore, there is a drawback that the hydrochloric acid cannot be purified economically by distillation from the reaction product since the reaction proceeds under very low pressure.

In Japanese Patent Publication No. 50-5681, 1 mole of 1,1,1-trichloroethane (hereinafter referred to as HCC-140a) is present at a ratio of 4 moles or more of AHF and HCFC without catalyst under a temperature of 70 to 140 ° C. Methods for preparing -141b and HCFC-142b are described. According to this method, HCFC-142b can be obtained with high selectivity in a lean reactor, while HFC-143a is hardly obtained. It also states that tar production can be increased at relatively high temperatures (about 150 ° C).

Japanese Patent Publication No. 64-3854 describes a method for producing HCFC-142b by reacting 1,1-dichloroethylene (hereinafter referred to as VDC) and AHF in the presence of a tin tetrachloride catalyst. According to this method, HCFC-142b is obtained at a selectivity of 96 mol% or more by operating in a state containing at least 40 mol% of organic compounds in the reactor. However, it is difficult to separate and remove oligomers and tars generated from side reactions from catalysts, and also problems such as catalyst deterioration and splash reaction cannot be solved at the source.

Japanese Patent Application Laid-open No. Hei 2-152935, U.S. Patent No. 5,434,320 and the like also describe a method for producing HCFC-141b and HCFC-142b by reacting HCC-140a with AHF without a catalyst. However, these documents do not mention how to prepare HCFC-142b and HFC-143a at the same time.

It is an object of the present invention to provide a method for simultaneously producing HCFC-142b and HFC-143a, which consists of reacting HCC-140a (or VDC) and AHF in a liquid phase.

It is also an object of the present invention to provide a method of arbitrarily adjusting the production ratio of HCFC-142b and HFC-143a when HCC-140a (or VDC) and AHF are reacted in a liquid phase.

It is also an object of the present invention to continuously produce HCFC-142a and HFC-143a by reacting HCC-140a (or VDC) with AHF under a catalyst, thereby deteriorating catalyst, entrainment of catalyst, and entrainment of the device. It is to provide a method for easier operation by preventing problems such as corrosion from occurring at the source.

The present invention is the organic compound (HCC-140a, VDC, HCFC-141b, HCFC-142b, HFC-143a, etc.) and AHF in the reactor at a pressure of 15 ~ 50bar and a temperature of 110 ~ 180 ℃ at a molar ratio of 1:10 or more It is to provide a method for producing a method for producing HCFC-142b and HFC-143a, which are continuously subjected to liquid phase reaction.

The production method according to the invention is carried out by the following process:

a) Process of continuously liquid phase reacting HCC-140a (or VDC) and AHF in a reactor at a pressure of 15-50 bar and a temperature of 110-180 ° C.

b) introducing a reaction product gas into the bottom of the reflux column and contacting and rectifying with refluxed AHF supplied from the top of the reflux column, the high-boiling compounds such as HCC-140a, HCFC-141b is introduced back into the reactor and hydrogen chloride Low volatility materials such as acid, HCFC-142b, HFC-143a, AHF are sent to condenser.

c) introducing a liquid-gas mixture through the condenser into the gas-liquid branch to evacuate the gas layer through the separator, and return the liquid layer to the top of the reflux column through the bottom of the separator; and

d) A step of separating and purifying the gas layer discharged from the layer separator by a conventional method to obtain 1-chloro-1,1-difluoroethane and 1,1,1-trifluoroethane.

Hereinafter, the method of the present invention will be described in more detail with reference to FIG.

In FIG. 1, the reaction raw material AHF is introduced in the reactor 1 through the tube 2. The reaction liquid introduced into the reactor 1 is heated to the boiling point by a heater 16 attached to the outside. The reaction is then initiated with constant flow rates of HCC-140a (or VDC) and AHF injected into reactor 1 through tube 2 and tube 3, respectively. The resulting HCFC-141b, HCFC-142b, HFC-143a, hydrochloric acid, unreacted HCC-140a (or VDC) and AHF and trace impurities are vaporized to lower the reflux column 6 through the tube 4. Is introduced. The gas introduced into the reflux tower 6 is rectified with the liquid refluxed to the top of the reflux tower, and the high boiling point materials such as HCC-140a and HCFC-141b are recycled to the reactor 1 and hydrochloric acid, HCFC-142b, HFC- Volatile substances such as 143a and AHF are recycled to the reflux tower 6 through the tube 8 and non-condensable gas is introduced into the hydrogen chloride distillation column through the tube 9. In this distillation column, the hydrogen chloride is discharged from the top of the column in a gaseous state, condensed in the condenser 12, and then discharged through the tube (14), and the hydrochloric acid discharged is converted into an aqueous hydrogen chloride solution using a conventional absorption tower. The hydrochloric acid-removed reaction product discharged from the column bottom through the tube (15) is subjected to the usual separation, purification, washing and drying processes to obtain the final products, HCFC-142b and HFC-143a.

In the reaction in the reactor (1), the molar ratio of AHF relative to the organic mixture is kept in excess. Preferably, the AHF is maintained at 10 moles or more with respect to 1 mole of the organic mixture present in the reactor, and more preferably 20 mole to 500 moles with respect to 1 mole of the organic mixture. As such, when AHF is excessively reacted compared to the organic mixture in the reactor, the reaction system has a small proportion of the organic layer even when forming a homogeneous phase or separation of the layer, so that the reaction rate is not only fast but also a large amount of by-product oligomer and tar is generated. Will be less. AHF added in excess is also condensed and refluxed back to reflux 6 for use in the reaction.

The reaction temperature is 110 to 180 ° C, preferably 120 to 160 ° C. If it is lower than this temperature, HCFC-12b production rate is slow and economic efficiency is low. On the contrary, when the reaction temperature is higher than this temperature, it becomes a condition of high temperature and high pressure, and thus the economical efficiency is lowered due to the corrosion of the apparatus and the increase in the apparatus cost. This preferred reaction temperature is determined below the boiling point of AHF at the pressure of the reactor.

The reaction pressure is 15 to 50 bar, preferably 20 to 40 bar. When reacted under this pressure, the produced hydrochloric acid can be removed more economically at low pressure from substances such as VDC, HCC-140a, HCFC-141b, HCFC-142b, HCFC-143a and AHF by distillation.

The advantage of the present invention is that by adjusting the reaction temperature, reaction pressure, reaction time or the ratio of the starting material according to the demand, it is possible to easily adjust the ratio of HCFC-142b and HFC-143a produced.

Another advantage of the present invention is that a catalyst is not necessary. In the method of the present invention, it is possible to use a catalyst conventionally used for fluorination of hydrocarbons in consideration of the reaction yield, but it is possible to obtain a satisfactory productivity even in the absence of a catalyst. Thus, in the case of the non-catalytic reaction, there are no problems caused by the degradation of the catalyst and the increase in the corrosion rate of the device, which may occur during the catalytic reaction. In catalysis, tar is generated as a result of the hydrogen fluorination reaction in the reactor, so tar must be removed. In order to remove the tar, a separate catalyst recovery device is required, and there is also a problem in that catalyst loss occurs and therefore, pollutants such as heavy metals have to be treated. However, in the reaction without a catalyst, such a device is not necessary and stable operation can be achieved.

Another advantage of the present invention is that the reaction is carried out continuously. More specifically, HCFC-142b and HFC-143a can be obtained with high reaction conversion and yield by continuously discharging the reaction products such as HCC-140a and hydrochloric acid and unreacted raw materials to the outside of the reactor. have.

Another advantage of the present invention is that the fluorination reaction proceeds in part in the reflux tower as well as in the reactor, thereby increasing the reaction conversion rate. More specifically, the reaction product and the unreacted mixed gas discharged from the reactor are injected into the bottom of the reflux tower and contacted with the AHF refluxed at the top of the reflux tower, thereby not only rectifying the unreacted HCC-140a ( Or VDC), the intermediate HCFC-141b and the reaction of AHF occurs, so that the yield of the product can be increased.

As the material of the reactor used in the present invention, metals such as X carbon steel, stainless steel, nickel, monel, Hastelloy, etc., which are corrosion resistant to AHF, may be used. In addition, a reactor coated with fluorine resin may be used.

The present invention will be described in detail with reference to Examples, but the scope of the present invention is not intended to be limited by these Examples.

Example 1

Into the reactor 1 having an internal volume of 3,500 ml and a material of SUS316L, 2,500 g of AHF was first added and heated to a boiling point at 26 bar. At this time, the cooling liquid flows to the condenser 10 to liquefy all the AHF passing through the reflux tower 6 to reflux to the top of the reflux tower (6). Subsequently, fluorination reaction was carried out while injecting HCC-140a at a flow rate of 197 ml / hr through the tube (2). The internal temperature of the reactor 1 was maintained at 138 ° C. by adjusting the flow rate of the coolant injected into the condenser 10. In addition, during the reaction, the liquid height in the reactor was maintained at about 2,500 ml by adjusting the AHF injection amount, and the reactor pressure was equal to the pressure of the HCl distillation column 11, which was injected by the HCl distillation column 11 into the condenser 12. It was adjusted using a constant flow rate of coolant temperature. The HCl gas discharged through the tube 14 in the HCl distillation column 11 is absorbed 100% in the absorption tank and quantified every hour to estimate the yield of the organic product. The reaction time was 24 hours in total. The total injection amount was 47.5 mol of HCC-140a and 130.7 mol of AHF, and the total HCl flow was 114.0 mol. During 7.5 hours of normal operation, the reactor 1 had an internal temperature of 138 ° C., HCC-140a injection rate of 14.6 mol, and HCl flow rate of 35.5 mol. As a result of analyzing the organic matter by gas chromatography, it can be assumed that only HCFC-142b and HFC-143a exist because the unreacted HCC-140a and HCFC-141b effluent are small. From the positive mass balance, HCFC-142b 56 mol% and HFC-143a 44 mol%.

Example 2

HCC-140a flow rate in the reactor of Example 1 was 195 mL / hr, and was carried out in the same manner as in Example 1 except that the internal temperature of the reactor (1) was partially changed. The reaction time was a total of 32 hours, the total injection amount was 62.8mol HCC-140a, the total HCl outflow was 151.0mol. During 6.0 hours of normal operation, the reactor 1 had an internal temperature of 127 ° C., HCC-140a injection rate of 12.2 mol, and HCl flow rate of 28.4 mol. Because of the small amounts of unreacted HCC-140a and HCFC-141b effluents, the organic product is 67 mol% HCFC-142b and 33 mol% HFC-143a from the water bath, assuming that only HCFC-142b and HFC-143a are present. During 22.0 hours of normal operation, the reactor 1 had an internal temperature of 140 ° C., HCC-140a injection rate of 43.5 mol, and HCl flow rate of 101.2 mol. It is 67 mol% of HCFC-142b and 33 mol% of HFC-143a from mass balance.

Example 3

In the reactor of Example 1 was carried out in the same manner as in Example 1 except for changing the HCC-140a flow rate to 143ml / hr, the reactor pressure of 27bar and the internal temperature of the reactor (1). The reaction time was a total of 26 hours, the total injection amount was HCC-140a 37.2mol, AHF 138.0mol, HCl total 97.4mol. During 21.0 hours of normal operation, the reactor 1 had an internal temperature of 140 ° C., HCC-140a injection rate of 30.2 mol, and HCl flow rate of 76.4 mol. Since the unreacted HCC-140a and HCFC-141b effluents are very small, 47 mol% of HCFC-142b and 53 mol% of HFC-143a from the mass balance, assuming that only organic HCFC-142b and HFC-143a exist.

Example 4

In the reactor of Example 1 was carried out in the same manner as in Example 1 except for changing the HCC-140a flow rate to 116ml / hr, reactor pressure 21bar, the internal temperature of the reactor (1). The reaction time was 28.3 hours and the total injection amount was 32.9mol HCC-140a, 93.0mol AHF, and 83.5mol total HCl. During 24.0 hours of normal operation, the reactor 1 had an internal temperature of 130 ° C., HCC-140a injection rate of 27.3 mol, AHF injection rate of 86.8 mol, and HCl outflow of 65.4 mol. Due to the small amount of unreacted HCC-140a and HCFC-141b effluents, assuming that only organic HCFC-142b and HFC-143a exist, HCFC-142b is 61 mol%, HFC-143a is 39 mol% and AHF / HCl molar ratio Is 1.33.

Example 6

In the reactor of Example 1 was carried out in the same manner as in Example 1 except that the HCC-140a flow rate was 124 ml / hr, and the internal temperature of the reactor 1 was partially changed. The reaction time was 32.5 hours, and the total injection amount was HCC-140a, 40.4mol, AHF 85.1mol, and HCl flow rate was 107.8mol. During 11.0 hours of normal operation, the internal temperature of the reactor 1 was 123 ° C, the HCC-140a injection amount was 131.1 mol, and the HCl discharge amount was 33.9 mol. Because of the small amounts of unreacted HCC-140a and HCFC-141b effluents, the organic product is 42 mol% HCFC-142b and 58 mol% HFC-143a from the mass balance, assuming that only HCFC-142b and HFC-143a are present. During 14.0 hours of normal operation, the reaction temperature was 133 ° C, HCC-140a injection amount was 17.1 mol, and HCl flow rate was 46.2 mol. It is 30 mol% of HCFC-142b and 70 mol% of HFC-143a from mass balance.

Example 7

The amount of tar generated by the reaction of Example 4, Example 5, and Example 6 was quantified. In each example, after completion of the reaction, the solution in reactor 1 was transferred to Teflon bottle. The amount of tar measured after evaporating the volatiles was 2.4 g. Since the HCC-140a used in the experiments of Examples 4, 5 and 6 was 100 mol (13.4 kg) in total, the production rate of tar was 0.02 wt% based on the HCC-140a injection amount.

Example 8

In the reactor of Example 1, the organic material was used in the same manner as in Example 1 except that VDC was used instead of HCC-140a, and the flow rate was 100 ml / hr, and the internal temperature of the reactor 1 was partially changed. The reaction time was 31 hours in total, and the total injection amount was 38.8 mol of VDC and 122.0 mol of AHF. In 20.0 hours of normal operation, the reactor 1 had an internal temperature of 135 ° C, a VCD injection rate of 25 mol, and an HCl flow rate of 41 mol. Because of the small amounts of unreacted VDC, HCC-140a and HCFC-141b effluents, assuming that only organic HCFC-142b and HFC-143a exist, HCFC-142b 35 mol% HFC-143a 65 mol%.

Claims (7)

Continuous liquid phase reaction of 1,1,1-trichloroethane or 1,1, -dichloroethylene with hydrofluoric anhydride at a reaction pressure of 15 to 50 bar and a reaction temperature of 110 to 180 ° C. in a molar ratio of 1: 10 or more. A method of simultaneously producing 1-chloro-1,1-difluoroethane and 1,1,1-trifluoroethane. The method of claim 1, wherein the reaction temperature is 120 ~ 160 ℃. The method of claim 1, wherein the reaction pressure is 20-40 bar. The process of claim 1 wherein the reaction is carried out in the absence of a catalyst. (a) a step of introducing liquid 1,1,1-trichloroethane or 1,1-dichloroethylene and hydrofluoric anhydride into the reactor to continuously liquid-phase react at a pressure of 15 to 50 bar and a temperature of 110 to 180 ° C., (b) introducing a reaction product gas into the bottom of the reflux column, and contacting the introduced gas with a mixed solution added at the top of the reflux column, the low volatile substances of the main components HCC-140a and HCFC-141b Recycling to the reactor and introducing a highly volatile material comprising organic product and hydrochloric acid into a condenser; (c) in the condenser, the high volatile material is separated into a gas layer composed mainly of hydrochloric acid, HCFC-142b and HFC-143a, and a liquid layer, and then the liquid layer is recycled to the top of the reflux column, and the gas Separating and purifying the layers to obtain 1-chloro-1,1-difluoroethane and 1,1,1-trifluoroethane, wherein 1-chloro-1,1-difluoroethane and 1,1, Process for the preparation of 1-trifluoroethane. A process according to claim 5, wherein the molar ratio of organic mixture and hydrofluoric anhydride in the reactor is from 1:20 to 1: 500. The process according to claim 5, wherein the reaction is carried out continuously.