JPS5944290B2 - 1.1.1- Trichloroethane Trichlorethylene perchlorethylene - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides 1,1,
This invention relates to a method for co-producing 1-trichloroethane, trichlorethylene, and perchlorethylene.

Conventionally, methods for producing 1,1,1-trichloroethane include (a) chlorination of 1,2-dichloroethane using a photochemical method or a reaction accelerator such as ethylene, or chlorination of vinyl chloride. A common method is to dehydrochloride the 1,1,2-trichloroethane thus obtained with an alkali to produce vinylidene chloride, and then add hydrogen chloride to this to produce 1,1,1-trichloroethane. Others, (mouth) 1
, A method for producing 1,1,1-trichloroethane by chlorinating 1-dichloroethane under light irradiation at a relatively low temperature, (c) A method for producing 1,1,1-trichloroethane by thermally chlorinating 1,1-dichloroethane
Methods for producing trichloroethane have been proposed.

In addition, as a method for producing trichlorethylene and perchlorethylene, (d)1,2-dichloroethane is chlorinated using a reaction accelerator such as ethylene to produce polychlorinated ethane, which is then thermally decomposed to produce trichlorethylene and perchlorethylene. (e) 1,1,2-trichloroethane obtained by chlorinating 1,2-dichloroethane using a photochemical method is further chlorinated in the presence of an aluminum chloride catalyst to produce 1,1,2 , 2-tetrachloroethane and penta,hexachloroethane are obtained and then thermally decomposed to produce them.

In addition, as a co-production method for 1,1,1-trichloroethane, trichlorethylene, and perchlorethylene, (to) 1
, 2-dichloroethane is chlorinated together with trans and cis dichloroethylene recycled from the subsequent step to produce 1,1
, 2-trichloroethane, 1,1,2,2-tetrachloroethane, penta and hexachloroethane, which were thermally decomposed to obtain vinylidene chloride, trans, cis dichloroethylene, trichlorethylene and perchlorethylene. , vinylidene chloride is added with hydrogen chloride to form 1,1,1-
Obtain trichloroethane.

Further, a method has been proposed in which trans,cis dichloroethylene is recycled to a chlorination reaction zone to co-produce 1,1,1-trichloroethane, trichlorethylene and perchlorethylene. However, the above-mentioned known methods have the following drawbacks.

Method (a) is a commonly used method, but it requires an alkali and when dehydrochlorinating 1,1,2-trichloroethane with an alkali, hydrochloric acid is fixed as a metal chloride; It has the fatal defect of not being able to be recovered and resulting in waste, and requires complicated processes such as pollution treatment of alkaline wastewater.

Furthermore, the vinylidene chloride obtained in this way needs to be dehydrated and dried before being supplied to the next hydrogen chloride addition step, and impurities such as by-produced cis dichloroethylene are
- Contaminates trichloroethane products. (gu) and (e)
This method requires ultraviolet irradiation equipment and its auxiliary equipment for chlorination, making it expensive and complicated.Furthermore, the lamp is made of glass, so there is a risk of breakage, and cooling water is required to cool the lamp. However, it is not suitable for reactions under high pressure to obtain by-product hydrogen chloride at high pressure, as it may cause serious corrosion due to lamp breakage and water intrusion into the system. Since method (c) is a high-temperature gas-phase chlorination reaction, it produces tar and carbon and high-boiling substances, resulting in lower yields, requires a large amount of diluent to control the reaction temperature, and requires a large amount of diluent to control the reaction temperature. At first, the diluent recovery equipment etc. become bulky, which is economically disadvantageous. In method (d), the reactor can be operated at high pressure and the reactor can be made small, but since ethylene is used as a reaction accelerator, this method
When applied to the production of 1,1,1-trichloroethane by chlorinating 1-dichloroethane, the reaction accelerator ethylene is chlorinated to produce 1,2-dichloroethane. 1,1,1-trichloroethane has a small difference in boiling point (83.5℃ and 74.1℃).
゜Cat760t0rr), it is difficult to separate by normal distillation, requires special distillation such as extractive distillation, and equipment costs are high, so it is not used for the co-production of 1,1,1-trichloroethane, trichlorethylene, and perchlorethylene. hard. (
Since the method (e) removes catalysts (aluminum chloride, etc.), it requires water/alkali washing equipment, dehydration drying equipment, and even processing equipment for washing waste water, which is economically disadvantageous.

In method (f), the thermal decomposition of 1,1,2-trichloroethane generally has a lower decomposition rate per pass than the thermal decomposition of tetrachloroethane and pentachloroethane, and a large amount of 1,
Recycling of 1,2-trichloroethane is required, which has the disadvantage of increasing utility usage and increasing the size of the equipment.

If an attempt is made to increase the decomposition rate, it generally has the disadvantage of increasing carbonization. The present invention solves the above-mentioned drawbacks.
This is a method for co-producing 1,1-trichloroethane, trichlorethylene, and perchlorethylene.

That is, the present invention provides 1,1,1-
When co-producing trichloroethane, trichlorethylene, and perchlorethylene, hydrogen chloride addition step 2 produces 1,1-dichloroethane by reacting hydrogen chloride with vinyl monochloride.The reaction product obtained in the hydrogen chloride addition step is free from radicals. A chlorination step in which chlorine is reacted in a liquid phase in the presence of a generator to obtain polychlorinated ethane and a gaseous composition mainly consisting of hydrogen chloride is taken out; 3. A part of the gaseous composition taken out in the chlorination step or a circulation step in which the whole is recycled to the hydrogen chloride addition step; 4. a 1,1-dichloroethane separation step in which 1,1-dichloroethane is distilled off from the polychlorinated ethane obtained in the chlorination step and recycled to the chlorination step; 51; 1 from polychlorinated ethane obtained from the 1-dichloroethane separation step.
, 1,1,1 to distill and separate 1,1-trichloroethane
- From the polychlorinated ethane obtained from the trichloroethane separation step and the 61,1,1-trichloroethane separation step,
a 1,1,2-trichloroethane separation step in which 1,1,2-trichloroethane is separated by distillation and recycled to a chlorination step;
7. A decomposition step in which polychlorinated ethane obtained from the separation step of 1,1,2-trichloroethane is thermally decomposed at a temperature of 350 to 60°C, and hydrogen chloride is separated by distillation from the polychloride obtained in the 8 decomposition step. 9. Hydrogen chloride separation step in which part or all of hydrogen chloride is recycled to the hydrogen chloride addition step; 9. Trichlorethylene separation step in which trichlorethylene is separated by distillation from the polychloride obtained from the hydrogen chloride separation step; [Phase] Trichlorethylene separation step A perchlorethylene separation step in which perchlorethylene is separated by distillation from the polychloride obtained from the perchlorethylene separation step, and a perchlorethylene separation step in which the polychloride obtained from the O perchlorethylene separation step is distilled at a temperature below the boiling point of pentachloroethane, and the distillate is sent to the decomposition step. 1,1,1- consisting of a circulating process
This is a co-production method for trichloroethane, trichlorethylene, and perchlorethylene.

Furthermore, the present invention also provides a method for controlling the production ratio of 1,1,1-trichloroethane, trichlorethylene, and perchlorethylene by introducing vinyl chloride in the chlorination step.

According to the method of the present invention, (a) by-product hydrogen chloride is completely recovered and effectively used for hydrochlorination of vinyl chloride or for other purposes.

In addition, there is no alkaline wastewater, no dehydration and drying is required, and such equipment is not required, and the product is not contaminated with cis-dichloroethylene. (b) Complex equipment such as ultraviolet irradiation and its auxiliary equipment is not required, there is no fear of the cooling water entering, high-pressure reactions are preferably used, and by-product hydrogen chloride can be obtained at high pressure.

(c) Because it is a low-temperature liquid phase reaction, there is no generation of tar or carbon at all, reaction heat can be removed by external cooling, and the reactor is extremely small, and if higher pressure is used, it will become even smaller.

(d) Since ethylene, 1,2-dichloroethane is not used, 1,2-dichloroethane does not exist in the system, so fractional distillation purification of 1,1,1-trichloroethane is easy.

(e) Washing waste water for decatalyst removal is also unnecessary.

(f) The feed to the thermal decomposition process is only tetrachloroethane, pentachloroethane, and a small amount of hexachloroethane, and the decomposition rate per pass is extremely high, so the amount of co-teility used is also small, and each equipment It also becomes smaller.
That is, according to the method of the present invention, in one plant, 1,1
, 1-trichloroethane, trichlorethylene, and perchlorethylene can be co-produced at high yields, and the production ratio of these can be greatly changed. Furthermore, chlorine can be used thoroughly and wastewater treatment is not required. 1,1,1-trichloroethane, 1,1,1-trichloroethane,
Turin can produce chlorethylene and perchlorethylene.

1,1-dichloroethane is reacted with chlorine in a liquid phase in the presence of a radical generator in the chlorination step.

As a result, 1,1,1-trichloroethane and 1,1,2-
Trichloroethane is produced, but since this reaction is a sequential reaction, highly chlorinated ethane more than tetrachloroethane is also produced as shown in the following formula. These generated mixtures are fractionated in a fractionation step to separate unreacted 1,1-dichloroethane and 1,1,2
- Trichloroethane is recycled to the chlorination step.

When you want to increase the production ratio of trichlorethylene and perchlorethylene, use 1,1,1-trichloroethane, 1,1
, 1,2-tetrachloroethane, and 1,1,2,2-tetrachloroethane, respectively, in part or in whole, to the chlorination step, as well as adding vinyl chloride in the chlorination step, as described below. This can be achieved very conveniently by Known radical generators can be used in the chlorination step, and azobisnitriles, peroxides, and the like are generally preferred.

Azobisnitriles are compounds in which the carbon at the α-position of a nitrile is bonded with an azo group, that is, a compound represented by the general formula.

In the above general formula, R, , R2, R3 and R4 are, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a cyclopropyl group, a cyclohexyl group, and the like. Specifically, azobisisobutyronitrile is preferably used. As peroxides, peroxides known as radical generators can be used, such as benzoyl peroxide, cumyl peroxide, dicumyl peroxide, ditertiary butyl peroxide, and triphenylmethyl peroxide. The radical generator is 0.0% relative to the solvent in the chlorination process.
It is sufficient to add 01 to 1.0% by weight, preferably 0.003 to 0.1% by weight, and the chlorine reaction rate is approximately 100%.
It is.

The radical generator may be directly charged into the reactor, or may be dissolved in the 1,1-dichloroethane solvent and/or the polychlorinated ethane solvent recycled from the next fractionation step and introduced into the reaction step. good. Generally known reaction conditions can be used as they are, for example, reaction temperatures from 20'C to the boiling point of the solvent under reaction pressure, and conditions under pressure where the solvent remains liquid are preferably employed.

In addition, generally known types of chlorination reactors,
For example, liquid column columns, packed columns, tray columns, wet wall columns, etc. can be suitably used. In the present invention, by newly introducing vinyl chloride into the chlorination step, the production ratio of 1,1,1-trichloroethane, trichlorethylene, and perchlorethylene can be controlled.

That is, when vinyl chloride is introduced into a chlorination process in which 1,1-dichloroethane, a radical generator, and chlorine are present, vinyl chloride not only becomes 1,1,2-trichloroethane through an addition reaction with chlorine, but also becomes 1,1,2-trichloroethane. 1-dichloroethane to 1,
Promotes the substitution reaction of 1,2-trichloroethane. Since these reactions are sequential reactions, tetrachloroethane, pentachloroethane, etc. are produced, and trichlorethylene and perchlorethylene are produced in the next thermal decomposition reaction step. That is, by newly introducing vinyl chloride into the chlorination process of 1,1-dichloroethane, the distribution state of polychlorinated ethane produced can be easily changed with high yield, and ultimately the amount of vinyl chloride introduced can be changed. Product 1 by adjusting
, 1,1-trichloroethane, trichlorethylene and perchlorethylene can be changed very easily. In addition, in the chlorination step, the reaction rate of 1,1,2-trichloroethane to 1,1,1,2-tetrachloroethane and 1,1,2,2-tetrachloroethane is 1,1,''1 -from trichloroethane 1,1,1,
The reaction rate of vinyl chloride to 1,1,1,2-tetrachloroethane and 1,1,2,2-tetrachloroethane is more than 5 times that of 2-tetrachloroethane. Experiments conducted by the present inventors have confirmed that the reaction rate of 1-dichloroethane to 1,1,1,2-tetrachlornitane and 1,1,2,2-tetrachloroethane is five times or more higher than that of 1-dichloroethane. .

From now on, it is not advantageous to recycle 1,1,1-trichloroethane to the chlorination process as a way to increase the production of tetrachloroethane, and it is also advantageous to increase the degree of chlorination of 1,1-dichloroethane. It turns out that it is advantageous to increase the production of tetrachloroethane by newly supplying vinyl chloride. Furthermore, because the reaction rate is fast, the reactor can be made much smaller, and because less polychlorinated ethane is recycled, the fractionation equipment can also be made smaller.
It has great economic benefits and is easy to operate. Although a small amount of unreacted vinyl chloride is contained in the hydrogen chloride gas generated in the chlorination step, this can be recycled to the vinyl chloride hydrochlorination step.

The present invention will be described below with reference to the accompanying drawings, but the present invention is not limited thereto.

FIG. 1 is a process diagram suitable for carrying out an example of the method of the present invention.

Raw material vinyl chloride (VCM) is introduced into the chlorination reactor via pipe 2 and/or into the hydrochlorinator 1 via pipe 1. The 1,1-dichloronitane produced in the hydrochlorinator 1 passes through a pipe 5, where a radical generating agent such as azobisnitrile is added, and chlorine (Ce,) is supplied via a pipe 3 to the subsequent fractionation process. It is introduced into a chlorination reactor together with 1,1-J dichloroethane, 1,1,2-trichloroethane, etc., which are circulated through tubes 8 and 12, and is chlorinated. By-product hydrogen chloride is circulated to the hydrochlorinator 11 via pipe 6. The chlorinated product passes through pipe 7 and is first extracted by fractionator I, with lower boiling point products than 1,1,1-trichloroethane being extracted via pipe 8, and higher boiling products are introduced into the fractionation tower via pipe 9. , where purified 1,1,1-trichloroethane (1,1,1TCE) is obtained and withdrawn via tube 10. The high boilers are then led to the fractionation column via pipe 11.
, 1,2,2-tetrachloroethane, the lower boiling point is in tube 1.
2 to the chlorination reactor together with the liquid in tube 8. High-boiling substances higher than tetrachloroethane obtained in the fractionation process pass through the pipe 13 and are decomposed in a thermal decomposition reactor, then rapidly cooled in a quenching tower and decomposed into 1,1,1,2-tetrachloroethane. Hydrogen chloride (HCI) is extracted from the distillation column through a pipe 15 and is withdrawn as a product through a pipe 17 or circulated through a pipe 16 to the hydrochlorinator 11. The light end is cut off in the fractionation tower and extracted from pipe 18, and the residue passes through pipe 19 and is sent to fractionation tower X, where purified trichlorethylene (Tr
ic) is extracted through tube 20. The residue is then led to a fractionation column M via a pipe 21, where perchlorethylene (Perc)
is extracted from the tube 22. Further, the residue passes through a pipe 23 in the column, where useful undecomposed tetrachloroethane and pentachloroethane are recovered and recycled via a pipe 24 to the pyrolysis reactor. The present invention will be described below with reference to Examples, but the present invention is not limited thereto.

Example 1 2.48 k9/Hr of liquid vinyl chloride monomer was introduced into the bottom of the reactor, and at the same time, 0.96 Nm3/Hr of hydrogen chloride gas, which was a by-product and circulated in the chlorination reactor, was introduced into the reactor, and 1 Hydrochlorination is carried out in a 1,1-dichloroethane solvent containing % by weight of ferric chloride.

The reactor was made of iron with an internal volume of 2 liters and was equipped with a stirrer, and was heated to a temperature of 4°C. Pressure is maintained at 4k9/CTil gauge. The liquid flowing out from this reactor is decatalyzed and weighed 3,90 kg/
1,1-dichloroethane of Hr is obtained. This 1,1
- Dichloroethane is recycled from the fractionation process 1
, 1-dichloroethane and 1,1,2-trichloroethane in liquid form into a nickel chlorination reactor,
At the same time, azobisisobutyronitrile is added to 50 ppm (by weight) in the chlorination reactor. The composition of the liquid supplied to the chlorination reactor is 1,1-dichloroethane 72
．． 5 mol%, 1,1,2-trichloroethane 24.0 mol%, other small amounts of vinyl chloride, 1,1,1-trichloroethane, 1,1,1,2-tetrachloroethane and dissolved in the liquid. Contains hydrogen chloride gas. The chlorination reactor is operated at a pressure of 8.5k9/(-11 gauge and a temperature of 110°C). At the same time, chlorine gas of 1.24Nm3/Hr is introduced to carry out a chlorination reaction, and the organic matter flowing out from the reactor is The compound is 12.53 kg/Hr and its composition is 1,1
-diccalethane 33.3 mol%, 1,1,1-trichloroethane 27.3 mol%, 1,1,2-trichloroethane 25.4 mol%, 1,1,1,2-tetrachloroethane7. Contains O mol%, 1,1,2,2-tetrachloroethane 5.4 mol%, pentachloroethane 2.0 mol%, and small amounts of vinyl chloride and hexachloroethane. , 1-dichloroethane, 1,1,2-trichloroethane are recycled to the chlorination reactor, and 1
, 1,1-trichloroethane is taken out of the system as a product, and highly chlorinated ethane of 1,1,1,2-tetrachloroethane or higher is used as a raw material for the thermal decomposition reaction in the next step. , 1,2-tetrachloroethane or higher polychlorinated ethane is mixed with undecomposed tetrachloroethane and pentachloroethane that are recycled from the purification process that follows the thermal decomposition process, and is in a liquid state at a pressure of 9.0k9/~gauge. , temperature 450
Supplied to a stainless steel pyrolysis reactor maintained at ℃. The total amount of this supplied liquid was 3.23 kg/Hr, and its composition was 1,1,2-tetrachloroethane 43.8 mol%,
1,1,2,2-tetrachloroethane 3.3.1 mol%
, pentachloroethane 19.3 mol%, hexachloroethane 0.8 mol%, and other small amounts of trichlorethylene,
Contains perchloroethylene, and 1,1,2-trichloroethane is 0.1% or less. The effluent from the pyrolysis reactor is rapidly cooled and then rectified in a purification process to eliminate hydrogen chloride gas.
．． 30Nm8/Hr, purified trichlorethylene 1.50
kg/Hr, purified perchlorethylene 0.30k9/H
A high boiler having a boiling point higher than that of r and perchlorethylene is obtained. Useful tetra and pentachloroethane are recovered from this high boiling point and recycled to the thermal decomposition reactor, but the recovered liquid has a concentration of 0.89k9/Hr and a composition of 1,1,1,2
-tetrachloroethane 30.0 mol%, 1,1,2,2
-Contains 24.5 mol% of tetrachloroethane, 36.3 mol% of pentachloroethane, and small amounts of trichloroethylene, perchlorethylene, and hexachloroethane. The final product obtained is 1,1,1-trichloroethane 3.34k9/Hr, trichlorethylene 1
．． 50k9/Hr, perchlorethylene 0.30kg/
Hr and gaseous hydrogen chloride 0.64 Nm8/Hr. Example 2 Same hydrochlorination reactor as Example 1. The reaction was carried out using a chlorination reactor and a thermal decomposition reactor at the same reaction pressure and reaction temperature (the tatami and thermal decomposition reaction temperatures were 43°C).

First, 0.53 kg/Hr of liquid vinyl chloride monomer and 0.21 Nm8/Hr of chlorinated by-product hydrogen chloride gas were added.
Reacted in the presence of 7% by weight ferric chloride, 0.84kg
/Hr of 1,1-dichloroethane is obtained, and 1,1-dichloroethane, 1,
The mixture was supplied together with 1,2-trichloroethane to the chlorination reactor, and at the same time 0.68 Nm8/Hr of chlorine gas and 0.56 k9/Hr of liquid vinyl chloride were newly introduced to carry out a chlorination reaction.

The concentration of azobisisobutyronitrile at this time is 10p
It was pm (weight). The composition of the supplied 1,1-dichloroethane and 1,1,2-trichloroethane is 39.6 mol% 1,1-dichloroethane and 58.1 mol% 1,1,2-trichloroethane? , others are a small amount of chloride, the reaction product is 6.65k9/Hr, and the composition is 1,1-dichloroethane 14.9 mol%, 1,1,1-trichloroethane 11.9 mol%, 1, 1,2-trichloroethane47.
9 mol%, 1,1,1,2-tetrachloroethane 10.
4 mol%, 1,1,2,2-tetrachloroethane10.
4 mol% of pentachloroethane, 3.4 mol% of pentachloroethane, and other small amounts of vinyl chloride and hexachloroethane, which are fractionated to produce 1,1,1-trichloroethane product and 2.02k9/ml of thermal decomposition reaction raw material. I got Hr. This was thermally decomposed and rapidly cooled and purified in the same manner as in Example 1 to obtain hydrogen chloride gas, trichlorethylene, and perchlorethylene products. The final product at this time was 1,1,1-trichloroethane 0.73 kg/Hr, trichlorethylene 1.2
5k9/Hr, perchlorethylene 0.25kq/Hr
, by-product hydrogen chloride gas was 0.5 Nm8/Hr.

[Brief explanation of the drawing]

FIG. 1 is a process diagram suitable for carrying out an example of the method of the present invention.

Claims (1)

[Claims] 1. When co-producing 1,1,1-trichloroethane, trichlorethylene and perchlorethylene from vinyl chloride and chlorine, (1) vinyl chloride is reacted with hydrogen chloride to produce 1,1- Hydrogen chloride addition step (2) to obtain dichloroethane
) A chlorination step (3) in which the reaction product obtained in the hydrogen chloride addition step is reacted with chlorine in a liquid phase in the presence of a radical generator to obtain polychlorinated ethane and to take out a gaseous composition mainly consisting of hydrogen chloride. ) A recycling step in which part or all of the gaseous composition taken out in the chlorination step is recycled to the hydrogen chloride addition step. (4) 1 from the polychlorinated ene obtained in the chlorination step.
, 1-dichloroethane is separated and recycled to the chlorination step 1
, 1-dichloroethane separation step (5) 1,1,
Separation step of 1,1,1-trichloroethane in which 1-trichloroethane is separated by distillation (6) From polychlorinated ethane obtained from the separation step of 1,1,1-trichloroethane, 1,1
, 1,1,2-trichloroethane separation step (7) 1 in which 2-trichloroethane is separated by distillation and recycled to the chlorination step.
, 1,2-Trichloroethane separation step. Decomposition step of thermally decomposing polychlorinated ethane at a temperature of 350 to 600°C. (8) Hydrogen chloride is distilled and separated from the polychloride obtained in the decomposition step, and chlorination Hydrogen chloride separation step (9) in which part or all of the hydrogen is recycled to the hydrogen chloride addition step (9) Trichlorethylene separation step in which trichlorethylene is distilled and separated from the polychloride obtained from the hydrogen chloride separation step (10) From the trichlorethylene separation step A perchlorethylene separation step in which perchlorethylene is separated by distillation from the obtained polychloride; and (11) a perchlorethylene separation step in which the polychloride obtained from the perchlorethylene separation step is distilled at a temperature below the boiling point of pentachloroethane to decompose the distillate. 1. A method for co-producing 1,1,1-trichloroethane, trichlorethylene, and perchlorethylene, characterized by comprising a step of recycling to other processes. 2. When co-producing 1,1,1-trichloroethane, trichlorethylene, and perchlorethylene from vinyl chloride and chlorine, (1) chlorination to obtain 1,1,1-dichloroethane by reacting vinyl chloride with hydrogen chloride. Hydrogenation step (2) The reaction product obtained in the hydrogen chloride addition step is reacted with chlorine while introducing vinyl chloride in the presence of a radical generator in a liquid phase to obtain polychlorinated ethane, and also to obtain polychlorinated ethane. Chlorination step (3) to extract the gaseous composition
) A recycling step in which part or all of the gaseous composition taken out in the chlorination step is recycled to the hydrogen chloride addition step. (4) 1,1-dichloroethane is separated from the polychlorinated ethane obtained in the chlorination step. 1,1,1-trichloroethane is separated by distillation from the polychlorinated ethane obtained from the 1,1-dichloroethane separation step (5) 1,1-dichloroethane separation step that is recycled to the chlorination step. Ethane separation step (6) 1,1,2-trichloroethane is separated by distillation from polychlorinated ethane obtained from the 1,1,1-trichloroethane separation step and recycled to the chlorination step.
Separation step of 2-trichloroethane (7) Decomposition step (8) of thermally decomposing the polychlorinated ethane obtained from the separation step of 1,1,2-trichloroethane at a temperature of 350 to 600°C
Hydrogen chloride separation step in which hydrogen chloride is distilled off from the polychloride obtained in the decomposition step and part or all of the hydrogen chloride is recycled to the hydrogen chloride addition step (9) Trichloride is removed from the polychloride obtained in the hydrogen chloride separation step. Trichlorethylene separation step (10) in which ethylene is separated by distillation; perchlorethylene separation step (11) in which perchlorethylene is separated by distillation from the polychloride obtained from the trichlorethylene separation step; and (11)
1 characterized by comprising a step of distilling the polychloride obtained from the perchlorethylene separation step at a temperature below the boiling point of pentachloroethane and circulating the distillate to the decomposition step.
, 1,1-trichloroethane, trichlorethylene and perchlorethylene co-production method.