DE1943614C - Process for the production of trichlorethylene and / or tetrachlorethylene - Google Patents

Description

The manufacture of trichlorotethylene or tetrachloride shows the least effect. At »Ilen chloro-ethylene by vapor phase pyrolysis of tetrachloride these chlorinated athanes WBt jwjocnaie pyrochloroethane or, pentachloroethene has long been known to lytic formation of carbon after latency and also the fact that driving the invention prevent Here carbon is created as a by-product. This 5 bisendlI) -ChIos used according to the invention generally separates as a layer on the wall, in the vapor phase, the bigensphalt, which The formation of carbon as a by-product also occurs in part wise in the form of fine particles together with the prevent and must therefore in the Keak main product on. tion zone are stirred in, so that it is then in steam

The technical pyrolysis of tetrachloroethane 10 is noisy. Since the point of contact of and pentachloroethane is iron (HI) chloride at 315 ° C, this phenomenon is undesirable. The vapor formed as a by-product is easily introduced into the reaction zone. Carbon adheres to the reaction tube wall. However, it may also include other methods and the coating is used with the reaction progresses, if the presence of Eisend 11)-always thicker and may, finally, the reaction i ₅ cblorid steam in the reaction zone to ensure pipe clogging. However, even if this is not on. If, for example, iron (III) chloride in Tetratritt, the chloroethane or pentachloroethane precipitated on the walls interferes with the heat transfer into the reaction zone, it can work together with the zone and makes a smooth reaction impossible. fenden chlorinated hydrocarbon evaporates and in dt ^ When the carbon reaction system adhering to the wall is introduced. Instead of the amount of hydrogen reaching a certain level, the oxygen chloride has to be fed in immediately; or in the vicinity of its inlet with substance-containing gas or in a mechanical way, a lot of iron rust is arranged so that the pyrolysing can be removed. In addition, contaminates or blocks the necessary amount of iron (III) chloride which, together with the main product of the formation of iron (III) chloride, absorbs chloride vapor! The carbon emerging from the reaction tube then introduces this vapor into the reaction system, if necessary downstream purification system and the pipes used as a catalyst according to the invention. This Sy- sentIl) chloride is also continuously in the reaction star must be cleaned regularly. It 30 system initiated and withdrawn from it. As a result, there is no doubt that such a method is unnecessary and the removal or replacement is disadvantageous. Catalyst, as is the case when working with stuck

It has now been found that vapor phase or moving contact is necessary. Pyrolysis of tetrachloroethane and / or pentachlor- To what extent the formation of carbon as a secondary

ethane no carbon is produced as a by-product, 35 product of pyrolysis prevents and the conversion of

if you vaporous EisenendII) chloride in the tetrachloroethane and pentachloroethane according to the invention

Reaction zone stirred in, and that this also increases manure depends on the concentration of the Trichlorethylene and tetrachlorethylene are removed by Pyro-Iron 11 (chloride. Its effect is reduced

lysis can be obtained in high yield. quickly when the ferric chloride concentration

The invention thus relates to a method for 40 below 0.001 mol percent, based on the as Production of trichlorethylene and / or tetra- starting material used tetrachloroethane or / chlorithylene by catalytic vapor phase pyroethane and pentachloroethane. The iron chloride concentrations of tetrachloroethane and / or pentachloroethane; tration in the reaction zone should be 0. (X) I MoI-the process is characterized in that one percent or higher, preferably 0.01 mol-dic pyrolysis at a temperature of 420 to 49 () C. 45 percent or more . A higher iron (II) chloride in the presence of 0.001 to 0.1 mol% vapor concentration also produces a worse effective iron (11) chloride, based on the amount, but if the concentration exceeds 0.5%, set chlorinated hydrocarbons. Only the consumption of iron (IIt) chloride is shown

Tetrachloroethane, a compound, (lic the pyro · in weight, but also the desired effect * ·

lysis according to the method according to the invention does not increase, and this can also occur

is thrown, can either as I, l.l.2-Te; rachlor

üthan or present as 1.1.2,2-Tetraehlorälhan. tiomrohrcs accumulate and the smooth drain of the

The process according to the invention can be very interfering with the reaction gas. In general, one can use

to be carried out advantageously when the pyrolyicrcndcn of an iron (III-Khlond concentration of approx

Starting materials, such as Tetrachloröfhun and Penta- 5J 0.02 mol percent, based on that to be pyrolyzed

chloroethane, present in high purity or a compound. Tetrachloroethane (especially 1.1,1.2-Te-

Form a mixture with each other, but also when they are trachloroethane) with a conversion of practically 100%

with chlorinated hydrocarbons such as 1.1,2-TrJ- and Pentachlorttihan with a conversion of test

chlorWhan or Hexachlorttthan. Add 100% without significant carbon formation.

When using chlorinated hydrocarbons with 60 The method according to the invention requires in the old

3 and more carbon atoms exists, however, the «mean with regard to the prevention of one

There is a tendency that carbon as a by-product of carbon volatilization has a low reaction temperature.

forms what should be avoided as much as possible, but to achieve better sales

should. Of the compounds that after ver · a high temperature. In general, a tem

drive of the invention are to be pyrolyzed, a temperature of 420 to 460 ° C is the most favorable. Achieved

1, f, t, 2 * Tetrachlorotthane with regard to the conversion rate, the reaction temperature is about 500 * C, this is how it arises

eration in the werfcwmiten. The next effective off · carbon in larger quantities, so that the benefits

gangsüofflil Pentachlorttthan, while!, 1, M-TeIfB- the invention in Prague «.

It is known that the pyrolysis of tetrachlorethylene and pentachloroethane after a Radnkalkettenrenktion runs and the addition of chlorine, carbon tetrachloride or hexachloroethane as a radical generator accelerates implementation. However, carbon is also used as a by-product generated. The invention can also be used as such Apply a reaction in which the presence of a radical generator is intended and lead to it to remarkable effects.

If, for example, a mixture of polychlorinated ethanes is used as the starting material, their The main components are 1,1,1,2- and 1,1,2,2-tetrachloroethane, as they are used in the chlorination of ethylene in liquid Phase is obtained without a catalyst, and if the rest of the procedure according to the invention, then 1,1,1,2-tetrachloroethane is almost completely converted and does not remain in the liquid product. The process according to the invention thus circumvents the difficulties in the separation of 1,1,1,2-trachloroethane from tetrachlorethylene, which is obtained by splitting off hydrogen chloride from pentachloroethane cr / eughed. It is known that the boiling points of these two substances do not differ significantly from each other.

The invention is described below by way of example, the percentages being expressed as MoI-pro / ent understand; χ

Example I.

A translucent fused silica reaction tube with an inner diameter of 28 mm and a length of 600 mm was filled with porcelain Raschig rings of 4x7 mm in size. The Steam of 1,1,1,2-tetrachloroethane with a content of 0.04% iron (IIl) chloride at a reaction temperature of 460 "C and at a speed from 300 NV / h (NV means here and in the following the normal volume, to the normal state of the steam reduced) and reacted for 12 hours. The 1,1,1,2-tetrachloroethane was 99.5%, so almost quantitatively, converted into trichlorethylene. A formation of carbon as a by-product was hardly observed.

A 1,1,1,2-tetrachloroethane free of iron chloride was then obtained at the same reaction temperature introduced in DampfTorm at a rate of 39 NV / h into the reaction vessel and to Implementation brought. Despite the low loading speed was the 1.1,1,2-Tctrachloräthan only 95.2% implemented.

Example 2

In the same reaction tube as in Example 1, the vapor of a mixture of multiply chlorinated ethanes (39% MU-tetrachloride, 45% 1,1.1,2-tetrachloride and 16% pttachloroethane) with a content of 0.05% Biten (Ut)> chloride initiated at a temperature of 410,435,460 or 49O ⁰ C at a rate of 150 NV / h «5 and implemented for 12 hours. The result of the conversion of each chlorinated athan · 1st in Table I.

Table I.

component

|, l, |, 2-T-2trachlarethane

1,1,2,2-tetrachloroethane

Pentachloroethane ..

Carbon formation

410

no

Temperature "C
435 460

97

83

61

no

100

96

75

no

490

100

Note 1

Note 1: The Raschig rings in the reaction tube were with Carbon covered and colored black.

The total yield of trichlorethylene and tetrachlorethylene was 98.8 mol percent (by-products: 0.2% vinylidene chloride, 0.4% dichloroethylene, 0.1% hexachloroethane, 0.5% higher-boiling components).

Furthermore, a mixture of the polychlorinated ethanes without iron (III) chloride addition was made according to this example subjected to the reaction at 460 ° C. The resulting conversion of each chlorinated Ethans is given in Table 2. In this case, the generation of carbon was a by-product considerably.

Table 2 component

Sales volume (%)

1,1,1,2-tetrachloroethane 79

1,1,2,2-tetrachloroethane 90

Penlachloroethane 55

Example 3

A translucent fused quartz tube with an inside diameter of 28 mm and a length of 850 mm was filled with porcelain Raschig rings 5 × 5 mm in size. While the temperature inside the tube was set to 460X, sym.-tetrachloroethane and / or pentachloroethane were introduced into the reaction tube at a rate of 140 NV / h for 20 hours in order to effect the pyrolysis. Table 3 shows the results with and without the addition of iron chloride vapor. The symbol (+) in the "Carbon Formation" columns in Table 3 indicates that the porcelain Raschig rings in the reaction tube were covered with carbon and colored black, while the symbol (-), conversely, means that the porcelain Raschig rings were as white as remained before the reaction, so the formation of carbon as a by-product was not observed. In experiment 5, however, a trace of carbon feat * was found (* · *). Experiment 6 (·) shows an example 1 "Ur the use of chlorine in your amount of 0.5%, based on the t, lJ ^ 2 * tetra-chlorine; Experiment 7 (· *} was with the addition of hexachlorophene in an amount of 1%, based on the 1,1,24-tetrachloroethane, carried out.

The results show that bis (IIl) chloride has a noticeable influence on the prevention of the formation of carbon from by-product of pyrolysis vtn 1,1,2,2'Tetrachloräthan and Pentaehlortthane shows and also promotes the implementation of relatively itark.

! 943 614 I.

Tfiboile 3

Output nutialicn Without iron II) chloride 90.0 additive Iron 11) - With iron dine chloride additive 84.7 Carbon-
education attempt 92.5 chloride-
Conc., 99.6 No. Umsiuz (%) carbon
education Mole percent Sales volume (%) 95.1 (-) 1,1,2,2-tetrachloroethane 0.1 Λ 1,1,2,2-tetrachlonithane (-) I. Pentachloroethane 76.4 (+) 0.3 98.7 (-). 2 Mix of 83.3 (+) 0.3 Pentachloroethane 3 1,1,2,2-tetrachorm 92.5 (+) 92.5 ethane and penta 1,1,2,2-tetrachloroethane 1,1,2,2-tetrachloroethane chloroethane 55.0 74.5 <->. like 3 Pentachloroethane 0.02 P '*' tachloroethane 4th like 3 (+) 92.1 1,1,2,2-tetrachloroethane 68.2 (-) *** like 3 0.005 Pentachloroethane 5 like 3 (+) 93.1 95.3 (-) 1,1,2,2-tetrachloroethane * 0.2 (-) 6th 1,1,2,2-tetrachlor <+) 0.1 η ethane ** (+)

The trichlorethylene yields and by-products
in the tests given in Table 3, in
Table 4 indicated:

Table 4

Ve-iuch
No. Trichlorethylene
exploit Byproducts
(Mole percent) 0.6 (Mole percent) 0.5 Dichloroethylene 0.6 1 98.3 Tetrachlorethylene 0.8 higher boiling best. 0.5 Dichloroethylene 2 98.7 Hexachloroethane higher boiling best. 0.2 sense 0.3 99.2 Dichloroethylene G, 3 3 (Trichlorethylene Hexachloroethane + Tetrachlor higher boiling best. ethylene) 4th like 3 like 3 5. like 3 something like: 3

T
attempt
No. Trichlorethylene
exploit
(Mole percent) Byproducts
(Mole percent) 6th
7th 97.8
98.5 Dichloroethylene 0.5
Tetrachlorethylene 1,2
higher boiling point 0.5
Dichloroethylene 0.5
Tetrachlorethylene 0.5
higher-boiling stock 0.5

Claims (2)

Patent claims: 1. Process? Ur production of trichlorethylene and / or tetrachlorethylene by catalytic vapor phase pyrolysis of tetrachloroethane and / or pentachloroethane, characterized in that the pyrolysis is carried out at a temperature of 410 to 490 ^° C. in the presence of 0.001 to 0.5 mole percent vaporous iron (III) chloride, based on the chlorinated hydrocarbons used, is carried out. 2. The method according to claim 1, characterized in that one carries out the reaction at a temperature of 420-460 ⁰ C.