DE1240842B - Process for the treatment of highly chlorinated, specifically heavy residues that arise during the industrial production of chlorinated hydrocarbons - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

C07c

German KL: 12 ο -2/05

Number: 1240 842

File number: P 33909IV b / 12 ο

Filing date: March 25, 1964

Opened on: May 24, 1967

In the industrial production of chlorinated hydrocarbons, highly chlorinated, specific ones fall heavy residues which, in addition to tar-like products, hexachlorobutadiene, chlorinated benzene derivatives, like the tetra-, penta- and hexachlorobenzenes, and hexachloroethane.

The compounds are thermally very stable and cannot be brought into circulation. The separation the presence of hexachloroethane makes it extremely difficult to find their constituents. By crystallization from a solvent, the hexachloroethane and the chlorinated benzene derivatives practically cannot be isolated in a satisfactory manner. Also the separation by fractionated Distillation is due to the separation of solid hexachloroethane in the pipelines Device impossible.

The solution to this problem is of great economic importance, since it is in industrial production of light chlorinated hydrocarbons for every tonne of usable light obtained 30 to 150 kg of residue products accumulate.

The present invention is based on the object of the specific economic exploitation heavy, highly chlorinated residues, especially their components hexachlorobutadiene and hexachloroethane to enable.

If hexachloroethane is subjected to thermal decomposition, this is known to arise chemical equilibrium

C ₂ Cl ₆ ^ = C ₂ Cl ₄ + Cl

a. It is also known that this equilibrium by binding the released chlorine with Using a suitable reactant, such as acetylene, ethylene, dichloroethane, and in general with Help of chlorinated hydrocarbons with 2 carbon atoms, the maximum 4 chlorine atoms contain, can be moved.

US Pat. No. 2,447,410 discloses the use of propane to bind the released chlorine and, e.g. B. Hexachloroethane heated to about 420 ° C in a quartz tube. If one tries to apply this process to mixtures obtained as residue which contain hexachloroethane, it is found that the reaction rate at the specified temperature is practically zero. If heated to a higher temperature, the content of hexachloroethane is reduced, but at the same time the process for the preparation of highly chlorinated, specifically heavy residues, which occurs in the
industrial production of chlorinated
Accumulate hydrocarbons

Applicant:

Produits Chimiques, Pechiney-Saint-Gobain,

Paris

Representative:

Dr. Ing.F. Wuesthoff, Dipl.-Ing. G. Pulse
and Dr. E. v. Pechmann, patent attorneys,
Munich 9, Schweigerstr. 2

Named as inventor:

Albert Antonini, Paris;

Maurice Goharel, Saint-Auban, Basses Alpes;

Georges Wetroff, Le Thillay, Seine-et-Oise

(France)

Claimed priority:

France of March 25, 1963 (929092)

desired thermal decomposition, the required contact time in the tube is extended so that the propane is cracked, whereby carbonaceous deposits are formed and, as a result, the pipes of the Device become clogged.

If the propane is replaced by other reactants, such as those indicated above, and if analogous residue mixtures are treated, then it is possible to work at a higher temperature without cracking of the reactants. Regardless of whether the work is being carried out in a quartz tube or in a metal vessel, it must be ^{heated to more than 500 °} C. for a relatively long contact time of the order of a few 10 seconds in order to achieve a considerable conversion of hexachloroethane. It has been shown that under these working conditions an increase in the content of heavy derivatives, in particular

709 587/565

3 4

on hexachlorobutadiene and hexachlorobenzene one of chlorine atoms on little substituted and / or

occurs, which is known to be desirable only in very specific cases, unsaturated hydrocarbon molecules

is, since generally the recovery of represents an exothermic reaction,

light products and the limitation on formation The invention is illustrated by the following examples

of heavy products to a minimum.

is striving. example 1

The inventive method avoids that

mentioned difficulties and made possible by the following Defined thermal conversion of the ethylene, dark colored, heavy, liquid starting material highly chlorinated, specifically heavy io siger residue with the following composition, reverse residues, in particular the hexa set contained therein:

chloroethane effective and with good yield in specific weight percent

fish lighter, recyclable products to- tetrachlorethylene 68.8

^wa? spindles. Hexachloroethane .. ""! "". '!.'. ' ^ 5

The invention relates to a method for processing 15 _TT ,,, _., ·,.

processing of highly chlorinated, specifically heavy reverse hexachlorobutadiene and others

stands in the industrial production of C ₄ compounds / u, 8

chlorinated hydrocarbons occur, and is chlorinated derivatives of benzene 1,4

characterized in that a mixture of tar products 1.5

3 to 16 parts by weight of the back 20

Standes and 1 part by weight of vinyl chloride, dichloro A mixture of 75 parts by weight of this Rückäthylenene, trichlorethylene, dichloroethane, trichlorethylene and 25 parts by weight of trichlorethylene was chloroethane, tetrachloroethane, ethylene, acetylene in an amount of 2.3 kg / h in an evaporator and / or propane or mixtures of the latter and preheated here to 230 to 250 ° C. The ten compounds in the vapor state with 400 to 25 preheated vapors were then passed into a ^{pressure of 550 ° C and 1.5 to 6 kg / cm 2} through a heat-resistant, corrosion-resistant nickel alloy, the ratio of which is the total ("Inconel" 73 ° / »Ni, protected designation) from the inner surface to the cross-sectional area more than the pipe, the inner diameter of which is 1000, the escape of the vapors being less than 0.5 cm and the length 1000 cm. The tube vortex formation, corresponding to a Reynold's 30, was rolled up in the form of a snake and in a number of more than 2000, took place. Chamber housed, which was heated to 450 ° C. The residue to be worked up is evaporated together. The surface of the inner walls of the pipe with the aforementioned acting as a chlorine acceptor thus carried 1570 cm ² and the ratio of its total compound and passed into the conversion space th inner surface to the surface of its. The cross-section emerging from this with the formation of eddies is approximately 8,000. The vapors in the pipe are condensed and degassed. The entering vapors were kept under a pressure of overall yield can be further increased by about 3 kg / cm ² . The contact time in the tube means that the thermal treatment according to the invention was about 2 to 3 seconds and is repeated when it precipitates with the condensate obtained. When the vapors emerged from the pipe, the mean sub-"total inner surface" of the Reac Reynolds number was 2500. The vapors are the surface of its lateral walls condensed and a liquid follows - inner walls and the contact surface of a given composition are preserved:
if necessary to understand the filling contained therein. Weight percent

According to the invention, the ratio of the total inner surface of the conversion space 45 to trichlorethylene is 23.5

to its cross-sectional area more than 1000. The tetrachlorethylene 59.6

the upper limit of the value of this ratio depends on pentachloroethane 0.1

of the size of the plant and technological hexachloroethane 15

Factors. The ratio mentioned is all the more _TT ,,, _. ,. , \

higher, the longer the implementation space. With the ₅ o ^ ÄnTuteV 14 9

The length of the implementation space also take the ^ * " ^{v erDmaun} S ^{en 1} ^

sen weight as well as the loss of material, which in the case of chlorinated derivatives of benzene 0.4
Passing the vapors through the conversion room

occurs. In addition, the resistance of the materials used after this treatment must be taken into account. 55 recovery 90 percent by weight,
In addition, an industrial plant can easily have a. For comparison, a sample of the residue used as a conversion space, with the same ratio of the total inner surface working conditions with trichlorethylene in area to the cross-section, a value of 4000 to one reaction vessel "Inconel" reached by 20,000. 60 knives 5 cm and the length 40 cm treated. According to a preferred embodiment, the reaction vessel was filled with chips made of "Inconel" of the method according to the invention and had an entire inner surface of vapors in the reaction space at a temperature of 3028 cm ² ; the surface of the side walls is heated to between 440 and 525 ° C. of the reaction ^{vessel was 628 cm 2} and in some cases it is advisable to use the free chlorine surface of the chips about 2400 cm ² . The ratio of the heat to be introduced into the reaction space in order to reduce the total internal surface area to the perpendicular transverse budget of the total conversion reaction of the cut surface was 154. It should be noted that heavy products improve, since the bond takes up the entire internal surface of this reaction region.

The vessel was larger than that of the pipe used first, 0.5 cm in diameter and length from 1000 cm.

During the thermal treatment, the pressure of the vapors in the reaction vessel was 1 kg / cm ² . Virtually no conversion of hexachloroethane was observed under these conditions, although the contact time of the vapors in the reaction vessel was about 4 seconds.

IO

Example 2

A residue of the following composition was obtained during the production of tetrachlorethylene used:

Weight percent

Tetrachlorethylene 66.7

Hexachloroethane 6.2

Hexachlorobutadiene and others

C ₄ compounds 25.6

Chlorinated derivatives of benzene 1.0

Tar products 0.5

This residue was introduced into a double-jacketed evaporator which had been heated to approximately 270 °, together with propane in _a5 liquid phase in an amount of 1.95 and 0.16 kg / h, respectively. The vapors obtained were introduced into a reaction tube according to Example 1, which was characterized by a ratio of its total inner surface to its perpendicular cross-sectional surface of 8000. This reaction tube was heated to a temperature of about 450 ° C. The absolute pressure of the vapors in the reaction vessel was 3 kg / cm ² and their residence time was 2.4 seconds.

The exiting steam flow was characterized by a Reynolds number of the order of magnitude of 2,600.

The emerging vapors were let down to 1 kg / cm ² and condensed by cooling to room temperature. The condensate was degassed, thereby removing most of the unreacted propane and the hydrochloric acid which was formed in an amount of 0.57 mol / h. The uncondensed gases were washed out with water, entraining the hydrochloric acid. These gases, which mainly contained propane along with a small amount of propylene, propyl chloride, isopropyl chloride, allyl chloride and tetrachlorethylene, were collected as a by-product.

In a continuous mode of operation, a condensate was thus obtained in an amount of 1.81 kg / h, which had the following composition:

Propane and other light

Hydrocarbons

Tetrachlorethylene

Hexachloroethane

Hexachlorobutadiene and others
C ₄ compounds

Chlorinated derivatives of benzene

Weight percent

70.9
2.4

24.4
0.3

On the bottom of the evaporator, a non-evaporated liquid settled in an amount of g / h, which was continuously withdrawn.

As in Example 1, an experiment was carried out for comparison under the same working conditions at a pressure of 1 kg / cm ² in an "Inconel" reaction vessel with a diameter of 5 cm and a length of 40 cm filled with chips made of "Inconel".

The exiting steam flow was indicated by a Reynolds number of 750. The relationship the entire inner surface of the reaction vessel to the surface of its perpendicular Cross section was 154.

No significant conversion of the hexachloroethane was found under these conditions, although the residence time of the vapors was 1.5 times as long as in the reaction tube with a diameter of 0.5 cm and the length 1000 cm.

Claims (3)

Patent claims: 1. A method for working up highly chlorinated, specifically heavy residues which arise in the industrial production of chlorinated hydrocarbons, characterized in that a mixture of 3 to 16 parts by weight of the residue to be worked up and 1 part by weight of vinyl chloride, dichloroethylenes, trichlorethylene, dichloroethanes, trichloroethanes, Tetrachlorethylene, ethylene, acetylene and / or propane or mixtures of the last-mentioned compounds in the vapor state at 400 to 550 ° C and 1.5 to 6 kg / cm ² pressure through a reaction space whose ratio of the total inner surface to the cross-sectional area is more than 1000 is, with the escape of the vapors with the formation of eddies, corresponding to a Reynolds number of more than 2000. 2. The method according to claim 1, characterized in that the temperature in the reaction space holds at 440 to 525 ° C. 3. The method according to claim 1 or 2, characterized in that chlorine is additionally introduced into the reaction space. 709 587/565 5.67 © Bundesdruckerei Berlin