DE1173085B - Process for the production of vinyl chloride - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: C 07 c

German KL: 12 o -19/02

Number: 1173 085

File number: S 71586IV b / 12 ο

Filing date: December 8, 1960

Opening day: July 2nd, 1964

Polymers and copolymers of vinyl chloride are becoming increasingly popular in the plastic compound industry used by polymerizing vinyl chloride alone or in admixture with one another copolymerizable monomer can be obtained. The technical processes generally used up to now consist in the fact that acetylene or ethylene is assumed, which is a relatively high purity own. The acetylene is then converted to vinyl chloride by adding it to atmospheric pressure and in The presence of a mercury chloride catalyst is reacted with gaseous ^ hydrochloric acid. If ethylene is used as a starting point, it is converted into vinyl chloride by reacting it with chlorine and the dichloroethane obtained is then purified and subjected to heat splitting.

Various processes for the large-scale production of acetylene and ethylene are known, but For economic reasons, mostly liquid hydrocarbons are now processed, such as naphtha or heavy gasoline fraction from petroleum distillation. To this end, these are liquid, beforehand Vaporized hydrocarbons are injected into hot combustion gases, whereupon the fission gases formed suddenly cooled down to stabilize them. In this way, a cracked gas is obtained, which in Mixture with other gaseous hydrocarbons contains both acetylene and ethylene.

So far, these fission gases have been further processed in such a way that they are separated and in a pure state the acetylene and the ethylene are obtained for a large number of chemical syntheses be used as raw materials. However, it has been found that a process for the production of vinyl chloride directly from one of these fission gases would be of great technical value because it would allow the separation and purification of the acetylene and ethylene contained in this cracked gas are, can be omitted, which, however, a substantial saving in terms of the construction costs the plant and treatment of the gas would be achieved.

The invention relates to a process for the production of vinyl chloride from a cracked gas obtained by pyrolysis and prepurified in a known manner in the presence of activated carbon impregnated with mercury chloride as a catalyst, characterized in that the acetylene contained in the cracked gas at 100 to 140 ⁰ C and a pressure of 10 atm., With a throughput of 125 to 175 l / h (measured at 0 ^° C. and 760 torr) and per liter of catalyst reacted with hydrogen chloride and separated and ge-method for the production of vinyl chloride

Applicant:

Societe Beige de l'Azote et des Produits

Chimiques du Marly, Liège (Belgium)

Representative:

Dr. W. Schalk, Dipl.-Ing. P. Wirth,

Dipl.-Ing. G. E. M. Dannenberg

and Dr. V. Schmied-Kowarzik, patent attorneys,

Frankfurt / M., Große Eschenheimer Str. 39

Named as inventor:

Frederic Francois Albert Braconier, Plainevaux,

Henri Ie Bihan, Liège (Belgium)

Claimed priority:

Great Britain December 18, 1959 (43 182)

optionally the unreacted ethylene with chlorine at 50 to 150 ⁰ C and reacted the dichloroethane obtained is cleaved in a known manner into vinyl chloride and hydrogen chloride.

The method of the invention thus comprises three main stages:

1. Synthesis of vinyl chloride from acetylene and hydrochloric acid according to the equation:

C ₂ H ₂ + HCl -> C ₂ H ₃ Cl + 25 kcal

2. Synthesis of dichloroethane from ethylene and chlorine according to the equation:

C ₂ H ₄ + Cl ₂ - * C ₂ H ₄ Cl ₂ + 41 kcal

3. Heat splitting of this dichloroethane in vinyl chloride according to the equation:

C ₂ H ₄ Cl ₂ -> C ₂ H ₃ Cl + HCl - 19 kcal

From these reaction equations it can be seen that that which occurs during the heat dissipation of dichloroethane Hydrochloric acid is sufficient for the synthesis of vinyl chloride from acetylene, especially since the corresponding Partial amounts of acetylene and ethylene can be regulated in the cracked gas.

Assumes a liquid, previously vaporized hydrocarbon and this hydrocarbon by injection into hot gases produced by burning a hydrogen-rich gas in oxygen be obtained in a manner known per se

409 628/328

3 4

Subjected to heat splitting, the partial lysis furnace can be sent. This reaction is a

Amounts of acetylene and ethylene are regulated, temperature from 50 to 120 ⁰ C under pressure and in that the presence of a catalyst, such as ferric is introduced into the hot combustion gases, the water vapor along the chloride or anhydrous calcium chloride, inside wall of the combustion chamber ther- 5 said catalysts also on a

mix forms a veil, namely in a carrier such as silica gel or activated carbon, to

Amount that the ratio of C ₂ H ₂ to C ₂ H _{4 can come} to about 1 turn. Will a reactor from

is held. If steel is used, no catalyst needs to be used

This heat splitting will take place at atmospheric pressure, since the reaction takes place through its walls or preferably introduced at about atmospheric pressure through or through particles of iron chloride

led, with the work under pressure which is in the, which is caused by the action of chlorine on the

the following description of the method mentioned walls are formed. The yield

Has advantages. of dichloroethane, calculated on ethylene, is

The cracked gas contains after the stabilization of at least 95% · This dichloroethane is then

formed acetylene applied sudden cooling '5 by cooling to a temperature below -1O ⁰ C

cooling impurities that condense in per se known, as a result of which dichloroethane is obtained,

Way must be removed. The soot and the tars are a small amount of higher molecular weights

are washed with water and oil and / or chlorine compounds such as trichloroethane, tetrachloro

by guiding the fission gases through moist electro-ethane and dichloroethylene. This dichloro

filter or some other suitable measure 20 Ethane is added to the dichloroethane that is used for

removed, whereupon the gas at low temperature with dissolution of the in the first catalytic reaction

Kerosene is washed. Through this washing, vinyl chloride is made, and this is what has been used

Almost all of the unsaturated hydrocarbon mixture is then distilled to remove the heavy ChIo-

Substances, which accompany the acetylene and the ethylene, separate ride that in the course of the heat splitting

In particular, the vinyl acetylene, the propylene, 25 of the dichloroethane under unwanted reactions

and the butadiene, removed. Formation of tars would result. That through

The cracked gas purified in this way contains the acetylene and some of the purified dichloroethane is distilled

the ethylene in a volume ratio of about 1, for the absorption of new quantities of vinyl chloride

but these hydrocarbons are reused by gaseous forms during the rest of the heat dissipation

Components such as hydrogen, nitrogen, carbon 30 is subjected. This heat split is under

monoxide, carbon dioxide, as well as methane and ethane at a pressure of about 8 ata at a temperature of

and traces of unsaturated hydrocarbons with more than 400 to 450 ⁰ C and in the presence of ash-free

accompanied as 2 carbon atoms carried by the activated carbon, as it is in the Belgian

Kerosene has not been fully retained. Patent 563,247 has been described. That

This gas is preheated under pressure and with 35 degrees of conversion of the dichloroethane into vinyl

gaseous hydrochloric acid mixed and this chloride per pass is at least 65%, what

The mixture is sent to a catalytic furnace, taking into account the recirculation of the not

Contains mercury chloride impregnated activated carbon, converted dichloroethane a yield in relation to

the temperature depending on the active on the conversion into vinyl chloride of over 95%

samidity of the catalyst between 100 and 140 ⁰ C 4 ° results,

is held. The gas obtained after this heat splitting

It was found that in the course of this syn- contains unconverted dichloroethane, vinylchlo-

theses reaction that accompanies the acetylene in the cracked gas, hydrogen chloride and small amounts of ethylene

tend to be gaseous constituents such as inert gases and acetylene. This gas mixture is cooled

behave and the extent of the conversion of the 45 to the unconverted dichloroethane, which the

Acetylene in vinyl chloride, which is 100% tewa, in hydrochloric acid and which contains vinyl chloride,

in no way affect. to condense. These components are in dichloro

At the exit of the first synthesis furnace, the ethanol contains separately, the vinyl chloride and the Gas these remaining inert gaseous loading with advantage with the vinyl chloride solution in the dichloro constituents as well as vinyl chloride, traces of acetylene 50 ethane is processed after the synthesis reaction and a slight excess of hydrogen chloride has been obtained from acetylene, and in hydrochloric acid from about 5 to 10%> that in the conversion with chemical acid, which is used for this synthesis. the the acetylene has been used. formed in this heat splitting of the dichloroethane

The vinyl chloride is converted from this gas by adding sufficient hydrochloric acid to conversion

Suitable measures gained, in particular by 55 with the acetylene from when the conditions of the

Dissolve in dichloroethane at a temperature of heat splitting of the used as starting product

0 to - 30 ° C. This vinyl chloride must be separated from hydrocarbons, especially naphtha

because it would otherwise be chosen in the following stage, namely that the gas obtained is acetylene

the synthesis of dichloroethane, with the chlorine after and the ethylene in a volume ratio of

would react to the following equation: 60 contains approximately 1.

η tr r \ 1 r \ , run The method according to the invention is illustrated by hand

of the example below.

The vinyl chloride is then from its solution in

the dichloroethane removed and by distillation example

cleaned. 65

Thereupon the cracked gas, which is no longer acetylene In a cracking furnace for hydrocarbons like him

contains, heated to a temperature of 70 to 90 ⁰ C in the Belgian patent 568 010 described

and mixed with chlorine before it has been put into the second catalytic converter, a hydrogen-rich fuel gas is used

Oxygen is burned, and in the thus obtained hot That is purified under pressure and in the pipe for the

Combustion gases will not contain the gas sent to a temperature of synthesis of vinyl chloride

about 600 ⁰ C preheated naphtha is injected. more than 120 parts per million hydrocarbons with

The processed naphtha has the following own 3 carbon atoms and 20 parts per million coal sheep th: 5 hydrogens with 4 carbon atoms.

Df = 0.703 The reactor for the synthesis of vinyl chloride

Kp. = 27 to 125 ° C consists of a steel tube 2.5 m in length and

Content of paraffin hydrocarbons = 77% ³³ ™ ^m * ^{icht icht icht} !, ' ^{That of a coat for the}

Umlaut is surrounded by a coolant. In this

The cracking furnace is operated under a pressure of 10 ata io tube, a mixture of cracking gas and chlorine. The fission gas, which has been quenched for thermal stabilization hydrogen with an excess of hydrogen chloride sation of the acetylene formed of about 5% compared to the stoichiometric, corresponds to the following composition (amount of ana introduced, namely in an amount of lysis calculated on the dry Gas): approx. 1501 (measured at O ⁰ C and 760 mm Hg) _TT „ _{n rr} . ,. . 15 per hour and liter of catalyst. This catalyst ^H * ^{38 '50} percent by volume ^J _{consists of activated carbon> which with 10} o _{/ o} Q _uec ksilber-

^N 2 is 3.23 percent by volume chloride impregnated. The synthesis reaction is at

CO 15.80 percent by volume at a temperature of about 120 ⁰ C and below one

CO ₂ carried out 11.84 percent by volume pressure of 10 ata. The yield at

CH ₄ ....'... '.'. '.'. '.'. '.'. '.'. '. 9.39 percent by volume ³⁰ Vinyl chloride is above 99.5 ° / _0th

“Ο ία ν 1 £ * ^{as there} is gas emerging from this reactor

^C 2 ^{H2 y} ' ^Jj volume _{percent alg0 from a mixture of} vinyl chloride and the

^C 2 ^H 4 · · 9.30 percent by volume of the main constituents of the cracked gas with the exclusion of

C ₂ H ₆ 0.39 percent by volume acetylene, of which only traces are left

Ca hydrocarbons are 1.38 percent by volume ² S, and part of the hydrocarbons with

^ -Hydrocarbons .... 0.84 percent by volume ³ » ^{and 4} carbon atoms.

This gas mixture is treated with dichloroethane,

The cracked gas is before it is in the plant for synthesis through which the vinyl chloride is dissolved. Instead of of the vinyl chloride is sent, a pre-cleaning dichloro can also use another solvent subjected to the carbon black and the tar material 30 used from this, but preferably dichloroethane is used as well as the unsaturated hydrocarbons with 3 and used as it is generated in the course of the overall process Remove 4 carbon atoms that will otherwise be on.

that used for the synthesis of vinyl chloride For this absorption of vinyl chloride by the

Polymerize the catalyst and thus this catalyst will deactivate about 21 dichloroethane per sator. 35 hours per 2.5 m ³ / h gas (measured at 0 ⁰ C and

The cracked gas also contains CO ₂ , which is a neutral component like 760 Torr) at a temperature of about -30 ° C, but is expediently used under a pressure of 10 ata. This is removed, because this CO ₂ unnecessarily dilutes the further dichloroethane, which has dissolved the vinyl chloride, to be processed. is sent to a degassing column, whose

These different components and in particular the temperature at the foot depends on the pressure, these hydrocarbons with 3 and 4 carbon - which is used in degassing. These degassing atoms using the in the Belgian sung can be carried out at atmospheric pressure Patent specification 582 826 ent- the temperature is then 80 to 95 ° C. If the far, that essentially from the following gasification carried out at 10 ata, then the driving stages: 45 temperature about 180 ° C, but in this case,

to prevent the polymerisation of vinyl chloride,

Removal of the carbon black and tar-like substances _e i _n a polymerization inhibitor, such as phenol or Hydro by washing with oil; quinone, can be added. To this polymerization

To prevent the removal of the carbonic acid by a hot one of ^the vinyl chloride, a phenol-potassium carbonate solution is sufficient; ⁵ ° concentration of about 0.1% of the weight of the

Dichlorathans.

Removing most of the hydrocarbons from solution in dichloroethane in freedom

Substances with 3 and 4 carbon atoms by put vinyl chloride contains a small amount Washing the cracked gas with kerosene. Hydrogen chloride, some of the ethylene and the

55 Total amount of hydrocarbons with 3 and

This cleaning with kerosene at a tem- 4 carbon atoms, which have been dissolved in the dichloroethane temperature from -30 to -40 ⁰ C using. The vinyl chloride is distilled, about 500 l of kerosene per 100 ± 5 m ^{3 of} cracked gas (calculated separated from the hydrogen chloride and then a rectibei0 ^c C and 760 Torr) carried out. One can, however, be subject to fication. The hydrogen chloride (also a less extensive purification with the 60 speaking the excess of 5%) and the ethylene carry out kerosene, ie at a slightly higher temperature are sent back into the reactor for the synthesis of the vinyl and with a smaller amount of chloride This gives the advantage of kerosene, provided that this purifying light, the degassing and the distillation is completed with a further purification, because it compresses the hydrogen chloride returned, for example, by the gas via activated carbon or 65 is avoided by being sent through sulfuric acid. The choice of which, however, would be necessary if this degassing depends on one or the other of these working methods and this distillation at atmospheric pressure depends mainly on economic considerations. be performed.

The gas mixture not dissolved in the dichloroethane has the following composition:

H ₂ 50.24 volume percent

N ₂ 4.21 volume percent

CO 20.62 percent by volume

CH ₄ 12.25 volume percent

C ₂ H ₂ 0.05 volume percent

C ₂ H ₄ 12.13 volume percent

C ₂ H ₆ 0.50 volume percent

To this gas mixture, based on the ethylene contained in this mixture, chlorine is added in a stoichiometric amount, and the reactants are then sent to a reactor for the synthesis of dichloroethane. This reactor consists of a steel tube 2.50 m long and 40 mm inside diameter, which is surrounded by a jacket for the circulation of cooling oil. The synthesis is carried out at a temperature of 130 ^° C. and under a pressure of 10 ata. The chlorine is maintained at a temperature of about 100 ⁰ C.

The reaction can be carried out without the use of a catalyst, since it is due to the Walls of the reaction tube or by ferric chloride particles is introduced by the action of the chlorine are formed on the walls.

It was found that under these conditions the ethylene with a yield of practically 100% is converted into dichloroethane and that the carbon monoxide and the others the ethylene accompanying gaseous constituents practically do not react.

The products emerging from this second reactor are under a pressure of 10 ata -33 ° C cooled, whereby on the one hand liquid dichloroethane is obtained, which is distilled, and on the other hand a residual gas that is used for the generation of the hot Gases is used in which the naphtha is split at the beginning of the cycle. This residual gas consists:

H ₂ 57.17 volume percent

N ₂ 4.79 volume percent

CO 23.46 percent by volume

CH ₄ 13.94 volume percent

C ₂ H ₂ 0.06 volume percent

C ₂ H ₆ 0.58 volume percent

The distilled, evaporated and preheated to a temperature of 450 ° C dichloroethane is cleaved under a pressure of 8 kg / cm ² in the presence of deashed activated carbon, ie according to the process described in Belgian patent 563,247. In this way a further amount of vinyl chloride is obtained as well as hydrogen chloride which is returned to the first reactor for the synthesis of vinyl chloride. The yield of this thermal cleavage is 99% with a conversion ratio of the dichloroethane from about 65% J ^s passage.

As a result of the totality of these procedural measures, 800 kg of oxygen, 900 kg of naphtha and kg of chlorine 1 t of vinyl chloride obtained, without the acetylene and ethylene in the pure beforehand State were transferred.

Claims (3)

Patent claims: 1. A process for the production of vinyl chloride prepurified from a in a known way, by pyrolysis cracking gas obtained in the presence of impregnated with mercury chloride activated carbon as catalyst, characterized in that the acetylene contained in the reformed gas at 100 to 14O ⁰ C and a pressure of 10 Atm , at a throughput of 125 to 175 l / h (measured at O ⁰ C and 760 Torr) and per liter of catalyst reacted with hydrogen chloride and separated and optionally reacted the unreacted ethylene with chlorine at 50 to 15O ⁰ C and the dichloroethane obtained in is cleaved in a known manner into vinyl chloride and hydrogen chloride. 2. The method according to claim 1, characterized in that the synthesis of dichloroethane from Ethylene and chlorine is catalyzed through the walls of the steel reactor in which the Synthesis is carried out. Considered publications:
German Patent No. 763 141;
British Patent No. 603,099; U11 m a η η, Encyclopedia of Technical Chemistry, 3rd edition, Vol. I. (1951), p. 789. 409 628/328 6.64 © Bundesdruckerei Berlin