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(11) | EP 0 000 847 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Vinyl chloride monomer production Herstellung von monomeren Vinylchlorid Production de chlorure de vinyle monomère |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The present invention relates to an essentially non-catalytic process for the preparation of vinyl chloride by the dehydrochlorination of mixtures of isomeric dichloroethanes.
[0002] It is known that vinyl chloride can be produced by the pyrolytic dehydrochlorination of 1,2-dichloroethane. The process involves the passing of 1,2-dichloroethane through a small diameter reaction tube in which it is heated to elevated temperatures to bring about the dehydrochlorination thereof. In contrast to this, it has not hitherto been possible to convert the isomeric 1,1-dichloroethane, which is a byproduct of the pyrolysis of 1,2-dichloroethane, into vinyl chloride in economic yields. US-A-2569923 describes a method of pyrolysing a mixture of 90% 1,1-dichloroethane and 10% 1,2-dichloroethane. However this mixture results only in a 35% conversion.
[0003] It has now been found that mixtures of these isomers can be pyrolysed without impairing the quality or yield of vinyl chloride monomer produced by regulating the concentration of the two isomers in the mixture being pyrolysed.
[0004] Accordingly, the present invention is a process for producing vinyl chloride comprising pyrolysing at elevated temperature 1,2-dichloroethane mixed with between 0.1 and 10% by weight of 1,1-dichloroethane.
[0005] The above reaction may be carried out in conventional tubular reactors as normally employed for the pyrolysis of 1,2-dichloroethane. The pyrolysis of mixtures of 1,1-dichloroethane and 1,2-dichloroethane in the specified range of concentrations significantly increases the conversion of 1, i-dichloroethane from about 20% (for the pure isomer) to above 90% (when present in the isomeric mixtures). Both below and above this range the conversion of the 1,2-isomer is depressed relatively. The amount of the 1,1-dichloroethane in the isomeric mixture being pyrolysed is preferably between 1 and 8%. The 1,1-isomer may be mixed with the pyrolysis feed prior to the introduction thereof into the reaction zone. Alternatively it may be incorporated in the pyrolysis feed in the reaction zone itself at the time of pyrolysis.
[0006] The pyrolysis of the isomeric mixtures may be carried out in packed or unpacked tubular reactors. Where packed reactors are used they may suitably be packed with ceramic spheres.
[0007] The pyrolysis of the isomeric mixture of dichloroethanes according to the present invention is suitably carried out at a temperature of between 450° and 550°C, preferably between 500° and 535°C.
[0008] The pyrolysis of the isomeric mixture of dichloroethanes may be carried out at subatmospheric, atmospheric or super-atmospheric pressures. It is, however, preferred to use super- atmospheric pressure, preferably below 35 atmospheres.
[0009] The pyrolysis of the isomeric mixture of dichloroethanes may be carried out in a continuous manner.
[0010] The advantages of the present invention are illustrated with reference to the following Examples.
EXAMPLES
[0011] The apparatus, run at atmospheric pressure, consisted of feed reservoir, metering pump, vaporiser, cracker tube, coolers, organic product receiver, hydrogen chloride scrubbing column, scrub liquor reservoir and wet gas meter. There was also a nitrogen diluent/carrier feed applied to the vaporiser inlet.
[0012] Feedstocks comprising pure 1,2-dichloroethane (1,2-EDC), 1,2-dichloroethane with up to 10 per cent by weight of 1,1-dich)oroethane (1,1-DCE) and also pure (98.2% by weight) 1,1-DCE were pyrolysed at a peak temperature of 500°C and a contact time of 4.5 seconds under conditions found to give a 50 per cent by weight conversion of pure 1,2-dichloroethane.
1. An essentially non-catalytic process for producing vinyl chloride by pyrofysing
.1,2-dichloroethane at elevated temperature characterised in that 1,2-dichloroethane
is mixed with between 0.1 and 10% by weight of 1,1-dichloroethane.
2. A process according to claim 1 characterised in that the amount of 1,1-dichloroethane
in the isomeric mixture being pyrolysed is between 1 and 8% by weight.
3. A process according to claim 1 or claim 2 characterised in that the pyrolysis of
the isomeric mixture of dichloroethanes is carried out at a temperature between 450°C
and 550°C.
4. A process according to claim 3 characterised in that the pyrolysis of the isomeric
mixture of dichloroethanes is carried out at a temperature between 500 and 535°C.
5. A process according to any of the preceding claims characterised in that the pyrolysis
of the isomeric mixture of dichloroethanes is carried out at superatmospheric pressures.
6. A process according to claim 5 characterised in that the superatmospheric pressure
is below 35 atmospheres.
7. A process according to any of the preceding claims characterised in that the pyrolysis
of the isomeric mixture of dichloroethanes is carried out in a continuous manner.
1. Procédé essentiellement non catalytique pour produire du chlorure de vinyle par
la pyrolyse du 1,2-dichloréthane à température élevee, caractérisé en ce qu'au 1,2-dichloréthane
est mélangé de 0,1 à 10% en poids de 1,1-dichloréthane.
2. Procédé selon la revendication 1, caractérisé en ce que la proportion du 1,1-dichloréthane
dans le mélange des isomères soumis à la pyrolyse se situe entre 1 et 8% en poids.
3. Procédé selon l'une des revendications 1 et 2, caractérisé en ce que la pyrolyse
du mélange des dichloréthanes isomères est effectuée à une température comprise entre
450°C et 550°C.
4. Procédé selon la revendication 3, caractérisé en ce que la pyrolyse du mélange
des dichloréthanes isomères est effectuée à une température comprise entre 500° et
535°C.
5. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce
que la pyrolyse du mélange des dichloréthanes isomères est effectuée à des pressions
supérieures à la pression atmosphérique.
6. Procédé selon la revendication 5, caractérisé en ce que la pression supérieure
à la pression atmosphérique est inférieure à 35 atmosphères.
7. Procédé selon l'une quelconque des revendications précédentes, caractérisé en ce
que la pyrolyse du mélange des dichloréthanes isomères est effectuée de façon continue.
1. Ein im wesentlichen nicht-katalytisches Verfahren zur Herstellung von Vinylchlorid
durch Pyrolyse von 1,2-Dichloräthan bei erhöhter Temperatur, dadurch gekennzeichnet,
daß 1,2-Dichloräthan mit zwischen 0,1 und 10 Gew.-% 1,1-Dichloräthan gemischt wird.
2. Ein Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, daß die Menge von 1,1-Dichloräthan
in der zu pyrolysierenden lsomerenmischung zwischen 1 und 8 Gew.-% liegt.
3. Ein Verfahren gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Pyrolyse
der lsomerenmischung der Dichloräthane bei einer Temperatur zwischen 450° und 550°C
durchgeführt wird.
4. Ein Verfahren gemäß Anspruch 3, dadurch gekennzeichnet, daß die Pyrolyse der Isomerenmischung
der Dichloräthane bei einer Temperatur zwischen 500° und 535°C durchgeführt wird.
5. Ein Verfahren gemäß einem der vorgehenden Ansprüche, dadurch gekennzeichnet, daß
die Pyrolyse der Isomerenmischung der Dichloräthane bei überatmosphärischen Drucken
durchgeführt wird.
6. Ein Verfahren gemäß Anspruch 5 dadurch gekennzeichnet, daß der überatmosphärische
Druck unterhalb 35 Atmosphären liegt.
7. Ein Verfahren gemäß einem der vorgehenden Ansprüche dadurch gekennzeichnet, daß
die Pyrolyse der Isomerenmischung der Dichloräthane kontinuierlich durchgeführt wird.