DE1100616B - Process for the production of vinyl chloride by thermal cleavage of ethylene chloride - Google Patents

Description

It is known that monomeric vinyl chloride can also be used in addition to the addition of hydrogen chloride to acetylene by alkaline, thermal or catalytic elimination of hydrogen chloride from ethylene chloride (1,2-dichloroethane) can produce. This process is particularly interesting because it uses ethylene as a starting material, which is much more economical to produce using petrochemicals than acetylene. Because of the only minor Lifetime of the catalysts for splitting off hydrogen chloride (e.g. barium chloride on activated carbon) usually the purely thermal elimination of hydrogen chloride is preferred. This runs smoothly at temperatures between 450 and 550 ° C in an empty pipe. The only disadvantage here is that very long reaction times (generally 5 to 20 seconds) are required and therefore the capacity of such systems is low. Large reaction spaces are required, which also have large heat exchange surfaces must be equipped to pass the heat of the gap through the reaction walls to be able to. It would now be obvious to shorten the reaction time by increasing the reaction temperature. However, this measure alone does not lead to success, since unwanted side reactions such. Legs On the other hand, there is an increase in the already considerable soot formation on the overheated reaction walls however, the corrosion on the metallic reaction walls can no longer be controlled.

The surprising finding has now been made that the reaction times can be reduced to 0.1 to 0.01 seconds can be shortened if you work between 450 and 900 ° C and the heat does not pass through the reaction walls through, but internally with the help of externally superheated steam. At the same time Soot formation in the reactor completely avoided. In addition, it is achieved that the reactor is no longer made of highly thermally conductive, metallic materials that are particularly susceptible to corrosion, but rather from heat-insulating, corrosion-resistant, ceramic material can be constructed.

It is still unclear whether the shortening of the reaction time achieved according to the invention is solely due to the increase in the (average) reaction temperature or, at least in part, a catalytic influence of the superheated Is attributable to water vapor.

Apparatus suitable for the process is outlined in the appendix.

In furnace 1, the one with air (at 2) and fuel (at 3) is charged, saturated water vapor (at 4) enters and is overheated in coil 5. He kicks (at 6) with 600 to 900 ° C and mixes in the reactor 7 with evaporated ethylene chloride, which occurs at 8. Of the Reactor 7 is made of ceramic material. The reaction products, consisting of vinyl chloride, hydrogen chloride, Steam and unreacted ethylene process for production

of vinyl chloride by thermal

Cleavage of ethylene chloride

Applicant: _

Farbwerke Hoechst Aktiengesellschaft

formerly Master Lucius & Brüning,

Frankfurt / M., Brüningstr. 45

Dr. Günter Rummert, Burghausen / Salzach,
has been named as the inventor

chloride, emerge from the reactor at around 450 ° C and into the cooler 9, which is constructed of graphite. The water vapor condenses and dissolves in the cooler 9 most of the hydrogen chloride. Furthermore, the unreacted ethylene chloride thaws and collects as lower layer under the hydrochloric acid in the accumulation tank 10, from which both products via the lines 16 (ethylene chloride) and 17 (concentrated hydrochloric acid) are drawn off separately.

The vinyl chloride escapes with small amounts of hydrogen chloride and traces of impurities Line 11 from and into the contact tube 12 with a catalyst made of mercury chloride Activated charcoal is filled and heated to 150 ° C. The purpose of the catalyst is to remove traces of chloroacetylene (ClC = CH) and dichloroacetylene (ClC = CCl), which arise as by-products and the polymerization would interfere to render harmless by the addition of hydrogen chloride. The thus purified vinyl chloride enters the tower 13, which is coated with packing elements, in which sodium hydroxide solution is circulated by means of a pump 14. Spent caustic soda is drawn off via line 19, while fresh lye is added via line 18 will. This caustic wash removes the rest of the hydrogen chloride, so that one that is free of hydrogen chloride Vinyl chloride exits through line 15. This is then rectified in the usual way in a column and can then be used for polymerization. A small part of the unreacted ethylene chloride still falls in the bottom of the vinyl chloride column. It is combined with the accumulated via line 16, together with distilled crude ethylene chloride and returned to the cleavage.

109 52S / 704

Claims (1)

3 4 An example should explain the process in more detail: Im announce in a temperature range of 450 to 900 ° C. Oven 1 generates 1000 kg of water vapor per hour 800 ° C overheated. This water vapor is conducted via impurities in the form of acetylene or halogen 8 1500 kg / h of ethylene chloride vapor of 200 ° C to produce acetylene. In addition, according to the invention admixed and in the reactor 7, which has a free volume 5, the ethylene chloride with an already otherwise übervon 301 owns, brought to sales. In the cooler 9, water vapor is heated only in a well-insulated reaction condensed, whereupon from the accumulation vessel 101300 kg / h chamber brought together and in this way the 31% hydrochloric acid and 460 kg of ethylene chloride deducted prevents carbon deposition, which would otherwise be high. 620 kg / h of pure vinyl chloride are obtained. From heated reaction tubes by the inevitable At the bottom of the vinyl chloride column, further overheating of the walls of the reaction space occurs kg / h of ethylene chloride recovered. occurs. It wasn't obvious that this was the case Way the carbon deposition can be prevented The following conclusion could be drawn: could. In the method of the invention promotes the water Enforced 1500 kg / h of ethylene chloride vapor on the one hand, the desired reaction and takes over In the accumulation tank 10, on the other hand, the role of the heat transfer medium is also retained, so that Wonnen 460 kg / h ethylene chloride a particularly soft and balanced form of the From the VC column back heating finds. obtained 35 kg / h of ethylene chloride " ^s :. 2i 1 claims: Implemented thus 1005 kg / h of ethylene chloride _{20 χ Ver} f Ahren by for the production of vinyl chloride Obtained from vinyl chloride ... 620kg / h thermal cleavage of ethylene chloride, thereby The yield is thus: characterized in that the reaction with externally QQ f) fi? N 1 fin heated steam and dwell times from 0.1 to = 97.7% 0.01 seconds in the temperature range from 450 to 62.5-1005 a ₅ 900 ° C is carried out and that the secondary 1005 products occurring chlorine compounds of the Ace- with a conversion per pass of __ = 67 ° / ₀ . _{tykns by} ^ i ^ rvng of hydrogen chloride in higher boiling compounds transferred and the latter After the distillation, the vinyl chloride was well poly- from the vinyl chloride formed by distillation merizable. 3 ° can be separated. A method is already known in which in counter- 2. The method according to claim 1, characterized by War of larger amounts of water vapor ethylene dichloride shows that in reaction chambers of fireproof, is pyrolyzed to vinyl chloride. But because they are working with ceramic material. Temperatures from 800 to 1000 ° C and very long process 3. The method according to claim 1, characterized in that while work is being carried out, this method results in 35 that the addition of hydrogen chloride side by side acetylene and vinyl chloride. The presence of the chlorine compounds of acetylene catalytically Lowing invention has set itself the task of being carried out. Pyrolysis of ethylene chloride essentially only Vinyl chloride and achieves this goal through considered publications: Use of very short dwell times of 0.1 to 0.01 seconds. 1 sheet of drawings © 103 525 / 704-2.61