DE1281432B - Process for the production of unsaturated chlorinated hydrocarbons - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN jmTQS® PATENT OFFICE

EDITORIAL

Int. Cl .:

German class:

Number: File number: Filing date: Display date:

C07c

BOIj

12 ο-19/02

12 g-11/00

P 12 81 432.3-42 (W 38432)

January 29, 1965

October 31, 1968

The elimination of hydrogen chloride (dehydrochlorination) from chlorinated hydrocarbons for extraction In chemical engineering, unsaturated compounds become largely catalytic, namely using surface-active substances optionally impregnated with metal salts, preferably Activated carbon. The requirements placed on the contact carriers used are usually very high placed, namely large active surface, favorable pore distribution, a relatively narrow area in the diameter of the micropores, sufficient access through macropores and finally great purity, in particular the absence of interfering metal salts.

Metallic impurities are either in the raw material, such as diatomaceous earth, clay or coal, Petroleum coke, contain, or there are relatively pure raw materials that are poor in interfering metals, z. B. Coconut shells or peat. Be used for chemical activation of the charred substances activating salts, such as zinc chloride, added, which cannot be completely washed out afterwards have it removed. Since various metal salts, ζ. Β. Iron (III) chloride in catalytic dehydrochlorination lead to the formation of by-products, the latter are made according to the process of the USA patent 2981764 with dilute nitric acid or according to US Pat. No. 2,912470 with dilute Hydrochloric acid dissolved out and removed by intensive rewashing. The analytical control shows, however, that it is not possible by the specified washing process to remove the metal salts contained to remove even remotely. In particular, iron and zinc compounds can only be used reduce a content of 60 to 70% of the original amount.

It has been now found a process for preparing unsaturated chlorinated hydrocarbons by dehydrochlorination of saturated or unsaturated chlorinated hydrocarbons at a higher temperature in the presence of catalysts found, which is characterized in that the dehydrochlorination at 130 to 34O ⁰ C in the presence of surface-active substances, preferably activated carbons one, which have been treated with solutions of the oxo acids or from alkali salts of the oxo acids of the elements phosphorus or silicon, performs as catalysts.

This makes it possible to make the disturbing impurities of the surface-active substances ineffective, so that the formation of by-products in the catalytic cleavage largely or completely does not occur.

Process for the production of unsaturated
Chlorinated hydrocarbons

Applicant:

Wacker-Chemie G. m. B. H.,

8000 Munich 22, Prinzregentenstr. 22nd

Named as inventor:

Dr. Otto Fruhwirth, 8263 Burghausen;

Eduard Pichl, 8261 Mehring

For the treatment of the surface-active substances, 0.1 to 50 percent, preferably 1 to 20 percent solutions of orthophosphoric acid or solutions of acidic salts of phosphoric acid, preferably the primary sodium phosphate is used.

Solutions of neutral alkali metal phosphates or alkali metal silicates, preferably trisodium phosphate, can also be used or potassium silicate. Solutions of the alkali salts of pyro- or meta-phosphoric acid, preferably tetrasodium pyrophosphate or sodium hexametaphosphate, can also to be used.

Furthermore, solutions of alkali salts of polymeric phosphoric acids, preferably sodium tripolyphosphate, use for the treatment of surface-active substances.

But also a pretreatment of the surface-active substances with 0.1 to 5 percent, preferably 0.5 to 3 percent aqueous solutions of the oxygen acids or salts of the elements phosphorus or silicon can be carried out and this an aftertreatment with concentrated solutions of Alkaline earth chlorides, preferably barium chloride, are connected downstream.

Both saturated and unsaturated chlorinated hydrocarbons are suitable for dehydrochlorination. The number of carbon atoms is 2 to 6, the number of chlorine atoms 1 to 11. That However, the process is preferred for the splitting off of hydrogen chloride from compounds with low chlorine content with 1 to 4 chlorine atoms, such as ethyl chloride, dichloroethane and trichloroethane or dichlorobutane, expedient because the resulting unsaturated compounds, such as vinyl chloride, dichloroethylene, the metallic impurities in the catalytic converter can easily lead to undesirable secondary problems

809 629/1462

3 4

pass over ducts. For example, vinyl chloride with the molecular weight of the chlorine used from the cleavage of 1,2-dichloroethane by trace hydrocarbons is not included in the calculation.
of aluminum, zinc, copper or cobalt chloride For example, when pentachloroethane is split with further, it is split into acetylene, which is loaded with chloride on the active granular activated carbon, which with 30% barium surface completely breaks down with soot formation, in the temperature range of 220 that an early inactivation of the carrier occurs. up to 270 ° C with a throughput of 22 kg HCl / cbm

The treatment of the surface-active substances, contact a splitting capacity of 3501 HCl, related

especially activated charcoal, is achieved either with diluted to 1 cbm contact. For dehydrochlorination

th, 0.1 to 5 percent aqueous solutions, e.g. B. tion of 1,1,2,2-tetrachloroethane is under the same

1 percent phosphoric acid. ίο chen conditions the splitting capacity 260 t HQ, for

This is distributed in an amount on the coal - the cleavage of 1,2-dichloroethane is generally brought about, which corresponds to the absorbency, afterwards only a splitting capacity of 601 HCl / cbm contact is achieved dries and, as usual, e.g. B. achieved with concentrated. Will the activated carbon before impregnation Barium chloride solution, to a content of 30 Ge with barium chloride of a pretreatment with a weight percent impregnated, dried again and a 15 percent solution of primary sodium phosphide If the catalyst produced in this way is subjected to phate or sodium silicate in the contact furnace, the gap is filled, performance of pentachloroethane, tetrachloroethane or

But you can also use concentrated 5- to dichloroethane up to 25% higher than with the same

50 percent solutions, such as 15 percent charcoal, without pretreatment.

Solution of primary sodium phosphate or an ao Implementation of the dehydrochlorination sodium silicate solution go out and this either reaction, with pressures of about 0.5 to 6 ata to by spraying or by dipping, z. B. can be used in Va- is expediently carried out in kuum, apply to the carrier. Subsequently, the interior of the apparatus is replaced by heat-emitting is dried and divided without re-impregnation in the walls that these one from the other Contact furnace filled. In this way it is possible to have a distance of at most approximately 70 mm. Both Dehydrochlorination process, for example, one works in cracking furnaces, in which one works improve and the hitherto almost exclusively used system of tubes is built in, through which with ten barium chloride catalyst (e.g. after German help of a heat transfer medium or with Patent 846 847) to be avoided in whole or in part. high pressure steam emanating outside the pipes

Whether it is more expedient to bring a treatment with the filling arranged to a uniform temperature of the substances mentioned in a diluted or concentrated temperature. But you can also carry out the Kon solution or put the surface-active tact substance into the tubes of a tube bundle. B. oil or a molten salt, on which and then with other, in particular alkali salts, 35 desired temperatures are maintained,
The elimination of hydrogen chloride can be carried out by the same surface-active substances themselves, in particular the extent to which they are contaminated in fluidized bed or fluidized bed reactors, as well as on the chlorinated carbons, the contact with the help of hydrogen, which causes the dehydrochlorination to fall below the flow rate of the Gas should be thrown in suspension. 40 is held. The heat is supplied in this

The surface-active case in question because of the favorable heat exchange through

Substances include both activated carbon in the external heating of the reactor or through in the

various shapes and properties as well as reaction space built-in heating devices, ζ. Β.

mineral substances or those that are activated by activating heating coils.

are obtained from mineral substances, such as. B. 45 The appropriate degree of conversion for one-time montmorillonite, fuller's earth, pumice stone, kieselguhr passage is largely from the starting materials or clay. addicted. In the case of highly chlorinated carbons, the activated carbons come into consideration, hydrocarbons which achieve an almost complete conversion from hard coal, petroleum coke and the like, whereas it is obtained when using low-chlorinated raw materials and is usually more advantageous through the action of 50 hydrocarbons, which have been activated with incomplete gases . They show a diger implementation (about 40 to 70%) to split. It has considerable ash content, which is largely made up of the dehydrochlorination of di-metal salts. However, active chloroethane, for example according to German patent 1135 451, carbon from organic raw materials, e.g. B. peat, wood carry out. In this case, it is advantageous to use the or nutshells, which are usually determined by chemical conditions described there, ie with activation, e.g. B. with zinc chloride, can be converted into a use attitude of a maximum vinyl chloride partial pressure of capable form. They contain as 0.5 ata, to be worked,
disturbing contamination mainly from the B '' el 1
metal salts derived from chemical activation, "

which are not completely removed by washing out 60 By a contact which corresponds to the

can be. Method of U.S. Patent 2,912,470

For the evaluation of the surface-active substances, 4-hour immersion of commercially available activated carbon for the dehydrochlorination of chlorinated hydrocarbons in 0, In-HCl at 80 ⁰ C and three times, 1-hour furnace, the amount of hydrogen chloride produced per unit of space, after washing with water and drying, is expediently used 65, is passed to 225 ⁰ C heated Tetrachlornachfolgend is referred to as splitting performance. This äthandampf and achieved according to Example 1 of this patent proves to be more expedient than the specification of the split 1300 lb trichlorethylene / lb catalyst. This produced a lot of chlorinated hydrocarbons, because this is 1441 HCl / cbm catalyst.

If the same carbon immersed with lprozentiger aqueous phosphoric acid for 2 hours, separated and re-impregnated after drying with saturated barium chloride solution at 60 ⁰ C, we obtained under the same experimental conditions 3001 HCl / cbm catalyst, so more of than twice the amount compared to the process U.S. Patent 2912470.

Example 2

A small-scale cracking furnace with a useful capacity of 11, consisting of a 1.5 m long iron pipe with a clear width of 32 mm, is filled with granular activated carbon obtained from peat, which has a chemical activation content of 0.2% zinc chloride and without pretreatment has been impregnated with 30 percent barium chloride. Therein is up to 270 ° C at a pressure of 1.5 ata pentachloroethane with a conversion of 95% per pass overall ^ao cleave the temperature range from the 220th With a HCl decrease of 22 g / h. a splitting capacity of 350 kg HCl / cbm catalyst is achieved.

If the same charcoal is treated with 15 percent sodium silicate solution at 60 ° C. for 2 hours, ^{a5 is} separated off and dried, an output of 400 kg HCl / cbm catalyst is achieved under otherwise identical conditions.

Example 3

In the cracking furnace according to Example 2, 1,2-dichloroethane vapor is introduced instead of pentachloroethane and in the temperature range of 240 to 340 ° C at a pressure of 0.8 ata with one reaction of 60%, corresponding to a vinyl chloride partial pressure of 0.24 ata of granulated activated carbon. This is made from hard coal, has an ash content of 6% after gas activation and has finally been impregnated with 26% barium chloride. One achieves in the absence of Water has a splitting capacity of 601 HCl / cbm catalyst.

If the same catalyst is treated with a 2 percent colloidal silica for 4 hours at 80 ° C, separated and dried, an increase in space-time performance of 30% is achieved Increase of the splitting capacity to 90 t HCl / cbm catalyst.

Example 4

Acid-activated montmorillonite with a residual content of 1.5% ferric oxide is mixed with a 20% Sodium tripolyphosphate solution poured over in vacuo at room temperature, dried at normal pressure and in a fluidized bed reactor for dehydrochlorination of 1,1-dichloroethane at 250 ° C with a conversion of 50% per pass used. There is one cracking capacity per cubic meter of catalyst achieved by HOt HCl.

Claims (5)

Patent claims: 1. Process for the production of unsaturated chlorinated hydrocarbons by dehydrochlorination of saturated or unsaturated chlorinated hydrocarbons at higher temperatures in Presence of catalysts, characterized in that the dehydrochlorination at 130 to 340 ° C in the presence of surface-active substances, preferably activated carbons, those with solutions of the oxo acids or of alkali salts of the oxo acids Elements phosphorus or silicon have been treated as catalysts. 2. The method according to claim 1, characterized in that that for catalytic dehydrochlorination, saturated or unsaturated chlorinated hydrocarbons with 2 to 6 carbon atoms can be used. 3. The method according to claim 1 and 2, characterized in that the dehydrochlorination chlorinated hydrocarbons obtained contain 1 to 11, preferably 1 to 4, chlorine atoms. 4. The method according to claim 1 to 3, characterized in that the surface-active Substances with 0.1 to 5 percent, preferably 0.5 to 3 percent aqueous solutions of the Oxygen acids or salts of the elements phosphorus or silicon pretreated and then aftertreated with concentrated solutions of alkaline earth chlorides, preferably barium chloride. 5. The method according to claim 1 to 4, characterized in that at pressures of about 0.5 to 6 ata works. Considered publications:
British Patent No. 950,976;
Japanese Patent Application No. 24870/64.