DE3804265A1 - Process for the preparation of trichloroethylene - Google Patents

Abstract

Trichloroethylene is prepared from perchloroethylene and hydrogen by impregnating the activated carbon/rhodium/copper contact catalyst with organic phosphine or phosphite compounds to increase the conversion.

Description

The invention relates to a new method of manufacture of trichlorethylene from perchlorethylene and hydrogen using of a copper / rhodium catalyst with phospines or phosphites is impregnated.

In EP-PS 5 263 a process for the production of Trichlorethylene from perchlorethylene and hydrogen under Using a catalyst described, which consists of a Activated carbon carrier, copper in elementary or chemically bound Form and palladium, ruthenium or rhodium in elementary or chemically bound form. Like this one Publication is an essential point of catalytic Hydrogenation of perchlorethylene to trichlorethylene, start the reaction at the lowest possible temperature, the decrease in activity of the catalyst over a longer operating period to be able to counteract this by increasing the temperature.

The object of the invention was therefore to provide a catalyst develop compared to known systems for manufacturing of trichlorethylene from perchlorethylene at lower Temperatures lead to higher sales.

Surprisingly, the problem came through using it of copper / rhodium contacts, which with phosphines or Phosphites have been impregnated.  

The invention relates to a method for manufacturing of trichlorethylene from perchlorethylene and hydrogen using a supported catalyst consisting of activated carbon more than 500 m² / g BET surface area, 0.5 to 20% by weight copper in elementary or chemically bound form and 0.01 to 0.5 % By weight of rhodium in elemental or chemically bound form, at a temperature of 150 to 300 ° C and one Hydrogen pressure from 1 to 10 bar, characterized in that the catalyst with 0.05 to 5 wt .-% of an organic Phosphine or phosphite compound is impregnated.

Activated carbon, preferably granular, is used as the catalyst support Form, with a BET surface area of more than 500 m² / g and a grain size of 1 to 5 mm.

The copper is 0.5 to 20 wt .-%, preferably 5 to 15 wt .-%, in elemental or chemically bound form applied the carrier. Preferably water-soluble Copper salts used. CuCl₂ is particularly preferably used.

Rhodium is 0.01 to 0.5 wt .-%, preferably 0.02 to 0.2% by weight, in elemental or chemically bound form applied. Water-soluble rhodium compounds are preferred used. Complex salts are particularly preferred of the Rh (III) chloride.

The catalyst support covered with copper and rhodium becomes with 0.05 to 5.0% by weight, preferably with 0.2 to 2.0% by weight, impregnated organic phosphine and / or phosphite compounds. Triarylphosphines and triarylphosphites are preferred used. Triphenylphosphine is particularly preferred and triphenyl phosphite.  

To produce the catalyst, the activated carbon is preferred with aqueous solutions of the copper or rhodium salt, sprayed and then dried in a stream of nitrogen. Contact with a solution can be used for impregnation of the phosphine or phosphite soaked in perchlorethylene and then dried. Other impregnation methods, e.g. B. Spray impregnation are also permitted. Another variant is that the perchlorethylene used for the reaction, the phosphines or Phosphites are introduced into the reactor.

To convert the perchlorethylene, the catalyst is in poured into a reaction tube. The Reaction is carried out at a temperature of 150 to 300 ° C and carried out under a pressure of 1 to 10 bar. The Perchlorethylene is used in amounts of 0.5 to 5 moles per hour and per liter of contact mass together with the 0.1 to 1 times the molar amount of hydrogen reacted.

example 1

Grained activated carbon of the name Degusorb WS IV Spezial, from Degussa, is soaked with an aqueous CuCl₂ solution and an aqueous Na₃RhCl₆ solution and dried so that the Rh content is 0.044% by weight and the Cu content is 10% .-% lies. The dried catalyst is pasted with triphenylphosphine dissolved in perchlorethylene, then the solvent is evaporated. The amounts were chosen so that 1 wt .-% triphenylphosphine, based on activated carbon, is present. The trichlorethylene production is carried out in a single-tube reactor with a catalyst volume of 400 ml. The reactor is charged with 48 g / h perchlorethylene and 10 l / h hydrogen. The reaction pressure is 1 bar _abs . The conversion rates to trichlorethylene depending on the reaction temperature are listed in Table 1.

Example 2

Analogous to Example 1, instead of triphenylphosphine Impregnated catalyst with triphenyl phosphite.

Comparative Example 1

Analogous to Example 1, but without the addition of phosphine or phosphite.

Table 1

Conversion to trichlorethylene in the reaction product in% by weight

Claims (4)

1. Process for the preparation of trichlorethylene from perchlorethylene and hydrogen using a supported catalyst consisting of activated carbon with more than 500 m² / g BET surface area, 0.5 to 20% by weight of copper in elemental or chemically bound form and 0.01 to 0.5% by weight of rhodium in elemental or chemically bound form, at a temperature of 150 to 300 ° C and a hydrogen pressure of 1 to 10 bar, characterized in that the catalyst contains 0.05 to 5% by weight of a organic phosphine or phosphite compound is impregnated. 2. The method according to claim 1, characterized in that the catalyst with 0.2 to 2.0 wt .-% of an organic Phosphine or phosphite compound is impregnated. 3. The method according to claim 1 or 2, characterized in that as an organic phosphine or phosphite compound Triarylphosphine or Triarylphosphite used will. 4. The method according to claim 1 or 2, characterized in that as an organic phosphine or phosphite compound Triphenylphosphine or triphenylphosphite used becomes.