Bulk catalysts based on chromium and on nickel for the gas-phase fluorination of halogenated hydrocarbons

Abstract

Catalysts which are useful in the fluorination of halogenated hydrocarbons by HF in the gas phase are obtained by simple impregnation of a bulk chromium oxide with a solution of a nickel derivative, the chromium oxide used exhibiting a BET specific surface of greater than 150 m 2 /g and a pore volume of greater than 0.15 ml/g.

1 . Bulk catalysts based on chromium and on nickel which are obtained by impregnation of an amorphous chromium III oxide with a solution of a nickel derivative, characterized in that the chromium oxide used exhibits a BET specific surface of greater than 150 m 2 /g and a pore volume of greater than 0.15 ml/g.  
     
     
         2 . Catalysts according to  claim 1 , which are obtained from a chromium oxide having a BET specific surface of greater than 180 m 2 /g.  
     
     
         3 . Catalysts according to  claim 1  or  2 , which are obtained from a chromium oxide exhibiting a pore volume of greater than 0.18 ml/g.  
     
     
         4 . Catalysts according to one of  claims 1  to  3 , in which the chromium oxide used originates from the calcination of a chromium III hydroxide precipitate or from the reduction of chromium VI oxide.  
     
     
         5 . Catalysts according to one of  claims 1  to  4 , in which the nickel derivative is a nickel II oxide, hydroxide, halide, oxyhalide, nitrate or sulphate, preferably nickel chloride.  
     
     
         6 . Catalysts according to one of  claims 1  to  5 , in which the Ni/Cr atomic ratio is between 0.01 and 1, preferably between 0.02 and 0.6 and more particularly between 0.02 and 0.4.  
     
     
         7 . Catalysts according to one of  claims 1  to  6 , which are obtained by means of an aqueous or alcoholic solution of a nickel derivative.  
     
     
         8 . Process for the catalytic fluorination of saturated or olefinic halogenated hydrocarbons by HF in the gas phase, characterized in that a catalyst according to one of  claims 1  to  7  is used.  
     
     
         9 . Process according to  claim 8 , in which, before it is used, the catalyst is dried under an inert gas or under air at a temperature of between 100 and 350° C. and then activated with HF.  
     
     
         10 . Process according to  claim 9 , in which the HF is first introduced diluted in air or, preferably, in an inert gas at a temperature ranging from 150 to 200° C. and then pure at a temperature of less than 400° C., preferably of between 350 and 380° C.  
     
     
         11 . Process according to one of  claims 8  to  10 , in which the fluorination temperature is between 50 and 500° C., preferably between 100 and 450° C. and more particularly between 120 and 400° C.  
     
     
         12 . Process according to one of  claims 8  to  11 , in which the contact time is between 3 and 100 seconds, preferably less than 30 seconds.  
     
     
         13 . Process according to one of  claims 8  to  12 , in which the molar ratio: HF/halogenated hydrocarbon(s) is between 1/1 and 30/1, preferably less than 20/1.  
     
     
         14 . Process according to one of  claims 8  to  13 , in which the fluorination is carried out at an absolute pressure of between 0.08 and 2 MPa, preferably between 0.1. and 1.5 MPa.  
     
     
         15 . Process according to one of  claims 8  to  14 , in which the fluorination is carried out in the present of an oxidizing agent, preferably oxygen or air.  
     
     
         16 . Process according to one of  claims 8  to  15 , in which the catalyst, deactived by coking, is regenerated by treatment with air or with oxygen or by a Cl 2 /HF mixture, at a temperature of between 250 and 400° C.  
     
     
         17 . Process according to one of  claims 8  to  16 , in which the halogenated hydrocarbon is perchloroethylene or 1-chloro-2,2,2-trifluoroethane.