Process and apparatus for obtaining krypton and/or xenon

Abstract

The process and apparatus are used to obtain krypton and/or xenon by cryogenic separation of air. Krypton and xenon are enriched to form a krypton/xenon concentrate. Krypton and/or xenon is obtained from the krypton/xenon concentrate by means of distillation. Prior to distillation, the krypton/xenon concentrate is passed over a catalyst bed which contains TiO<SUB>2 </SUB>and/or ZrO<SUB>2</SUB>. In the process, at least one halogen compound contained in the krypton/xenon concentrate is reacted.

1 . Process for obtaining krypton and/or xenon by cryogenic separation of air, in which krypton and xenon are enriched to form a krypton/xenon concentrate and krypton and/or xenon are obtained from the krypton/xenon concentrate by means of distillation, characterized in that the krypton/xenon concentrate is passed over a catalyst bed which contains a transition metal oxide, in particular TiO 2  and/or ZrO 2 , and at least one fully halogenated compound contained in the krypton/xenon concentrate, in particular at least one fully fluorinated compound, is reacted in the catalyst bed.  
     
     
         2 . Process according to  claim 1 , characterized in that the catalyst bed is operated at a temperature of 650° C. or more, in particular of 700° C. or more.  
     
     
         3 . Process according to  claim 1  or  2 , characterized in that at least one hydrogen halide is produced during the reaction and the krypton/xenon concentrate, downstream of the catalyst bed, is fed to a purification stage for removing the hydrogen halide.  
     
     
         4 . Process according to  claim 3 , characterized in that the purification stage includes a scrub, in particular a water or lye scrub.  
     
     
         5 . Process according to one of  claims 1  to  4 , characterized in that the krypton/xenon concentrate, downstream of the catalyst bed, is passed through an adsorption bed.  
     
     
         6 . Process according to one of  claims 1  to  5 , characterized in that at least one of the compounds CF 4 , C 2 F 6 , SF 6 , NF 3 , CClF 3  and C 3 F 8  is reacted in the catalyst bed.  
     
     
         7 . Process according to  claim 6 , characterized in that at least one of the following reactions is carried out in the catalyst bed:  
         CF 4 +2H 2 O→CO 2 +4HF  C 2 F 6 +3H 2 O+0.5O 2 →2CO 2 +6HF  SF 6 +3H 2 O→SO 3 +6HF  NF 3 +1.5H 2 O→NO x +3HF  CF 3 Cl+2H 2 O→CO 2 +3HF+HCl  
     
     
         8 . Apparatus for obtaining krypton and/or xenon by cryogenic separation of air, having at least one separation column for nitrogen/oxygen separation, having means for extracting a krypton/xenon concentrate from the separation column, having a distillation device for obtaining krypton and/or xenon from the krypton/xenon concentrate, characterized by a purification device which has a catalyst bed that contains TiO 2  and/or ZrO 2 , the purification device being arranged upstream of the distillation device for obtaining krypton and/or xenon from the krypton/xenon concentrate and having means for introducing krypton/xenon concentrate into the catalyst bed.  
     
     
         9 . Apparatus according to  claim 8 , characterized by a purification stage for removing hydrogen halide from the krypton/xenon concentrate, the purification stage being arranged downstream of the catalyst bed and upstream of the distillation device and in particular having a scrubbing column.  
     
     
         10 . Apparatus according to  claim 8  or  9 , characterized by an adsorption bed for purifying the krypton/xenon concentrate, which is arranged downstream of the catalyst bed and upstream of the distillation device.