Electrode and electrode coating

Abstract

The invention describes an electrode and an electrode coating which are based on a catalyst containing finely divided carbon modifications and noble metal (oxide)s.

1 . A catalyst for preparing chlorine by means of electrolysis of electrolytes comprising chlorine ions, wherein said catalyst comprises at least one noble metal of transition group VIIIa (Fe, Ru, Rh, Pd, Os, Ir, Pt) of the Periodic Table of the Elements and/or an oxide of these noble metals, wherein said catalyst additionally comprises at least one finely divided carbon modification selected from the group consisting of diamond, doped diamond, fullerene, carbon nanotubes, and vitreous carbon, and wherein said catalyst optionally comprises at least one valve metal and/or valve metal oxide. 
     
     
         2 . The catalyst of  claim 1 , wherein said catalyst comprises from 10 to 90 mol % of said at least one finely divided carbon modification and from 0.05 to 40 mol % of said at least one noble metal and/or noble metal oxide. 
     
     
         3 . The catalyst of  claim 2 , wherein said catalyst comprises from 20 to 80 mol % of said at least one finely divided carbon modification and from 1 to 20 mol % of said at least one noble metal and/or noble metal oxide. 
     
     
         4 . The catalyst of  claim 1 , wherein said catalyst comprises from 0.05 to 40 mol % of said at least one noble metal and/or noble metal oxide, from 9.95 to 60 mol % of said at least one valve metal and/or valve metal oxide, and from 20 to 90 mol % of said at least one finely divided carbon modification. 
     
     
         5 . The catalyst of  claim 1 , wherein said at least one finely divided carbon modification is diamond and/or boron-doped diamond. 
     
     
         6 . The catalyst of  claim 1 , wherein said at least one noble metal and/or noble metal oxide is selected from the group consisting of iridium, ruthenium, rhodium, palladium, platinum, and oxides thereof. 
     
     
         7 . The catalyst of  claim 1 , wherein said at least one valve metal and/or valve metal oxide is selected from the group consisting of titanium, zirconium, tungsten, tantalum, niobium, and oxides thereof. 
     
     
         8 . The catalyst of  claim 7 , wherein said at least one valve metal and/or valve metal oxide is tantalum and/or tantalum oxide. 
     
     
         9 . An electrode for producing chlorine by electrolysis of electrolytes containing chlorine ions, wherein said electrode comprises at least one electrically conductive support and a catalytically active coating, wherein said catalytically active coating comprises the catalyst of  claim 1 . 
     
     
         10 . The electrode of  claim 9 , wherein said at least one electrically conductive support comprises a valve metal selected from the group consisting of titanium, zirconium, tungsten, tantalum, and niobium. 
     
     
         11 . The electrode of  claim 9 , wherein said at least one electrically conductive support comprises titanium. 
     
     
         12 . The electrode of  claim 9 , wherein the noble metal loading of the electrode surface is from 0.1 to 20 g of noble metal/m 2  and/or the loading of the electrode surface with finely divided carbon is from 0.1 to 50 g of carbon/m 2 . 
     
     
         13 . A process for producing electrodes for preparing chlorine, wherein said process comprises applying a layer of (1) at least one carbon-containing compound selected from the group consisting of diamond, doped diamond, fullerenes, and carbon nanotubes, (2) optionally, at least one valve metal, valve metal oxide, or mixture thereof, and (3) a noble metal of the Periodic Table of the Elements and/or an oxide of these noble metals to a base material comprising a valve metal selected from the group consisting of titanium, zirconium, tungsten, tantalum and niobium, wherein said application is achieved by applying a mixture of (1) a powder of a carbon modification, a solvent, a soluble noble metal compound, and optionally a valve metal compound soluble in said solvent to said base material and drying and/or sintering said mixture to remove said solvent. 
     
     
         14 . The process of  claim 13 , wherein said application, drying, and/or sintering is repeated up to 20 times. 
     
     
         15 . The process of  claim 14 , wherein said application, drying, and/or sintering is repeated up to 10 times. 
     
     
         16 . The process of  claim 13 , wherein said suspension has a solids content of up to 20% by weight. 
     
     
         17 . The process of  claim 16 , wherein said suspension has a solids content of up to 10% by weight. 
     
     
         18 . (canceled) 
     
     
         19 . The catalyst of  claim 1 , wherein said at least one finely divided carbon modification is fullerene. 
     
     
         20 . The catalyst of  claim 4 , wherein said at least one finely divided carbon modification is diamond and/or boron-doped diamond, and wherein said at least one noble metal and/or noble metal oxide is selected from the group consisting of iridium, ruthenium, rhodium, palladium, platinum, and oxides thereof.