Anode for electrolytic evolution of chlorine
AssigneeIndustrie De Nora S.P.A.
InventorsChristian Urgeghe, Chiara Pezzoni, Antonio Lorenzo Antozzi
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Abstract
An electrode suitable for chlorine evolution in electrolysis cells consists of a metal substrate coated with two distinct compositions applied in alternate layers, the former comprising oxides of iridium, ruthenium and valve metals, for instance tantalum, and the latter comprising oxides of iridium, ruthenium and tin. The thus-obtained electrode couples excellent characteristics of anodic potential and selectivity towards the chlorine evolution reaction.
Claims14
An electrode for evolution of gaseous products in electrolytic cells consisting of a metal substrate coated with a plurality of alternating layers of at least one first catalytic composition and at least a second catalytic composition,
- said first catalytic composition comprises a mixture of oxides of iridium, of ruthenium and of at least one valve metal and being free of tin,
- said second catalytic composition comprises a mixture of oxides of iridium, of ruthenium, of tin, niobium and at least one noble metal selected from the group consisting of palladium and platinum,
- wherein the innermost of said plurality of alternating layers corresponds to said first catalytic composition,
- wherein the electrode reduces chlorine overvoltage without reduction in oxygen overvoltage,
- wherein said valve metal of said first catalytic composition is titanium and said oxides of iridium, ruthenium and titanium present in said first catalytic composition are Ru=10-30%, Ir=5-25%, Ti=35-80% atomic percentage referred to the metals, and
- wherein said second catalytic layer is obtained by applying a solution containing precursors of ruthenium, iridium, tin, niobium, and at least one noble metal selection from the group consisting of palladium and platinum, wherein tin is in the form of tin hydroxyacetochloride such that after thermal treatment said oxides of iridium, of ruthenium and of tin present in said second catalytic composition are Ru=20-60%, Ir=1-20%, Sn=35-65%, atomic percentage referred to the metals, wherein Nb and at least Pd or Pt make up the remainder of the composition's atomic proportions.
An electrode for evolution of gaseous products in electrolytic cells consisting of a metal substrate coated with a plurality of alternating layers of at least one first catalytic composition and at least a second catalytic composition,
- said first catalytic composition comprises a mixture of oxides of iridium, of ruthenium, of platinum and of at least one valve metal and being free of tin,
- said second catalytic composition comprises a mixture of oxides of iridium, of ruthenium, of tin, niobium and at least one noble metal selected from the group consisting of palladium and platinum,
- wherein the innermost of said plurality of alternating layers corresponds to said first catalytic composition,
- wherein the electrode reduces chlorine overvoltage without reduction in oxygen overvoltage,
- wherein said valve metal of said first catalytic composition is titanium and said oxides of iridium, ruthenium, platinum, and titanium present in said first catalytic composition are Ru=10-30%, Ir=5-25%, Ti=35-80% atomic percentage referred to the metals, wherein Pt makes up the remainder of the composition's atomic proportions. and
- wherein said second catalytic layer is obtained by applying a solution containing precursors of ruthenium, iridium, tin, niobium, and at least one noble metal selection from the group consisting of palladium and platinum, wherein tin is in the form of tin hydroxyacetochloride such that after thermal treatment said oxides of iridium, of ruthenium and of tin present in said second catalytic composition are Ru=20-60%, Ir=1-20%, Sn=35-65%, atomic percentage referred to the metals, wherein Nb and at least Pd or Pt make up the remainder of the composition's atomic proportions.
Dependencies are inferred from the claim text.