Recycling of Spent Hydrodehalogenation Catalysts – Problems Dealing with Separation of Aluminium

Abstract

Our study is focused on utilization and recycling of copper and nickel applicable for reductive degradation of tetrabromobisphenolA (TBBPA), the high use brominated flame retardant for printed circuit boards. Deactivated and/or poisoned hydrodebrominationcatalysts are produced by reductive destruction of brominated phenol (TBBPA) dissolved in alkaline aqueous solution using RaneyAl-Ni and/or Devarda´s Al-Cu-Zn alloys. Spent metallic slurry is treated with aqueous sulfuric acid to dissolve residual aluminiumand/or zinc and decanted residual metal is subsequently treated under oxidation conditions and dissolved in excess of mineralacid by co-action of oxidant. The corresponding metal salt is separated from corresponding leachates containing excess of acid byevaporation and recycling of volatile components. Obtained copper or nickel salts were used as sources of Raney type hydrodebrominationcatalysts produced for in-situ by action of NaBH4.