Polymer halogenation process with catalyst recovery

1) A process for brominating a styrenic polymer comprising:

• a) contacting, in a bromination reaction zone, in the presence of an antimony halide catalyst and an organic solvent under effective bromination conditions, a styrenic polymer with an effective amount of bromine chloride thereby forming a reaction mass comprising at least a brominated styrenic polymer and antimony halide catalyst residues;
• b) extracting at least a portion of the antimony catalyst residues from the reaction mass by contacting the reaction mass with an effective amount of aqueous hydrochloric acid thereby forming an acidic aqueous phase comprising antimony halide catalyst residues and aqueous hydrochloric acid and an organic phase comprising brominated styrenic polymer;
• c) separating the acidic aqueous phase and the organic phase;
• d) optionally, concentrating the acidic aqueous phase;
• and
• e) solvent exchanging under effective solvent exchange conditions the acidic aqueous phase with a solvent exchange solvent, thereby forming a solvent exchanged solution comprising antimony halide catalyst and the solvent exchange solvent,
• wherein HBr is added to the acidic aqueous phase at a point after the extraction step in an amount ranging from about 0.1 to about 5 moles of HBr per mole of antimony present in the antimony halide catalyst used in the bromination reaction zone thereby converting at least a portion of any insoluble antimony values into at least one antimony value that is soluble in the hydrochloric acid.