Method for recovering rhodium from reaction products of oxosynthesis
AssigneeCelanese Chemicals Europe GmbH
InventorsHans-Willi Bohnen, Richard Fischer, Mark Hewlett, Wolfgang Zgorzelski, Norbert Schopper
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Abstract
The invention relates to a method for separating and recovering rhodium from reaction products of oxosynthesis, especially reaction products containing cobalt. The invention also relates to the reuse of rhodium as a catalyst for hydroformulation and to a catalyst for hydroformulation itself. The inventive method is characterized by the following: extraction of the organic solution with an aqueous phosphate solution or a phosphate solution, water washing, oxidative treatment of the organic phase, and extraction of the organic phase with an aqueous water-soluble arylphosphine solution.
Claims24
A process for recovering rhodium from organic solutions comprising rhodium complexes with or without cobalt complexes and with or without complexing ligands, which comprises
- extracting the organic phase with an aqueous solution of a phosphate of the formula (O)P(OR1)(OR2)(OR3), where R1, R2 and R3 are identical or different and are hydrogen, a straight-chain or branched alkyl radical having 1-10 carbon atoms or a substituted or unsubstituted aryl radical having 6-10 carbon atoms, and the aryl radical is substituted by straight-chain or branched alkyl radicals having 1-4 carbon atoms, or with a phosphonate of the formula R4P(O)(OR5)(OR6), where R4, R5 and R6 are identical or different and are hydrogen, a straight-chain or branched alkyl radical having 1-10 carbon atoms or a substituted or unsubstituted aryl radical having 6-10 carbon atoms, and the aryl radical is substituted by straight-chain or branched alkyl radicals having 1-4 carbon atoms;
- washing the organic phase with water at a pH of from 0 to 8;
- treating the organic phase after phase separation with an oxidizing agent at a temperature of from 0 to 100° C.;
- treating the organic phase with an aqueous solution of a water-soluble arylphosphine at elevated temperature and elevated pressure;
- and removing the rhodium-containing aqueous solution from the organic phase by phase separation.
Dependencies are inferred from the claim text.