Recovery of rhodium from carbonylation residues
AssigneeThe Halcon SD Group, Inc.
InventorWalter C. Davidson
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Abstract
Residues are formed in the carbonylation of esters or ethers, particularly in the production of acetic anhydride or ethylidene diacetate. Such residues contain noble metal, typically rhodium used as a catalyst, which must be recovered before the residues can be disposed of. In the process of the invention, the rhodium values are freed from the residues by a series of treatments with amines and other reagents, thereby enabling the rhodium to be extracted by subsequent contact with an aqueous halogen acid.
Claims10
A process for recovering Group VIII noble metals from the residues of noble metal catalyzed carbonylation reactions comprising:
- (a) separating said residues from the carbonylation reaction mixture;
- (b) vaporizing the volatile components of said residues of (a) at low temperatures under vacuum and recovering a heavy material therefrom;
- (c) treating said heavy material of (b) with a reagent comprising an amine in an amount sufficient to free a portion of said noble metals bound to said residue;
- (d) extracting said treated heavy material of (c) with an aqueous halogen acid in the presence of a solvent able to dissolve heavy material, thereby recovering a portion of said noble metals in said aqueous acid;
- (e) evaporating said solvent of (d) and recovering a dissolved residue depleted in noble metal;
- (f) repeating steps (c) (d) and (e) until a predetermined desired fraction of the noble metal in the heavy material of (b) has been removed.
Dependencies are inferred from the claim text.