Rhodium recovery from hydroformylation still heel with triaryl phosphite ligand

Abstract

A process for recovering rhodium present in a still heel from the hydroformylation of an unsaturated hydrocarbon wherein rhodium and a triaryl phosphite ligand were used by a process comprising (a) pretreating the still heel with a compatible organic solvent or a mixture thereof, at least 5 ml of water per 100 g of still heel, oxygen gas or a precursor thereof and sufficient base to produce a pH of 2 to 7 in the reaction mixture after rhodium precipitation; (b) heating to a temperature of from 0.degree. to 80.degree. C to oxidize the triaryl phosphite ligand to the corresponding phosphate compound; (c) heating the mixture from (b) for from about 15 minutes to about 120 minutes at about 115.degree. C to about 175.degree. C to precipitate zero valent rhodium; and optionally purifying the precipitated rhodium from (c) by (d) separating the rhodium precipitate; (e) washing the rhodium precipitate with a solvent-acid solution at a pH of 3 to 4; (f) treating the rhodium precipitate with an alkaline reducing solution to reduce the trivalent rhodium impurity to zero valent rhodium; (g) quenching the rhodium with glacial acetic acid; (h) separating the rhodium; (i) washing the rhodium with an acid solution at a pH of 3 to 4; (j) drying the rhodium in an inert atmosphere at from 250.degree. to 400.degree. C; and (k) oxidizing the rhodium at a temperature of from 300.degree. to 900.degree. C to convert the rhodium to Rh.sub.2 O.sub.3.

Dependencies are inferred from the claim text.