Process for purifying and recovering the contaminated catalyst solution arising in the carbonylation of methanol and/or methyl acetate and/or dimethyl ether

US5002914A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Heinz Erpenbach · Cologne, DE
• Winfried Lork · Lechenich, DE
• Norbert Weferling · Hürth, DE
• Peter Prinz · Ethel, US

Key dates

• Filing date: Mar 9, 1990
• Grant date: Mar 26, 1991
• Expiry date: Mar 9, 2010

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02P20/584
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A process for purifying and recovering the contaminated catalyst solution arising from the carbonylation of methanol, methyl acetate and/or dimethyl ether. The solution contains carbonyl complexes of rhodium, quaternary organophosphorus compounds as organic promoters, undistillable organic impurities, and acetic acid, acetic anhydride and ethylidene diacetate. The carbonyl complex of rhodium together with acetic acid, acetic anhydride and ethylidene diacetate are extracted from the contaminated catalyst solution by using a tri-C.sub.3 - to C.sub.8 -alkylphosphine. The trialkylphosphine phase is separated from the promoter phase and is separated into the volatile constituents acetic acid, acetic anhydride and ethylidene diacetate as well as trialkylphosphine. The rhodium carbonyl complex remaining as the residue and the recovered trialkylphosphine is used for further extraction. The contaminated promoter phase is freed of the organic impurities by extraction with dialkyl ethers, carboxylic acid esters or hydrocarbons and, after the extractant phase has been separated off, is recombined with the recovered acetic acid/acetic anhydride and ethylidene diacetate mixture and with the rhod…