Process for the purification and recovery of the contaminated solution of the catalyst produced on carbonylation of methanol and/or methyl acetate and/or dimethyl ether

A process for the purification and recovery of a contaminated catalyst solution produced during carbonylation of at least one substance selected from methanol, methyl acetate and dimethyl ether, the contaminated catalyst solution consisting essentially of 1 to 10% by mass of carbonyl complexes of rhodium, 35 to 80% by mass of quaternary heterocyclic aromatic nitrogen compounds or quaternary organo-phosphorus compounds as organic promoters, or 35 to 80% by mass of alkali metal salts or compounds of carbonyl-forming base metals as inorganic promoters, 0.5 to 10% by mass of undistillable organic impurities and 20 to 50% by mass of acetic acid, acetic anhydride and ethylidene diacetate the process comprising removing the organic impurities together with the acetic acid, acetic anhydride and ethylidene diacetate from the contaminated catalyst solution by extraction at pressures from 35 to 450 bar and temperatures from 0.degree. to 120.degree. C. with 0.5 to 80 parts by weight of liquefied or supercritical gas selected from the group consisting of carton dioxide sulfur hexafluoride dinitrogen monoxide, fluorohydrocarbon, chlorofluorohydrocarbons, bromofluorohydrocarbons, bromochlorofluorohydrocarbons, saturated or unsaturated C.sub.2 - to C.sub.4 -hydrocarbons, ammonia or mixtures thereof per part by weight of contaminated catalyst solution, and separating the phase of the liquefied or supercritical gas from the purified promoter-containing catalyst solution, separating the phase of the liquefied or supercritical gas by flash vaporization, re-employing the recovered gas for extraction, separating acetic acid, acetic anhydride end ethylidene diacetate from the component which remains liquid and combining it with the purified catalyst complex so as to obtain fresh catalyst solution containing at least 99.90% of the rhodium contained in the original contaminated catalyst solution, and purging the organic impurities which remain as the residue when the phase of the liquefied or supercritical gas is separated.