Process for the preparation of acetaldehyde

A process of producing acetaldehyde by hydrocarbonylating methanol which comprises:

• reacting methanol with a mixture of carbon monoxide and hydrogen, at a temperature of between about 180.degree. C. and about 300.degree. C. under a total pressure of between about 50 and about 600 bars, in the presence of cobalt and ruthenium, of at least one ionic halide, the cation of which is chosen from the group consisting of alkali-metal cations, alkaline earth metal cations, quaternary ammonium cations, and quaternary phosphonium cations, and of at least one alkyl halide, the alkyl halide having an alkyl radical of up to about sixteen carbon atoms, the molar ratio X.sup.- /Co, X.sup.- being the halide ion originating from the ionic halide, being at least about 5, the content of halogen X, X being the halogen originating from the alkyl halide, being at least about 2 millimols per liter of reaction medium, the concentration of cobalt being at most about 50 milligram atoms per liter of reaction medium and the molar ratio of ruthenium to cobalt being at most about 2.