Process for carbonylating alcohols, employing a catalyst based on rhodium or iridium in a non-aqueous ionic liquid, with efficient catalyst recycling

A process for carbonylating alcohols with carbon monoxide in the liquid phase, said process comprising,

• carrying out the carbonylation reaction in a reaction zone at a temperature of 50° C. to 150° C. and at a pressure in the range 0.5 MPa to 20 MPa in the presence of at least one catalyst comprising at least one rhodium and/or iridium complex and a halogenated promoter in at least one non-aqueous ionic liquid comprising at least one salt of the formula Q+A−, in which Q30 represents a quaternary ammonium and/or a quaternary phosphonium cation, and A is an anion capable of forming a liquid salt below 90° C. said salt having a melting point of less than 90° C.
• withdrawing an effluent from the reaction zone and separating from the effluent the non-aqueous ionic liquid containing in dissolved form substantially all rhodium and/or iridium values in the effluent;
• and
• recycling at least partly the resultant separated non-aqueous ionic liquid to the reaction zone.
• wherein said process is continuous and said effluent front said reaction zone is depressurized to a pressure as low as 0.5 MPa, at a temperature of at most 100° C., before separating said non-aqueous ionic liquid.