Patent ID: 7009070
Filing Date: 2006-03-07
Classification: C07C,Y02P

Abstract:
1. In a process for continuous manufacture of acetic acid and/or methyl acetate by carbonylation of methanol or a carbonylatable derivative of methanol into acetic acid and/or methyl acetate in a homogeneous liquid phase and under carbon monoxide pressure, in the presence of a homogeneous catalyst system comprising a rhodium-based homogeneous catalyst and a halogenated promoter, and in the presence of at least 14% by weight water, said continuous process being carried out in a plant comprising a reaction zone I, with a temperature maintained at a value between 150 and 250° C. a total pressure between 5.10 the improvement comprising: adding an iridium compound to the catalyst system gradually over time, in order to gradually modify the composition of the homogeneous catalyst system, to obtain a catalyst system containing a predetermined atomic ratio of rhodium to iridium, thereby modifying the catalyst composition without stopping the process, and continuing the continuous manufacture of acetic acid and/or methyl acetate, while maintaining the catalyst system containing said predetermined atomic ratio by adding a rhodium compound, an iridium compound or both a rhodium and an iridium compound.