A General View on the Effects of Iodide salts in Iridium Catalyst in Methanol Carbonylation Process

In this work some iodide salts and carbonyl complexes of metals have been used as a promoter in the carbonylation of methanol in an iridium/iodide based catalyst. The iridium catalyzed carbonylation of methanol to acetic acid is promoted by two distinct classes of promoters; simple iodide salts of Zinc, Cadmium, Mercury, Indium and Gallium and carbonyl or halocarbonyl complexes of Tungsten, Rhenium, Osmium and Ruthenium. All these promoters are used to increase the rate of methanol carbonylation. In this research, the effect of a ruthenium promoter on the rate of methanol carbonylation has been observed. High reaction rate is achieved by increasing the ruthenium concentration. Some experiments were also carried out to identify the effect of different promoters. In the presence of ruthenium and iridium, the maximum activity is achieved between 5 to 6 weight percent of water.

Keywords:

Methanol carbonylation , Iridium , Promoter , Iodide salt