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Production of Ethanoic Acid: The Cativa Process.







In 1996 BP chemicals announced their successful development of a new commercial process based on a promoted iridium iodide catalyst, the Cativa process. The running conditions of the actual plants are known only to BP.




Batch experiments are carried out because they allow a lot of process variables and additives to be rapidly assessed. The research workers studied the effects of varying CO partial pressure, water concentration, methyl iodide concentration, and catalyst poisoning. Corrosion means that iodide complexes of iron, nickel and chromium are typically present and their effect on the catalyst must be determined.

A key feature of the iridium process is the use of promoters. When ruthenium compounds are added they can cause a threefold increase in the rate of the iridium catalysed reaction. On its own ruthenium has negligible catalytic activity.





Just testing the iridium catalyst under normal plant conditions does not work because it turns out that the detailed mechanism is different. Iridium works best under very different conditions from rhodium.


Autoclaves of different volumes
used for research and development work