Cativa process

The Cativa process is a method for the production of acetic acid by the carbonylation of methanol. The technology, which is similar to the Monsanto process, was developed by BP Chemicals and is under license by BP Plc. [cite journal
title = The Cativa^TM Process for the Manufacture of Acetic Acid
author = Jones, J. H.
journal = Platinum Metals Review
year = 2002
volume = 44
issue = 3
pages = 94–105
url = http://www.platinummetalsreview.com/pdf/pmr-v44-i3-094-105.pdf] [cite journal
title = High productivity methanol carbonylation catalysis using iridium - The Cativa^TM process for the manufacture of acetic acid
author = Sunley, G. J., Watson, D. J.
journal = Catalysis Today
year = 2000
volume = 58
issue = 4
pages = 293–307
doi = 10.1016/S0920-5861(00)00263-7] The process is based on an iridium-containing catalyst, such as the complex [Ir(CO)₂I₂] ⁻.

The Cativa and Monsanto processes are sufficiently similar that they can use the same chemical plant. Initial studies by Monsanto had shown that iridium to be less active than the rhodium for the carbonylation of methanol. Subsequent research, however, showed that the iridium catalyst could be promoted by ruthenium, and this combination leads to a catalyst that is superior to the rhodium-based systems. The switch from rhodium to iridium also allows the use of less water in the reaction mixture. This change reduces the number of drying columns necessary, decreases by-products formation, and suppresses the water gas shift reaction. Furthermore, the process allows a higher catalyst loading. Compared with the Monsanto process, the Cativa process generates less propionic acid by-product.

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