You could check this paper:

https://www.researchgate.net/publication/286616785_Reaction_mechanism_and_intrinsic_kinetics_of_acetic_acid_synthesized_by_methanol_carbonylation_in_gas_phase

The preferred industrial method for its manufacture is by the carbonylation of methanol and this accounts for approximately 60 per cent of the total world acetic acid manufacturing capacity. The carbonylation of methanol, catalysed by rhodium, was invented by Monsanto in the 1960s and for 25 years was the leading technology. In 1996 a new, more efficient, process for the carbonylation of methanol was announced by BP Chemicals, this time using an iridium catalyst. This article describes the new process and looks at the ways in which it improves upon the prior technology..

The apparatus of the present invention is used in connection with the carbonylation of methanol, and/or its reactive derivatives, with carbon monoxide in a homogeneous catalytic reaction system comprising a reaction solvent (typicallyacetic acid), methanol and/or its reactive derivatives, a soluble rhodium catalyst .

A process as provided for producing an acetic acid process stream having less than 400 ppm propionic acid and less than 1500 ppm water. Methanol or a reactive derivative thereof and carbon monoxide is fed to a carbonylation reactor in which there is maintained during the course of the process a liquid reaction composition containing an iridium carbonylation catalyst, methyl iodide co-catalyst, a promoter, water at a concentration of less than about 8% by weight, methyl acetate, acetic acid, and propionic acid by-product and its precursors. Liquid reaction composition is withdrawn from the carbonylation reactor and introduced to a flash zone to form a vapor fraction comprising water, acetic acid product, propionic acid by-product, methyl acetate, methyl iodide and propionic acid precursors, and a liquid fraction comprising involatile iridium catalyst, involatile optional promoter or promoters, acetic acid and water. The liquid fraction is recycled from the flash zone to the carbonylation reactor and introduced into a first distillation zone where a light ends recycle stream is removed and recycled to the carbonylation reactor, A process stream is removed from the first distillation zone comprising acetic acid, propionic acid by-product and less than 1500 ppm water. If the process stream comprises greater than 400 ppm propionic acid, the process stream is introduced into a second distillation zone where propionic acid by-product is removed together with an acetic acid process stream containing less than 400 ppm propionic acid and less than 1500 ppm water.

https://www.researchgate.net/publication/8680965_Promotion_of_Iridium-Catalyzed_Methanol_Carbonylation_Mechanistic_Studies_of_the_Cativa_Process

https://www.researchgate.net/profile/Rick_Manner/post/Working_on_project_for_the_production_of_acetic_acid_by_methanol_carbonylation_using_cativa_process_and_I_want_kinetic_data_for_this_reaction/attachment/59d648c479197b80779a36b9/AS%3A468360388452352%401488677226869/download/Captiva+process+pmr-v44-i3-094-105.pdf

https://www.che.utah.edu/~ring/Design%20I/Lecture_Ppts/13-L1-L2-Reactor%20Design.ppt