Catalytic composition for carbonylation including iridium and pyridine polymers

The present invention relates generally to the manufacture of acetic acid and more particularly to a catalytic composition for use in a methanol carbonylation process including a homogeneous iridium catalyst system and a vinyl-pyridine polymer. An improvement to methanol carbonylation processes utilizing a homogeneous iridium catalyst system comprises adding a rate-promoting amount of an insoluble pyridine ring-containing polymer. Typically, polyvinylpyridine is added to the reactor in amounts of up to about 2 wt. percent.