Patent ID: 8318977

Claim:
A method of operating an absorber tower in a carbonylation unit for making acetic acid of the class including a reactor and a light ends column comprising: (a) feeding vent gas from the carbonylation unit to the absorber tower, the vent gas including methyl iodide and optionally additional volatile components; (b) supplying a first scrubber solvent to the absorber tower, the first scrubber solvent consisting essentially of acetic acid; (c) contacting the vent gas with the first scrubber solvent thereby removing methyl iodide and optionally additional volatile components from the gas and absorbing methyl iodide and optionally additional volatile components into the first scrubber solvent; (d) feeding an absorber return stream including first scrubber solvent and absorbed methyl iodide and optionally additional absorbed volatile components to the light ends column and/or dehydration column; (e) terminating the supply of first scrubber solvent to the absorber tower; (f) supplying a second scrubber solvent to the absorber tower, the second scrubber solvent comprising methanol, methyl acetate or mixtures thereof; (g) contacting the vent gas with the second scrubber solvent thereby removing methyl iodide and optionally additional volatile components from the gas and absorbing methyl iodide and optionally additional volatile components into the second scrubber solvent; and (h) feeding an absorber return stream including second scrubber solvent and absorbed methyl iodide and optionally additional absorbed volatile components to the reactor.