Processes for treating off-gas in an acetic acid production unit

A process for scrubbing an off-gas stream comprising carbon monoxide and methyl iodide in an absorption column of an acetic acid production unit, the absorption column comprising

• a bottom section comprising a feed inlet and one or more liquid outlets;
• and above the bottom section, a top section comprising one or more liquid inlets and a vapour outlet;
• the process comprising
• through the feed inlet, introducing the off-gas stream to the absorption column;
• through a liquid inlet of the one or more liquid inlets, introducing a methanol stream at a first flow rate, the methanol stream having a first temperature at the liquid inlet, the first temperature being at least 18° C.;
• in the absorption column, contacting the off-gas stream with the methanol stream;
• through a liquid outlet of the one or more liquid outlets, withdrawing a first liquid effluent from the absorption column, the first liquid effluent comprising methanol and methyl iodide;
• and
• through the vapour outlet, withdrawing a vapour effluent from the absorption column,
• the process further comprising separating the withdrawn vapour effluent in a heat exchanger to provide a vapour fraction and a liquid fraction comprising methanol, wherein
• the vapour fraction comprises at most 2.5 wt % methanol, and
• the methanol stream includes at least a portion of the liquid fraction comprising methanol;
• the process further comprising, after introducing the methanol stream to the absorption column,
• decreasing the flow rate of methanol transferred to the absorption column;
• through a liquid inlet of the one or more liquid inlets, transferring an acetic acid stream to the top section of the column at a third flow rate, the acetic acid stream having a third temperature at the inlet;
• and
• in the absorption column, contacting the off-gas stream with the acetic acid stream:
• wherein the third temperature is in the range 18° C. to 40° C.
• and wherein the third temperature differs from the first temperature by at most 5° C.