Process for removing chlorine from gas stream

Abstract

A process for the scrubbing of chlorine is scrubbed from a chlorine-containing gas using an aqueous feed liquor containing an excess of alkali to give an effluent liquor containing chloride and hypochlorite ions is disclosed. The effluent liquor is recycled as part or all of the aqueous feed liquor. For at least part of the time, at least part of the effluent liquor is passed through a fixed bed of a catalyst for the decomposition of hypochlorite ions whereby hypochlorite ions are decomposed to oxygen gas and chloride ions. The resultant catalyst-treated liquor is mixed with the remainder, if any, of the effluent liquor and recycled, optionally together with added fresh alkali solution, as the aqueous feed liquor. Part of the effluent liquor is optionally discharged as a purge stream before or after passage through catalyst bed. The process may be operated in a continuous mode or in a semi-continuous mode wherein a reservoir holding the liquor to be recycled is periodically discharged, preferably through the catalyst bed, and then recharged with fresh alkali solution. Alternatively two reservoirs may be employed with one supplying the aqueous feed liquor while the other is being discharged and replenished. In the latter case, the reservoir being discharged may have its liquor discharged through the catalyst bed.