Method for recovering hci from a hci containing gas stream

Abstract

The invention pertains to a method for recovering HCl from a HCl containing gas stream wherein a HCl containing gas stream with a temperature of −20 to 25° C. is provided to an adiabatic absorption unit where it is contacted with water as an absorbent, resulting in the formation of a top gas stream and a aqueous HCl product solution, wherein the temperature of the top gas stream is at least 70° C. and wherein the aqueous HCl product solution has a HCl concentration in the range of 5-20 wt. %. It is preferred for the HCl-containing gas stream to be derived from a hydrogenation step wherein a feed comprising monochloroacetic acid (MCA) and dichloroacetic acid (DCA) is reacted with hydrogen to form a HCl-containing gas stream and a product stream comprising MCA and a reduced amount of DCA. The HCl product solution is preferably diluted to a concentration of 1-8 wt. %, and the diluted solution is used as absorbent in a second absorption step, wherein HCl is absorbed from a further HCl-containing gas stream to form a second aqueous HCl solution. The further HCl-containing gas stream is preferably derived from a chlorination step wherein acetic acid is reacted with chlorine, resulting in the formation of the further HCl-containing gas stream and a feed comprising monochloroacetic acid (MCA) and dichloroacetic acid (DCA).