Process for the selective removal and subsequent isolation of sulphur dioxide from flue gas

摘要

Process for the selective removal of sulphur dioxide from flue gas by absorption by an amine/solvent mixture and subsequent isolation of the sulphur dioxide by thermal desorption. Regenerative flue gas desulphurisation processes which operate with aromatic amines, such as xylidine, toluidine/water mixtures have not been used because of the problems occurring with them which impaired handling, such as sulphate formation, and because of the weak absorption properties. The novel process is distinguished by simple handling with respect to the absorption-desorption of sulphur dioxide and can be carried out at low temperatures. A tertiary amine/solvent mixture, containing antioxidant additives, at temperatures up to 40@C and atmospheric pressure selectively absorbs up to 10 % by weight of sulphur dioxide from flue gas. Desorption is performed with boiling of the solvent used here with n-heptane at 90@C with a release rate of 45 %. Mild operating conditions and antioxidants as additives produce simple handling and long service lives of the process mixture with respect to absorption-desorption.