GB370466A - Improvements in desulphurisation of gases - Google Patents

Abstract

The recovery of sulphur from gases containing sulphuretted hydrogen in excess of 7 grams of sulphur per cubic metre by catalytic oxidation by active carbon is effected by so treating the gases prior to the catalysis that the sulphur content is reduced below the limit referred to. This may be effected (1) by diluting the gas to be treated with gases free from or low in sulphur, or (2) by carrying out the oxidation in stages, the necessary amount of air being added before each stage. Alternatively, all the oxygen required may be added in one stage, the gas being cooled and moistened between each stage. In the first instance, the desulphurized gas is preferably used as the diluent, or industrial waste gases, hydrogen, nitrogen, or carbon dioxide may be employed. Oxidation in either case may be facilitated by the addition of basic substances, such as ammonia, ammonium carbonate, or sodium bicarbonate, to the gas or the catalyst. Injurious ingredients in the gas to be treated, such as benzene hydrocarbons, are removed by absorption in sulphuric acid &c. In an example, waste cracking gases containing 25 grams of sulphur per cubic metre are diluted with hydrogen or nitrogen, the requisite amount of air and 0,1 gram of ammonia per cubic metre are added. The issuing gases are afterwards used as the diluent. In a second example, cracking gases are treated in two stages, cooling being effected after the first stage with addition of ammonia and further air.