Process for regenerating an aluminium oxide catalyst loaded with nitric acid and sulphuric acid

摘要

A granular aluminium oxide catalyst which has served for removal of nitrogen oxides and sulphur oxides from combustion gases and contains nitric acid and sulphuric acid is regenerated by treatment in a plurality of regeneration zones and reused for gas purification. The loaded catalyst is brought into direct contact in the first regeneration zone with SO2-rich gas from the second regeneration zone at temperatures of from 100 to 200 DEG C, the nitric acid being reacted with SO2 to form sulphuric acid and nitrogen oxide (NO). In the second regeneration zone, the catalyst is brought into direct contact with H2S from the third regeneration zone, at least the majority of the sulphuric acid being reduced to SO2 at temperatures of from 200 to 400 DEG C. The SO2 is passed into the first regeneration zone. In the third regeneration zone, H2S is generated from hydrogen and sulphur at temperatures of from 400 to 500 DEG C and passed into the preceding zone. Preferably, the sulphur reacted in the third zone is the elemental sulphur loading of the catalyst. In the fourth zone, the hot catalyst freed from its loading is cooled in direct contact with hydrogen.