FIELD: sulfuric acid production. SUBSTANCE: invention relates to oxidizing sulfur dioxide into sulfur trioxide in production of sulfuric acid from brimstone or when treating sulfur-containing industrial gas releases. Reaction mixture containing sulfur dioxide and oxygen is successively passed through several vanadium catalyst layers, layer temperature being maintained in the range 360-500 C. Passage of sulfur dioxide through at least one of layers is alternated every 1-75 min with passage of air or oxygen in countercurrent to reaction mixture passage. Method may also be effected by way of passing reaction mixture through at least one catalyst layer both in direct and back directions. EFFECT: improved parameters of process. 2 cl
