Catalyst used for formation of sulphur trioxide using sulphur dioxide and oxygen
Answers
Explanation:
United States Patent CONVERSION OF SULPHUR DIOXIDE TO SULPHUR TRIOXIDE Phineas ,Davies, Norton-on-Tees, England, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain N Drawing, Application September 7, 1954, Serial No. 454,606
Claims priority, application Great Britain October 2, 1953 11 Claims. (Cl. 23-176) This invention relates tothe oxidation of sulphur dioxide tosulphur trioxide.
Ithas already been proposed to produce a catalyst comprising vanadium oxides and a potassium compound on silica-gel by slowly adding a potassium-silicate solution to dilute sulphuric acid, thereby causing a silica'sol to be formed, mixing this sol with a solution of a vanadium compound, co-precipitating silica and a hydrated vanadium oxide by the slow addition of ammonia, and finally drying, calcining and grinding the product. Inthis mode of producing the catalyst, the potassiumcontent is derived from potassium silicate. Catalysts of this type have been used in the oxidation of sulphur dioxide to sulphur trioxide. In particular, it has been proposed'to use catalysts having a potassiumzvanadium molar ratio, expressed as-KzOzVzOs, of 4:1 in this reaction and to operate at temperatures of 440 C. and above. It has also been proposed that catalysts of the type disclosed should contain 7% to 12% by weight of vanadium, expressed as V205.
The catalysts already proposed for the oxidation of sulphur dioxide to sulphur trioxide are active at temperatures of 430 C. and above. As will be described'laterin this specification, a considerable advantage would be obtained by using a catalyst already possessing a marked activity at substantially lower temperatures.
Explanation:
Adding an excess of oxygen to sulfur dioxide in the presence of the catalyst vanadium pentoxide at 450 °C and 1-2 atm. The sulfur trioxide formed is added to sulfuric acid which gives rise to oleum (disulfuric acid) The oleum is then added to water to form sulfuric acid which is very concentrated.