| abstract |
Sulfur trioxide is formed by a process wherein a first gaseous stream comprised of SO 2 , SO 3 , and oxygen and/or air is passed into a bed of a vanadium-containing catalyst that oxidizes S0 2 to SO 3 and that releases therefrom a second gaseous stream comprised of sulfur trioxide. This process is improved in a first case by providing vaporized sulfur in the first gaseous stream so that the resultant mixture passes through a substantial portion of the catalyst bed, and maintaining the catalyst bed at one or more temperatures in the range of about 450 to about 700° C. The sulfur is oxidized to S0 2 . As a result, the second gaseous stream released from the downstream end portion of the catalyst bed has an enriched content of sulfur trioxide, which can be used for production of compounds such as tetrabromophthalic anhydride. In a second case, a stream of sulfur dioxide is generated from sulfur and an oxidant, and this stream is introduced into the first gaseous stream referred to above. In this second case, the feed of sulfur dioxide replaces the vaporized sulfur used in the first case. As in the first case, an enriched stream of sulfur trioxide is released from the downstream end of the catalyst and can be used for producing compounds such as tetrabromophthalic anhydride. |