| 摘要 |
A process is described for preparing phthalic anhydride by catalytic gas phase oxidation of o-xylene, in, in a main reactor, a gaseous mixture of o-xylene and an oxygenous gas is passed through at least two reaction zones whose temperature can be controlled independently, and converted to a gaseous intermediate reaction product which comprises unconverted o-xylene, phthalic anhydride underoxidation products and phthalic anhydride, and the intermediate reaction product is introduced into a postreactor, wherein the temperature of the reaction zones in the main reactor is regulated in such a way that the concentration of unconverted o-xylene in the intermediate reaction product is at least 0.5% by weight. The process allows an increase in the overall yield of phthalic anhydride without or without significant deterioration in the product quality. |
