Patent ID: 8901320
Filing Date: 2014-12-02
Classification: C07D

Abstract:
1. A process for controlling a gas phase oxidation reactor for preparation of phthalic anhydride, which comprises passing a gas stream which comprises an aromatic hydrocarbon and molecular oxygen through a multitude of reaction tubes arranged in the gas phase oxidation reactor, each of which comprises a bed of at least one catalyst and the temperature of which can be controlled by means of a heat transfer medium, at least one control parameter being measured and correcting interventions for control of the control parameter being determined, the at least one control parameter comprising the phthalic anhydride yield and the correcting parameter used being the temperature of the heat transfer medium, which comprises limiting the change in the correcting parameter to a maximum of 0.4 K within a period of 30 days over at least 95% of the lifetime of the catalyst, wherein the loading of the gas stream which comprises an aromatic hydrocarbon is 90 to 110 g/m 3 (STP).