Process for preparing an unsaturated aldehyde and/or an unsaturated carboxylic acid

摘要

An α,β-unsaturated aldehyde and/or an α,β-unsaturated carboxylic acid are prepared by gas phase oxidation of alkene with molecular oxygen over a fixed catalyst bed comprising a bed of hollow cylindrical shaped catalyst bodies having a multimetal oxide active composition. The fixed catalyst bed comprises at least three successive reaction zones; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor outlet; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor inlet; and the value WT=(ED−ID)/2 in the reaction zone in which the highest local temperature in the fixed catalyst bed occurs is lower than in the other reaction zones, in which ED is the external diameter and ID is the internal diameter of the shaped catalyst body. The yield of the products of value is enhanced in this way.

主权项

1. A process for preparing an α,β-unsaturated aldehyde and/or an α,β-unsaturated carboxylic acid, the process comprising:
reacting an alkene with molecular oxygen by gas phase oxidation in a reactor with an inlet and an outlet over a fixed catalyst bed comprising a bed of hollow cylindrical shaped catalyst bodies comprising a multimetal oxide active composition, wherein the fixed catalyst bed comprises at least three successive reaction zones; the highest local temperature in the fixed catalyst bed does not occur in a reaction zone closest to the reactor outlet; the highest local temperature in the fixed catalyst bed does not occur in a reaction zone closest to the reactor inlet; and a value WT calculated according to the following equation in a reaction zone in which the highest local temperature in the fixed catalyst bed occurs is lower than WT values in the other reaction zones:WT=ED-ID2 where ED is an external diameter and ID is an internal diameter of the cylindrical shaped catalyst body.