Verfahren zur Herstellung von Schalenkatalysatoren für die katalytische Gasphasenoxidation von aromatischen Kohlenwasserstoffen und so erhältliche Katalysatoren

摘要

The invention relates to a method for producing shell catalysts for the catalytic vapor-phase oxidation of aromatic carboxylic acids and/or carboxylic acid anhydrides comprised of a supporting core and of catalytically active metal oxides which are deposited in a shell-shaped manner on said supporting core. The inventive catalysts are obtained by spraying an aqueous active mass suspension, said suspension containing the active metal oxides, at higher temperatures onto the hot supporting material which has a temperature ranging from 50 to 450 DEG C. The aqueous active mass suspension contains 1 to 10 wt. %, with regard to the solid content of the active mass suspension, of a binding agent comprised of A) a polymerizate obtained by radical polymerization, containing 5 to 100 wt. % of monomers (a) in the form of ethylenically unsaturated acid anhydrides or ethylenically unsaturated dicarboxylic acids whose carboxyl groups can form an anhydride and containing 0 to 95 wt. % monoethylenically unsaturated monomers (b) with the provision that the monomers (a) and (b) comprise, on average, a maximum of 6 carbon atoms which are not functionalized with groups containing oxygen, and of B) an alkanolamine having at least 2 OH groups, a maximum of 2 nitrogen atoms and a maximum of 8 C-atoms, whereby the weight ratio A:B ranges from 1:0.05 to 1:1.