Patent ID: 6528683
Filing Date: 2003-03-04
Classification: B01J,C07C,Y10T

Abstract:
A process for the preparation of coated catalysts for the catalytic gas phase oxidation of aromatic hydrocarbons to a member selected from carboxylic acids and anhydrides, said catalysts consisting essentially of a carrier core and catalytically active metal oxides applied thereto in layer form, which process comprises spraying an aqueous active material suspension containing the active metal oxides at relatively high temperatures onto the carrier core material at 50 to 450Â° C., wherein the aqueous active material suspension contains 1 to 10% by weight, based on solids content of the active material suspension, of a binder, consisting essentially ofA) a polymer obtained by free-radical polymerization comprising 5 to 100% by weight of monomers (a) in the form ethylenically unsaturated acid anhydrides or ethylenically unsaturated dicarboxylic acids whose carboxyl groups can form an anhydrides and 0 to 95% by weight of further monoethylenically unsaturated monomers(b), with the proviso that the monomers (a) and (b) on average have at most 5 carbon atoms which are not functionalized by groups comprising oxygen, and B) an alkanolamine having at least 2 OH groups, at most 2 nitrogen atoms and at most 8 C-atoms, the weight ratio A:B being 1:0.05 to 1:1.