Basf Aktiengesellschaft

Gerhard Hefele

Thomas Heidemann

Frank Rosowski

Heiko Arnold

Gerd Linden

Michael Seufert

Peter M Lorz

Walter Scheidmeir

Otto Kratzer

Herbert Wanjek

Bernhard Ulrich

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, 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.

Method for producing shell catalysts for the catalytic vapor-phase oxidation of aromatic hydrocarbons and catalysts obtained in such a manner

In a process for preparing phthalic anhydride by catalytic gas-phase oxidation of o-xylene or naphthalene or o-xylene/naphthalene mixtures with a gas comprising molecular oxygen over a coated catalyst comprising an inert, nonporous support material on which a catalytically active composition comprising titanium dioxide and vanadium pentoxide is applied in layer form, a catalyst whose catalytically active composition comprises from 3 to 6% by weight of vanadium pentoxide, calculated as V O , from 0.3 to 0.5% by weight of a cesium compound, calculated as Cs, and the remainder to 100% by weight of titanium dioxide in the anatase modification is used in the presence or absence of a coated catalyst, differing therefrom, for the catalytic gas-phase oxidation of o-xylene or naphthalene or o-xylene/naphthalene mixtures and, in the presence of such a second catalyst, the latter is used in a combined bed with the catalyst of the above composition in the reactor.

Method for producing acid phthalic anhydride and an appropriate shell catalyst containing titanium-vanadium-cesium

In a process for preparing phthalic anhydride by catalytic gas-phase oxidation of o-xylene/naphthalene mixtures by molecular oxygen, use is made of a catalyst I in a first zone on the gas inlet side which makes up from 25 to 75 percent by volume of the total catalyst volume, comprising, in each case based on the catalytically active composition, from 1 to 10% by weight of vanadium oxide (calculated as V  ), from 1 to 10% by weight of antimony oxide (calculated as Sb  ) and from 80 to 98% by weight of titanium dioxide of the anatase type having a BET surface area of from 13 to 28 m /g and also from 0.05 to 1% by weight of cesium (calculated as Cs) applied to a steatite support and a catalyst II in a second zone which makes up the remaining 75 to 25 percent by volume of the total catalyst volume, comprising, in each case based on the catalytically active composition, from 1 to 10% by weight of vanadium oxide (calculated as V  ), from 1 to 10% by weight of antimony oxide (calculated as Sb  ) and from 80 to 98% by weight of titanium dioxide of the anatase type having a BET surface area of from 13 to 28 m /g and from 0.01 to 1% by weight of phosphorus oxide (calculated as P) and also from 0.01 to 0.2% by weight of cesium (calculated as Cs) applied to a steatite support, wherein the cesium content of the catalyst II is less than 15% by weight of the cesium content of the catalyst I and the catalyst I and the catalyst II have been prepared without addition of compounds of niobium.

Method for producing phthalic anhydride by means of catalytic vapor-phase oxidation of o-xylol/naphthalene mixtures

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Römerberg, Germany

Gerhard Hefele