Basf Aktiengesellschaft

Herbert Wanjek

Thomas Heidemann

Michael Hesse

Ekkehard Schwab

Wolfgang Hoelderich

Matthias Irgang

Wolf D Mross

Heiko Arnold

Hans-Martin Allmann

Michael Jolyon Sprague

Gerd Linden

Andrea Frenzel

Gerhard Hefele

Cristina Freire Erdbr&uuml;gger

Claus Witte

Phthalic anhydride is prepared by catalytic gas-phase oxidation of xylene and/or naphthalene by a gas comprising molecular oxygen in a fixed bed at elevated temperature and using at least three coated catalysts arranged in superposed zones, which catalysts have a layer of catalytically active metal oxides applied to a core of support material. In the process described, the catalyst activity rises from zone to zone from the gas inlet end to the gas outlet end and the activity of the catalysts of the individual zones is set such that the least active catalyst comprises a lower amount of active composition and, if desired, additionally more alkali metal selected from the group consisting of potassium, rubidium and cesium as dopant than the catalyst of the next zone and the subsequent even more active catalyst comprises the same amount of active composition and even less alkali metal as dopant or a greater amount of active composition and, if desired, less alkali metal as dopant than the catalyst of the second zone, with further conditions.

Method for producing phthalic anhydride

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

A catalyst comprising at least one metal of the 10th group of the Periodic Table of the Elements and at least one metal of the 11th group of the Periodic Table of the Elements on an aluminum oxide support, wherein the metal or metals of the 10th group is or are essentially concentrated in an outer layer close to the surface of the catalyst particle, the metal or metals of the 11th group is or are distributed essentially uniformly over the volume of the catalyst particle and the weight ratio of the metal or metals of the 11th group to the metal or metals of the 10th group is not more than 1.95.

Catalyst and process for the selective hydrogenation of unsaturated compounds in hydrocarbon streams

Copper-containing catalysts for low temperature shift conversion at from 150.degree. to 300.degree. C. and under from 10 to 40 bar, which additionally contain aluminum and zinc, if necessary in the form of the compounds or oxides and are prepared by coprecipitation, the copper-containing catalysts containing potassium and having a BET surface area adapted to the potassium content, and the potassium content being brought to 0.1-3.0% by weight at a BET surface of from 30 to 160 m.sup.2 /g, are used for the preparation of hydrogen and carbon dioxide from carbon monoxide and water.

Copper-containing catalyst for low temperature shift conversion

Growing community of inventors

Maxdorf, Germany

Herbert Wanjek