Abstract: In a process for the thermal treatment of the precursor material of a catalytically active material in a rotary tube furnace through which a gas stream flows, at least a proportion of the gas stream flowing through the rotary tube furnace is circulated, and the associated rotary tube furnace apparatus and tube-bundle reactors for the partial gas-phase oxidation of acrolein to acrylic acid are loaded with catalysts whose catalytically active material is obtainable by the process for the thermal treatment.

Abstract: Catalytically active multielement oxide materials which contain at least one of the elements Nb and W and the elements Mo, V and Cu are prepared by a process in which an intimate dry blend containing ammonium ions is prepared and said dry blend is subjected to a thermal treatment in an atmosphere having a low molecular oxygen content at elevated temperatures, a portion of the ammonium ions contained in the intimate dry blend being decomposed with liberation of ammonia and the oxygen content of the thermal treatment atmosphere being increased in the course of the thermal treatment.

Abstract: Novel catalyst beds comprising a physical mixture of catalytically active and catalytically inactive shaped bodies, in which the catalytically inactive shaped bodies have rounded edges on the external rubbing surfaces.

Abstract: Catalysts for the purification of ethylene containing copper and zinc, optionally one or more promoters or supports. These catalysts are produced by precipitation, drying, calcination and compression, optionally with the addition of additives, the compressed catalyst particles are calcinated at a temperature between from 300 to 700° C.

Abstract: Catalysts containing passivated copper and zinc oxide and/or alumina are prepared by (1) precipitating a mixture of catalyst precursor components dissolved or suspended in a diluent with anion-containing precipitating agents, washing and drying to form a solid catalyst precursor in the form of powder or granules, (2) calcining the solid catalyst precursor obtained in stage (1) to an anion content from the precipitating agent of from 0.1 to 2.5% by weight and (3) shaping and, if required, reducing and passivating the calcined catalyst precursor from stage (2) in any desired order to form the catalyst.

Abstract: In a process for the catalytic hydrogenation of a carbonyl compound or a mixture of two or more carbonyl compounds in the presence of catalyst tablets which comprise an inorganic, TiO2-containing support and, as active component, copper or a mixture of copper with at least one metal selected from the group consisting of zinc, aluminum, cerium, nobel metals and metals of transition group VIII and whose copper surface area is not more than 10 m2/g, the diameter d and/or the height h of the tablets is less than 3 mm.

Abstract: A process for the preparation of a catalyst comprising iron oxide, potassium oxide, a magnesium compound and a cerium compound, wherein the catalyst has one or more Fe/K phases K2O.Fe2O3 1:n, where n is a natural number from 1 to 11, and a process for the dehydrogenation of ethylbenzene to styrene.

Abstract: A process for producing solids by precipitation in a mixer to form a mixture of solid and liquid, where the starting materials are fed into a mixing apparatus which has essentially a rotationally symmetrical mixing chamber which has a rotor disposed therein and is formed by a peripheral wall and two end walls, and where a) the starting materials are each fed to at least one inlet opening in the peripheral wall of the mixing chamber, and b) the solid-containing mixture which is formed is removed from at least one outlet opening in the peripheral wall of the mixing chamber.