Abstract: The present invention relates to a process for gas-phase oxidation, in which a gaseous stream comprising an aromatic hydrocarbon and molecular oxygen is passed through two or more catalyst zones. Furthermore, the present invention relates to a catalyst system for gas-phase reaction using a preliminary zone.

Abstract: What is described is a process for starting up a gas phase oxidation reactor for oxidation of o-xylene to phthalic anhydride, said reactor comprising at least one catalyst layer and being temperature-controllable by means of a heat carrier medium, wherein a) the catalyst layer is interrupted by a moderator layer which is less catalytically active than the catalyst layer or is catalytically inactive, b) a gas stream is passed through the reactor with an initial loading of o-xylene and at an initial temperature of the heat transfer medium, c) the loading of the gas stream is increased to a target loading and, in parallel, the temperature of the heat transfer medium is lowered to an operating temperature. The introduction of the moderator layer allows the loading to be increased more rapidly and the startup time to be shortened.

Abstract: The present invention relates to a process for gas-phase oxidation, in which a gaseous stream comprising an aromatic hydrocarbon and molecular oxygen is passed through two or more catalyst zones. Furthermore, the present invention relates to a catalyst system for gas-phase reaction using a preliminary zone.

Abstract: The invention relates to a catalyst for the oxidation of SO2 to SO3. The catalyst contains an active substance which contains vanadium, alkali metal compounds and sulfate applied to a support. The support contains naturally occurring diatomaceous earth, wherein the support contains at least one relatively soft naturally occurring uncalcined diatomaceous earth which has a percentage reduction of at least 35% in its D50 value determined in a particle size determination according to the dry method in comparison with the wet method.

Abstract: The present invention relates to a process for gas-phase oxidation, in which a gaseous stream comprising an aromatic hydrocarbon and molecular oxygen is passed through two or more catalyst zones. Furthermore, the present invention relates to a catalyst system for gas-phase reaction using a preliminary zone.

Abstract: A process for gas phase oxidation in which a gaseous stream which comprises at least one aromatic hydrocarbon and molecular oxygen is passed through one or more catalyst layers, wherein a moderator layer is arranged between two catalyst layers arranged in succession in flow direction of the gaseous stream, the moderator layer being less catalytically active than the catalysts adjacent upstream and downstream or being catalytically inactive. The desired oxidation products are obtained in high yield over prolonged periods.

Abstract: The invention relates to a catalyst for the oxidation of SO2 to SO3 and also a process for producing it and its use in a process for the oxidation of SO2 to SO3.

Abstract: The invention relates to a catalyst for the oxidation of SO2 to SO3 and also a process for producing it and its use in a process for the oxidation of SO2 to SO3.

Abstract: What is described is a process for starting up a gas phase oxidation reactor for oxidation of o-xylene to phthalic anhydride, said reactor comprising at least one catalyst layer and being temperature-controllable by means of a heat carrier medium, wherein a) the catalyst layer is interrupted by a moderator layer which is less catalytically active than the catalyst layer or is catalytically inactive, b) a gas stream is passed through the reactor with an initial loading of o-xylene and at an initial temperature of the heat transfer medium, c) the loading of the gas stream is increased to a target loading and, in parallel, the temperature of the heat transfer medium is lowered to an operating temperature. The introduction of the moderator layer allows the loading to be increased more rapidly and the startup time to be shortened.

Abstract: The present invention relates to a process for gas-phase oxidation, in which a gaseous stream comprising an aromatic hydrocarbon and molecular oxygen is passed through two or more catalyst zones. Furthermore, the present invention relates to a catalyst system for gas-phase reaction using a preliminary zone.

Abstract: The present invention relates to a catalyst system for preparing carboxylic acids and/or carboxylic anhydrides which has at least three catalyst layers arranged one on top of the other in the reaction tube, with the proviso that the most inactive catalyst layer is preceded in the upstream direction by a more active catalyst layer. The invention further relates to a process for gas phase oxidation in which a gaseous stream which comprises one hydrocarbon and molecular oxygen is passed through a plurality of catalyst layers, the least active catalyst layer being upstream of a more active catalyst layer.

Abstract: A process for gas phase oxidation in which a gaseous stream which comprises at least one aromatic hydrocarbon and molecular oxygen is passed through one or more catalyst layers, wherein a moderator layer is arranged between two catalyst layers arranged in succession in flow direction of the gaseous stream, the moderator layer being less catalytically active than the catalysts adjacent upstream and downstream or being catalytically inactive. The desired oxidation products are obtained in high yield over prolonged periods.

Abstract: Methods comprising: providing an oxidation catalyst bed; and starting up the oxidation catalyst at a temperature of 360° C. to 400° C. with an amount of air of 1.0 to 3.5 standard m3/h and a hydrocarbon loading of 20 to 65 g/standard m3, such that a hot spot having a temperature of 390° C. to <450° C. is formed in the first 7-20% of the catalyst bed.

Abstract: Processes comprising providing a catalyst precursor, and heating the catalyst precursor to a temperature of at least 350° C. in an atmosphere comprising air, wherein air is fed into the atmosphere at a rate of 0.05 to 4.0 standard m3/h, and wherein the catalyst precursor is activated at a temperature of at least 350° C. for more than 9 hours are described along with catalysts formed thereby and uses for such catalysts.

Abstract: Alkenylaromatics are produced by catalytic oxidative dehydrogenation of alkylaromatics employing a redox catalyst which is bismuth oxide, in combination with an additive compound of an alkali metal and/or an alkaline earth metal, on a titanium diooxide carrier. In a first reaction step, an alkylaromatic starting material is oxidatively dehydrogenated with the redox catalyst in the absence of molecular oxygen with attending reduction of the redox catalyst. In a second reaction step, the reduced redox catalyst is reoxidized with an oxygen-containing gas.

Abstract: A process for the preparation of olefinically unsaturated compounds by catalytic oxidation, ie oxidative dehydrogenation by transferring oxygen from a previously oxidized oxygen carrier acting as catalyst, in the absence of molecular oxygen, the catalyst being regenerated after exhaustion, wherein, during the operating phase of the catalyst (oxidation/dehydration partial step), the residence time, space velocity and/or temperature of the reactants in the reactor is/are adjusted, ie, controlled, continuously or in discrete steps, in a manner appropiate to the momentary state of activity of the redox catalyst by adjusting--continuously or stepwise--the residence time of the reactants in the freshly regenerated catalyst (ie at the commencement of the reaction) to a shorter time, and/or the temperature to a lower value, than the corresponding parameter(s) in the partially reduced catalyst.

Abstract: A process for the deoxygenation of organic oxo compounds, in particular phosphine oxides to phosphines and nitrobenzene to aniline, with reduced redox catalysts in a non-steady-state reaction with decoupled reductive regeneration of the redox catalyst entails the redox catalyst being reduced to a lower oxidation state and being reused for the deoxygenation.