Abstract: Catalyst systems for preparing phthalic anhydride by means of gas-phase oxidation of o-xylene and/or naphthalene, and a process for preparing phthalic anhydride using the catalyst systems.

Abstract: What is described is a method for starting a gas phase oxidation reactor that contains a bed of a first catalyst whose active material comprises a catalytically active silver-vanadium oxide bronze, and at least one bed of a second catalyst whose catalytically active material comprises vanadium pentoxide and titanium dioxide, and whose temperature is controllable by means of a heat transfer medium. In the operating state, a gas stream which comprises a loading cop of a hydrocarbon and molecular oxygen is passed through the reactor over the bed of the first and second catalyst at a temperature Top of the heat transfer medium. For the startup, a) a gas stream is passed through the reactor with a starting loading c0 which is less than cop, and at a starting temperature T0 of the heat transfer medium which is less than Top, and b) the temperature of the heat transfer medium is brought to Top and the loading of the gas stream to cop.

Abstract: Catalytic titanium dioxide mixtures comprising: a first anatase titanium dioxide having a BET surface area greater than 15 m2/g and a hydrogen uptake for the reduction of Ti4+ to Ti3+ of from 5 to 20 ?mol/m2; and a second anatase titanium dioxide having a BET surface area less than or equal to 15 m2/g and a hydrogen uptake for the reduction of Ti4+ to Ti3+ of from 0.6 to 7 ?mol/m2, processes for preparing catalysts containing the same, catalysts containing active compositions including such titanium dioxide mixtures on support materials, and catalyst systems using the same.

Abstract: Catalyst systems for preparing phthalic anhydride by means of gas-phase oxidation of o-xylene and/or naphthalene, and a process for preparing phthalic anhydride using the catalyst systems

Abstract: Catalyst systems for preparing phthalic anhydride by means of gas-phase oxidation of o-xylene and/or naphthalene, and a process for preparing phthalic anhydride using the catalyst systems.

Abstract: Catalyst systems for preparing carboxylic acids and/or anhydrides, the catalyst system comprising a reaction zone and a layered catalyst, the reaction zone comprises a gas inlet region and a gas outlet region, the layered catalyst comprises an active composition and one or more middle layers, one or more first layers disposed on a side of the one or more middle layers toward the gas inlet region, and one or more second layers on a side of the one or more middle layers toward the gas outlet region, wherein the active composition content of one or more of the middle catalyst layers, based on total mass of the layered catalyst, is lower than the active composition content of the one or more first catalyst layers and is lower than one or more second catalyst layers; and processes for gas phase oxidation employing a layered catalyst of the present invention.

Abstract: A process is described for converting a precatalyst which comprises an inert support, an organic carbon source and a multimetal oxide comprising silver and vanadium to a gas phase oxidation catalyst which comprises the inert support and a catalytically active silver vanadium oxide bronze, by treating the precatalyst thermally at a temperature of at least 350° C. in a gas atmosphere which comprises less than 10% by volume of oxygen, wherein, before the thermal treatment, the amount of the carbon source in the precatalyst is adjusted to a value below a critical amount The carbon content is reduced by burning-off at a temperature of from 80 to 200° C. in an oxygenous atmosphere with decomposition of a portion of the carbon source. The catalysts obtained serve for the gas phase partial oxidation of aromatic hydrocarbons to aldehydes, carboxylic acids and/or carboxylic anhydrides.

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 is described for producing a catalyst for gas-phase oxidations, in which a suspension of TiO2 and V2O5 particles is applied to a fluidized inert support, wherein at least 90% by volume of the V2O5 particles have a diameter of 20 ?m or less and at least 95% by volume of the V2O5 particles have a diameter of 30 ?m or less. The defined particle size distribution of the V2O5 allows a high coating efficiency.

Abstract: The present invention relates to a catalyst system for preparing carboxylic acids and/or carboxylic anhydrides which has at least four catalyst layers arranged one on top of another in the reaction tube, the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers being between 1.4 and 2. The present invention further relates to a process for gas phase oxidation in which a gaseous stream which comprises a hydrocarbon and molecular oxygen is passed through a plurality of catalyst layers, the ratio of the bed lengths of the more selective catalyst layers to the bed lengths of the more active catalyst layers being between 1.4 and 2.

Abstract: The present invention relates to a catalytically active composition comprising as active component Pd and Bi and at least one element selected from the group (a) consisting of Rh, Au, Sb, V, Cr, W, Mn, Fe, Co, Ni, Na, Cs and Ba, or Pd, Rh and Bi and optionally an element selected from the group (a?) consisting of Au, Sb, V, Cr, W, Mn, Fe, Co, Ni, Pt, Cu, Ag, Na, Cs, Mg, Ca and Ba. The present invention further provides a process for dehydrogenating hydrocarbons, preferably oxo-functionalized hydrocarbons such as cyclopentanone, cyclohexanone and isovaleraldehyde, using the catalytically active composition.

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: A multimetal oxide of the formula I, Aga-cQbMcV2Od*e H2O,??I where a is from 0.3 to 1.9, Q is an element selected from among P, As, Sb and/or Bi, is from 0 to 0.3, M is a metal selected from among Nb, Ce, W, Mn, Ta, Pd, Pt, Ru and/or Rh, c is from 0.001 to 0.5, with the proviso that (a-c)?0.1, d is a number which is determined by the valence and abundance of the elements other than oxygen in the formula I and e is from 0 to 20, and also precatalysts and catalysts produced therefrom for the partial oxidation of aromatic hydrocarbons are described.

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: The invention relates to a process for preparing phthalic anhydride, in which the catalytic gas-phase oxidation of o-xylene and/or naphthalene is carried out over at least three zones of catalysts of increasing activity, with only the last zone of the catalyst system containing phosphorus and the last zone also comprising at least 10% by weight of vanadium (calculated as V2O5) based on the active composition of the catalyst and having a ratio of vanadium (calculated as V2O5) to phosphorus of greater than 35.

Abstract: A description is given of a process for preparing aldehydes, carboxylic acids and/or carboxylic anhydrides, in particular phthalic anhydride, in which a gaseous stream comprising an aromatic hydrocarbon and molecular oxygen is passed at elevated temperature over a bed of a first catalyst and a bed which is made up of a second catalyst having a higher activity than the first catalyst and is located downstream of the first catalyst in the flow direction of the gaseous stream, wherein the catalytically active composition of the first catalyst comprises at least vanadium oxide, titanium dioxide and antimony oxide and the ratio of vanadium, calculated as V2O5, to antimony, calculated as Sb2O3, in the first catalyst is from 3.5:1 to 5:1. The source of antimony oxide used for the first catalyst is preferably particulate antimony trioxide having a mean particle size of from 0.5 to 5 ?m. The process allows the desired oxidation products to be obtained in high yield over longer periods of time.

Abstract: Catalytic titanium dioxide mixtures comprising: a first anatase titanium dioxide having a BET surface area greater than 15 m2/g and a hydrogen uptake for the reduction of Ti4+ to Ti of from 5 to 20 ?mol/m2; and a second anatase titanium dioxide having a BET surface area less than or equal to 15 m2/g and a hydrogen uptake for the reduction of Ti4+ to Ti3+ of from 0.6 to 7 ?mol/m2, processes for preparing catalysts containing the same, catalysts containing active compositions including such titanium dioxide mixtures on support materials, and catalyst systems using the same.

Abstract: A catalyst is described which has a catalytically active composition which contains a phase A and a phase B in the form of three-dimensional delimited regions, wherein phase A is a silver-vanadium oxide bronze and phase B a mixed oxide phase based on titanium dioxide and vanadium pentoxide. The catalyst serves to prepare aldehydes, carboxylic acids and/or carboxylic anhydrides from aromatic or heteroaromatic hydrocarbons by gas phase oxidation.

Abstract: Multimetal oxides corresponding to the general formula (I), processes for their preparation, precatalysts containing such oxides and catalysts made therefrom for gas phase partial oxidation of hydrocarbons: Aga-cQbMcV12Od.eH2O??(I) wherein a represents a number having a value of 5 to 9; Q represents an element selected from the group consisting of P, As, Sb, Bi and mixtures thereof; b represents a number having a value of 0.

Abstract: A catalyst is described which has a catalytically active composition which contains a phase A and a phase B in the form of three-dimensional delimited regions, wherein phase A is a silver-vanadium oxide bronze and phase B a mixed oxide phase based on titanium dioxide and vanadium pentoxide. The catalyst serves to prepare aldehydes, carboxylic acids and/or carboxylic anhydrides from aromatic or heteroaromatic hydrocarbons by gas phase oxidation.