Abstract: Multimetal oxide composition comprising Mo, Bi, Fe, Cu and one or more than one of the elements Co and Ni and use thereof.

Abstract: Multimetal oxide composition comprising Mo, Bi, Fe, Cu and one or more than one of the elements Co and Ni and use thereof.

Abstract: The invention relates to a catalyst molded body for preparing maleic anhydride by gas-phase oxidation of a hydrocarbon having at least four carbon atoms using a catalytically active composition containing vanadium, phosphorus and oxygen. The shaped catalyst body has an essentially cylindrical body having a longitudinal axis. The cylindrical body has at least two parallel internal holes which are essentially parallel to the cylinder axis of the body and go right through the body. The catalyst molded body has a large outer surface area, a lower pressure loss and sufficient mechanical stability.

Abstract: The invention relates to an oxidation catalyst comprising at least one inorganic, oxidic or ceramic, shaped support body having a BET surface area of less than 0.5 m2/g, based on the support, which is at least partly coated with a catalytically active multielement oxide, the catalyst being precious metal-free and the shaped support body having the form of a saddle whose saddle surface is curved oppositely in the two principal directions, to a process for producing it, to its use in various catalytic gas phase oxidations, and to corresponding processes for catalytic gas phase oxidation.

Abstract: A hollow cylindrical shaped catalyst body for gas phase oxidation of an alkene to an ?,?-unsaturated aldehyde and/or an ?,?-unsaturated carboxylic acid comprises a compacted multimetal oxide having an external diameter ED, an internal diameter ID and a height H, wherein ED is in the range from 3.5 to 4.5 mm; the ratio q=ID/ED is in the range from 0.4 to 0.55; and the ratio p=H/ED is in the range from 0.5 to 1. The shaped catalyst body is mechanically stable and catalyzes the partial oxidation of an alkene to the products of value with high selectivity. It provides a sufficiently high catalyst mass density of the catalyst bed and good long-term stability with acceptable pressure drop.

Abstract: Shaped catalyst bodies comprising a multielement oxide I having the general stoichiometry I [Bi1WbOx]a[Mo12Z1cZ2dFeeZ3fZ4gZ5hOy]1 (I), where Z1=Ni or Co, Z2=alkali metal or alkaline earth metal, Z3=zinc, phosphorus, arsenic, boron, antimony, tin, cerium, vanadium, chromium or bismuth, Z4=silicon, aluminum, titanium, tungsten or zirconiurn, Z5=copper, silver, gold, yttrium, lanthanum and lanthanides, a=0.1 to 3, b=0.1 to 10, c=1 to 10, d=0.01 to 2, e=0.01 to 5, f=0 to 5, g=0 to 10, h=0 to 1 and x, y=numbers determined by the valence and abundance of the elements other than oxygen in I, as active composition are produced by preforming a mixed oxide Bi1WbOx by coprecipitation from an aqueous environment at a pH in the range from 1.

Abstract: Process for preparing a vinylidenecarboxylic acid or ester thereof, wherein a reaction gas comprising gaseous formaldehyde, molecular oxygen and an alkycarboxylic acid or ester thereof is brought into contact with a solid catalyst whose active composition comprises a vanadium-phosphorus oxide having an average oxidation state of vanadium of from +4.40 to +5.0 to give a product gas comprising the vinylidenecarboxylic acid or ester thereof.

Abstract: What is described is a catalyst for preparation of an ?,?-unsaturated carboxylic acid by gas phase oxidation of an ?,?-unsaturated aldehyde, comprising a shaped support body with an active composition applied thereto, wherein the active composition coverage q q = Q ( 100 - Q ) ? S m is at most 0.3 mg/mm2, where Q is the active composition content of the catalyst in % by weight and Sm is the specific geometric surface area of the shaped support body in mm2/mg. Also described are a process for preparing the catalyst and a process for preparing an ?,?-unsaturated carboxylic acid by gas phase oxidation of an ?,?-unsaturated aldehyde over a fixed catalyst bed comprising a bed of the catalyst. The catalyst, with constantly high conversion of acrolein, reduces overoxidation to COx and increases the selectivity of acrylic acid formation.

Abstract: The invention relates to a catalyst molded body for preparing maleic anhydride by gas-phase oxidation of a hydrocarbon having at least four carbon atoms using a catalytically active composition containing vanadium, phosphorus and oxygen. The shaped catalyst body has an essentially cylindrical body having a longitudinal axis. The cylindrical body has at least two parallel internal holes which are essentially parallel to the cylinder axis of the body and go right through the body. The catalyst molded body has a large outer surface area, a lower pressure loss and sufficient mechanical stability.

Abstract: An ?,?-unsaturated aldehyde and/or an ?,?-unsaturated carboxylic acid are prepared by gas phase oxidation of alkene with molecular oxygen over a fixed catalyst bed comprising a bed of hollow cylindrical shaped catalyst bodies having a multimetal oxide active composition. The fixed catalyst bed comprises at least three successive reaction zones; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor outlet; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor inlet; and the value WT=(ED?ID)/2 in the reaction zone in which the highest local temperature in the fixed catalyst bed occurs is lower than in the other reaction zones, in which ED is the external diameter and ID is the internal diameter of the shaped catalyst body. The yield of the products of value is enhanced in this way.

Abstract: An eggshell catalyst consisting of a hollow cylindrical support body of length 2 to 10 mm, external diameter 4 to 10 mm and wall thickness 1 to 4 mm, and an eggshell, applied to the outer surface of the support body, of catalytically active oxide material of the general formula I, Mo12V2 to 4W0 to 3Cu0.8 to 1.5X10 to 4X20 to 40On??(I) in which the variables are each defined as follows: X1=one or more elements of the alkali metals and alkaline earth metals; X2=one or more elements from the group of Si, Al, Ti and Zr; and n=the stoichiometric coefficient of the element oxygen, which is determined by the stoichiometric coefficients of the elements other than oxygen and the charges thereof in I.

Abstract: The invention relates to a catalyst molded body for preparing maleic anhydride by gas-phase oxidation of a hydrocarbon having at least four carbon atoms using a catalytically active composition contains vanadium, phosphorus and oxygen, where the shaped catalyst body has an essentially cylindrical body having a longitudinal axis, wherein the cylindrical body has at least two parallel internal holes which are essentially parallel to the cylinder axis of the body and go right through the body. The catalyst molded body has a large outer surface area, a lower pressure loss and sufficient mechanical stability.

Abstract: The invention relates to an oxidation catalyst comprising at least one inorganic, oxidic or ceramic, shaped support body having a BET surface area of less than 0.5 m2/g, based on the support, which is at least partly coated with a catalytically active multielement oxide, the catalyst being precious metal-free and the shaped support body having the form of a saddle whose saddle surface is curved oppositely in the two principal directions, to a process for producing it, to its use in various catalytic gas phase oxidations, and to corresponding processes for catalytic gas phase oxidation.

Abstract: A process for producing a catalytically active composition being a mixture of a multielement oxide comprising the elements Mo and V and at least one oxide of molybdenum, in which spray drying of an aqueous solution or of an aqueous suspension of starting compounds comprising the elements of the multielement oxide produces a spray powder P, a pulverulent oxide of molybdenum and optionally shaping assistants are added thereto, shaped bodies are shaped from the resulting mixture and these are converted to the catalytically active composition by thermal treatment.

Abstract: A hollow cylindrical shaped catalyst body for gas phase oxidation of an alkene to an ?,?-unsaturated aldehyde and/or an ?,?-unsaturated carboxylic acid comprises a compacted multimetal oxide having an external diameter ED, an internal diameter ID and a height H, wherein ED is in the range from 3.5 to 4.5 mm; the ratio q=ID/ED is in the range from 0.4 to 0.55; and the ratio p=H/ED is in the range from 0.5 to 1. The shaped catalyst body is mechanically stable and catalyzes the partial oxidation of an alkene to the products of value with high selectivity. It provides a sufficiently high catalyst mass density of the catalyst bed and good long-term stability with acceptable pressure drop.

Abstract: An ?,?-unsaturated aldehyde and/or an ?,?-unsaturated carboxylic acid are prepared by gas phase oxidation of alkene with molecular oxygen over a fixed catalyst bed comprising a bed of hollow cylindrical shaped catalyst bodies having a multimetal oxide active composition. The fixed catalyst bed comprises at least three successive reaction zones; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor outlet; the highest local temperature in the fixed catalyst bed does not occur in the reaction zone closest to the reactor inlet; and the value WT=(ED?ID)/2 in the reaction zone in which the highest local temperature in the fixed catalyst bed occurs is lower than in the other reaction zones, in which ED is the external diameter and ID is the internal diameter of the shaped catalyst body. The yield of the products of value is enhanced in this way.

Abstract: Process for producing a supported silver catalyst, which comprises (a) reacting oxalic acid with an alkali metal base in a solvent, preferably water, to the second equivalence point of oxalic acid to give alkali metal oxalate; (b) reacting the alkali metal oxalate obtained according to (a) with silver salt in a solvent, preferably water, to give silver oxalate; (c) forming a complexation of the silver oxalate obtained according to (b) with a diamine compound in a solvent, preferably water, to give a diamine-silver oxalate complex.

Abstract: What is described is a catalyst for preparation of an ?,?-unsaturated carboxylic acid by gas phase oxidation of an ?,?-unsaturated aldehyde, comprising a shaped support body with an active composition applied thereto, wherein the active composition coverage q q = Q ( 100 - Q ) ? S m is at most 0.3 mg/mm2, where Q is the active composition content of the catalyst in % by weight and Sm is the specific geometric surface area of the shaped support body in mm2/mg. Also described are a process for preparing the catalyst and a process for preparing an ?,?-unsaturated carboxylic acid by gas phase oxidation of an ?,?-unsaturated aldehyde over a fixed catalyst bed comprising a bed of the catalyst. The catalyst, with constantly high conversion of acrolein, reduces overoxidation to COx and increases the selectivity of acrylic acid formation.

Abstract: The present invention relates to a shaped catalyst body for preparing ethylene oxide, which comprises at least silver and rhenium applied to an alumina support, and also to a process for producing it, wherein the alumina support has the geometry of a hollow cylinder and the shaped catalyst body has a rhenium content CR and CR/ppm by weight, based on the wall thickness of the hollow cylinder dW in mm, and calculated as element, in the range 120?CR/dW?200.

Abstract: In a process for controlling a gas phase oxidation reactor for preparation of phthalic anhydride, by passing a gas stream which comprises an aromatic hydrocarbon and molecular oxygen through a multitude of reaction tubes arranged in the gas phase oxidation reactor, each of which comprises a bed of at least one catalyst and the temperature of which can be controlled by means of a heat transfer medium, at least one control parameter is measured and correcting interventions for control of the control parameter are determined, the at least one control parameter comprising the phthalic anhydride yield and the correcting parameter used being the temperature of the heat carrier medium. Over at least 90% of the lifetime of the catalyst, the change in the correcting parameter is limited to a maximum of 0.5 K within a period of 30 days. In this way, the cumulated phthalic anhydride yield over the lifetime of the catalyst is maximized.