Abstract: The invention relates to a process for preparing butadiene from n-butenes, comprising the steps of: A) providing an input gas stream a comprising n-butenes, B) feeding the input gas stream a comprising n-butenes and a gas containing at least oxygen into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream b comprising butadiene, unconverted n-butenes, water vapor, oxygen, low-boiling hydrocarbons and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling the product gas stream b by contacting with a cooling medium in at least one cooling zone, the cooling medium being at least partly recycled and having an aqueous phase and an organic phase of an organic solvent, wherein the organic solvent is selected from the group consisting of toluene, o-, m- and p-xylene, mesitylene, mono-, di- and triethylbenzene, mono-, di- and triisopropylbenzene and mixtures thereof, and the mass ratio of

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: The present invention relates to a process for preparing acrylic acid from acetic acid and formaldehyde, which comprises (a) provision of a stream S1 comprising acetic acid and formaldehyde, where the molar ratio of acetic acid to formaldehyde in the stream S1 is in the range from 0.5:1 to 2:1; (b) contacting of the stream S1 with an aldol condensation catalyst comprising vanadium, phosphorus and oxygen to give a stream S2 comprising acrylic acid, where, in (b), the space velocity WHSV is in the range from 0.35 to 7.0 kg/kg/h.

Abstract: The present invention relates to the use of gamma iron(III) oxide (?-Fe2O3) containing particles for the prevention of biofouling and/or growth of microorganisms. Furthermore, it relates to a method for preventing biofouling of a substrate and to a method of imparting biocidal properties to the surface of a substrate.

Abstract: The present invention relates to a catalyst system for oxidation of o-xylene and/or naphthalene to phthalic anhydride (PA), comprising a plurality of catalyst zones arranged in succession in the reaction tube, which has been produced using antimony trioxide consisting predominantly of the senarmontite modification of which all primary crystallites have a size of less than 200 nm. The present invention further relates to a process for gas phase oxidation, in which a gas stream comprising at least one hydrocarbon and molecular oxygen is passed through a catalyst system which comprises a plurality of catalyst zones arranged in succession in the reaction tube and which has been produced using an antimony trioxide consisting predominantly of the senarmontite modification with a median primary crystallite size of less than 200 nm.

Abstract: A process for preparing butadiene from n-butenes, comprising the steps of A) providing an input gas stream a1 comprising n-butenes; B) feeding the input gas stream a1 comprising n-butenes, an oxygenous gas and an oxygenous cycle gas stream a2 into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream b comprising butadiene, unconverted n-butenes, steam, oxygen, low-boiling hydrocarbons and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling the product gas stream b and optionally at least partly removing high-boiling secondary components and steam, giving a product gas stream b?, Cb) compressing and cooling the product gas stream b? in at least one compression and cooling stage, giving at least one aqueous condensate stream c1 and one gas stream c2 comprising butadiene, n-butenes, steam, oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without ine

Abstract: The invention relates to a process for preparing butadiene from n-butenes having a start-up phase and an operating phase, wherein the process in the operating phase comprises the steps: A) provision of a feed gas stream a1 comprising n-butenes; B) introduction of the feed gas stream a1 comprising n-butenes, of an oxygen-comprising gas stream a2 and of an oxygen-comprising recycle gas stream d2 into at least one oxidative dehydrogenation zone and oxidative dehydrogenation of n-butenes to butadiene, giving a product gas stream b comprising butadiene, unreacted n-butenes, water vapor, oxygen, low-boiling hydrocarbons, high-boiling secondary components, possibly carbon oxides and possibly inert gases; C) cooling and compression of the product gas stream b and condensation of at least part of the high-boiling secondary components, giving at least one aqueous condensate stream c1 and a gas stream c2 comprising butadiene, n-butenes, water vapor, oxygen, low-boiling hydrocarbons, possibly carbon oxides and possibly

Abstract: The invention relates to a catalyst which comprises a catalytically active multimetal oxide which comprises molybdenum and at least one further metal has the general formula (I) Mo12BiaMnbCocFedX1eX2fOx??(I), where the variables have the following meanings: X1=Si and/or Al; X2=Li, Na, K, Cs and/or Rb; a=0.2 to 1; b=0 to 2; c=2 to 10; d=0.5 to 10; e=0 to 10; f=0 to 0.5; and x=is a number determined by the valence and abundance of the elements other than oxygen in (I).

Abstract: The present invention relates to a process for preparing acrylic acid from acetic acid and formaldehyde, which comprises (a) provision of a stream S1 comprising acetic acid and formaldehyde, where the molar ratio of acetic acid to formaldehyde in the stream S1 is in the range from 0.5:1 to 2:1; (b) contacting of the stream S1 with an aldol condensation catalyst comprising vanadium, phosphorus and oxygen to give a stream S2 comprising acrylic acid, where, in (b), the space velocity WHSV is in the range from 0.35 to 7.0 kg/kg/h.

Abstract: The invention relates to a process for preparing butadiene from n-butenes, comprising the steps of: A) providing an input gas stream a comprising n-butenes; B) feeding the input gas stream a comprising n-butenes and an oxygenous gas into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, giving a product gas stream b comprising butadiene, unconverted n-butenes, water vapor, oxygen, low-boiling hydrocarbons and high-boiling secondary components, with or without carbon oxides and with or without inert gases; Ca) cooling the product gas stream b by contacting it with a coolant and condensing at least a portion of the high-boiling secondary components; Cb) compressing the remaining product gas stream b in at least one compression stage, giving at least one aqueous condensate stream c1 and one gas stream c2 comprising butadiene, n-butenes, water vapor, oxygen and low-boiling hydrocarbons, with or without carbon oxides and with or without inert gases; Da) removing

Abstract: The invention relates to a process for the oxidative dehydrogenation of n-butenes to butadiene, which comprises two or more production steps (i) and at least one regeneration step (ii) and in which (i) a starting gas mixture comprising n-butenes is mixed with an oxygen-comprising gas in a production step and the mixed gas is brought into contact with a multimetal oxide catalyst which comprises at least molybdenum and a further metal and is arranged in a fixed catalyst bed at a temperature of from 220 to 490° C. in a fixed-bed reactor, with a product gas mixture comprising at least butadiene, oxygen and water vapor being obtained at the outlet of the fixed-bed reactor, and (ii) the multimetal oxide catalyst is regenerated in a regeneration step by passing an oxygen-comprising regeneration gas mixture over the fixed catalyst bed at a temperature of from 200 to 450° C.

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: 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: 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: 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: 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: 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: In a process for preparing acrylic acid, a reaction gas which comprises a gaseous formaldehyde source and gaseous acetic acid and in which the partial pressure of the formaldehyde source, calculated as formaldehyde equivalents, is at least 85 mbar and in which the molar ratio of the acetic acid to the formaldehyde source, calculated as formaldehyde equivalents, is at least 1 is contacted with a solid condensation catalyst. The space-time yield can be enhanced significantly by increasing the partial pressure of the reactants. The space-time yield remains high even after prolonged process duration.

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.