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 have been produced using antimony trioxide comprising a noticeable proportion of senarmontite wherein some of the 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 comprising a noticeable proportion of senarmontite wherein some of the primary crystallites have a size of less than 200 nm.

Abstract: The present invention relates to a process for preparing phthalic anhydride by gas phase oxidation of aromatic hydrocarbons, in which a gas stream comprising at least one aromatic hydrocarbon and molecular oxygen is passed continuously over a thermostatted catalyst and the supply of the at least one aromatic hydrocarbon to the catalyst is temporarily interrupted after putting the catalyst on stream.

Abstract: A process for preparing carboxylic acids and/or carboxylic anhydrides by gas phase oxidation of aromatic hydrocarbons, in which a gas stream comprising at least one aromatic hydrocarbon and molecular oxygen is passed continuously over a catalyst thermostatted by a heat carrier medium, which comprises keeping the temperature of the heat carrier medium constant during the startup of the reactor for at least 24 hours, during which neither the loading of the gas stream with hydrocarbons nor the gas stream volume is increased by more than 3%.

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 have been produced using antimony trioxide comprising a noticeable proportion of senarmontite wherein some of the 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 comprising a noticeable proportion of senarmontite wherein some of the primary crystallites have a size of less than 200 nm.

Abstract: A process for preparing carboxylic acids and/or carboxylic anhydrides by gas phase oxidation of aromatic hydrocarbons, in which a gas stream comprising at least one aromatic hydrocarbon and molecular oxygen is passed continuously over a catalyst thermostatted by a heat carrier medium, which comprises keeping the temperature of the heat carrier medium constant during the startup of the reactor for at least 24 hours, during which neither the loading of the gas stream with hydrocarbons nor the gas stream volume is increased by more than 3%.

Abstract: The present invention relates to a process for preparing phthalic anhydride by gas phase oxidation of aromatic hydrocarbons, in which a gas stream comprising at least one aromatic hydrocarbon and molecular oxygen is passed continuously over a thermostatted catalyst and the supply of the at least one aromatic hydrocarbon to the catalyst is temporarily interrupted after putting the catalyst on stream.

Abstract: The present invention relates to the use of vanadium-containing particles as a biocide, in particular to the use of vanadium-containing particles comprising at least one vanadium compound and a support material or of a support material in which some metal atoms from the crystal lattice have been replaced by vanadium. Furthermore, it relates to method for preventing biofouling of a substrate and to a method of imparting biocidal properties to the surface of a substrate.