Abstract: An annular unsupported catalyst for the heterogeneously catalyzed partial gas phase oxidation of propene to acrolein at a propene hourly space velocity on the fixed catalyst bed of ?120 1 (STP)/l·h and a total CO2 and saturated hydrocarbon content of the starting reaction gas mixture of below 15 mol %, the catalysts of the fixed catalyst bed are the annular unsupported catalysts whose active composition is a multimetal oxide in which the molar Co/Fe ratio=from 2 to 4 and the molar Co/Mo ratio=from 0.3 to 0.7.

Abstract: A process for the long-term operation of a two-stage heterogeneously catalyzed gas phase partial oxidation of propene to acrylic acid, in which the temperature of the fixed catalyst beds is increased over the time and the gas phase partial oxidation is interrupted from time to time and an oxygen-containing gas mixture is conducted through the fixed catalyst beds at elevated temperature of the fixed catalyst beds.

Abstract: In a process for heterogeneously catalyzed partial gas phase oxidation of propene to acrolein, the starting reaction gas mixture is oxidized over a fixed catalyst bed which consists of at least two fixed catalyst bed zones and is accommodated in two successive temperature zones A, B, and the transition from temperature zone A to temperature zone B does not spatially coincide with a transition from one fixed catalyst bed zone to another fixed catalyst bed zone.

Abstract: Acrolein is prepared by a process of heterogeneous catalyzed partial gas phase oxidation, by passing a starting reaction gas mixture which comprises propene, molecular oxygen and at least one inert gas, in which the molecular oxygen to propene (O2:C3H6) mole ratio is ?1, and carbon dioxide and saturated hydrocarbons together in a total amount of at most 15 mol %, at elevated temperature and at an hourly space velocity on the fixed catalyst bed of propene present in the starting reaction gas mixture of ?120 l (STP)/l·h through a fixed catalyst bed whose catalysts are comprised of annular unsupported catalysts whose active component is at least one multimetal oxide of formula I, Mo12WaCobFecBidSieKfOn??(I) wherein a ranges from ?1 to ?3, b ranges from ?3 to ?8, c ranges from ?1 to ?4, d ranges from ?0.5 to ?1.5, e ranges from ?0 to ?10, and f ranges from ?0 to ?0.

Abstract: A process prepares methacrolein from isobutane by subjecting isobutane to a partial catalytic dehydrogenation in the gas phase and using the isobutenic product gas mixture to charge an oxidation zone in which the isobutene is oxidized to methacrolein in the gas phase with heterogeneous catalysis using molecular oxygen accompanied by molecular nitrogen as the oxygen source.

Abstract: In a process for the heterogeneously catalyzed gas-phase partial oxidation of precursor compounds of (meth)acrylic acid over a fixed catalyst bed which contains, as a catalyst, a mixed oxide active material shaped into a geometric body, the geometric body is a geometric base body into whose surface a cavity has been introduced.

Abstract: In a process for heterogeneously catalyzed partial gas phase oxidation of propene to acrylic acid, the propene-containing starting reaction gas mixture is oxidized in a first reaction stage using a fixed catalyst bed 1 which consists of a plurality of fixed catalyst bed zones and is accommodated in two successive temperature zones A, B, and the acrolein-containing product gas mixture of the first reaction stage is then oxidized in a second reaction stage using a fixed catalyst bed 2 which consists of a plurality of fixed catalyst bed zones and is accommodated in two successive temperature zones C, D, and the transition from one temperature zone to another temperature zone within one reaction stage does not spatially coincide with a transition from one fixed catalyst bed zone to another fixed catalyst bed zone.

Abstract: In a process for heterogeneously catalyzed partial gas phase oxidation of acrolein to acrylic acid, the starting reaction gas mixture is oxidized over a fixed catalyst bed 1 which consists of at least two fixed catalyst bed zones and is accommodated in two successive temperature zones A, B, and the transition from temperature zone A to temperature zone B does not coincide with a transition from one fixed catalyst bed zone to another fixed catalyst bed zone.

Abstract: A process for the long-term operation of a heterogeneously catalyzed gas phase partial oxidation of propene to acrolein, in which the temperature of the fixed catalyst bed is increased over the time and the gas phase partial oxidation is interrupted at least once per calendar year and the gas mixture G consisting of molecular oxygen, inert gas and optionally steam is conducted through the fixed catalyst bed at a temperature of the fixed catalyst bed of from 250 to 550° C.

Abstract: The invention relates to a method for the heterogenically catalyed gas-phase partial oxidation of precursor compounds of (meth)acrylic acid in a fixed catalyst bed, containing as the catalyst an activated mass of mixed oxide, shaped to form a geometric body. Said geometric body is a geometric base body, into whose surface a cavity is incorporated.

Abstract: Coated catalysts which are suitable for the gas-phase catalytic oxidation of propene to acrolein are prepared by a process in which rings are used as supports and water is used as a binder.

Abstract: A process for the heterogeneously catalyzed gas-phase partial oxidation of an organic compound over a fixed catalyst bed present in a fixed-bed reactor having a plurality of catalyst tubes, in which the reduction of the quality of the catalyst load with increasing duration of operation is restored by a partial catalyst change, is described.

Abstract: The present invention relates to a process for charging a reactor with a catalyst, to the resulting charged reactors, and to the use thereof for carrying out catalytic gas phase reactions.

Abstract: A process for preparing an organic target compound by heterogeneously catalyzed gas phase partial oxidation of an organic precursor compound with molecular oxygen in two oxidation reactor lines operated in parallel and removal of the target compound from the mixture of the product gas streams in a workup line, wherein the catalyst charge of one of the oxidation lines comprises a portion of catalyst over which the heterogeneously catalyzed gas phase partial oxidation has already been carried out for longer than over the portions of catalyst of the catalyst charge of the other oxidation reactor line.

Abstract: In a process for partially oxidizing propene to acrylic acid in the gas phase under heterogeneous catalysis, a starting reaction gas mixture comprising propene and oxygen and having a specific composition is oxidized in a first reaction stage over a first fixed catalyst bed having a volume-specific activity which is constant or increases in the flow direction and the acrolein-containing product gas mixture of the first reaction stage is subsequently oxidized in a second reaction stage over a second fixed catalyst bed having a volume-specific activity increasing in the flow direction, and the shaped catalyst bodies of both fixed catalyst beds are annular and each have a specific multimetal oxide composition.

Abstract: In a process for the preparation of acrylic acid by heterogeneously catalyzed gas-phase oxidation of propene with molecular oxygen in a reaction zone, the catalytically active material is a multimetal oxide which contains the elements Mo, V, Te and/or Sb and has a specific structure.

Abstract: A process for the long-term operation of a heterogeneously catalyzed gas phase partial oxidation of acrolein to acrylic acid, in which the temperature of the fixed catalyst bed is increased over time and partial oxidation is interrupted and an oxygen-containing gas is conducted through the fixed catalyst bed before the temperature increase is 8° C.

Abstract: In a process for partially oxidizing propene to acrylic acid in the gas phase under heterogeneous catalysis, a starting reaction gas mixture comprising propene and oxygen and having a specific composition is oxidized in a first reaction stage over a first fixed catalyst bed having a volume-specific activity which is constant or increases in the flow direction and the acrolein-containing product gas mixture of the first reaction stage is subsequently oxidized in a second reaction stage over a second fixed catalyst bed having a volume-specific activity increasing in the flow direction, and the shaped catalyst bodies of both fixed catalyst beds are annular and each have a specific multimetal oxide composition.

Abstract: In a process for heterogeneously catalyzed partial gas phase oxidation of propene to acrolein, the starting reaction gas mixture is oxidized at a propene loading of <160 l (STP) of propene/l of fixed catalyst bed·h over a fixed catalyst bed which is accommodated in two successive reaction zones A, B, the highest temperature of the reaction gas mixture within reaction zone A being above the temperature of the reaction gas mixture within reaction zone B.

Abstract: A process for preparing (meth)acrolein and/or (meth)acrylic acid by heterogeneously catalyzed gas phase partial oxidation of an organic precursor compound over a fresh fixed catalyst bed, in which the process is started up at a reduced hourly space velocity of charging gas mixture on the fixed catalyst bed.