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: Process for preparing phthalic anhydride by gas-phase oxidation of xylene, naphthalene or mixtures thereof in a shell-and-tube reactor thermostatted by means of a heat transfer medium over three or more different fixed-bed catalysts arranged in zones, wherein the process is carried out so that the maximum temperature in the second catalyst zone in the flow direction is up to 50° C. lower than the maximum temperature in the first catalyst zone and the maximum temperature in the third zone from the gas inlet is from 30 to 100° C. lower than that in the first catalyst zone. The process of the present invention makes it possible to prepare phthalic anhydride in high yields under industrially relevant conditions.

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: The invention relates to a pump (1) having a pump guide tube (13) for the transport of a heat-exchange medium (6) for a reactor having a bundle of catalyst tubes (2), where the pump (1) has a casing (14) which surrounds the pump guide tube (13), having an aperture (15) in the lower part of the casing (14) via which the heat-exchange medium (6) discharged from the lower region of the reactor by means of the pump (1) flows into the casing (14), flows upward in the region between the inner wall of the casing (14) and the outer wall of the pump guide tube (13), if desired via a heat exchanger (18), flows into the interior of the pump guide tube (13) via an aperture (16) in the upper region of the pump guide tube (13), flows through the pump guide tube (13) from top to bottom and flows via an aperture (17) in the lower region of the pump guide tube (13) into the reactor, into the upper region of the interspace between the catalyst tubes (2).

Abstract: A multimetal oxide of the formula I, Aga-cQbMcV2Od*eH2O,??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: A catalyst for gas-phase oxidations which comprises an inert support and a catalytically active composition comprising transition metal oxides applied thereto, or a precatalyst, is described. The (pre)catalyst is obtained by treating the inert support with an aqueous suspension or solution of the transition metal oxides or their precursor compounds, where the suspension contains a binder dispersion and the binder is a copolymer of an ?-olefin and a vinyl-C2-C4-carboxylate whose vinyl C2-C4-carboxylate content is at least 62 mol %.

Abstract: A process for preparing (meth)acrylic acid by conducting a saturated hydrocarbon precursor compound through a catalyst bed I whose catalysts I have, as the active composition, a multimetal oxide I which has a specific X-ray diffractogram and contains the elements Mo and V, at least one of the elements Te and Sb, and also at least one of the elements from the group consisting of Nb, Ta, W, Ce and Ti, wherein the catalyst bed I is interrupted by at least one catalyst bed II whose catalysts II have, as the active composition, a multimetal oxide II which contains the elements Mo, Bi and Fe.

Abstract: A process for preparing (meth)acrylic acid, in which a saturated hydrocarbon precursor compound is conducted through a catalyst charge which consists of two spatially successive catalyst beds I, II in the flow direction of the reaction mixture, each of which contains different catalysts and has different reaction-selectivity behavior.

Abstract: A process for the hydrothermal preparation of Mo- and V-comprising multimetal oxide materials, substantially exclusively sources from the group consisting of oxides, hydrated oxides, oxygen acids and hydroxides being used as sources of the elemental constituents of the multimetal oxide material, and a portion of the sources comprising the elemental constituent contained with an oxidation number which is below its maximum oxidation number.

Abstract: A process prepares methacrylic acid from isobutane by subjecting isobutane to a partial catalytic dehydrogenation in the gas phase and charging an oxidation zone with the isobutenic product gas mixture after the components other than isobutane and isobutene have been substantially removed from the product gas mixture. The oxygen required to charge the oxidation zone is introduced accompanied by nitrogen.

Abstract: Process for preparing phthalic anhydride by gas-phase oxidation of xylene, naphthalene or mixtures thereof in a shell-and-tube reactor thermostatted by means of a heat transfer medium over three or more different fixed-bed catalysts arranged in zones, wherein the process is carried out so that the maximum temperature in the second catalyst zone in the flow direction is up to 50° C. lower than the maximum temperature in the first catalyst zone and the maximum temperature in the third zone from the gas inlet is from 30 to 100° C. lower than that in the first catalyst zone. The process of the present invention makes it possible to prepare phthalic anhydride in high yields under industrially relevant conditions.

Abstract: A process for preparing (meth)acrylic acid, in which a saturated hydrocarbon precursor compound is conducted through a catalyst charge which consists of two spatially successive catalyst beds I, II in the flow direction of the reaction mixture, each of which contains different catalysts and has different reaction-selectivity behavior.

Abstract: A process for preparing (meth)acrylic acid by conducting a saturated hydrocarbon precursor compound through a catalyst bed I whose catalysts I have, as the active composition, a multimetal oxide I which has a specific X-ray diffractogram and contains the elements Mo and V, at least one of the elements Te and Sb, and also at least one of the elements from the group consisting of Nb, Ta, W, Ce and Ti, wherein the catalyst bed I is interrupted by at least one catalyst bed II whose catalysts II have, as the active composition, a multimetal oxide II which contains the elements Mo, Bi and Fe.

Abstract: A process for preparing (meth)acrylic acid by heterogeneously catalyzed gas phase partial oxidation of a saturated hydrocarbon precursor compound, in which the charging gas mixture contains from 5 to 25% by volume of steam and the molar ratio of molecular oxygen present in the charging gas mixture to saturated hydrocarbon precursor compound present in the charging gas mixture is from 1.5:1 to 2.5:1.

Abstract: A process prepares methacrylic acid from isobutane by subjecting isobutane to a partial catalytic dehydrogenation in the gas phase and charging an oxidation zone with the isobutenic product gas mixture after the components other than isobutane and isobutene have been substantially removed from the product gas mixture. The oxygen required to charge the oxidation zone is introduced accompanied by nitrogen.

Abstract: The invention relates to a process for preparing unsaturated nitrites from the corresponding alkanes which comprises the steps:

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 preparation of acrolein or acrylic acid or a mixture thereof from propane, the propane is subjected, in a first reaction stage, to a partial dehydrogenation under heterogeneous catalysis to give propene, of the components contained in the product gas mixture formed in the first reaction stage other than propene and propane at least a portion of the molecular hydrogen present is then separated off from said mixture and the product gas mixture is then used for the preparation of acrolein and/or acrylic acid by gas-phase catalytic propylene oxidation, molecular nitrogen being present for diluting the reaction gas mixture during the propylene oxidation.

Abstract: The invention relates to a pump (1) having a pump guide tube (13) for the transport of a heat-exchange medium (6) for a reactor having a bundle of catalyst tubes (2), where the pump (1) has a casing (14) which surrounds the pump guide tube (13), having an aperture (15) in the lower part of the casing (14) via which the heat-exchange medium (6) discharged from the lower region of the reactor by means of the pump (1) flows into the casing (14), flows upward in the region between the inner wall of the casing (14) and the outer wall of the pump guide tube (13), if desired via a heat exchanger (18), flows into the interior of the pump guide tube (13) via an aperture (16) in the upper region of the pump guide tube (13), flows through the pump guide tube (13) from top to bottom and flows via an aperture (17) in the lower region of the pump guide tube (13) into the reactor, into the upper region of the interspace between the catalyst tubes (2).

Abstract: A reactor for testing catalyst systems which has a plurality of catalyst tubes (2) which are arranged parallel to one another in the interior space of the reactor and whose ends are welded into tube plates and also has caps (3) at each end of the reactor which each bound a cap space (4), with a fluid reaction medium (5) being fed via one cap space (4) into the catalyst tubes (2), flowing through the catalyst tubes (2) and being discharged via the other cap space (4), and is also provided with a heat exchange medium circuit in which the heat exchange medium (6) is fed in at one end of the reactor, flows through the intermediate space between the catalyst tubes (2) and flows out at the other end of the reactor, wherein the catalyst tubes (2) are arranged in two or more catalyst tube regions (7) which are thermally separate from one another, is proposed.