Abstract: Acrolein and/or acrylic acid are prepared from propane and/or propene by a process comprising the following steps: (a) separation of propane and/or propene from a propane- and/or propene-containing gas mixture by absorption in an absorbent, (b) separation of the propane and/or propene from the absorbent to give a gas B and (c) use of the gas B obtained in stage (b) for an oxidation of propane and/or propene to acrolein and/or acrylic acid, no heterogeneously catalyzed dehydrogenation of propane without supply of oxygen being carried out between steps (b) and (c).

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: A process for the preparation of maleic anhydride by heterogeneously catalyzed gas-phase oxidation in a reactor with feed for the reaction mixture at one end of the reactor and discharge of the product mixture at the opposite end of the reactor, and with devices for dissipating the heat of reaction which are arranged in the reactor interior and through which a heat-exchange medium flows and which are designed as heat-exchanger plates.

Abstract: A process for preparing acrylic acid or methacrylic acid comprises (a) preparing a gaseous product mixture having essentially the composition of a reaction mixture of the catalytic gas phase oxidation of C3-/C4-alkanes, -alkenes, -alkanols and/or -alkanals and/or precursors thereof to form acrylic acid or methacrylic acid, characterized by (b) condensing said product mixture, (c) crystallizing acrylic acid or methacrylic acid from the solution obtained in step (b), and (d) removing the resulting crystals from the mother liquor.

Abstract: A process for the preparation of maleic anhydride by heterogeneously catalyzed gas-phase oxidation in a reactor with feed for the reaction mixture at one end of the reactor and discharge of the product mixture at the opposite end of the reactor, and with devices for dissipating the heat of reaction which are arranged in the reactor interior and through which a heat-exchange medium flows and which are designed as heat-exchanger plates.

Abstract: A process for preparing acrylic acid or methacrylic acid comprises preparing a gaseous product mixture having essentially the composition of a reaction mixture of the catalytic gas phase oxidation of C3-/C4-alkanes, -alkenes, -alkanols and/or -alkanals and/or precursors thereof to form acrylic acid or methacrylic acid. The product is removed from the gaseous product mixture by a process comprising the following steps: (a) condensing said gaseous product mixture, (b) crystallizing acrylic acid or methacrylic acid from the solution obtained in step (a), (c) removing the resulting crystals from the mother liquor, and (d) recycling at least a portion of said mother liquor from step (c) into step (a).

Abstract: A process for the preparation of acrylic acid by: (a) preparation of a gaseous product mixture which essentially has the composition of a reaction mixture of catalytic gas-phase oxidation of C3-alkanes, C3-alkenes, C3-alkanols and/or C3-alkanals and/or intermediates thereof to acrylic acid, which comprises (b) condensation of the gaseous product mixture, (c) crystallization of the acrylic acid from the solution obtained in stage (b), with partial evaporation of the solution under reduced pressure, (d) isolation of the resulting crystals from the mother liquor, (e) recycling of at least a part of the mother liquor from stage (d) to stage (b) and (f) recycling of at least a part of the evaporated solution from stage (c) to stage (b).

Abstract: In a process for the preparation of acrolein and/or acrylic acid from propane, the propane is subjected, in a first reaction stage, to a partial oxydehydrogenation with molecular oxygen under homogeneous and/or heterogeneous catalysis to give propene and the product gas mixture formed in the first reaction stage is then used for the preparation of acrolein and/or acrylic acid by gas-phase catalytic propene oxidation.

Abstract: In a process for the preparation of acrolein and/or acrylic acid from propane, the propane is subjected, in a first reaction stage, to an oxydehydrogenation with molecular oxygen under homogeneous and/or heterogeneous catalysis to give propene and the product gas mixture formed in the first reaction stage is then used for the preparation of acrolein and/or acrylic acid by gas-phase catalytic propene oxidation.

Abstract: A process for the continuous recovery of (meth)acrylic acid from a liquid starting mixture containing (meth)acrylic acid, a high-boiling organic solvent and low boilers, medium boilers and high boilers is proposed, the mixture being separated into a first part-stream (a), which, in addition to (meth)acrylic acid, contains the low boilers and a part each of the medium boilers and high boilers, and a second part-stream (b), which contains the predominant part of the (meth)acrylic acid and is completely or virtually completely free of low boilers, and the (meth)acrylic acid being recovered from the part-stream (b).

Abstract: In a process for the preparation of acrolein by gas-phase partial oxidation under heterogeneous catalysis, a reaction gas starting mixture which contains propene and molecular oxygen in a molar C3H6:O2 ratio of >1 is reacted in reaction zones connected in series, at elevated temperatures, over solid-state catalysts, further molecular oxygen being added to the reaction gas mixture in the course of the partial oxidation.

Abstract: In a process for the preparation of acrolein and/or acrylic acid from propane, the propane is subjected, in a first reaction stage, to a partial oxydehydrogenation with molecular oxygen under homogeneous and/or heterogeneous catalysis to give propene and the product gas mixture formed in the first reaction stage is then used for the preparation of acrolein and/or acrylic acid by gas-phase catalytic propene oxidation.

Abstract: A process for the continuous recovery of (meth)acrylic acid from a liquid starting mixture containing (meth)acrylic acid, a high-boiling organic solvent and low boilers, medium boils and high boils is proposed, the mixture being separated into a first part-stream (a), which, in addition to (meth)acrylic acid, contains the low boilers and a part each of the medium boilers and high boilers, and a second part-stream (b). which contains the predominant part of the (meth)acrylic acid and is completely or virtually completely free of low boilers, and the (meth)acrylic acid being recovered from the part-stream (b).

Abstract: A process for the continuous recovery of (meth)acrylic acid from the reaction gases of a catalytic gas-phase oxidation by (I) absorption in a high-boiling solvent, (II) isolation of the (meth)acrylic acid from the mixture with the solvent and, if required, further purification of the (meth)acrylic acid isolated, (III) purification of the solvent and (IV) recycling of the purified solvent to absorption stage (I) is proposed, the temperature in each process stage not exceeding 155° C., in particular 140° C., preferably 120° C.

Abstract: A process for the continuous recovery of (meth) acrylic acid from the reaction gases of a catalytic gas-phase oxidation by (I) absorption in a high-boiling solvent, (II) isolation of the (meth)acrylic acid from the mixture with the solvent and, if required, further purification of the (meth)acrylic acid isolated, (III) purification of the solvent and (IV) recycling of the purified solvent to absorption stage (I) is proposed, the temperature in each process stage not exceeding 155° C., in particular 140° C., preferably 120° C.

Abstract: (Meth)acrylic acid is recovered continuously from the reaction gas containing (meth)acrylic acid, low boilers, medium boilers and high boilers and originating from a catalytic gas-phase oxidation by

Abstract: In a process for the continuous heterogeneously catalyzed gas-phase partial oxidation of an organic compound in an oxidation reactor, whose feed gas mixture comprises, apart from the organic compound to be partially oxidized and molecular oxygen as oxidant, at least one diluent gas which is essentially inert under the conditions of the heterogeneously catalyzed gas-phase partial oxidation, where the essentially inert diluent gas consists partly of combustible gases, after passage through the oxidation reactor, the combustible constituents of the inert diluent gas present in the product gas stream leaving the oxidation reactor are not recirculated to the heterogeneously catalyzed gas-phase partial oxidation, but are put to further use for the purposes of another chemical reaction.

Abstract: Acrylic acid or methacrylic acid is purified by(a) subjecting a mixture comprising the acrylic acid or methacrylic acid to a sharply defined separation process essentially in the absence of an organic solvent, with the composition of the phase in which the acrylic acid or methacrylic acid accumulates remaining essentially constant when the composition of the other phases participating in the mass transfer changes, then taking off this phase and(b) subjecting at least a part of the remaining phase from stage(a) to a less sharply defined separation process and(c) feeding one of the phases formed in stage (b) to the sharply defined separation process in stage (a).In addition, the invention provides a process for preparing acrylic acid or methacrylic acid which includes the abovementioned purification process.

Abstract: A process for preparing acrylic acid and/or esters comprises the steps of:(a) catalytic gas phase oxidation of propene and/or acrolein to acrylic acid to obtain a gaseous reaction product comprising acrylic acid,(b) solvent absorption of the reaction product,(c) distillation of the solvent loaded with acrylic acid to obtain a crude acrylic acid and the solvent,(d) purification of the crude acrylic acid by crystallization and(e) optionally esterification of the crystalline acrylic acid.

Abstract: In a process for preparing acrolein, acrylic acid or a mixture thereof from propane, propane is partially dehydrogenated to propylene in a first stage, the product gas mixture resulting therefrom is, after separating off hydrogen and water vapor, used as feed to an oxidation reactor, the propylene formed in the dehydrogenation is partially oxidized in the oxidation reactor using molecular oxygen in the presence of non-dehydrogenated propane as inert diluent gas to give acrolein, acrylic acid or a mixture thereof and the propane present in the product gas mixture of the partial oxidation is subsequently recirculated to the dehydrogenation stage A.