Abstract: The present invention relates to a process for recovering acrylic acid which is obtained by catalytic gas phase oxidation of propene, wherein, in an absorption stage (K2), the acrylic acid is absorbed from the reaction mixture (1) from the gas phase oxidation with a first solvent (3) and is drawn off for distillative purification, and a gas mixture from the absorption stage (K2) is passed onward to a condensation stage, wherein, in the condensation stage, the gas mixture is condensed, and a condensed phase of the gas mixture is drawn off as acid water (4) and is subjected to a phase separation operation in a phase separation vessel (B1), comprising the steps of a) feeding the aqueous phase (4*) of the acid water (4) drawn off from the condensation stage that has been obtained in the phase separation vessel (B1) to an extraction stage (K7) in which acrylic acid present in the acid water (4) is extracted with a second solvent (5), b) feeding the acrylic acid-comprising extract (6) to a stripping column (K8) in

Abstract: A process for production of acrylic acid includes preparing a product gas mixture by a catalytic gas-phase oxidation of a C3 precursor; cooling and contacting the cooled product gas mixture in an absorption column having at least two cooling loops in countercurrent with an absorbent to obtain an absorbate A, containing the absorbent and absorbed acrylic acid; condensing a high boiler fraction of the product gas mixture in a first cooling loop; condensing a low boiler fraction of the product gas mixture in a second cooling loop; maintaining a temperature of the absorbate A in the second cooling loop at a value of at least 56° C.; removing an acid water stream comprising glyoxal from the absorption column at a side take-off located above the second cooling loop; and removing a stream F of absorbate A from the absorption column at a side take-off, located at a height of the absorption column between the first cooling loop and the second cooling loop.

Abstract: The invention is related to a process for production of acrylic acid comprising the following steps: a) preparation of a product gas mixture by a catalytic gas-phase oxidation of at least one C3 precursor compound to acrylic acid, wherein acrylic acid is formed as a main product of the catalytic gas-phase oxidation and glyoxal is formed as a by-product and the product gas mixture comprises acrylic acid and glyoxal, b) cooling of the product gas mixture, c) contacting the product gas mixture in countercourrent with an absorbent, wherein an absorbate A, comprising the absorbent and absorbed acrylic acid, is formed, d) introducing a feed stream F (2) comprising at least part of the absorbate A into a rectification column comprising a rectifying section and a stripping section, e) enriching the absorbent in the stripping section and enriching acrylic acid in the rectifying section, f) withdrawing a stream C of crude acrylic acid comprising at least 90% by weight of acrylic acid out of the rectifying section as a

Abstract: A process for inhibiting unwanted free-radical polymerization of acrylic acid present in a liquid phase P whose acrylic acid content is at least 10% by weight and which, based on the weight of the acrylic acid present therein, additionally comprises at least 100 ppm by weight of propionic acid and at least 100 ppm by weight of glyoxal, in which at least one chemical compound of the element copper is added to the liquid phase P, and the resulting liquid phases P to which a chemical compound of the element copper has been added.

Abstract: In a method of stabilizing acrylic compounds, a liquid phase containing at least one acrylic compound is mixed with at least one metal and at least one ligand. The acrylic compound can be acrylic acid, methacrylic acid, and their respective esters. The metal can be copper, manganese, and cerium. The ligand can be a quinoline compound of formula (I), an N-oxide of a compound of formula (I), 2,2?-bis(2,3-dihydro-3-oxoindolylidene), or an aliphatic y-dentate ligand with y being 2-6 and comprising at least two nitrogen atoms joined by aliphatic or aromatic C1-C4 bridges comprising y-2 further coordinating nitrogen atoms or heteroatoms: where X is OH, NH2, O—(C1-C4)-alkyl, O—C(O)—(C1-C4)-alkyl, or O—C(O)-phenyl; R1 is H, or (C1-C4)-alkyl; R2 is H, (C1-C4)-alkyl, Cl, Br, or SO3H; and R3 is H, Cl or Br.

Abstract: A process for inhibiting unwanted free-radical polymerization of acrylic acid present in a liquid phase P whose acrylic acid content is at least 10% by weight and which, based on the weight of the acrylic acid present therein, additionally comprises at least 100 ppm by weight of propionic acid and at least 100 ppm by weight of glyoxal, in which at least one chemical compound of the element copper is added to the liquid phase P, and the resulting liquid phases P to which a chemical compound of the element copper has been added.

Abstract: In a method of stabilizing acrylic compounds, a liquid phase containing at least one acrylic compound is mixed with at least one metal and at least one ligand. The acrylic compound can be acrylic acid, methacrylic acid, and their respective esters. The metal can be copper, manganese, and cerium. The ligand can be a quinoline compound of formula (I), an N-oxide of a compound of formula (I), 2,2?-bis(2,3-dihydro-3-oxoindolylidene), or an aliphatic y-dentate ligand with y being 2-6 and comprising at least two nitrogen atoms joined by aliphatic or aromatic C1-C4 bridges comprising y-2 further coordinating nitrogen atoms or heteroatoms: where X is OH, NH2, O—(C1-C4)-alkyl, O—C(O)—(C1-C4)-alkyl, or O—C(O)-phenyl; R1 is H, or (C1-C4)-alkyl; R2 is H, (C1-C4)-alkyl, Cl, Br, or SO3H; and R3 is H, Cl or Br.

Abstract: A process for inhibiting polymerization of (meth)acrylic acid and/or (meth)acrylic esters by introducing an oxygenous gas into the (meth)acrylic acid and/or the (meth)acrylic ester, in which the (meth)acrylic acid and/or the (meth)acrylic ester has a degree of purity of at least 95% and is in the liquid state.

Abstract: A process for separating acrylic acid present as a main product and glyoxal present as a by-product in a product gas mixture of a partial gas phase oxidation of a C3 precursor compound, in which a liquid phase P is obtained, which consists of acrylic acid to an extent of at least 70% of its weight and, based on the molar amount of acrylic acid present therein, comprises at least 200 molar ppm of glyoxal, in which the glyoxal is separated from the acrylic acid in the liquid phase P by crystallization.

Abstract: A process for inhibiting unwanted free-radical polymerization of acrylic acid present in a liquid phase P whose acrylic acid content is at least 10% by weight and which, based on the weight of the acrylic acid present therein, additionally comprises at least 100 ppm by weight of propionic acid and at least 100 ppm by weight of glyoxal, in which at least one chemical compound of the element copper is added to the liquid phase P, and the resulting liquid phases P to which a chemical compound of the element copper has been added.

Abstract: A process for conveying a stream of a liquid F comprising (meth)acrylic monomers with a delivery pump P through a pipeline with circular cross-sectional area OF in which is mounted a restrictor B which firstly closes an area portion of the open cross-sectional area QF and secondly leaves open an area portion TF of the cross-sectional area QF, the outline of which comprises a circular arc of the circular outline of the cross-sectional area QF, said circular arc being within the lower tenth of the circular outline of the cross-sectional area QF.

Abstract: A process for inhibiting polymerization of (meth)acrylic acid and/or (meth)acrylic esters by introducing an oxygenous gas into the (meth)acrylic acid and/or the (meth)acrylic ester, in which the (meth)acrylic acid and/or the (meth)acrylic ester has a degree of purity of at least 95% and is in the liquid state.

Abstract: A process for removal of a crude acrylic acid from a product gas mixture which comprises glyoxal as a by-product from a heterogeneously catalyzed partial gas phase oxidation of at least one C3 precursor compound, which comprises the absorption of the acrylic acid in a high-boiling absorbent and the rectificative workup of the resulting adsorbate, and in which absorbent present in the bottoms liquid withdrawn from the bottom space of the absorption column is distilled off in a distillation unit and recycled into the absorption, before high boilers which remain are discharged, and in which the glyoxal content of the crude acrylic acid is reduced by restricting the high boiler residence time in the distillation unit.

Abstract: A process for transferring heat to a liquid mixture comprising at least one (meth)acrylic monomer in an indirect heat exchanger, wherein a quaternary ammonium salt, a tertiary amine or a salt thereof with a Brønsted acid is added to the liquid mixture to reduce fouling.

Abstract: A process for separating acrylic acid present as a main product and glyoxal present as a by-product in a product gas mixture of a partial gas phase oxidation of a C3 precursor compound, in which a liquid phase P is obtained, which consists of acrylic acid to an extent of at least 70% of its weight and, based on the molar amount of acrylic acid present therein, comprises at least 200 molar ppm of glyoxal, in which the glyoxal is separated from the acrylic acid in the liquid phase P by crystallization.

Abstract: A process for transferring heat to a liquid F comprising dissolved monomeric acrylic acid, Michael acrylic acid oligomers, and acrylic acid polymer with the aid of an indirect heat exchanger to which are supplied the liquid F with a temperature TF of ?150° C. and a fluid heat carrier W with a temperature of TW>TF, wherein the formation of gas bubbles and/or of thin layers of liquid F adjoining a gas phase is brought about in the liquid F during the flow through the heat exchanger.

Abstract: A method of charging a vertical tube having an internal diameter of 50 mm or less with catalyst particles, which comprises introducing a filling aid into the vertical tube, where the filling aid comprises a flexible elongated body and the ratio of the cross section of the flexible elongated body to the cross section of the tube is from 0.003 to 0.08, and introducing the catalyst particles into the tube.

Abstract: A separating column containing a sequence of mass transfer trays that are supported by at least one covered double-T support and/or covered U-shaped support.

Abstract: A process for transferring heat to a liquid mixture comprising at least one (meth)acrylic monomer in an indirect heat exchanger, wherein a quaternary ammonium salt, a tertiary amine or a salt thereof with a Brønsted acid is added to the liquid mixture to reduce fouling.

Abstract: (Meth)acrylic monomers are separated by a thermal separation process by ascending at least one ascending gaseous stream in a separating column containing a sequence of mass transfer trays and a liquid stream that contains dissolved polymerization inhibitor which descends in the separating column, and in at least one of the streams being (meth)acrylic monomers; and spraying the inner surface of the separating column with the descending liquid stream that contains the dissolved polymerization inhibitor, and the separating column having internals, certain areas of which are shadow regions of the sprayed descending liquid stream; and which shadow regions are equipped by covering means which prevent contact of the shadow regions with (meth)acrylic monomers and consequently undesired polymerization of monomer.