Abstract: The present invention relates to a method of redissociating Michael adducts of acrylic acid present in a liquid F in a redissociation apparatus comprising at least one separating column K, an evaporator V and a pump P, wherein, in the event of an unwanted rise in the viscosity of the residue R in the bottom space of the separating column K, the feed of the liquid F into the redissociation apparatus is stopped, the residue R in the bottom space of the separating column K is diluted and cooled with a solvent 1, and the bottom space of the separating column K is emptied.

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 recharging the reaction tubes of a tube bundle reactor with a new fixed catalyst bed, in which a heterogeneously catalyzed partial gas phase oxidation of an organic compound had been performed beforehand in a preceding fixed catalyst bed comprising Mo-comprising multielement oxide active compositions to form a steam-comprising product gas mixture, in which, before the recharge, solid deposit which had been deposited on the tube inner walls and comprises molybdenum oxide and/or molybdenum oxide hydrate is brushed away with the aid of a brush.

Abstract: A continuous process for preparing (meth)acrylates of C10-alcohol mixtures by reaction of glacial (meth)acrylic acid with an isomer mixture of C10-alcohols composed of 2-propylheptanol as the main isomer and at least one of the C10-alcohols 2-propyl-4-methylhexanol, 2-propyl-5-methylhexanol, 2-isopropylheptanol, 2-isopropyl-4-methylhexanol, 2-isopropyl-5-methylhexanol and/or 2-propyl-4,4-dimethylpentanol, and the use of a diester of dicarboxylic acids which have been esterified with N-oxyl-containing compounds as polymerization inhibitors in such a process.

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 recharging the reaction tubes of a tube bundle reactor with a new fixed catalyst bed, in which a heterogeneously catalyzed partial gas phase oxidation of an organic compound had been performed beforehand in a preceding fixed catalyst bed comprising Mo-comprising multielement oxide active compositions to form a steam-comprising product gas mixture, in which, before the recharge, solid deposit which had been deposited on the tube inner walls and comprises molybdenum oxide and/or molybdenum oxide hydrate is brushed away with the aid of a brush.

Abstract: A process for recharging the reaction tubes of a tube bundle reactor with a new fixed catalyst bed, in which a heterogeneously catalyzed partial gas phase oxidation of an organic compound had been performed beforehand in a preceding fixed catalyst bed comprising Mo-comprising multielement oxide active compositions to form a steam-comprising product gas mixture, in which, before the recharge, solid deposit which had been deposited on the tube inner walls and comprises molybdenum oxide and/or molybdenum oxide hydrate is brushed away with the aid of a brush.

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 transporting a liquid monomer phase which has been withdrawn from a storage vessel and comprises methacrylic monomers to an extent of ?90% by weight, in a tank truck or in a tanker ship, in which the liquid monomer phase is subjected to a separating operation on the route from the storage vessel into the tank of a tank truck or of a tanker ship in order to separate polymer of the monomer present in dissolved form in the liquid monomer phase.

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 continuous process for preparing (meth)acrylates of C10-alcohol mixtures by reaction of glacial (meth)acrylic acid with an isomer mixture of C10-alcohols composed of 2-propylheptanol as the main isomer and at least one of the C10-alcohols 2-propyl-4-methylhexanol, 2-propyl-5-methylhexanol, 2-isopropylheptanol, 2-isopropyl-4-methylhexanol, 2-isopropyl-5-methylhexanol and/or 2-propyl-4,4-dimethylpentanol, and the use of a diester of dicarboxylic acids which have been esterified with N-oxyl-containing compounds as polymerization inhibitors in such a process.

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 redissociating apparatus to carry out a process for redissociating Michael adducts which are present in a liquid F with a proportion by weight of ?10% by weight and have been formed in the preparation of acrylic acid or esters thereof is provided. The apparatus comprises a pump P, a separating column K with separating internals and a circulation heat exchanger UW, wherein, for the purpose of supplying the cleavage energy, the pump P sucks in bottoms liquid from the bottom space of the separating column K and, via the circulation heat exchanger UW, continually recycles it into the bottom space above the level of the bottoms liquid, and wherein the pump P is a radial circulation pump with an open impeller.

Abstract: A process for redissociating Michael adducts which are present in a liquid F with a proportion by weight of ?10% by weight and have been formed in the preparation of acrylic acid or esters thereof in a redissociating apparatus which comprises a pump P, a separating column K with separating internals and a circulation heat exchanger UW, wherein, for the purpose of supplying the cleavage energy, the pump P sucks in bottoms liquid from the bottom space of the separating column K and, via the circulation heat exchanger UW, continually recycles it into the bottom space above the level of the bottoms liquid, and wherein the pump P is a radial circulation pump with an open impeller.

Abstract: A process for purifying removal of a chemical target compound from a suspension of crystals thereof in mother liquor in a wash column with forced transport of the crystal bed from the top downward, in which crystals are removed from the lower end of the crystal bed with a rotating removal device and melted, and a portion of the crystal melt is conducted back toward the crystal bed as wash melt, the removal device being secured with a drive shaft conducted into the wash column from the bottom through an inlet having a seal, said drive shaft being driven about its longitudinal axis by a drive unit for rotation and being mounted so as to be rotatable about its longitudinal axis in more than one bearing, such that the mounting in one of the bearings absorbs the downward force acting on the drive shaft, the mounting in two or more bearings absorbs forces acting radially outward from the drive shaft, and the mounting in one bearing is additionally capable of absorbing an upward force acting on the drive shaft.

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 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.