Abstract: A process for storing a monomer phase which is liquid under the conditions of storage and comprises methacrylic monomers to an extent of ?95% by weight and has been obtained by condensation out of a gaseous phase or by melting a crystalline phase, in a storage vessel, in which polymer of the monomer present in dissolved form in the liquid monomer phase is removed therefrom on the route from its generation into the storage vessel, and also a process for withdrawing liquid monomer phase from the storage vessel in which polymer of the monomer present in dissolved form in the monomer phase is likewise removed.

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absorbent and the rectificative workup of the resulting adsorbate, and in which absorbent present in the bottoms liquid withdrawn from the bottom space of the absorption column is distilled off in a distillation unit and recycled into the absorption, before high boilers which remain are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 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 method of charging catalyst tubes of a bundle of catalyst tubes in a structured fashion, in which uniformly predispensed portions of formulations of shaped catalyst bodies are used for producing a section of charge.

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 method of charging catalyst tubes of a bundle of catalyst tubes in a structured fashion, in which uniformly predispensed portions of formulations of shaped catalyst bodies are used for producing a section of charge.

Abstract: A process for continuously removing a target product X in the form of fine crystals from a liquid phase P comprising the target product X and constituents other than the target product X by cooling suspension crystallization in an indirect heat transferer, in which the crystal suspension formed is conducted out of the heat transferer first into a mixed buffer tank and, from there, fed to an apparatus for separating the crystal suspension into crystals and liquid phase, and wherein external measures dissipade the oversaturation of the crystal suspension fed to the buffer vessel with target product X.

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 process for storing a monomer phase which is liquid under the conditions of storage and comprises methacrylic monomers to an extent of ?95% by weight and has been obtained by condensation out of a gaseous phase or by melting a crystalline phase, in a storage vessel, in which polymer of the monomer present in dissolved form in the liquid monomer phase is removed therefrom on the route from its generation into the storage vessel, and also a process for withdrawing liquid monomer phase from the storage vessel in which polymer of the monomer present in dissolved form in the monomer phase is likewise removed.

Abstract: A process for preparing acrylic acid, in which an acrylic acid-comprising product gas mixture obtained by catalytic gas phase partial oxidation of a C3 precursor of acrylic acid is fractionally condensed in a condensation column provided with internals ascending into itself with side draw removal of crude acrylic acid and with liquid phase draw removal of acrylic acid-comprising acid water, and acrylic acid present in acid water is taken up into an extractant and then removed from the extractant and recycled into the condensation column, or taken up in aqueous metal hydroxide, or sent to further purification of the crude acrylic acid.

Abstract: A process for rectificatively separating an acrylic acid-containing liquid, by withdrawing an acrylic acid-rich stream from the rectification column above the feed point and polymerization-inhibiting the upper section of the rectification column by means of diacrylic acid.

Abstract: A process for rectificatively separating at least one (meth)acrylic monomer-containing fluid by feeding the fluid into a rectification column containing at least one sieve tray without a runoff segment, wherein an elementary cell is obtained from a number of centers of passages in a sieve tray, and the cell shifts regularly and repeatedly along its edges, the lengths of two shifting vectors being the lengths of the edges of the cell along which the shifting is effected; an arrangement of the centers is such that the positions of an ideal center and a real center are separated by ?1% of half of the sum of the lengths of the two shifting vectors; and an arrangement of the passages is such that the sum of non-overlapping surface areas of an ideal passage with a real passage and vice versa is ?1% of the surface area of the ideal passage.

Abstract: A process for continuously removing a target product X in the form of fine crystals from a liquid phase P comprising the target product X and constituents other than the target product X by cooling suspension crystallization in an indirect heat transferee, in which the crystal suspension formed is conducted out of the heat transferer first into a mixed buffer tank and, from there, fed to an apparatus for separating the crystal suspension into crystals and liquid phase, and wherein external measures dissipade the oversaturation of the crystal suspension fed to the buffer vessel with target product X.

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 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: A process for preparing acrylic acid, in which an acrylic acid-comprising product gas mixture obtained by catalytic gas phase partial oxidation of a C3 precursor of acrylic acid is fractionally condensed in a condensation column provided with internals ascending into itself with side draw removal of crude acrylic acid and with liquid phase draw removal of acrylic acid-comprising acid water, and acrylic acid present in acid water is taken up into an extractant and then removed from the extractant and recycled into the condensation column, or taken up in aqueous metal hydroxide, or sent to further purification of the crude acrylic acid.

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 tray column is proposed which includes column trays, two or more supports which are arranged on the underside of the column trays and support them and a bearing ring for the column trays on the inner wall of the tray column, wherein three-way joints of inner column wall, bearing ring and support are prevented by cutouts in the bearing ring.