Abstract: A supply system for feeding a fluid to a vessel (1) is described, which is provided with a feedline (10), having a reservoir which is filled with the fluid and a compressed-gas store (14) which can be brought into communication with this reservoir (13), in which system the reservoir (13) and the compressed-gas store (14) are arranged in immediate proximity to one another, and wherein the reservoir (13) can, when required, be brought into communication with the feedline (10) via connection pieces (11, 12).

Abstract: A method is described of stabilizing (meth)acrylic esters against unwanted free-radical polymerization, in which the mixture to be stabilized has added to it a polymerization inhibitor mixture comprising at least one nitroxyl radical and/or at least one organic compound having at least one nitroso group, and at least one p-phenylenediamine.

Abstract: Free radical polymerizations immediately terminated by a process comprising the addition of an inhibitor solution which contains phenothiazine and at least 50% (w/w) N-alkylpyrrolidone to a system undergoing free radical polymerization, wherein the inhibitor solution also contains p-methoxyphenol (MEHQ).

Abstract: The process for the esterification of (meth)acrylic acid with an alkanol in the presence of an esterification catalyst, in which unconverted starting compounds and the (meth)acrylate to be formed are separated off by distillation and an oxyester-containing bottom product is formed and is separated off, and (a) in the bottom product separated off, the oxyesters present are cleaved, if required after the addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, directly in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, and the cleavage products are removed, a cleavage residue remaining, or (b) the oxyesters are first removed by distillation from the cleavage product separated off, a distillation residue remaining, and the oxyesters removed are cleaved, if required after addition of (meth)acrylic acid and/or oligomeric (meth)acrylic acid, in the presence of acid catalysts differing from (meth)acrylic acid and/or oligomeric (meth)acrylic acid, a

Abstract: An ester of an &agr;,&bgr;-unsaturated carboxylic acid is prepared by reacting the carboxylic acid with a C6-C12-alkanol, cyclopentanol or cyclohexanol in the presence of an acidic esterification catalyst and of an entraining agent for removing the water of reaction formed in the esterification, by a process in which the entraining agent used is the olefin on which the alkanol is based.

Abstract: A method of transporting and/or storing pure acrylic acid comprises ensuring by means of appropriate measures that the pure acrylic acid is partly crystalline during the entire duration of transport and/or storage.

Abstract: Plant parts which are used for the production or processing of (meth)acrylic esters are cleaned by

Abstract: In a process for the preparation of acrylic acid, a product gas mixture obtained by catalytic gas-phase oxidation of a C3-precursor of acrylic acid and containing acrylic acid is directly cooled with a quench liquid and then subjected to fractional condensation in a separation column provided with baffles, said product gas mixture ascending into itself and a crude acrylic acid being removed via a side take-off, and the acrylic acid oligomers formed are cleaved and recycled.

Abstract: A method of transporting and/or storing pure acrylic acid comprises ensuring by means of appropriate measures that the pure acrylic acid is partly crystalline during the entire duration of transport and/or storage.

Abstract: A process for preparing pure (meth)acrylic acid or a (meth)acrylate starting from a crude (meth)acrylic acid, which comprises the following stages: A: treating the crude (meth)acrylic acid with at least one compound which is able to remove aldehydes, to give an aldehyde-free crude (meth)acrylic acid; B: subjecting the aldehyde-free crude (meth)acrylic acid to imprecise distillation, to give a low-boiling fraction comprising (meth)acrylic acid and acetic acid and a high-boiling fraction comprising (meth)acrylic acid and high boilers; C: isolating a pure (meth)acrylic acid from the high-boiling fraction and, if desired, D: esterifying the low-boiling fraction comprising (meth)acrylic acid and acetic acid that is obtained in stage B by means of one or more alkanols, to give an esterification mixture comprising one or more (meth)acrylates, one or more acetic esters, and one or more alkanols.

Abstract: Pure acrylic acid is stored and/or transported by a process in which the pure acrylic acid is stored and/or transported as liquid aqueous solution at ≦15° C.

Abstract: In a process for the preparation of (meth)acrylic acid from a mixture which contains (meth)acrylic acid and a solvent having a boiling point above the boiling point of (meth)acrylic acid by distillation of the mixture in a column which is connected to an evaporator and has a stripping section and a rectifying section, between which the mixture is fed in, and a side take-off for the (meth)acrylic acid, a polymeization inhibitor is fed into the column in the region of the top of the column and in the region of the side take-off, that amount of polymerization inhibitor which is introduced in the region of the top of the column being smaller than the amount introduced in the region of the side take-off.

Abstract: A method for continuous production of (meth)acrylic alkyl esters by reacting (meth)acrylic acid with alkanols containing 1-8 C-atoms, whereby raw (meth)acrylic acid containing acetic acid is used as a starting compound and the alkyl acetate that is formed as a by-product is evacuated in an appropriate area.

Abstract: In a process for esterifying (meth)acrylic acid with an alkanol, oxy ester formed as a byproduct of the esterification is recleaved under acid catalysis with addition of monomeric and/or oligomeric (meth)acrylic acid and water.

Abstract: (Meth)acrylic esters are prepared by reacting (meth)acrylic acid with a C4-C12-alkanol in the presence of sulfuric acid or a mono-C4-C12-alkyl sulfate as catalyst, wherein a) the reaction is carried out in an esterification unit which comprises a first reactor and at least one further reactor, b) a mixture of (meth)acrylic acid, C4-C12-alkanol and catalyst which contains not more than 5% by weight of water, based on the sum of the starting materials, is introduced into the first reactor, c) the esterification in the first reactor is conducted without removing ester, alkanol or water to a (meth)acrylic acid conversion of at least 40%, but only so far that the mixture remains a single phase, and d) the esterification is continued in at least one further reactor with the water formed being removed by distillation.

Abstract: An apparatus for introducing a fluid into a container includes a supply leading into the interior of the container, closed by a bursting disk and connected to a supply line for the fluid. In order to increase the operational safety and to avoid clogging of the bursting disk, the supply is in the form of a telescopic tube which can be extended by the pressure of the fluid into the interior of the container and is mounted above the highest level in the container.

Abstract: In a process for the separation by rectification of (meth)acrylic acid from a mixture containing (meth)acrylic acid and an inert hydrophobic organic liquid having a boiling point higher than that of (meth)acrylic acid as main constituents and also lower aldehydes as secondary constituents, a primary amine and/or a salt thereof are added.

Abstract: Crude (meth)acrylic acid is purified by a process in which a primary amine compound and an organic sulfonic acid are added to the crude (meth)acrylic acid and the latter is then worked up by distillation.

Abstract: The disclosure is a process for preparing (meth)acrylic esters by reacting (meth)acrylic acid with C4-C6-alkanols in the presence of a strong inorganic acid or of a C4-C6-monoalkyl ester of a polybasic strong acid as catalyst, which comprises removing the unconverted alkanol from the resulting reaction mixture by distillation and thereafter removing the catalyst from the resulting mixture.

Abstract: Free radical polymerizations are immediately terminated by adding a phenothiazine-containing solution whose solvent comprises at least 50% of its weight of an N-alkylpyrrolidone.