Abstract:
The invention relates to a method for cleaving Michael adducts that are contained in a fluid F at a weight proportion of = 10 wt % and that were formed in the production of acrylic acid or esters thereof, in a cleaving device, which comprises a pump P and a separation column K having installations that effect separation and a recirculation heat exchanger UW, wherein for the purpose of feeding the cleaving energy, the pump P draws sump fluid from the sump chamber of the separation column K and continuously feeds said sump fluid back into the sump chamber above the level of the sump fluid through the recirculation heat exchanger UW, and wherein the pump P is a radial centrifugal pump having an open impeller.
Abstract:
The invention relates to a method for stabilising acrylic compounds, wherein a liquid phase, which contains at least one acrylic compound from the group acrylic acid, methacrylic acid and their respective esters, is mixed with at least one metal from the group copper, manganese and cerium and at least one ligand from the group consisting of a) quinoline compounds of formula (I), wherein the symbols have the following meanings: X is OH, NH2, O-C1-C4-alkyl, preferably OCH3, O-C(O)-C1-C4-alkyl, preferably O-C(O)-CH3, O-C(O)-C2H5 or O-C(O)-phenyl; R1 is H, or (C1-C4)-alkyl, preferably methyl; R2 is H, C1-C4-alkyl, preferably methyl, Cl, Br or SO3H and R3 is H, Cl or Br; and N-oxides of compounds of formula (I), b) 2,2'-bis(2,3-dihydro-3-oxoindolylides) and c) aliphatic y-dentate ligands where y = 2-6, containing at least two nitrogen atoms and y-2 further coordinating aliphatic or aromatic C1-C4 carbon bridges containing nitrogen atoms or heteroatoms.
Abstract:
The invention relates to a method for separating a raw acrylic acid from a product gas mixture comprising glyoxal as auxiliary product of a heterogeneously catalyzed partial gas phase oxidation of at least one C3-precursor compound, comprising the absorption of the acrylic acid in a high-boiling absorption agent and the rectificative processing of the resulting absorbent, and wherein, in a distillation unit, an absorption agent contained in the sump fluid that has been removed from the sump chamber of the absorption column is distilled and is fed back into the absorption before remaining high-boiling components are removed, and wherein the glyoxal content of the raw acrylic acid is reduced by limiting the duration of the high-boiling components in the distillation unit.
Abstract:
A method is disclosed for transferring heat to a liquid F containing dissolved monomeric acrylic acid, acrylic acid oligomers obtained by Michael addition, and acrylic acid polymer with the help of an indirect heat exchanger to which the liquid F is fed at a temperature TF = 150°C and a heat transfer fluid W is fed at a temperature Tw > TF. In said method, gas bubbles or thin layers of liquid F bordering a gas phase are generated in the liquid F while said liquid F flows through the heat exchanger.
Abstract:
A continuous method for producing (meth)acrylates from C10 alcohol mixtures by reacting pure (meth)acrylic acid with an isomeric mixture of C10 alcohols of 2-propylheptanol as 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 are esterified with N-oxyl group containing compounds, as polymerisation inhibitors in such a method.
Abstract:
Process for transferring heat to a liquid mixture comprising at least one (meth)acrylic monomer with the aid of an indirect heat exchanger comprises introducing the liquid mixture simultaneously into the primary side of the heat exchanger by a liquid heat carrier and secondary side of the heat exchanger, where: the liquid mixture comprising at least one (meth)acrylic monomer contains at least one added active compound other than (meth)acrylic monomers from tertiary amine or salts formed from a tertiary amine and Bronsted acid, and quaternary ammonium compounds. Process for transferring heat to a liquid mixture comprising at least one (meth)acrylic monomer with the aid of an indirect heat exchanger comprises introducing the liquid mixture simultaneously into the primary side of the heat exchanger by a liquid heat carrier and secondary side of the heat exchanger, where: the liquid mixture comprising at least one (meth)acrylic monomer contains at least one added active compound other than (meth)acrylic monomers from tertiary amine or salts formed from a tertiary amine and Bronsted acid, and quaternary ammonium compounds, with proviso that none of the tertiary and quaternary nitrogen atoms in the active compound bears a phenyl group, but at least partly contains an alkyl group.
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:
L'invention concerne un procédé de séparation en continu d'un produit cible X sous la forme d'un cristallisat finement divisé à partir d'une phase liquide contenant le produit cible X et des composants différents du cible X par cristallisation d'une suspension de refroidissement dans un échangeur de chaleur indirect, dans lequel la suspension de cristallisat formée est acheminée de l'échangeur de chaleur tout d'abord dans un réservoir tampon mélangé et, de celui-ci, à un dispositif de séparation de la suspension en cristallisat et en phase liquide, et dans lequel, par des mesures externes, la sursaturation de la suspension de cristallisat en produit cible X acheminée au réservoir tampon est supprimée.
Abstract:
The method involves supplying a suspension stream in a process chamber (7) to a supply-end, and delivering a mother liquor stream (2) from the chamber from a suspension stream under retention of crystals and formation of crystal bed (5). Force that is applied at a drive shaft (18) in a longitudinal direction in normal operation is continuously adjusted upwards. The shaft is rotatably supported around a longitudinal axis in mountings. Two bearings e.g. guiding bearing and radial bearing, are arranged in one of two mountings such that the bearings accommodate the force in one of the mountings.