Abstract:
The invention relates to a method for starting a heterogeneously catalyzed partial gas phase oxidation of acrolein into acrylic acid or of methacrolein into methacrylic acid at a fixed catalyst bed that is located in a shell-and-tube reactor cooled with a heat exchanger means, wherein the temperature of the heat exchanger means is = 290°C, and wherein the temperature of the reactor bottom surface facing the reactor gas inlet mixture and the temperature of the reaction gas inlet mixture are = 285°C.
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:
Inhibiting the unwanted radical polymerization of acrylic acid present in a liquid phase (P1), comprises adding at least one chemical compound of copper to the liquid phase (P1). The amount of acrylic acid is 10 wt.%. The liquid phase additionally contains propionic acid (at least 100 wt. parts per million, based on wt. of acrylic acid in the liquid phase) and glyoxal (at least 100 wt. parts per million, based on wt. of acrylic acid in the liquid phase). An independent claim is also included for the liquid phase (P1), comprising at least one chemical compound of copper.
Abstract:
Dispositivo colector de líquidos para su uso en una columna que contiene al menos un lecho de empaquetadura,que comprende - un dispositivo colector para recolectar el líquido que sale del lecho de empaquetadura y - al menos una extracción de la columna, caracterizado porque todos los elementos del dispositivo colector están separados con respecto a la pared decolumna o con respecto a la pared de columna y al menos una pared separadora que se encuentra en la columna,de modo que el líquido que baja por la pared no llega al interior de la extracción del dispositivo colector de líquidos,estando los elementos unidos mediante elementos distanciadores con la pared de columna y/o dado el caso con lapared separadora, estando los elementos colocados de forma suelta sobre dispositivos de apoyo, y/o estando loselementos fijados en una rejilla de soporte del lecho de empaquetadura que se encuentra por encima de loselementos.
Abstract:
Ein Verfahren der Abtrennung einer rohen Acrylsäure aus einem Glyoxal als Nebenprodukt enthaltenden Produktgasgemisch einer heterogen katalysierten partiellen Gasphasenoxidation wenigstens einer C-Vorläuferverbindung, das die Absorption der Acrylsäure in einem hochsiedenden Absorptionsmittel sowie die rektifikative Aufarbeitung des resultierenden Absorbats umfasst, und bei dem von aus dem Sumpfraum der Absorptionskolonne entnommener Sumpfflüssigkeit in einer Destillationseinheit darin enthaltenes Absorptionsmittel abdestilliert und in die Absorption rückgeführt wird, bevor dabei verbliebene Schwersieder ausgeschleust werden, und bei dem durch Beschränkung der Schwersiederverweilzeit in der Destillationseinheit der Glyoxalgehalt der rohen Acrylsäure vermindert wird.
Abstract:
A process for removing trioxane from a use stream I of formaldehyde, trioxane and water, by a) providing a use stream I of formaldehyde as the main component and trioxane and water as the secondary components, b) mixing the use stream I with a recycle stream VII to obtain a feed stream Ia, c) distilling the use stream Ia in a first distillation stage to obtain a stream II of formaldehyde as the main component and water as the secondary component, and a stream III of trioxane as the main component and water and formaldehyde as the secondary components, d) distilling the stream III in a second distillation stage having a pressure higher than in the first distillation stage, to obtain a stream IV of trioxane and a stream V of trioxane as the main component and water and formaldehyde as the secondary components, e) distilling the stream V in a third distillation stage to obtain a stream VI of water and the recycle stream VII of trioxane as the main component and water and formaldehyde as the secondary components.