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:
Ein Verfahren zur Rückspaltung von in einer Flüssigkeit F mit einem Gewichtsanteil von ≧ 10 Gew.-% enthaltenen Michael-Addukten, die bei der Herstellung von Acrylsäure oder deren Ester gebildet wurde, in einer Rückspaltvorrichtung, die eine Pumpe P, eine Trennkolonne K mit trennwirksamen Einbauten und einem Umlaufwärmeaustauscher UW umfasst, wobei zum Zwecke der Zufuhr der Spaltenergie die Pumpe P aus dem Sumpfraum der Trennkolonne K Sumpfflüssigkeit ansaugt und über dem Umlaufwärmeaustauscher UW laufend oberhalb des Stands der Sumpfflüssigkeit in den Sumpfraum zurückführt und wobei die Pumpe P eine Radialkreiselpumpe mit offenem Laufrad ist.
Abstract:
Following a prior reaction in the tube bundle reactor, and between extraction and re-charging, the solid layer of molybdenum oxide or and/or molybdenum oxide hydrates deposited on the insides of the reactor tubes, is brushed away. Cylindrical, especially spirally-configured tube brushes are used. The coating is brushed away immediately on its formation. The preceding process is one of heterogeneous catalysis promoting partial gas phase oxidation. Examples of prior reactions carried out, include conversion of: propylene to acrolein and/or acrylic acid, acrolein to acrylic acid, iso-butene to methacrolein and/or methacrylic acid, methacrolein to methacrylic acid, propane to acrolein and/or acrylic acid, iso-butane to methacrolein and/or methacrylic acid, propylene to acrylonitrile, propane to acrylonitrile, isobutene to methacrylonitrile, isobutane to methacrylonitrile, C 4-hydrocarbon(s) to maleic acid anhydride or methanol to formaldehyde. The after-care or servicing described, complements use of a multi-element, formed oxide catalyst, containing molybdenum oxide in its active mass. The product gas contains steam.