Abstract: In process for cleaning tray columns which are used for the purposes of rectifiying liquids comprising (meth)acrylic compounds, a basic liquid is conveyed downward through the tray column and a gas is passed through the column in countercurrent to the basic liquid at an average gas phase differential pressure over all trays of at least 0.5 mbar/tray.

Abstract: Process for operating a continuous heterogeneously catalyzed gas phase partial oxidation of at least one organic compound using compressed air as the oxygen source which is filtered before its compression.

Abstract: Process for stabilizing polymerizable compounds to polymerization during working-up, storage and/or transport, in which at least one free radical scavenger which contains at least two glycine units is used, with the proviso that the free radical scavenger is not selected from ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), trans-1,2-cyclohexanediaminetetraacetic acid (CYDTA) and the alkali metal and alkaline earth metal salts thereof.

Abstract: A process for preparing and/or working up mixtures by (meth)acrylic acid and/or (meth)acrylic ester in the presence of at least one polymerization inhibitor and at least one oxygenous gas, which comprises metering in at least part of the oxygenous gas at an exit rate of at least 50 mm/s.

Abstract: A process for the continuous recovery of (meth)acrylic acid from the reaction gas of a catalytic gas-phase oxidation comprising the following process stages is proposed: I quenching of the reaction gas by evaporative cooling using a high-boiling solvent, II separation of the (meth)acrylic acid from the quenched reaction gas by absorption into the high-boiling solvent, III separation of the solvent laden with (meth)acrylic acid by rectification into a first part-stream IIIA), which contains predominantly (meth)acrylic acid, and into a second part-stream IIIB) which contains predominantly the solvent, IV recycling of the stream IIIB) to process stage II and V distillative production of (meth)acrylic acid from stream IIIA), all liquid residual streams obtained in process stage V being recycled to process stage I.

Abstract: A continuously operated heterogeneously catalyzed gas-phase partial oxidation of at least one organic compound in an oxidation reactor is operated safely by a process in which an explosion diagram for the feed gas mixture is deposited as the basis of a cut-out mechanism in a computer.

Abstract: A tray column is proposed which comprises 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.

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 preparing and/or working up mixtures by (meth)acrylic acid and/or (meth)acrylic ester in the presence of at least one polymerization inhibitor and at least one oxygenous gas, which comprises metering in at least part of the oxygenous gas at an exit rate of at least 50 mm/s.

Abstract: Organic compounds are prepared by heterogeneously catalyzed partial gas-phase oxidation of precursor compounds by a process in which a portion of the reaction gas starting mixture is brought from a low initial pressure to a higher final pressure by means of a radial compressor.

Abstract: In a process for rectificatively separating (meth)acrylic monomer-containing fluids, a rectification column is employed which has at least one sieve tray without runoff segment in which the passages are arranged regularly.

Abstract: Acrylic acid or methacrylic acid is purified by crystallization to obtain crystals and a mother liquor, by a process in which the crystals are washed with a wash liquid containing the acid and having a temperature from 15 to 40° C. Furthermore, a process for the preparation of acrylic acid or methacrylic acid comprises the abovementioned purification process.

Abstract: In process for cleaning tray columns which are used for the purposes of rectifiying liquids comprising (meth)acrylic compounds, a basic liquid is conveyed downward through the tray column and a gas is passed through the column in countercurrent to the basic liquid at an average gas phase differential pressure over all trays of at least 0.5 mbar/tray.

Abstract: The invention described herein relates to a process for removing solids from tubes of a tube bundle heat exchanger, wherein a drill driven by a drilling machine is inserted into a tube of the tube bundle heat exchanger and clears out solids present in the tube. In a first variant of the process according to the invention, the drill is a spiral drill and has, cut out in the outer casing of the drill, a spiral conveyor groove in which the solids particles loosened and isolated by the drill tip on insertion of the drill into the tube can be transported out of the tube. More preferably, the drill is a hollow drill 10 which is provided with a substantially circular drill tip 11 and has a central recess running along the rotational axis in the longitudinal direction of the drill and opening into the drill tip 11 at the free end of the drill. At the drill tip 11 are provided toothlike projections 12.

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: Process for operating a continuous heterogeneously catalyzed gas phase partial oxidation of at least one organic compound using compressed air as the oxygen source which is filtered before its compression.

Abstract: The use of amidoximes for stabilisation of ethylenically-unsaturated compounds against undesired radical polymerisation is disclosed. Combinations of amidoximes with phenol and/or phenothiazine compounds have a synergistic effect. Preferred amidoximes are nitrilotris(acetamidoxime) and nitrilotris(propionamidoxime).

Abstract: Organic compounds are prepared by heterogeneously catalyzed partial gas-phase oxidation of precursor compounds by a process in which a portion of the reaction gas starting mixture is brought from a low initial pressure to a higher final pressure by means of a radial compressor.

Abstract: A process for the continuous recovery of (meth)acrylic acid from the reaction gas of a catalytic gas-phase oxidation comprising the following process stages is proposed:

Abstract: Noninvasive process for inline and/or online determination of polymer deposited from (meth)acrylic acid and/or (meth)acrylic esters by means of sound velocity measurements, measurements of the absorption coefficients in the infrared, near infrared, ultraviolet and/or visible region of the spectrum of electromagnetic radiation, or Raman spectroscopy, which allows precise control of the process parameters to be carried out during the thermal purification.