Abstract: Thermal separating process between at least one gaseous and at least one liquid stream, of which at least one comprises (meth)acrylic monomers, in a separating column whose separating internals are mass transfer trays, in which the liquid stream is polymerization-inhibited and used for spraying the surface of the separating column, and internal surfaces which are in the shadow region of the spraying are removed from the shadow region by covering.

Abstract: In a process for rectificative isolation of (meth)acrylic acid from a mixture containing, as main components, (meth)acrylic acid and an organic liquid having a higher boiling point than (meth)acrylic acid, the rectification is carried out with the addition of a surfactant.

Abstract: The invention relates to a method for the production of a purified melt of a monomer melt obtained by condensation, absorption or extraction in a crystallizer, wherein the inlet to the crystallizer is subjected to a mechanical solid/liquid separation operation.

Abstract: The invention relates to a method for purifying a raw melt of at least one monomer by crystallization, wherein suspension crystallization is initially used and the resulting remaining melt or the suspension crystals that have been molten once again and separated are subjected to a mechanical separation operation before undergoing subsequent purification by crystallization.

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 hydraulically sealed crossflow mass transfer tray, separating columns which contain the hydraulically sealed crossflow mass transfer tray and the use of such separating columns for thermal separating processes.

Abstract: In a process for preparing acrylic acid, an acrylic acid-containing product gas mixture obtained by catalytic gas phase partial oxidation of a C3 precursor of acrylic acid, after direct cooling with a quench liquid, is fractionally condensed in a separating column provided with internals, rising into itself with sidestream takeoff of crude acrylic acid, and the acrylic acid oligomers which form are dissociated and the resulting dissociation gas is subjected to a countercurrent rectification before it is recycled.

Abstract: (Meth)acrylic acid is worked up in the presence of at least one stabilizer by a process in which a stabilizer-containing mixture originating from the working-up and substantially freed from (meth)acrylic acid is passed into a distillation apparatus and a stabilizer-containing low boiler stream obtained from said apparatus is recycled to the working-up.

Abstract: A process for the heterogeneously catalyzed gas-phase partial oxidation of an organic compound over a fixed catalyst bed present in a fixed-bed reactor having a plurality of catalyst tubes, in which the reduction of the quality of the catalyst load with increasing duration of operation is restored by a partial catalyst change, is described.

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 method for measuring the temperature of fluid masses being treated in a tubular reactor apparatus which comprises carrying out the treatment in reactor apparatus comprises at least two same-type tubular reactors which are filled with solid particles, at least one tubular reactor containing a temperature measuring unit, the tubular reactors being designed such that both the ratio of the mass of the solid particles to the free cross-sectional area of the respective tubular reactor and the pressure drop measured by an inert gas being conducted transversely to the free cross-sectional area are each substantially identical across the respective tubular reactor. The apparatus is suitable for treating fluid masses while generating or consuming thermal energy, the temperature being measured.

Abstract: Pyridyldiimine ligands having one of the following structures: 1

Abstract: A process for the catalytic gas-phase oxidation of propene to acrylic acid, in which the reaction gas starting mixture is oxidized, with an increased propene loading, in a first reaction stage, over a first fixed-bed catalyst and then the acrolein-containing product gas mixture of the first reaction stage is oxidized, in a second reaction stage, with an increased acrolein loading, over a second fixed-bed catalyst, the catalyst moldings in both reaction stages having an annular geometry.

Abstract: A polymerization process for polymerizing at least one olefin in the presence of a pyridyldiimine metal complex as a catalyst having one of the following structures: The metal M of the complex is a transition metal from Group 4b, 5b or 6b of the Periodic Table such as vanadium. The invention also relates to the use of these metal complexes as olefin polymerization or oligomerization catalysts, optionally in combination with metal alumoxane and similar catalyst activators.

Abstract: In a process for the catalytic gas-phase oxidation of acrolein to acrylic acid, the reaction gas starting mixture is passed, with an acrolein loading of ≧150 l (s.t.p.)/l.h, over a fixed-bed catalyst which is housed in two spatially successive reaction zones A, B, the reaction zone B being kept at a higher temperature than the reaction zone A.

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: In a process for the catalytic gas-phase oxidation of propene to acrolein, the reaction gas starting mixture is passed with a propene loading of ≧160 l(S.T.P.)/l·h over a fixed-bed catalyst which is housed in two spatially successive reaction zones A,B, the reaction zone B being kept at a higher temperature than the reaction zone A.

Abstract: A reactor apparatus comprises at least two same-type tubular reactors which are filled with solid particles, at least one tubular reactor containing a temperature measuring unit, the tubular reactors being designed such that both the ratio of the mass of the solid particles to the free cross-sectional area of the respective tubular reactor and the pressure drop measured by an inert gas being conducted transversely to the free cross-sectional area are identical across the respective tubular reactor. The apparatus is suitable for treating fluid masses while generating or consuming thermal energy, the temperature being measured.

Abstract: The multimetal oxide materials essentially consisting of Mo12BiaX1bFecX2dX3eOy  (I) where: X1 is Co and/or Ni, X2 is Si and/or Al, X3 is an alkali metal, 0.3≦a≦1, 2≦b≦10, 0.5≦c≦10, 0≦d≦10, 0≦e≦0.5 and y is the absolute value of the number which, assuming charge neutrality, is obtained from the sum of the valences and the stoichiometric coefficients of the other elements, the crystalline fractions containing, in addition to &bgr;-X1MoO4 as the main component, Fe2(MoO4)3 as a secondary component and no MoO3.

Abstract: In a process for the disposal of low, mediun, and high-boiling secondary components formed during the preparation of (meth)acrylic acid the gaseous low-boiling secondary components are burned, whilst low-boiling and medium-boiling secondary components that are dissolved in water optionally together with high-boiling secondary components treated with solvent are added.