Abstract: A tray column is proposed which includes 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 process for the production of membranes which contain at least one solid layer on one side of a porous substrate by treating, with a synthesis solution forming the solid layer, that side of the substrate which is to be coated is described, wherein, in the production of the solid layer on the porous substrate, the space which, viewed from the substrate, is behind that side of the porous substrate which is not to be coated is filled with an inert fluid, the pressure and/or the temperature of the fluid being chosen so that contact of the synthesis solution with that side of the porous substrate which is not to be coated is substantially prevented.

Abstract: The present invention provides a process for preparing 1,6-hexanediol from a carboxylic acid mixture which comprises adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols and is obtained as a by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol with oxygen or oxygen-containing gases and by water extraction of the reaction mixture, by esterification of the acids and hydrogenation, in which a) the mono- and dicarboxylic acids present in the aqueous dicarboxylic acid mixture are reacted with a low molecular weight alcohol to give the corresponding carboxylic esters, b) the resulting esterification mixture is freed of excess alcohol and low boilers in a first distillation stage, c) a separation of the bottom product is carried out in a second distillation stage into an ester fraction substantially free of 1,4-cyclohexanediols and a fraction comprising at least the majority of the 1,4-cyclohexanediols, d) the ester fraction substantially free of 1,4-cyclohexanediols is

Abstract: A process for producing a liquid formulation of salts of sulfonated azo dyes by coupling an at least equimolar amount of diazotized aminoarylsulfonic acids I H2N—Ar—SO3H??(I), where Ar is phenylene (which may be monosubstituted by sulfo) or naphthylene (which may be mono- or disubstituted by sulfo and/or monosubstituted by hydroxyl) onto the coupling product of an unsubstituted or methyl-substituted phenylenediamine with itself comprises dissolving the azo dye in a basic medium and then subjecting the solution to a nanofiltration.

Abstract: A process for producing a liquid formulation of a basic azo dye from a phenylenediamine I, which may be alkyl or alkoxy substituted, by diazotizing and coupling in acidic solution comprises diazotizing the phenylenediamine with sodium nitrite in the presence of at least two organic acids comprising at least one first acid (A) having a pkA value of ?40 and at least a second acid (B) having a pKA value ?4.1 and performing a nanofiltration after the coupling has ended.

Abstract: A process for heterogeneously catalyzed partial gas phase oxidation of propylene to acrylic acid in the absence of propane as an inert diluent gas, in which, in the starting reaction gas mixture, cyclopropane is substantially avoided as an impurity and crude propylene is used additionally as a propylene source.

Abstract: Composite membranes comprising at least one porous substrate layer and at least one microporous separation layer, comprising at least one zeolite of the MFI type, are described, the separation layer being produced by a hydrothermal synthesis in which the molar ratio of silicon to aluminum is greater than 120 and the separation layer contains less than 10% by weight of aluminum in elemental or chemically bound form in a zone of at least 100 nm adjacent to the separation layer.

Abstract: The present invention provides a process for preparing 1,6-hexanediol from a carboxylic acid mixture which comprises adipic acid, 6-hydroxycaproic acid and small amounts of 1,4-cyclohexanediols and is obtained as a by-product in the oxidation of cyclohexane to cyclohexanone/cyclohexanol with oxygen or oxygen-containing gases and by water extraction of the reaction mixture, by esterification of the acids and hydrogenation, in which a) the mono- and dicarboxylic acids present in the aqueous dicarboxylic acid mixture are reacted with a low molecular weight alcohol to give the corresponding carboxylic esters, b) the resulting esterification mixture is freed of excess alcohol and low boilers in a first distillation stage, c) a separation of the bottom product is carried out in a second distillation stage into an ester fraction substantially free of 1,4-cyclohexanediols and a fraction comprising at least the majority of the 1,4-cyclohexanediols, d) the ester fraction substantially free of 1,4-cyclohexanediols is ca

Abstract: A process for preparing at least one target product by partial oxidation and/or ammoxidation of propylene, in which the propylene source used is a propane dehydrogenation, the propane used therein being obtained by a rectificative prepurification of crude propane.

Abstract: A process is described for continuously preparing alkyl esters of (meth)acrylic acid by reacting (meth)acrylic acid and alkanols having from 1 to 5 carbon atoms in homogeneous, liquid, solvent-free phase at elevated temperature and in the presence of an acidic esterification catalyst, in which the (meth)acrylic acid, the alkanol and the acidic esterification catalyst are fed to a reaction zone (5, 6), the water formed during a residence time is removed rectificatively as a constituent of an alkanol-comprising mixture in a rectification unit III attached to the reaction zone (5, 6), the distillate obtained here is separated into an alkanol-comprising organic phase and a water-comprising aqueous phase, the organic phase is recycled into the rectification unit III and the aqueous phase is discharged, and a reaction mixture (21) is discharged from the reaction zone (5, 6), which comprises feeding the reaction mixture (21) discharged from the reaction zone (5, 6) to a catalyst removal unit V and separating it i

Abstract: A chimney tray for a column for the thermal treatment of a liquid, comprising an upper tray and a lower tray which are spaced apart from one another, arranged substantially horizontally in the column, comprising chimneys, and also comprising drawing of the liquid via a drainage spout arranged at the edge of the chimney tray, wherein the upper tray and the lower tray have a minimum separation from one another of from 10 to 500 mm and, between the upper tray and the lower tray, a gas having a thermal conductivity of less than 0.5 watt/m/K has been incorporated.

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 process for preparing acrolein or acrylic acid or a mixture thereof by heterogeneously catalyzed partial gas oxidation of propylene, in which the starting reaction gas mixture has the following contents: from 6 to 9% by volume of propylene, from 8 to 18% by volume of molecular oxygen, from 6 to 30% by volume of propane and from 32 to 72% by volume of molecular nitrogen.

Abstract: The present invention relates to a process for preparing acrylic acid by two-stage heterogeneously catalyzed partial gas phase oxidation of propylene, in which the propylene source used is a preceding propane dehydrogenation and in which the first oxidation stage is operated with restricted propylene conversion, and unconverted propane and propylene present in the product gas mixture of the second partial oxidation stage are recycled substantially into the preceding propane dehydrogenation.

Abstract: A process for heterogeneously catalyzed partial direct oxidation of propane and/or isobutane, in which target product is removed in a workup stage from the product gas mixture obtained in the reaction stage, the remaining residual product gas mixture is divided into two portions of the same composition, one portion is recycled into the reaction stage and the other portion is discharged, and both the reaction stage and the workup stage are operated at elevated pressure.