Abstract: The present invention provides a process for hydrogenating aromatic nitro compounds to the corresponding amines in the presence of hydrogenation catalysts, which comprises using hydrogenation catalysts in which nickel and platinum are present on a support in the form of an alloy having an atomic ratio of nickel to platinum in the alloy of between 30:70 and 70:30.

Abstract: Process for the work-up of naphtha, wherein a) naphtha or a stream produced from naphtha in a pretreatment step is separated in a membrane unit into a stream A which is depleted in aromatics and a stream B which is enriched in aromatics, with the aromatics concentration in stream A being from 2 to 12% by weight (step a), b) at least part of the substream A is fed to a steam cracker (step b), c) at least part of the substream B is fed to a unit in which it is separated by means of a thermal process into a stream C which has a lower aromatics content than stream B or a plurality of streams C?, C?, C?? . . . which each have lower aromatics contents than stream B and a stream D which has a higher aromatics content than stream B or a plurality of streams D?, D?, D?? . . .

Abstract: The present invention relates to a process for separating at least one propylene glycol from a mixture (M) comprising water and said propylene glycol, said process comprising (I) evaporating the mixture in at least two evaporation and/or distillation stages at decreasing operating pressures of the evaporators and/or distillation columns obtaining mixture (M?) and mixture (M?); (II) separating the mixture (M?) obtained in (I) in at least one further distillation step, obtaining a mixture (M-I) comprising at least 70 wt.-% of water and a mixture (M-II) comprising less than 30 wt.-% of water.

Abstract: The invention relates to a process for the preparation of sodium dithionite, comprising the steps (a) provision of a synthesis batch comprising sodium formate, sulfur dioxide and an alkaline sodium compound in aqueous methanolic solution with formation of a sodium dithionite mother liquor, (b) isolation of sodium dithionite from the sodium dithionite mother liquor, a residual mother liquor being obtained, (c) separation of methanol from the residual mother liquor, (d) separation of the residual mother liquor into a thiosulfate-rich first part-stream and a thiosulfate-poor, formate-containing second part-stream by means of nanofiltration, (e) concentration of sodium formate in the second part-stream and (f) recycling of the concentrated second part-stream to process step (a).

Abstract: The present invention provides a process for hydrogenating aromatic nitro compounds to the corresponding amines in the presence of hydrogenation catalysts, which comprises using hydrogenation catalysts in which nickel and platinum are present on a support in the form of an alloy having an atomic ratio of nickel to platinum in the alloy of between 30:70 and 70:30.

Abstract: Process for preparing chlorine from hydrogen chloride, which comprises the steps: a) feeding of a stream a1 comprising hydrogen chloride and of a stream a2 comprising oxygen into an oxidation zone and catalytic oxidation of hydrogen chloride to chlorine, giving a product gas stream a3 comprising chlorine, water, oxygen, carbon dioxide and inert gases; b) cooling of the product gas stream a3 and removal of water and hydrogen chloride as aqueous hydrochloric acid, leaving a gas stream b comprising chlorine, water, oxygen, carbon dioxide and inert gases; c) optional drying of the gas stream b) to leave a gas stream c which is substantially free of water and comprises chlorine, oxygen, carbon dioxide and inert gases; d) at least partial liquefaction of the gas stream c and of a chlorine-rich recycle stream f1 comprising chlorine, oxygen and carbon dioxide by compression and cooling, giving an at least partially liquefied stream d; e) gas/liquid separation of the stream d into a gas stream e1 comprising chlorine,

Abstract: The invention relates to a process for preparing aromatic amines by hydrogenation of nitroaromatics in the presence of catalysts, in which a fluid reaction mixture which comprises amines and from which the catalysts are separated off is formed in a reactor. After the catalysts have been separated off, a measurement of the absorption of UV/VIS radiation by the reaction mixture is carried out to determine the concentration of nitro and nitroso compounds in the reaction mixture.

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: 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: The present invention provides a process for hydrogenating aromatic nitro compounds to the corresponding amines in the presence of hydrogenation catalysts, which comprises using hydrogenation catalysts in which nickel and platinum are present on a support in the form of an alloy having an atomic ratio of nickel to platinum in the alloy of between 30:70 and 70:30.

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: Process for preparing polymer powder from an aqueous polymer dispersion with water-soluble compounds, the fraction of such compounds being smaller than that of said aqueous polymer dispersion and being based on the polymer present in the form of polymer particles insoluble in water, which comprises subjecting the aqueous polymer dispersion to membrane filtration in a first step of the process and to spray drying in a subsequent second step of the process.

Abstract: A process for separating a mixture comprising a) a monoolefinically unsaturated compound which is obtainable by adding two terminal olefins which bear the functional groups required to prepare the monoolefinically unsaturated compound containing at least two functional groups, or a saturated compound obtained by hydrogenating such a compound, b) a compound which is obtainable by adding more than two of the terminal olefins mentioned in a) or a compound obtained by hydrogenating such a compound, and c) a compound which contains a transition metal, is homogeneous with respect to the mixture and is suitable as a catalyst for preparing a monoolefinically unsaturated compound by adding two terminal olefins which bear the functional groups required to prepare the monoolefinically unsaturated compound containing at least two functional groups, by means of a semipermeable membrane to obtain a permeate and a retentate in such a way that the weight ratio of component b) to component c) in the mixture fed to the semiper

Abstract: In a process for concentrating an at least partially crystalline solid containing at least one zeolite in a mixture comprising at least one auxiliary, for example a template compound, and said solid, the mixture is ultrafiltrated in a step (II) to divide the mixture into a retentate and a permeate, the solids content in the retentate being higher than that in the mixture and the solids content in the permeate being lower than that in the mixture. This procedure allows auxiliaries, in particular template compounds, present in the permeate to be recycled into a crystallizing step (I) upstream of step (II).

Abstract: The invention provides a process for preparing amines by catalytic hydrogenation of nitroaromatics and subsequent removal of the catalysts from the reaction mixture, which contains at least one aromatic amine and water, which comprises carrying out the removal of the catalysts by means of membrane filtration, which is carried out at a pressure on the suspension side of from 5 to 50 bar, a pressure difference between the suspension side and the permeate side of at least 0.3 bar and a flux rate on the suspension side of from 1 to 6 m/s.

Abstract: A process for continuously preparing a compound which bears at least two functional groups which are each independently selected from the group consisting of nitrile group, carboxylic acid group, carboxylic ester group and carboxamide group, comprising the steps of a) adding two terminal olefins which bear the functional groups required to prepare the compound as per a1) containing at least two functional groups, in the presence of a compound as per a3) which is suitable as a catalyst for this addition and is homogeneous with respect to the reaction mixture to obtain a mixture comprising a1) a compound which is obtained by monoaddition of the two terminal olefins mentioned and bears at least two functional groups which are each independently selected from the group consisting of nitrile group, carboxylic acid group, carboxylic ester group and carboxamide group, a2) a compound which is obtained by polyaddition of the two terminal olefins mentioned and a3) the compound which is suitable as a catalyst for this a

Abstract: The present invention relates to a process for the recovery of N-phosphonomethylglycine from an aqueous mixture which contains N-phosphonomethylglycine, ammonium halides, and alkali metal or alkaline earth metal halides and optionally organic impurities in dissolved form, where (a) the pH of the mixture is adjusted to a value in the range from 2 to 8, (b) a separation of the mixture on a selective nanofiltration membrane is performed, a retentate which is richer in N-phosphonomethylglycine and poorer in halides and a permeate which is richer in halides and poorer in N-phosphonomethylglycine being obtained, and (c) the N-phosphonomethylglycine is recovered from the retentate. The process according to the invention makes possible the recovery of the N-phosphonomethylglycine with simultaneous separation of the halide salts.

Abstract: A method of preparing a finely divided emulsion from a crude emulsion is proposed where the crude emulsion is forced through a porous membrane, wherein the porous membrane is constructed from two or more superimposed layers which differ in pore diameter.

Abstract: The invention relates to phosphacyclohexanes of general formulae I and II, wherein the following designations, among others, apply: R can represent hydrogen, C1-100-alkyl, C7-20-aralkyl, C7-20-alkaryl, and C6-12-aryl: R1 to R10 can independently represent hydrogen, C1-20-alkyl, C7-20-aralkyl, C7-20-alkaryl, and C6-12-aryl: W, W? can independently represent single bonds or bridges comprising 1 to 20 carbon atoms, which can form part of a cyclic or aromatic group and can be interrupted by heteroatoms. Said phosphacyclohexanes are used as ligands in transition metal complexes of transition metals belonging to groups VIII to X of the periodic table.