Abstract: The present invention relates to a process for producing diamines and polyamines of the diphenylmethane series (MDA) by reacting aniline and formaldehyde in the presence of an acid catalyst, wherein the aniline contains in total less than 0.5 wt. %, based on the total weight of aniline, of one or more compounds which contain at least one carbonyl group or of one or more compounds that are formed by reaction of these compounds which contain at least one carbonyl group with aniline.

Abstract: The invention relates to a process for purifying aniline produced by gas-phase hydrogenation of nitrobenzene, by fractional condensation of the crude reaction product obtained in gaseous form so that at least two liquid process products, a partial condensate (PK) and a total condensate (TK), are obtained.

Abstract: Aromatic amines are produced by adiabatic hydrogenation of nitroaromatic compounds in the gas phase on one or more fixed catalysts. The nitroaromatic reactant is passed over the catalyst under pressure and at elevated temperature with hydrogen, water, optionally nitrogen and substantially in the absence of the aromatic amine produced from the nitroaromatic.

Abstract: The invention relates to a process for purifying aniline produced by gas-phase hydrogenation of nitrobenzene, by fractional condensation of the crude reaction product obtained in gaseous form so that at least two liquid process products, a partial condensate (PK) and a total condensate (TK), are obtained, wherein the condensation leading to the formation of PK is carried out at higher temperature than the temperature leading to the formation of TK, a product stream originating from PK and a product stream originating from TK are each passed separately from one another into a distillation column consisting of at least one stripping section and at least one rectifying section, wherein the product stream originating from PK is introduced into the lower section of the distillation column between the lowermost stripping section and the section which follows, and the product stream originating from TK is introduced into the top of the distillation column above the uppermost rectifying section, and the desired purif

Abstract: The present invention relates to a process for simplified separation of a reaction product (P) from reaction gas mixtures by means of partial condensation of the reaction gas mixture consisting of the reaction product (P), at least one high boiler (H) and at least one low boiler (L).

Abstract: An isocyanate is produced by continuously reacting an amine with phosgene in the presence of an inert substance in the gas phase. In this process, a phosgene-containing stream and a stream containing both the amine and the inert substance are fed into a reactor. The molar ratio of the inert substance to the amino groups in the stream is greater than 0 but less than 45 mol %. This molar ratio changes by no more than 99% during a 20 minute period.

Abstract: Aromatic amines which have been obtained by reduction of aromatic nitro compounds are purified by mixing the crude amine obtained after phase separation with an aqueous, alkali metal hydroxide solution and subsequent distillation of this mixture over a distillation column. The distillation column has at least an upper and a lower rectifying part and a stripping part. The bottom product of the distillation column is partly to completely sluiced out and is partly evaporated in a main evaporator and at least one downstream re-evaporator and partly recycled back into the column.

Abstract: An isocyanate is produced by continuously reacting an amine with phosgene in the presence of an inert substance in the gas phase. In this process, a phosgene-containing stream and a stream containing both the amine and the inert substance are fed into a reactor. The molar ratio of the inert substance to the amino groups in the stream is greater than 0 but less than 45 mol %. This molar ratio changes by no more than 99% during a 20 minute period.

Abstract: Aromatic amines produced by hydrogenation of the corresponding nitroaromatic compounds are purified in a specified manner. In the purification procedure, the particular amine is initially mixed with an aqueous solution of a base. The organic and aqueous phases are then separated by adding excess water.

Abstract: Nitroaromatic compounds are hydrogenated in the gas phase to form aromatic amines with hydrogen in the presence of one or more catalysts arranged in stationary or virtually stationary beds in a reactor. In this process, the catalyst in the reactor is at least partly replaced continuously or at periodic intervals. At least 10% of the catalyst is replaced within each 20 day interval subsequent to start up of the reaction.

Abstract: The present invention relates to a process for producing diamines and polyamines of the diphenylmethane series (MDA) by reacting aniline and formaldehyde in the presence of an acid catalyst, wherein the aniline contains in total less than 0.5 wt. %, based on the total weight of aniline, of one or more compounds which contain at least one carbonyl group or of one or more compounds that are formed by reaction of these compounds which contain at least one carbonyl group with aniline.

Abstract: Aromatic amines which have been obtained by reduction of aromatic nitro compounds are purified by mixing the crude amine obtained after phase separation with an aqueous, alkali metal hydroxide solution and subsequent distillation of this mixture over a distillation column. The distillation column has at least an upper and a lower rectifying part and a stripping part. The bottom product of the distillation column is partly to completely sluiced out and is partly evaporated in a main evaporator and at least one downstream re-evaporator and partly recycled back into the column.

Abstract: Compounds containing phenolic hydroxy groups are removed from a gas stream which contains at least one aromatic amine generated during the gas-phase hydrogenation reaction of the corresponding nitroaromatic compounds with hydrogen, by adsorption on a basic solid.

Abstract: Aromatic amines are produced by adiabatic hydrogenation of nitroaromatic compounds in the gas phase on one or more fixed catalysts. The nitroaromatic reactant is passed over the catalyst under pressure and at elevated temperature with hydrogen, water, optionally nitrogen and substantially in the absence of the aromatic amine produced from the nitroaromatic.

Abstract: Compounds containing phenolic hydroxy groups are removed from a gas stream which contains at least one aromatic amine generated during the gas-phase hydrogenation reaction of the corresponding nitroaromatic compounds with hydrogen, by adsorption on a basic solid.