Abstract: Aromatic amines are produced by catalytic hydrogenation of aromatic nitro compounds. The reaction mixture generated by this hydrogenation is then worked up by distillation in a manner which makes it possible to substantially free the amine of water with increased energy efficiency. Water free of amine and low boilers and the low boiling materials are also obtained.

Abstract: The invention relates to an energy efficient process for the distillative working-up of aqueous amine solutions that occur in the catalytic hydrogenation of nitroaromatic compounds. In this process, the amine is freed from water and also the water is obtained free from amine and low-boiling compounds and the concentrated low-boiling compounds are obtained.

Abstract: Aromatic amines are produced by catalytic hydrogenation of aromatic nitro compounds. The reaction mixture generated by this hydrogenation is then worked up by distillation in a manner which makes it possible to substantially free the amine of water with increased energy efficiency. Water free of amine and low boilers and the low boiling materials are also obtained.

Abstract: The invention describes a stirring device made from a gassing stirrer and a liquid mixer or two liquid mixers, which are arranged on a shaft and each have a feed and at least one exit opening, wherein the exit openings of the gassing stirrer and of the liquid mixer or the liquid mixers are at a distance from one another, the ratio, a/d, of the distance, a, between the exit openings to the diameter, d, of the gassing stirrer or liquid mixer being 0.02 to 0.5 and the ratio, b/d, of the distance, b, between the outer edges to the diameter, d, of the gassing stirrer or liquid mixer being 0.01 to 0.4.

Abstract: Toluenediamine is produced and separated from by-products of the reaction by: a) hydrogenating dinitrotoluene in the presence of a catalyst, b) separating the catalyst, water and optionally solvent from the hydrogenation reaction mixture to give crude toluenediamine, and c) separating by distillation the crude toluenediamine in a separating wall column into at least four product streams P1, P2, P3 and P4. The product stream P1 is a stream containing low boilers. The product stream P2 is a stream containing o-toluenediamine. The product stream P3 is a stream containing m-toluenediamine. The product stream P4 is a stream containing high boilers and m-toluenediamine.

Abstract: Toluenediamine is produced and separated from by-products of the reaction by: a) hydrogenating dinitrotoluene in the presence of a catalyst, b) separating the catalyst, water and optionally solvent from the hydrogenation reaction mixture to give crude toluenediamine, and c) separating by distillation the crude toluenediamine in a separating wall column into at least four product streams P1, P2, P3 and P4. The product stream P1 is a stream containing low boilers. The product stream P2 is a stream containing o-toluenediamine. The product stream P3 is a stream containing m-toluenediamine. The product stream P4 is a stream containing high boilers and m-toluenediamine.

Abstract: The invention describes a stirring device made from a gassing stirrer and a liquid mixer or two liquid mixers, which are arranged on a shaft and each have a feed and at least one exit opening, wherein the exit openings of the gassing stirrer and of the liquid mixer or the liquid mixers are at a distance from one another, the ratio, a/d, of the distance, a, between the exit openings to the diameter, d, of the gassing stirrer or liquid mixer being 0.02 to 0.5 and the ratio, b/d, of the distance, b, between the outer edges to the diameter, d, of the gassing stirrer or liquid mixer being 0.01 to 0.4.

Abstract: The invention relates to an energy efficient process for the distillative working-up of aqueous amine solutions that occur in the catalytic hydrogenation of nitroaromatic compounds. In this process, the amine is freed from water and also the water is obtained free from amine and low-boiling compounds and the concentrated low-boiling compounds are obtained.