Abstract: Hydroxylammonium salts are eliminated from wastewaters containing such salts by a process which comprises treating a wastewater containing such salts with not less than 0.5 mole of manganese (IV) oxides per mole of hydroxylamine in the form of hydroxylammonium salts at a pH of from 1 to 4 and at from 10.degree. to 100.degree. C.

Abstract: Distillation residues from the purification of caprolactam are worked up by heating in the presence of sodium hydroxide or potassium hydroxide and in the presence of a high-boiling hydrocarbon at from 250.degree. to 500.degree. C. and continuously removing the caprolactam.

Abstract: Hydroxylammonium salts are prepared by catalytic reduction of nitrogen monoxide with hydrogen at elevated temperature in a dilute aqueous solution of a mineral acid in the presence, in suspension, of a supported platinum catalyst obtainable by precipitating metallic platinum from an aqueous platinum solution onto a support by means of a reducing agent in the presence of an organic chelating agent and partially poisoned with sulfur.

Abstract: Caprolactam is recovered from caprolactam distillation low boilers or high boilers or mixtures thereof by the following steps:(a) crystallizing a low or high boiler or a mixture thereof to form purified capro-lactam crystals and a mother liquor,(b) separating off the purified caprolactam crystals to leave a mother liquor,(c) recycling from 5 to 90% by weight of the mother liquor of stage (b) into stage (a) and transferring the remainder of the mother liquor into the subsequent stage (d),(d) crystallizing the remaining mother liquor portion from stage (c) to form caprolactam crystals and a mother liquor, separating off the caprolactam crystals of stage(e) (d) and recycling the same into stage (a) to leave a mother liquor,(f) recycling from 20 to 99% by weight of mother liquor of stage (e) into stage (d) and channeling out the remainder of the impurity-containing mother liquor of stage (e).

Abstract: Cyclohexanone oxime containing ammonium sulfate is purified by a process in which cyclohexanone oxime in the molten state is passed over an acidic ion exchanger and a basic ion exchanger.

Abstract: Pure hydroxylammonium salts of fatty acids of 1 to 4 carbon atoms are prepared by reacting hydroxylammonium sulfate and alkali metal salts of fatty acids with 1 to 4 carbon atoms in solution at elevated temperatures and separating off the hydroxylammonium salts of fatty acids of 1 to 4 carbon atoms by(a) reacting hydroxylammonium sulfate and alkali metal salts of fatty acids of 1 to 4 carbon atoms in solution in water or alkanols of 1 to 3 carbon atoms or mixtures thereof at 20.degree.-70.degree. C.,(b) evaporating the solvent out of the reaction mixture to obtain a dry residue,(c) isolating the hydroxlammonium salts of fatty acids of 1 to 4 carbon atoms from the dry residue thus obtained by sublimation under reduced pressure.

Abstract: Reaction mixtures obtained by Beckmann rearrangement of cyclohexanone oxime with sulfuric acid or oleum are neutralized by a process which comprises the following steps:(a) mixing the reaction mixture with recycled ammonium sulfate mother liquor whose concentration is chosen so that no solid ammonium sulfate is precipitated during the neutralization,(b) neutralization by feeding gaseous ammonia which contains water or an aqueous ammonium sulfate solution in finely divided liquid form through a plurality of nozzle orifices into the solution of the reaction mixture in the ammonium sulfate mother liquor at elevated temperatures,(c) separation of crude lactam from the aqueous ammonium sulfate solution,(d) evaporation of the ammonium sulfate solution under reduced pressure and with separation of the crystalline ammonium sulfate from the ammonium sulfate mother liquor and(e) recycling of the ammonium sulfate mother liquor to stage a).

Abstract: Water-immiscible solvents are removed from offgases containing same by washing with water-containing caprolactam.

Abstract: Frozen crystal layers are purified by a process in which these crystal layers, after they have been frozen out from a melt or solution on a cooling surface, are brought into contact with a purifying liquid and thus purified over their entire thickness, after which the said layers are separated from the purifying liquid and then melted, wherein the temperature of the crystal layers and of the purifying liquid is close to the melting point or solubility temperature, mass transfer at the phase boundary is intensified by forced convection, and this purification is carried out in the course of from 1 to 60 minutes on layers having a thickness of from 0.2 to 10 mm.

Abstract: Aqueous solutions of free hydroxylamine are prepared by a process in which(a) hydroxylammonium sulfate is reacted with ammonia in a lower alkanol as solvent, and a solution of free hydroxylamine and solid ammonium sulfate with residues of hydroxylammonium sulfate is obtained,(b) solid ammonium sulfate and hydroxylammonium sulfate are separated off from the resulting reaction mixture, and an alcoholic solution of free hydroxylamine is obtained as the filtrate,(c) a stabilizer and water are added to the resulting alcoholic solution of free hydroxylamine, and(d) the alkanol is distilled off from the alcoholic solution containing free hydroxylamine, the stabilizer and water.

Abstract: Hydroxylamine-O-sulfonic acid is prepared by(a) reacting hydroxylammonium sulfate with oleum at elevated temperatures,(b) isolating sulfuric acid from the hydroxylamine-O-sulfonic acid formed,(c) diluting the sulfuric acid which was obtained in stage (b) and which still contains hydroxylamino-O-sulfonic acid with water to 2-6N and heating it to 30.degree.-80.degree. C. for 1-10 hours,(d) preparing hydroxylamine by catalytic reduction of nitrogen monoxide with hydrogen using the dilute sulfuric acid from stage (c) in the presence of a noble metal catalyst at elevated temperatures.

Abstract: Wastewaters containing hydroxylamine or its salts are worked up by a process in which the said wastewaters are passed over a strongly acidic ion exchanger, after which a 5-15% strength by weight aqueous sulfuric acid is passed over the said ion exchanger and a solution of hydroxylammonium sulfate in aqueous sulfuric acid is obtained.

Abstract: Caprolactam is obtained by cleaving oligomers of caprolactam by a process in which the oligomers, in a liquid or solid state, are introduced into a fluidized alumina bed and cleaved at from 290.degree. to 400.degree. C. in the presence of steam, and, in addition to the amount of inert gas required to fluidize the alumina bed, from 0.1 to 3 times this amount of inert gas is introduced above the fluidized bed.

Abstract: Caprolactam is obtained by treating .epsilon.-aminocaproic acid with steam at elevated temperatures in the presence of a catalyst by a process in whcih .epsilon.-aminocaproic acid is introduced into a fluidized alumina bed and treated in the presence of steam at from 290.degree. to 400.degree. C.

Abstract: A method of separation by fractional crystallization from a liquid mixture in which the liquid mixture is repeatedly passed in turbulent flow through an indirectly cooled crystallization zone, which must be kept full. The liquid remaining after deposition of a layer of crystals on the wall of the crystallization zone is removed, whereupon the surface of the layer of crystals is washed and the crystals are melted by passing a melt of similar compositions to that of the layer of crystals through the crystallization zone. During crystallization the melt is maintained at the temperature of crystallization and crystallization is stopped when the frozen fraction is from 70 to 98%.

Abstract: In a process for obtaining caprolactam by cleaving caprolactam oligomers by passing them through an alumina catalyst bed at an elevated temperature, the improvement that the oligomers are introduced, as liquid or solid, into a fluidized bed of alumina and are cleaved at from 290.degree. to 400.degree. C. in the presence of steam.

Abstract: In a process for continuously extracting caprolactam from an aqueous solution, containing caprolactam and its oligomers, with organic solvents, by introducing the aqueous solution into the upper part of an extraction zone and organic solvents into the lower part, and taking off a solution of caprolactam in organic solvents at the upper end and an aqueous phase containing caprolactam oligomers at the lower end, the improvement that liquid aromatic hydrocarbons are used and the extraction is carried out at a pH of from 2.0 to 6.0.

Abstract: A process for purifying caprolactam, which has been obtained by a Beckmann rearrangement, by extracting crude caprolactam with solvents, distilling the extract in the presence of alkali, and isolating pure caprolactam, wherein, in a first stage, caprolactam is distilled from the alkaline distillation residue at a bottom temperature of 130.degree.-160.degree. C., and is recycled to the distillation stage, the residue thus obtained is distilled, in a second stage, at a bottom temperature of 140.degree.-180.degree. C., and the distillate is treated with strongly acidic agents in a third stage and is then recycled to the extraction stage.

Abstract: A process for the preparation of caprolactam wherein, in a first stage, cyclohexanone-oxime is vaporized, in the presence of inert gases, by bringing it into contact with a fluidized bed of inert solid particles at from 150.degree. to 250.degree. C., and the mixture of cyclohexanone-oxime vapor and inert gases is passed into a second stage, where the cyclohexanone-oxime is rearranged to caprolactam at from 230.degree. to 450.degree. C. over a supported catalyst, containing boron trioxide, in a fluidized bed.

Abstract: Caprolactam is obtained by cleaving oligomers of caprolactam by a process in which the oligomers, in a liquid or solid state, are introduced into a fluidized alumina bed and cleaved at from 290.degree. to 400.degree. C. in the presence of steam, and, in addition to the amount of inert gas required to fluidize the alumina bed, from 0.1 to 3 times this amount of inert gas is introduced above the fluidized bed.