Abstract: A friction-welding device for the integral joining of components, having an oscillator, which generates a periodic movement of a component and a welding surface provided thereon relative to another, static component and a welding surface provided thereon, with directions of movement parallel to the welding surfaces, having a compression device which presses the welding surfaces together, and a cartridge which accommodates the moved component. The oscillator includes two or a greater, even number of piezoactuators, which are arranged in pairs on a line of application and are able to be prestressed with respect to the cartridge from opposite sides under pressure generation and are able to be moved in a synchronous, oscillating manner together therewith and the component.

Abstract: Caprolactam is recovered from oligomers and/or polymers of caprolactam by cleavage of oligomers and/or polymers of caprolactam and subsequent working up by distillation of the caprolactam obtained in the cleavage, by a process including(a) cleaving oligomers and/or polymers of caprolactam to obtain an aqueous reaction mixture which contains caprolactam,(b) removing water from the reaction mixture obtained under (a) to obtain a residue,(c) distilling the residue obtained under (b) in an acidic medium and(d) then distilling the distillate in an alkaline medium to obtain caprolactam, or(c') distilling the residue obtained under (b) in an alkaline medium and(d') then distilling the distillate in an acidic medium to obtain caprolactam.

Abstract: A process for preparing caprolactam by cyclization of 6-aminocapronitrile in the presence of water at elevated temperature and in the presence or absence of a catalyst and a solvent, comprisesa) removing from the cyclization reaction effluent ("reaction effluent I") caprolactam and all components boiling higher than caprolactam ("high boilers"),b) treating the high boilers of stage a) with phosphoric acid and/or polyphosphoric acid at from 200 to 350.degree. C. to obtain a reaction effluent II, andc) removing caprolactam formed and any 6-aminocapronitrile from reaction effluent II of stage b) to obtain separation from unconverted high boilers and acid used.

Abstract: Caprolactam is obtained from caprolactam-containing polymers in the presence of a base under reduced pressure by depolymerizing polymers which contain the repeating unit --[--N(H)--(CH.sub.2).sub.5 --C(O)--] or mixtures consisting essentially offrom 50 to 99.99% by weight of a polymer containing the repeating unit --[--N(H)--(CH.sub.2).sub.5 --C(O)--]--from 0.01 to 50% by weight of additives selected from the group consisting of inorganic fillers, organic and inorganic pigments and dyes,from 0 to 10% by weight of organic and/or inorganic additives,from 0 to 40% by weight of non-polyamide-containing polymers andfrom 0 to 20% by weight of polyamides, with the exception of polycaprolactam and copolyamides prepared from caprolactam,in at least two depolymerization reactors connected in series.

Abstract: Crude capronitrile is purified by hydrogenation, subsequent treatment in an acidic medium and subsequent distillation in an alkaline medium, by a process in which(a) 6-aminocapronitrile is converted into crude caprolactam by reaction with water,(b) high boilers and low boilers are separated off from the crude caprolactam from step (a),(c) the crude caprolactam from step (b) is treated with hydrogen at from 50.degree. to 150.degree. C. and from 1.5 to 250 bar in the presence of a hydrogenation catalyst and, if desired, of a solvent to give a mixture A,(d1) mixture A in a solvent is passed, at from 30.degree. to 80.degree. C. and from 1 to 5 bar, over an ion exchanger containing terminal acid groups to give a mixture B1, or(d2) mixture A is distilled in the presence of sulfuric acid, any solvent present being removed before the addition of the sulfuric acid, to give a mixture B2, and(e) mixture B1 or mixture B2 is distilled in the presence of a base to give pure caprolactam.

Abstract: A process for the purification of caprolactam from crude caprolactam by distilling the crude caprolactam in the presence of an anorganic or organic acid.

Abstract: Recovery of caprolactam and of an alkali metal carbonate from distillation residues which are obtained in the purification of caprolactam and contain caprolactam and/or oligomers and/or polymers of caprolactam and also alkali metal hydroxides by(a) melting the distillation residues, the caprolactam and/or oligomers and/or polymers of caprolactam and alkali metal hydroxides,(b) continuously removing caprolactam from the melt,(c) after removing caprolactam, cooling the melt and obtaining a residue,(d) dissolving the residue thus obtained in water and(e) subjecting the aqueous solution thus obtained to combustion with the formation of an alkali metal carbonateis described.

Abstract: A process for recovering caprolactam from oligomers and/or polymers of caprolactam comprises the following steps:a) treating oligomers and/or polymers of caprolactam with from 1 to 20 parts by weight of water per part by weight of oligomer or polymer at from 200.degree. to 350.degree. C. under superatmospheric pressure with a residence time of from 0.5 to 10 hours to form an aqueous reaction mixture comprising polycaprolactam, monomeric caprolactam and oligomers thereof, andb) passing the aqueous reaction mixture obtained in a) into a fluidized bed of alumina at from 250.degree. to 400.degree. C. to obtain a mixture of steam and caprolactam.

Abstract: Caprolactam is recovered from polycaprolactam by hydrolyric cleavage of polycaprolactam with from 5 to 50 parts by weight of water per part by weight of polycaprolactam at from 200.degree. to 350.degree. C. under superatmospheric pressure to give an aqueous solution or suspension which contains monomeric caprolactam and oligomers thereof and may contain polycaprolactam and subsequent isolation of monomeric caprolactam from the aqueous solution or suspension by distillation or extraction, by a process in which the hydrolyric cleavage is carried out in the presence of an alkali metal hydroxide at a pH of from 5 to 10.

Abstract: A process for preparing caprolactam by Beckmann rearrangement of cyclohexanone oxime with oleum at from 85.degree. to 125.degree. C. in a plurality of rearrangement stages arranged in series entails returning a portion of the reaction mixture leaving the last rearrangement stage to at least one of the preceding rearrangement stages.

Abstract: A process for the preparation of hydroxylammonium salts by the reduction of nitrogen oxide (NO) with hydrogen in dilute aqueous mineral acid in the presence of a suspended platinum catalyst which is partially poisoned with arsenic, at elevated temperature, wherein the catalyst used is one which has been produced by precipitation of metallic platinum from an aqueous solution on to a suspended support in the presence of an oxidic arsenic compound, by means of a reducing agent.

Abstract: A platinum-on-graphite catalyst having a platinum content of from 0.01 to 5% w/w, wherein the graphite support has an apparent density of from 1.7 to 2.2 g/ml and the use thereof as a hydrogenation catalyst.

Abstract: A process for working up aqueous mother liquors containing hydrochloric acid, sulfuric acid and their hydroxylammonium and ammonium salts, entails the mother liquors being intimately mixed with an excess of cyclohexanone based on the content of hydroxylammonium salts, while maintaining a pH of from 3 to 5.5 by adding alkali metal hydroxide solutions, and the cyclohexanone phase which contains cyclohexanone oxime being removed and washed with water until essentially free of chloride.

Abstract: A platinum-on-graphite catalyst having a platinum content of from 0.01 to 5% w/w, wherein the graphite support has a particle size of from 1 to 600 .mu.m and the following particle size distribution:______________________________________ 183 to 600 .mu.m 15% v/v .+-. 15% absolute 68.3 to 183 .mu.m 30% v/v .+-. 20% 31.0 to 68.3 .mu.m 25% v/v .+-. 20% 17.1 to 31.0 .mu.m 15% v/v .+-. 10% 5.2 to 17.1 .mu.m 12% v/v .+-. 10% .sup. <5.2 .mu.m 5% v/v .+-. 5%.

Abstract: Caprolactam is purified continuously by passing a 75-95% strength by weight aqueous caprolactam solution together with hydrogen at 50.degree.-95.degree. C. and 1.5-100 bar upward through a fixed-bed supported palladium or nickel catalyst in a tubular zone while maintaining a residence time of from 10 to 100 min.

Abstract: Crystalline hydroxylammonium sulfate is prepared by a process which comprises the following steps:(a) Bringing an aqueous solution which contains from 0.02 to 0.3 part by weight of ammonium sulfate and from 0.02 to 0.2 part by weight of sulfuric acid per part by weight of hydroxylammonium sulfate into contact with a basic ion exchanger and obtaining a solution which has a pH of from 3.0 to 4.0,(b) separating off the basic ion exchanger from the aqueous hydroxylammonium sulfate solution,(c) evaporating down the resulting aqueous hydroxylammonium sulfate solution under reduced pressure at <100.degree. C. and obtaining a concentrated hydroxylammonium sulfate solution,(d) crystallizing out not more than 70% by weight of the hydroxylammonium sulfate present in the aqueous solution to give crystalline hydroxylammonium sulfate and a mother liquor, and(e) isolating and crystalline hydroxylammonium sulfate from the mother liquor.

Abstract: The storability of molten cyclohexanone oxime containing 0.5-15% by weight of cyclohexanone and 1-8% by weight of aqueous ammonium bisulfate solution is improved by washing the molten cyclohexanone oxime with a 10-42% strength by weight aqueous ammonium sulfate solution and maintaining a pH of 4.5-5.8.

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: Cyclohexyl hydroperoxide containing reaction mixtures obtained by oxidation of cyclohexane with molecular oxygen or molecular oxygen containing gases in the liquid phase at from 130.degree. to 200.degree. C. and under from 5 to 125 bar are worked up by reaction with cycloolefins at elevated temperature in the presence of catalysts to react cyclohexyl hydroperoxide with cyclohexene at elevated temperatures in the presence of cyclohexene-soluble compounds of transition metals of groups 4 or 5 or 6 of the periodic table or of one or more cyclohexane-insoluble compounds of a transition metal of group 4 or 5 or 6, or in the presence of selenium, tellurium or a boride, and the resulting cyclohexene oxide at elevated temperatures to cyclohexanol in the presence of hydrogenation catalysts.