Abstract: An apparatus and a process for crystallizing substances from solutions or dispersions containing these substances, in a crystallizer containing a classifying zone (3), comprise a) an inner and an outer circulation system (1; 2), the inner circulation system (1) being present in the crystallizer, the inlet of the outer circulation system (2) being connected to the inner circulation system (1) via the classifying zone (3), the outer circulation system, being present outside the crystallizer, the outlet of the outer circulation system (2) being connected to the inner circulation system (1) of the crystallizer, and a means for dissolving crystals being arranged in the outer circulation system (2), before its outlet, b) an inflow (4) for solution and/or dispersion, which inflow is present on the crystallizer or on the outer circulation system, and c) an outflow (5) for dispersions, which outflow is arranged on the crystallizer or on the outer circulation system.

Abstract: An apparatus and a process for crystallizing substances from solutions or dispersions containing these substances, in a crystallizer containing a classifying zone (3), comprise

Abstract: A hydrogenation catalyst is prepared by reduction of platinum in an oxidation state of not less than two using a reducing agent in an aqueous medium in the presence of a carbon-containing support after partial poisoning, where use is made of a compound of the general formula I ##STR1## where X, Y and Z can be identical or different and are hydrogen, C.sub.1 -C.sub.18 -alkyl, C.sub.5 -C.sub.10 -cycloalkyl, halogen, hydroxyl, C.sub.1 -C.sub.6 -alkoxy and --NR'R", where R, R' and R" can be identical or different and can be hydrogen, C.sub.1 -C.sub.18 -alkyl or C.sub.5 -C.sub.10 -cycloalkyl. Such a hydrogenation catalyst can be used for preparing hydroxylammonium salts and the process for preparing the above catalysts can also be used for regenerating hydrogenation catalysts based on platinum.

Abstract: A carbon-containing catalyst support is prepared by treating the carbon-containing catalyst support with a compound of the formula IM(OR).sub.m X.sub.n Iwhere M is Ti or Zr, X is Cl or Br, and R is C.sub.1 -C.sub.20 -alkyl, and m and n are integers from zero to four, where the sum of m and n is equal to four.

Abstract: A process for the preparation of a hydrogenation catalyst by reduction of platinum in an oxidation stage of not less than 2 in an aqueous medium in the presence of a carboniferous support, optionally following partial poisoning with a sulfur, arsenic, tellurium, or antimony-containing compound, using a reducing agent, in which the reducing agent used is an ammonium or phosphonium salt of the general formula I?XR.sup.4 !.sub.n Y Iin which X stands for N or P, R stands for hydrogen, C.sub.1 --C.sub.18 alkyl, C.sub.5 --C.sub.10 cycloalkyl, phenyl radical, and also a C.sub.1 --C.sub.4 alkyl radical substituted by phenyl, the phenyl radicals being mono-to tri-substituted by C.sub.1 --C.sub.6 alkyl, halogen, nitro or amino, if desired, provided that the radicals R may be the same or different but cannot simultaneously denote hydrogen, if X is P, n is an integer of 1 to 3, and Y is an organic anion which can reduce platinum in an oxidation stage other than zero to platinum in the oxidation stage of zero.

Abstract: A hydrogenation catalyst, obtainable by carrying out essentially the following steps:(a) treatment of a platinum metal salt with finely divided sulfur followed by(b) reduction of the platinum metal salt to metallic platinum metal.

Abstract: A process of use of hydrogenation catalyst, obtainable by carrying out essentially the following steps:(a) treatment of a platinum metal salt with finely divided sulfur followed by(b) reduction of the platinum metal salt to metallic platinum metal.

Abstract: A process for the preparation of hydroxylammonium salts by catalytic reduction of nitrogen monoxide using hydrogen in the presence of a hydrogenation catalyst, comprises(a) in a first step, filtering the reaction mixture obtained after the reaction, giving a solution of essentially hydroxylammonium salt and a filter residue essentially comprising a mixture of hydrogenation catalyst and a solution of essentially hydroxylammonium salt, and(b) in a second step, subjecting the filter residue to a further separation process in order to concentrate the hydrogenation catalyst, giving a mixture having a higher concentration of hydrogenation catalyst than the filter residue and a mixture having a lower concentration of hydrogenation catalyst than the filter residue.

Abstract: A hydrogenation catalyst, obtainable by carrying out essentially the following steps:(a) treatment of a platinum metal salt with finely divided sulfur followed by(b) reduction of the platinum metal salt to metallic platinum metal.

Abstract: 5-Methylbutyrolactone is prepared by a process in which a pentenoic ester of the formula IX--CO.sub.2 R (I),where X is CH.sub.2 .dbd.CH--CH.sub.2 --CH.sub.2 --, CH.sub.3 --CH.dbd.CH--CH.sub.2 -- or CH.sub.3 --CH.sub.2 --CH.dbd.CH-- and R is alkyl, cycloalkyl, aralkyl or aryl, or a mixture of these esters is reacted with water at from 50.degree. to 350.degree. C. in the presence or absence of a diluenta) over a zeolite and/or phosphate catalyst orb) in the presence of from 0.01 to 0.25 mole of a sulfonic acid, a Lewis acid and/or a non-oxidizing mineral acid per mole of pentenoic ester or over from 0.

Abstract: 5-Formylvaleric esters are prepared by a process which comprises the following steps:(a) Hydroformylation of a pentenoic ester by reaction with carbon monoxide and hydrogen at elevated temperatures and under superatmospheric pressure in the presence of a carbonyl complex of a metal of group 8 of the Periodic Table with formation of a mixture of 5-, 4- and 3-formylvaleric esters,(b) Isolation of the 5-formylvaleric ester from the resulting mixture of 5-, 4- and 3-formylvaleric esters, a mixture essentially consisting of 4- and 3-formylvaleric esters remaining,(c) Cleavage of the mixture essentially consisting of 4- and 3-formylvaleric esters at from 50.degree. to 400.degree. C. in the presence of a catalyst to give pentenoic esters and(d) Recycling of the pentenoic esters to stage (a).

Abstract: .delta.-Formylvalerates are prepared by a process wherein a 3-pentenoate is treated with an isomerization catalyst at elevated temperatures and a 4-pentenoate is distilled off, and the resulting 4-pentenoate is reacted with carbon monoxide and hydrogen at from 80 to 160.degree. C. under from 1 to 30 bar in the presence of a rhodium carbonyl complex which has been modified with tertiary organic phosphines or phosphites.

Abstract: In an improved process for the preparation of 6-aminocaproates by reacting a 5-formylvalerate with ammonia and hydrogen using an alkanol as a solvent in the presence of a hydrogenation catalyst at elevated temperatures and under superatmospheric pressure, the improvement comprises carrying out the reaction at from 40.degree. to 95.degree. C.

Abstract: Cyclic ketones of the formula ##STR1## where n is an integer from 4 to 6, are prepared by converting an aliphatic dicarboxylate of the formulaR.sup.1 OCC--(CH.sub.2).sub.n --COOR.sup.2 IIwhere n has the above meaning, R.sup.1 and R.sup.2 are each alkyl, cycloalkyl, aralkyl or aryl and R.sup.2 may furthermore be hydrogen, at from 150.degree. to 450.degree. C. over a solid oxide catalyst.

Abstract: Caprolactam is prepared by a process in which(a) a 5-formylvalerate is reacted with excess ammonia and hydrogen in the presence of an alkanol as a solvent and in the presence of a hydrogenation catalyst under superatmospheric pressure in the liquid phase at from 40.degree. to 130.degree. C.,(b) excess ammonia and hydrogen are separated off from the reaction mixture and(c) the reaction mixture thus obtained is heated to 150.degree.-250.degree. C. and .epsilon.-caprolactam is obtained.

Abstract: C.sub.1 -C.sub.4 -alkyl pentenoates are obtained from reaction mixtures which contain this and which are obtained by reacting butadiene, or a butadiene-containing hydrocarbon mixture, with carbon monoxide and a C.sub.1 -C.sub.4 -alkanol, in the presence of a cobalt carbonyl catalyst and a tertiary nitrogen base at elevated temperatures and under superatmospheric pressure by a process in which(a) the liquid reaction mixture freed from excess carbon monoxide is treated with hydrogen at elevated temperatures and under from 5 to 80 bar,(b) hydrocarbons are distilled off from the resulting liquid reaction mixture,(c) the C.sub.1 -C.sub.4 -alkyl pentenoate, the alkanol and the nitrogen base are then distilled off under reduced pressure, and(d) the C.sub.1 -C.sub.4 -alkyl pentenoate is obtained by fractional distillation from the distillate containing this compound, the alkanol and the tertiary nitrogen base.

Abstract: Methyl 4-pentenoate is isolated from mixtures containing this and methyl 3-pentenoate by a process in which from 0.25 to 0.4 part by weight of water is added per part by weight of methyl 4-pentenoate, and the azeotrope of methyl 4-pentenoate and water is distilled off.

Abstract: A process for the manufacture of pent-3-enoic acid and its alkyl esters, of the general formulaCH.sub.3 --CH.dbd.CH--CH.sub.2 --CO--ORwhere R is hydrogen or alkyl of 1 to 4 carbon atoms, comprising carbonylating butadiene with carbon monoxide and a compound ROH at from 300 to 1,000 bars CO pressure and from 100.degree. to 160.degree. C. in the presence of cobalt catalysts and nitrogen bases, wherein C.sub.4 cuts are used as starting materials and a tertiary amine having a pK.sub.A of from 3 to 11 is used as the nitrogen base. The pent-3-enoic acid or alkyl esters produced may be used for the manufacture of adipic acid or its alkyl esters, which compounds are starting materials for the manufacture of nylons.

Abstract: Pure monoesters of adipic acid are prepared by a process in which(a) a pentenoate is reacted with carbon monoxide and hydrogen at from 90.degree. to 140.degree. C. and under from 5 to 300 bar in the presence of a carbonyl complex of cobalt or of rhodium, and a 5-formylvalerate is separated off, and(b) the 5-formylvalerate thus obtained is oxidized with molecular oxygen, or with a gas containing this, at from 20.degree. to 100.degree. C. under from 1 to 10 bar.

Abstract: 4-Pentenoates are prepared by isomerization of isomeric pentenoates in the presence of a catalyst, by a process in which isomeric pentenoates are treated at elevated temperatures with an acidic ion exchanger or acidic zeolite which contains a noble metal of group eight of the periodic table, and the 4-pentenoate is distilled off from the reaction mixture.