Abstract: The present invention relates to a process for preparing oligomers consisting mainly of repeating units derived from 1- or 2-butene from a hydrocarbon stream consisting substantially of branched and linear hydrocarbon compounds having 4 carbon atoms, and comprising olefinic branched and linear hydrocarbon compounds having 4 carbon atoms (C4 starting stream) by a. in step a), separating the C4 starting stream into a fraction consisting mainly of linear hydrocarbon compounds having 4 carbon atoms (l-C4 fraction) and a fraction consisting mainly of branched hydrocarbon compounds having 4 carbon atoms (b-C4 fraction), by contacting the C4 starting stream with a membrane which is easier to pass for linear hydrocarbon compounds having 4 carbon atoms than for branched hydrocarbon compounds having 4 carbon atoms, b. in step b), optionally after removing butanes, oligomerizing the olefinic hydrocarbon compounds having 4 carbon atoms present in the l-C4 fraction, c.

Abstract: In a process for concentrating an at least partially crystalline solid containing at least one zeolite in a mixture comprising at least one auxiliary, for example a template compound, and said solid, the mixture is ultrafiltrated in a step (II) to divide the mixture into a retentate and a permeate, the solids content in the retentate being higher than that in the mixture and the solids content in the permeate being lower than that in the mixture. This procedure allows auxiliaries, in particular template compounds, present in the permeate to be recycled into a crystallizing step (I) upstream of step (II).

Abstract: The invention provides a process for preparing amines by catalytic hydrogenation of nitroaromatics and subsequent removal of the catalysts from the reaction mixture, which contains at least one aromatic amine and water, which comprises carrying out the removal of the catalysts by means of membrane filtration, which is carried out at a pressure on the suspension side of from 5 to 50 bar, a pressure difference between the suspension side and the permeate side of at least 0.3 bar and a flux rate on the suspension side of from 1 to 6 m/s.

Abstract: The invention relates to a fuel cell having a moderate operating temperature which comprises a cathode, an anode and an electrolyte, where at least the cathode comprises a material having the composition (Sr1-xCax)1-yAyMn1-zBzO3-? and A is at least one element from the group consisting of Ba, Pb, Na, K, Y and the lanthanide group, B is at least one element from the group consisting of Mg, Al, Ga, In, Sn and sub-group elements from the 4th, 5th or 6th period, and x adopts values of from 0.2 to 0.8, y adopts values of from 0 to 0.4, z adopts values of from 0 to <1, and ? adopts values which arise taking into account the electroneutrality principle.

Abstract: The present invention relates to a process and an apparatus for the deionization of a cooling medium of a fuel cell circulating in a cooling circuit. According to the invention, a liquid deionizing agent is allowed to act at least intermittently on the cooling medium so that the deionizing agent can take up ions from the cooling medium. For this purpose, the fuel cell apparatus (10) of the present invention, which comprises at least one fuel cell (11) and at least one cooling circuit (20) for the fuel cell, has at least one deionization apparatus (23) in which a liquid deionizing agent can act on the cooling medium in the cooling circuit (20). The deionization apparatus can comprise static mixers (28, 34) downstream of which membrane separators (29, 35) are installed.

Abstract: The present invention relates to a process for the recovery of N-phosphonomethylglycine from an aqueous mixture which contains N-phosphonomethylglycine, ammonium halides, and alkali metal or alkaline earth metal halides and optionally organic impurities in dissolved form, where

Abstract: The invention relates to phosphacyclohexanes of general formulae I and II, wherein the following designations, among others, apply: R can represent hydrogen, C1-100-alkyl, C7-20-aralkyl, C7-20-alkaryl, and C6-12-aryl: R1 to R10 can independently represent hydrogen, C1-20-alkyl, C7-20-aralkyl, C7-20-alkaryl, and C6-12-aryl: W, W′ can independently represent single bonds or bridges comprising 1 to 20 carbon atoms, which can form part of a cyclic or aromatic group and can be interrupted by heteroatoms. Said phosphacyclohexanes are used as ligands in transition metal complexes of transition metals belonging to groups VIII to X of the periodic table.

Abstract: Reactor membranes for used in oxidation reactions of hydrocarbons involving oxygen comprising a selective oxidation catalyst on a mixed conducting, oxide ion selective ceramic membrane of the composition (Sr1-xCax)1-yAyMn1-zBzO3-&dgr;, where A is Ba, Pb, Na, K, Y, an element of the lanthanide group or a combination thereof, B is Mg, Al, Ga, In, Sn, an element of the 3d or 4d period or a combination thereof, x is from 0.2 to 0.8, y is from 0 to 0.4, z is from 0 to 0.6, and &dgr; is a number, dependent on x, y and z, that renders the composition charge neutral.

Abstract: In a process for working up polyether monools which have been prepared by ring-opening polymerization of epoxides by means of OH-functional starters using at least one heterogeneous catalyst, the heterogeneous catalyst or catalysts is/are separated off from the polyether monool by means of a membrane separation process.

Abstract: The invention relates to an improved method for the production of D-pantothenic acid and/or salts thereof and use thereof as adjunct for animal feedstuffs.

Abstract: A process for fractionating water-soluble or water-dispersible amino-containing synthetic polymers having a broad molar mass distribution by ultrafiltration, wherein the polymer solution or dispersion to be fractionated is fed continuously into an ultrafiltration circulation with at least one ultrafiltration unit, and retentate having a narrower molar mass distribution and permeate are discharged continuously, in such a way that the ultrafiltration circulation is essentially in a steady state, the polymers obtainable by this process and their use.

Abstract: In a process for concentrating an at least partially crystalline solid containing at least one zeolite in a mixture comprising at least one auxiliary, for example a template compound, and said solid, the mixture is ultrafiltrated in a step (II) to divide the mixture into a retentate and a permeate, the solids content in the retentate being higher than that in the mixture and the solids content in the permeate being lower than that in the mixture. This procedure allows auxiliaries, in particular template compounds, present in the permeate to be recycled into a crystallizing step (I) upstream of step (II).

Abstract: The invention relates to a fuel cell having a moderate operating temperature which comprises a cathode, an anode and an electrolyte, where at least the cathode comprises a material having the composition (Sr1-xCax)1-yAyMn1-zBzO3-&dgr; and

Abstract: Reactor membranes advantageously useful in oxidation reactions of hydrocarbons involving oxygen comprise a selective oxidation catalyst on a mixed conducting, oxide ion selective ceramic membrane of the composition (Sr1-xCax)1-yAyMn1-zBzO3-&dgr;, where

Abstract: The invention relates to a method for the production of aldehydes or aldehydes and alcohols by hydroformylation of olefins in the presence of a complexing catalyst homogeneously dissolved in a reaction mixture, containing a metal of Group VIIIa of the periodic table of the elements and a phosphorus-free, polydentate nitrogen compound suitable for complex formation as ligand at temperatures ranging from 50 to 100° C.

Abstract: A process for the simultaneous production of dicarboxylic acids and diamines from a) polymers based on polyamides of dicarboxylic acids or their derivatives with diamines, orb) compositions containing essentially such polymers, by splitting these polymers into their monomeric constituents, comprises treating these polymers or compounds with a base in alcoholic medium, and subsequently converting the resulting dicarboxylate salts electrochemically into the corresponding dicarboxylic acids and bases.

Abstract: The invention is directed to an air spring (2) having a flexible member wherein a roll-off piston (8) is connected to a flexible member (6) of the air spring (2) via a threaded fastener assembly. The piston volume (8a) is used to provide a softer spring constant in that the piston volume (8a) and the volume (6a) of the flexible member (6) communicate with each other. The sealing ring configured at the lower edge (6c) of the flexible member (6) is clamped tightly between a clamping plate (12) and the sealing surface (8c) of the piston by utilizing a threaded spindle (10) which is sufficiently long. The clamping plate (12) is provided with holes (14). The clamping plate (12) can be configured as a deep-drawn pot provided with several bores (14).

Abstract: Salt-free aqueous solutions of bisaminoxyalkanes (I) are prepared by a process in whicha) a dihaloalkane (II) is converted with a ketoxime (III) in an aqueous solution of a strong mineral base into the alkylene bisoxime ether (IV),b) the alkylene bisoxime ether (IV) is cleaved with a strong mineral acid and water to give the ketone and the salt of the mineral acid with the bisaminoxyalkane (I), and the ketone is separated off in a conventional manner,c) an alkali metal hydroxide is added to the remaining aqueous solution to liberate the bisaminoxyalkane (I) andd) the ionic components are removed from the resulting aqueous solution by electrodialysis.

Abstract: Benzaldehyde dialkyl acetals of the general formula I ##STR1## where R.sup.1 is C.sub.1 -C.sub.6 -alkyl, R.sup.2 is C.sub.1 -C.sub.6 -alkyl, C.sub.1 -C.sub.6 -alkoxy, halogen, cyano or carboxyalkyl where the alkyl group is of 1 to 6 carbon atoms, n is an integer of from 1 to 3 and the radicals R.sup.2 may be identical or different when n is >1, are prepared by electrochemical oxidation of a substituted toluene compound of the general formula II ##STR2## by a process in which a substituted toluene compound II is oxidized in the presence of an alkanol R.sup.

Abstract: A process for preparing ultrapure polymers (or solutions thereof) which contain at least 20% by weight of N-vinylpyrrolidone as copolymerized units and have a Fikentscher K value of from 10 to 45 by customary free-radical polymerization in solution and subsequent purification of the solution with or without drying comprises purifying the solutions of the polymers by separating off the low molecular weight impurities by means of ultrafiltration at from 20.degree. to 100.degree. C. and from 1 to 80 bar.