Abstract: A vane pump has a pump flange, a cam ring, a pressure plate and at least one pin extending axially through the pump flange, the cam ring and the pressure plate, the pin being preloaded in an axial direction thereof by means of at least one spring element.

Abstract: A vane cell pump comprises a contour ring having an inner peripheral face and a rotatable rotor which has a plurality of conveying elements displaceable radially relative to a rotation axis. The inner peripheral face includes a plurality of pump portions each constructed with an intake region and a pressure region which are passed through by the conveying elements during rotation of the rotor. A narrow location at which the conveying elements are displaced radially inward toward the rotation axis to a greatest extent, is located between a pressure region and a subsequent intake region. By applying a part-stroke, an auxiliary start contour which is arranged between the rotation axis and the inner peripheral face radially inside the conveying elements in the region of at least one pump portion displaces the conveying elements to the greatest extent radially inwardly.

Abstract: A vane cell pump comprises a contour ring having an inner peripheral face and a rotatable rotor which has a plurality of conveying elements displaceable radially relative to a rotation axis. The inner peripheral face includes a plurality of pump portions each constructed with an intake region and a pressure region which are passed through by the conveying elements during rotation of the rotor. A narrow location at which the conveying elements are displaced radially inward toward the rotation axis to a greatest extent, is located between a pressure region and a subsequent intake region. By applying a part-stroke, an auxiliary start contour which is arranged between the rotation axis and the inner peripheral face radially inside the conveying elements in the region of at least one pump portion displaces the conveying elements to the greatest extent radially inwardly.

Abstract: A vane pump has a pump flange, a cam ring, a pressure plate and at least one pin extending axially through the pump flange, the cam ring and the pressure plate, the pin being preloaded in an axial direction thereof by means of at least one spring element.

Abstract: There are described a vane cell pump and a method for operating a vane cell pump. The vane cell pump comprises a hollow-cylindrical contour ring which is arranged between two side plates and which has an inner peripheral face and a rotor which is rotatably supported about a rotation axis which extends parallel with the cylinder axis of the contour ring and which has a plurality of conveying elements which can be displaced radially relative to the rotation axis and which are urged against the inner peripheral face during a rotation of the rotor. The inner peripheral face is formed in such a manner that a number corresponding to the number of flows of the vane cell pump in respect of pump portions are each constructed with an intake region and a pressure region which are passed through by the conveying elements during a rotation of the rotor.

Abstract: A process for reducing the content of oxygen-containing and/or nitrogen-containing compounds in streams having an isobutene content of at least 10% by weight, which comprises passing the stream in the liquid state at a temperature T [in K] and a linear velocity v [in cm/min] over a fixed bed of an acid-free zeolite having a mean pore size of from 0.3 to 1.5 nm, where the fixed bed has a length l [in cm] in the flow direction of the stream and T, v and l obey the relationship 2(T?283 K)/10 K·l/v?500 min, is described. The process avoids the formation of isobutene oligomers.

Abstract: A process for reducing the content of oxygen-containing and/or nitrogen-containing compounds in streams having an isobutene content of at least 10% by weight, which comprises passing the stream in the liquid state at a temperature T [in K] and a linear velocity v [in cm/min] over a fixed bed of an acid-free zeolite having a mean pore size of from 0.3 to 1.5 nm, where the fixed bed has a length l [in cm] in the flow direction of the stream and T, v and l obey the relationship 2(T?283 K)/10 K·l/v?500 min, is described. The process avoids the formation of isobutene oligomers.

Abstract: A polyisobutene composition having a global maximum of the differential molecular weight distribution curve at a molecular weight Mmax of from 3 500 to 8 000 is described, which comprises at least one local maximum at a molecular weight of from 112 to 560. The isobutene oligomers present act as flow improvers and boiling assistants. They are added to higher molecular weight isobutene polymers, preferably before or in the course of a distillation, for removing unconverted isobutene and/or an inert diluent.

Abstract: A process for working up a liquid reaction discharge of the cationic polymerization of isobutene, which substantially comprises polyisobutene, unconverted isobutene and an inert diluent, in which the reaction discharge is heated and is let down into a flash container, is described, the reaction discharge separating, as a result of the flashing, into a polyisobutene-containing liquid phase and a gas phase containing the main amount of the isobutene contained in the reaction discharge and of the diluent.

Abstract: The invention relates to a method for deactivating and recovering boron trifluoride when producing polyisobutenes by means of cationic polymerization of isobutene or hydrocarbon streams containing isobutene in the liquid phase in the presence of boron trifluoride or in the form of a boron trifluoride catalyst complex. The catalyst complex is separated, essentially in the liquid phase, from the reactor discharge. The method comprises the following steps: a) removing from the polymerization reactor at ?60 to 020 C., methanol, ethanol or a mixture of methanol and ethanol in such a quantity that an alcohol phase rich in boron trifluoride is formed; b) separating the alcohol phase according to (a) and, (c) optionally recycling the boron trifluoride of the alcohol phase obtained from (b) to the method in a suitable manner.

Abstract: Polyisobutenes are prepared by cationic polymerization of isobutene or isobutene-containing hydrocarbon streams in the liquid phase in the presence of boron trifluoride as a catalyst, the catalytic activity of the boron trifluoride being partially or completely eliminated at a desired time by means of a solid deactivator, by a process in which the solid deactivator has boron trifluoride-binding primary, secondary, tertiary and/or quaternary nitrogen atoms and is insoluble in the reaction mixture.

Abstract: A polyisobutene composition having a global maximum of the differential molecular weight distribution curve at a molecular weight Mmax of from 3 500 to 8 000 is described, which comprises at least one local maximum at a molecular weight of from 112 to 560. The isobutene oligomers present act as flow improvers and boiling assistants. They are added to higher molecular weight isobutene polymers, preferably before or in the course of a distillation, for removing unconverted isobutene and/or an inert diluent.

Abstract: A process for working up a liquid reaction discharge of the cationic polymerization of isobutene, which substantially comprises polyisobutene, unconverted isobutene and an inert diluent, in which the reaction discharge is heated and is let down into a flash container, is described, the reaction discharge separating, as a result of the flashing, into a polyisobutene-containing liquid phase and a gas phase containing the main amount of the isobutene contained in the reaction discharge and of the diluent.

Abstract: A process for the preparation of polyisobutylenes by cationic polymerization of isobutylene or isobutylene-containing hydrocarbon streams in the liquid phase in the presence of boron trifluoride acting as catalyst, the catalytic activity of boron trifluoride being partially or completely stopped by means of a solid deactivator following a given timelapse, which deactivator is an inorganic, anhydrous or hydrous oxygen compound of aluminum which is insoluble in the reaction mixture.

Abstract: The invention relates to a method for deactivating and recovering boron trifluoride when producing polyisobutenes by means of cationic polymerisation of isobutene or hydrocarbon streams containing isobutene in the liquid phase in the presence of boron trifluoride or in the form of a boron trifluoride catalyst complex. Said catalyst complex is separated, essentially in the liquid phase, from the reactor discharge. Said method contains the following steps, a) removing from the polymerisation reactor at −60 to 0° C., methanol, ethanol or a mixture of methanol and ethanol in such a quantity that an alcohol phase rich in boron trifluoride is deposited b) separating the alcohol phase according to (a) and, (c) from the alcohol phase according to (b) is reintegrated into the inventive method in a suitable manner if desired.

Abstract: Polyisobutenes are prepared by cationic polymerization of isobutene or isobutene-containing hydrocarbon streams in the liquid phase in the presence of boron trifluoride as a catalyst, the catalytic activity of the boron trifluoride being partially or completely eliminated at a desired time by means of a solid deactivator, by a process in which the solid deactivator has boron trifluoride-binding primary, secondary, tertiary and/or quaternary nitrogen atoms and is insoluble in the reaction mixture.

Abstract: A process for the preparation of polyisobutylenes by cationic polymerization of isobutylene or isobutylene-containing hydrocarbon streams in the liquid phase in the presence of boron trifluoride acting as catalyst, the catalytic activity of boron trifluoride being partially or completely stopped by means of a solid deactivator following a given timelapse, which deactivator is an inorganic, anhydrous or hydrous oxygen compound of aluminum which is insoluble in the reaction mixture.

Abstract: A process for removing impurities from 3-(2′-acetoxyethyl)-dihydro-2(3H)-furanone (I), which comprises initially preparing the 3-(2′-acetoxyethyl)-dihydro-2(3H)-furanone containing the undesirable impurities in a manner known per se by acetylating 3-(2′-hydroxylethyl)-dihydro-2(3H)-furanone, subsequently treating it with strong mineral acids and finally removing the decomposition products of the undesirable impurities from I.

Abstract: Preparation of mixtures of O-phenoxyalkylhydroxylamines Ia and Ib ##STR1## and the corresponding salt mixtures by a) converting mixtures of isomers of O-(2-hydroxyethyl)oximes IIa and IIb ##STR2## with a sulfonyl halide III ##STR3## into a mixture of sulfonates IVa and IVb ##STR4## b) reacting this mixture of IVa and IVb with a phenol HO-Ar (V) to give a mixture of O-phenoxyalkoximes VIa and VIb ##STR5## c) hydrolyzing this mixture in the presence of an acid and, if desired d) liberating the O-phenoxyalkylhydroxylamines Ia and Ib from the resulting salts using a mineral acid.Compounds Ia/Ib and VIa/VIb are important intermediates for crop protection agents.

Abstract: A process for the preparation of tetrahydropyran-4-carboxylic acid and esters thereof of the general formula I ##STR1## in which R.sup.1 denotes hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.5 -C.sub.8 cycloalkyl, or aryl by the reaction of a dihydro-2(3H)furanone of the general formula II ##STR2## in which R.sup.2 denotes hydrogen, C.sub.1 -C.sub.6 alkyl, or --CO--R.sup.3 andR.sup.3 denotes hydrogen or C.sub.1 -C.sub.6 alkyl, with water or an alcohol of the general formula IIIR.sup.1 --OH (III),in whichR.sup.1 has the aforementioned meaning,at temperatures ranging from 200.degree. to 350.degree. C. in the presence of a heterogenous acid catalyst, in which use is made of a fixed heterogenous acid catalyst.