Abstract: A screw compressor includes a first rotor and a second rotor, and each rotor is provided with a synchronisation gear. The screw compressor is further provided with an electric motor and one or two driving gears for driving the first rotor or second rotor. At least one of the synchronisation gears or driving gears is provided with spokes between a rim supporting a gear mesh and a corresponding gear hub.

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 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 motor vehicle exhaust emission control system has two adsorber parts connected in parallel for alternate adsorption and desorption of nitrogen oxides contained in the exhaust from an internal combustion engine and components for conducting further downstream the exhaust that emerges in the adsorber part that is operating at any given time in the adsorption mode and for returning the exhaust that emerges from the other adsorber part that is then operating in the desorption mode, to an intake line of the engine. An oxidizing converter is located upstream of the adsorber part and near the engine for oxidation of the NO contained in the exhaust to form NO.sub.2, so as to permit an increase in the NO.sub.X adsorption rate for the nitrogen adsorber parts.