Abstract: A process for preparing a long chain branched polypropylene in presence of two metallocene-based active catalyst systems is provided. The polypropylene obtained therefrom has new molecular architecture and improved elasticity properties. The polypropylene is further characterized by new signals in its 13C NMR spectrum.

Abstract: A process for preparing a long chain branched polypropylene in presence of two metallocene-based active catalyst systems is provided. The polypropylene obtained therefrom has new molecular architecture and improved elasticity properties. The polypropylene is further characterized by new signals in its 13C NMR spectrum.

Abstract: The invention relates to a method for determining a parameter representative of the stability of an asphaltene-containing petroleum product, said petroleum product being an effluent derived from a hydrocarbon feedstock conversion process or being a mixture of hydrocarbons, using proton NMR to determine a threshold value of said parameter representative of the stability, this threshold value constituting a boundary between a stability domain and an instability domain of a petroleum product. According to the invention, the parameter representative of the stability is a T2mean/T1mean or T1mean/T2mean ratio. The invention also relates to a method for monitoring a conversion process, in particular a deep conversion process, or a mixture of hydrocarbons, using this method of determination.

Abstract: A process for preparing a long chain branched polypropylene in presence of two metallocene-based active catalyst systems is provided. The polypropylene obtained therefrom has new molecular architecture and improved elasticity properties. The polypropylene is further characterized by new signals in its 13C NMR spectrum.

Abstract: The present invention relates to a process for preparing silica-alumina carriers preferably under the form of extrudates. Further, the present invention also provides hydrogenation catalysts prepared thereof. These catalysts are used in an improved process for the reduction of the aromatic hydrocarbons content present in hydrocarbon streams.

Abstract: A process for producing a Ziegler-Natta catalyst, the process comprising reacting an organo magnesium compound with a halogenated compound to produce crystalline magnesium halide having an intense diffraction line in an x-ray spectrum thereof at lattice distance within the range of from 2.56 to 3.20 Angstroms and titanating the magnesium halide by mixing the magnesium halide with a titanium compound whereby the titanated magnesium halide hasp in an x-ray spectrum thereof, a halo appearing at a lattice distance within the range from 2.56 to 3.30 Angstroms.

Abstract: The present invention relates to a process for preparing silica-alumina carriers preferably under the form of extrudates. Further, the present invention also provides hydrogenation catalysts prepared thereof. These catalysts are used in an improved process for the reduction of the aromatic hydrocarbons content present in hydrocarbon streams.

Abstract: The present invention relates to a process for preparing silica-alumina carriers preferably under the form of extrudates. Further, the present invention also provides hydrogenation catalysts prepared thereof. These catalysts are used in an improved process for the reduction of the aromatic hydrocarbons content present in hydrocarbon streams.

Abstract: A process is disclosed for improving the yield in the production of high octane gasoline after naphtha reforming by utilizing a transalkylation step to upgrade the heavy and light fractions coming from the reforming step.

Abstract: A process for producing a Ziegler-Natta catalyst, the process comprising reacting an organo magnesium compound with a halogenated compound to produce crystalline magnesium halide having an intense diffraction line in an x-ray spectrum thereof at lattice distance within the range of from 2.56 to 3.20 Angstroms and titanating the magnesium halide by mixing the magnesium halide with a titanium compound whereby the titanated magnesium halide hasp in an x-ray spectrum thereof, a halo appearing at a lattice distance within the range from 2.56 to 3.30 Angstroms.

Abstract: Silicalite to be used as catalyst in the isomerization of olefins is pretreated by passing steam thereon at a temperature of 300 to 750.degree. C. Particularly, isobutene is selectively produced by isomerization of n-butenes.

Abstract: Medium-chain olefins containing as impurities 2-alkyl substituted isomers having a close boiling point are purified by (i) passing over a solid acid catalyst under mild conditions to selectively double-bond isomerise said impurities, and (ii) separating said isomerised olefins by distillation.