Abstract: Process for preparing polyolefins having high molecular weights in the presence of a catalyst comprising an organic transition metal compound in a gas-phase fluidized-bed reactor, where the polyolefins prepared have a melt flow rate at 2.16 kg and 190° C. in accordance with ISO 1133 of less than 4 g/10 min. According to the present invention, a start-up phase during which a polyolefin having an increased melt flow rate of above 4 g/10 min is produced for a transitional period is provided. In this way, trouble-free start-up of the reactor is ensured even in the case of polymer products having a high molecular weight and a melt flow rate below 4 g/10 min and even when using catalysts based on organic transition metal compounds, in particular metallocene catalysts.

Abstract: The present invention relates to organometallic transition metal compounds of the formula (I) Z1AnZ2MXm??(I) where Z1 is a coordinating group which comprises a six-?-electron central group which coordinates directly to M, A is a divalent bridge between the groups Z1 and Z2, Z2 is a coordinating group having the same meaning as Z1 or is a group comprising an open pentadienyl, a cyclopentadienyl-containing group or a heterocyclic, 5- or 6-membered group containing six ? electrons, n=zero or 1, M is an element of group 3, 4, 5 or 6 of the Periodic Table of the Elements, the radicals X are identical or different and are each an organic or inorganic radical, m is 0, 1 or 2, and at least one of the three molecule fragments Z1, Z2 and A bears a monovalent organic radical.

Abstract: A process for producing a polymer of ethylene containing from 0.1 to 50% by weight of one or more derived units of alpha-olefins fo formula CH2?CHR, wherein R is a C2-C20 alkyl radical, comprising contacting, under polymerization conditions, ethylene and one or more alpha-olefins in the presence of a catalyst system obtainable by contacting: a) a metallocene compound of formula (I) wherein: M is zirconium titanium or hafminum, X, equal to or different from each other, is hydrogen halogen or an hydrocarbyl radical, R1, R2, R3, R4, R5, R6, R7, R8 and R9, equal to or different from each other are hydrogen atoms, halogen atoms, or hydrocarbyl radicals; and b) an alumoxane or a compound capable of forming an alkyl metallocene cation.

Abstract: The present invention relates to organometallic transition metal compounds of the formula (I) Z1AnZ2MXm??(I) where Z1 is a coordinating group which comprises a six-?-electron central group which coordinates directly to M, A is a divalent bridge between the groups Z1 and Z2, Z2 is a coordinating group having the same meaning as Z1 or is a group comprising an open pentadienyl, a cyclopentadienyl-containing group or a heterocyclic, 5- or 6-membered group containing six ? electrons, n=zero or 1, M is an element of group 3, 4, 5 or 6 of the Periodic Table of the Elements, the radicals X are identical or different and are each an organic or inorganic radical, m is 0, 1 or 2, and at least one of the three molecule fragments Z1, Z2 and A bears a monovalent organic radical.

Abstract: Metallocene having two cyclic dienyl groups connected by a single carbon having an aryl substituent and a terminally unsaturated hydrocarbyl substituent, olefin polymerization catalyst systems prepared therefrom, and the use of such catalyst systems are disclosed.

Abstract: A process for producing a polymer of ethylene containing from 0.1 to 50% by weight of one or more derived units of alpha-olefins fo formula CH2?CHR, wherein R is a C2-C20 alkyl radical, comprising contacting, under ploymerization conditions, ethylene and one or more alpha-olefins in the presence of a catalyst system obtainable by contacting: a) a metallocene compound of formula (I) wherein: is zirconium titanium or hafminum, X, equal to or different from each other, is hydrogen halogen or an hydrocarbyl radical, R1, R2, R3, R4, R5, R6, R7, R8 and R9, equal to or different from each other are hydrogen atoms, halogen atoms, or hydrocarbyl radicals; and b) an alumoxane or a compound capable of forming an alkyl metallocene cation.

Abstract: Metallocene having two cyclic dienyl groups connected by a single carbon having an aryl substituent and a terminally unsaturated hydrocarbyl substituent, olefin polymerization catalyst systems prepared therefrom, and the use of such catalyst systems are disclosed.

Abstract: Metallocenes having a 9-fluorenyl group and another cyclic dienyl group connected by a single carbon having a terminally unsaturated hydrocarbyl substituent wherein the 9-fluorenyl group has a hydrocarbyl substituent in the 4 position, olefin polymerization catalyst systems prepared therefrom, and the use of such catalyst systems are disclosed.

Abstract: The invention relates to particles comprises of organopolysiloxane microgel particles having a diameter of 5 to 200 nm and organo-aluminum compounds immobilized thereon. The particles can be used as cocatalysts together with metal compounds of the 4, 5, 6 and 8-10 sub-groups of the periodic table for oligomerization, cyclization of polymerization of olefins.

Abstract: Metallocenes having a 9-fluorenyl group and another cyclic dienyl group connected by a single carbon having a terminally unsaturated hydrocarbyl substituent wherein the 9-fluorenyl group has a hydrocarbyl substituent in the 4 position, olefin polymerization catalyst systems prepared therefrom, and the use of such catalyst systems are disclosed.

Abstract: A solid cocatalyst is prepared by reacting a suitable support base with an organoaluminum compound and then reacting that product with an activity promoting amount of water. The solid cocatalyst can be combined with a polymerization catalyst to form a catalyst system useful for the polymerization of olefins.

Abstract: Metallocene having two cyclic dienyl groups connected by a single carbon having an aryl substituent and a terminally unsaturated hydrocarbyl substituent, olefin polymerization catalyst systems prepared therefrom, and the use of such catalyst systems are disclosed.