Reactor systems, reactor coolant systems, and associated processes for polymerizing polyolefins are described. The reactor systems generally include a reactor pipe and a coolant system, in which the coolant system includes a jacket pipe surrounding at least a portion of the reactor pipe to form an annulus therebetween, at least one spacer coupling the jacket to the reactor pipe, and a coolant which flows through the annulus to remove heat from the reactor pipe. At least one of the external surface of the reactor pipe, the internal surface of the jacket, and at least one spacer, are independently modified, for example by polishing, coating, or reshaping, to reduce the fluid resistance of the coolant flow through the annulus.

Reactor systems, reactor coolant systems, and associated processes for polymerizing polyolefins are described. The reactor systems generally include a reactor pipe and a coolant system, in which the coolant system includes a jacket pipe surrounding at least a portion of the reactor pipe to form an annulus therebetween, at least one spacer coupling the jacket to the reactor pipe, and a coolant which flows through the annulus to remove heat from the reactor pipe. At least one of the external surface of the reactor pipe, the internal surface of the jacket, and at least one spacer, are independently modified, for example by polishing, coating, or reshaping, to reduce the fluid resistance of the coolant flow through the annulus.

The present disclosure relates to dual-headed organoaluminum compositions having the formula (I) and processes to prepare the same. In at least one aspect, the compositions having the formula (I) may be used during olefin polymerization.

The present disclosure relates to dual-headed organoaluminum compositions having the formula (I) and processes to prepare the same. In at least one aspect, the compositions having the formula (I) may be used during olefin polymerization.

The present disclosure relates to dual-headed organoaluminum compositions having the formula (I) and processes to prepare the same. In at least one aspect, the compositions having the formula (I) may be used during olefin polymerization.

A process for producing an olefin polymer employs a gas phase polymerization reactor having a product discharge system comprising first and second pairs of lock hoppers, wherein each pair comprises an upstream lock hopper connected by valve means to the reactor and a downstream lock hopper connected by valve means to the upstream lock hopper and by further valve means to a product recovery system, and wherein a first cross-tie is provided between the upstream lock hoppers of the first and second pairs of lock hoppers and a second cross-tie is provided between the downstream lock hoppers of the first and second pairs of lock hoppers. Operation of the second cross-tie during product removal cycles is controlled in accordance with reactor pressure.

Cyclic organosilicon compounds having a structure represented by the general formula ##STR00001##
and a method for using thereof as a component of catalysts for producing propylene polymer having a very high melt-flowability are disclosed. The cyclic organosilicon compounds are employed as external electron donors in Ziegler-Natta catalyst systems to dramatically improve the hydrogen response, and therefore the catalyst systems can be used to prepare polymer having high melt-flowability and high isotacticity at high yield.

Cyclic organosilicon compounds having a structure represented by the general formula ##STR00001##
and a method for using thereof as a component of catalysts for producing propylene polymer having a very high melt-flowability are disclosed. The cyclic organosilicon compounds are employed as external electron donors in Ziegler-Natta catalyst systems to dramatically improve the hydrogen response, and therefore the catalyst systems can be used to prepare polymer having high melt-flowability and high isotacticity at high yield.

Cyclic organosilicon compounds having a structure represented by the general formula ##STR00001##
and a method for using thereof as a component of catalysts for producing propylene polymer having a very high melt-flowability are disclosed. The cyclic organosilicon compounds are employed as external electron donors in Ziegler-Natta catalyst systems to dramatically improve the hydrogen response, and therefore the catalyst systems can be used to prepare polymer having high melt-flowability and high isotacticity at high yield.

The present invention relates to a novel ligand compound, a transition metal compound and a catalyst composition comprising the same. The novel ligand compound and the transition metal compound of the present invention may be useful as a catalyst of polymerization reaction for preparing an olefin-based polymer having a low density.