Abstract: Multimodal high-density ethylene polymers or copolymers (HDPE) of broad molecular weight distribution suitable for blow-molding and films are prepared with a chromium oxide catalyst mixed with a MgO-supported Ziegler catalyst, modified with an alkene and with alkyl aluminum hydride, and with an MgO additive.

Abstract: A blend for blown film which exhibits improved MD/TD tear balance. The blend is a bimodal molecular weight ethylene resin containing two fractions of different molecular weight. The weight fraction of a higher molecular weight component of the blend is about 0.35 to 0.75.

Abstract: A modified supported catalyst composition for polymerizing olefins, particularly alpha-olefins, for example, ethylene or ethylene and 1-hexane, is prepared by combining a chromium compound-containing catalyst with a modifier which is an oxide of an element of Group IIIA of the Periodic Table of the Elements. The modifier contains a small quantity of water. The resulting modified catalyst composition produces polymer resins having higher values of High Load Melt Index -HLMI (I.sub.21) than catalyst compositions without the modifier.There is also disclosed a process for polymerizing olefins, at relatively lower temperatures than was heretofore possible, to obtain resins of relatively high HLMI, using the above-identified modified catalyst composition. The resulting polymers can be used for the fabrication of blow-molded products, e.g., household and industrial containers.

Abstract: A method for regenerating a spent porous crystalline catalyst, optionally associated with a metal component such as noble and/or base metal(s), is described. The method comprises contacting the spent catalyst which has become deactivated by accumulation of carbonaceous residue with one or more light aromatic compounds under conditions resulting in reactivation of said catalyst. The light aromatic compounds employed are ones which have the capability of penetrating the catalyst, so as to contact the carbonaceous residue contained therein, undergoing alkylation by alkyl fragments contributed by components of the carbonaceous residue and diffusing from or otherwise escaping the catalyst.