This invention relates to a catalyst system comprising a half sandwich chromocene compound featuring a tethered P-donor, with an activator and optional supportation on silica which produces ethylene homopolymer or copolymer.

Methods for preparing supported chromium catalysts containing a chromium (III) compound and an activator-support are disclosed. These supported chromium catalysts can be used in catalyst compositions for the polymerization of olefins to produce polymers having low levels of long chain branching, and with greater sensitivity to the presence of hydrogen during polymerization.

Methods for preparing supported chromium catalysts containing a chromium (III) compound and an activator-support are disclosed. These supported chromium catalysts can be used in catalyst compositions for the polymerization of olefins to produce polymers having low levels of long chain branching, and with greater sensitivity to the presence of hydrogen during polymerization.

Disclosed are methods for polymerizing olefin monomers comprising contacting one or more olefin monomers with a cosupported catalyst system and an activator. Also disclosed are polymers produced using the catalyst systems and methods disclosed herein. The polymers have a multimodal molecular weight distribution and may be produced in a single reactor.

Disclosed are methods for polymerizing olefin monomers comprising contacting one or more olefin monomers with a cosupported catalyst system and an activator. Also disclosed are polymers produced using the catalyst systems and methods disclosed herein. The polymers have a multimodal molecular weight distribution and may be produced in a single reactor.

A supported metallocene catalyst can include a silica-based carrier and an aluminum alkyl halide, a cocatalyst compound, and a metallocene compound supported in the silica-based carrier. The aluminum alkyl halide is supported at higher rate on the surface of the silica-based carrier than inside the pores, and the cocatalyst compound is supported at higher rate inside the pores of the silica-based carrier than on the surface of the silica-based carrier. Such a supported metallocene catalyst can be prepared by: (i) supporting an aluminum alkyl halide in a silica-based carrier; (ii) supporting a cocatalyst compound in the silica-based carrier in which the aluminum alkyl halide is supported; and (iii) supporting a metallocene compound in the carrier in which the aluminum alkyl halide and the cocatalyst compound are supported. Such a supported metallocene catalyst can be used to polymerize polyolefins with excellent activity and polyolefin with a uniform powder morphology.

An improved catalyst for cyclic olefin polymerization. The catalyst includes a transition metal carbene having the following structure: M.sup.v(OR).sub.c*mX.sub.(v-c*m-2)C(R*).sub.2 wherein M.sup.v is a Group 5 transition metal having a valence (v) of 5 or a Group 6 transition metal having a valence (v) of 5 or 6; each R is independently a monovalent organic moiety comprising from 8 to 40 atoms selected from Groups 14-17; c is an integer from 1 to 3; m is 1/3, 1/2, 1, 3/2, 2, 3, or 4 and c*mv2; X is a halogen; and each R* is independently H or a C.sub.1 to C.sub.7 alkyl. The catalyst is particularly useful for ring-opening metathesis polymerization (ROMP).