Abstract: The present invention provides new catalyst compositions, methods of preparing a catalyst composition, and methods for polymerizing ethylene and other olefins. In one aspect, a catalyst composition comprising an ion-exchangable support such as a pillared clay; a transition metal compound in which the metal has a dn electron configuration, wherein n is greater than or equal to 4 and less than or equal to 8; and an organometal cocatalyst is disclosed.

Abstract: A catalyst system composition comprising a chromium compound supported on a silica-titania support, wherein said catalyst system has been reduced with carbon monoxide, and a cocatalyst selected from the group consisting of i) alkyl lithium compounds, ii) dialkyl aluminum alkoxides in combination with at least one metal alkyl selected from the group consisting of alkyl zinc compounds, alkyl aluminum compounds, alkyl boron compounds, and mixtures thereof and iii) mixtures thereof can be used to polymerize olefins to produce a low density polymer with a decreased melt index and/or high load melt index. This catalyst system also can be used with a Ziegler-Natta catalyst system to polymerize olefins. Polymerization processes using these catalyst system compositions are also provided.

Abstract: A catalyst system composition comprising a chromium compound supported on a silica-titania support, wherein said catalyst system has been reduced with carbon monoxide, and a cocatalyst selected from the group consisting of i) alkyl lithium compounds, ii) dialkyl aluminum alkoxides in combination with at least one metal alkyl selected from the group consisting of alkyl zinc compounds, alkyl aluminum compounds, alkyl boron compounds, and mixtures thereof and iii) mixtures thereof can be used to polymerize olefins to produce a low density polymer with a decreased melt index and/or high load melt index. This catalyst system also can be used with a Ziegler-Natta catalyst system to polymerize olefins. Polymerization processes using these catalyst system compositions are also provided.