Patent ID: 8637616

Claim:
A catalyst composition comprising: (i) an activator-support comprising a solid oxide treated with an electron-withdrawing anion; and (ii) an ansa-metallocene compound having formula (I): E(Cp A R A m )(Cp B R B n )MX q (I), wherein: an activity of the catalyst composition in an ethylene/α-olefin polymerization is substantially constant over a range of from about 100 ppm to about 500 ppm added hydrogen under slurry polymerization conditions, using isobutane as a diluent, with a polymerization temperature of 90° C., and a reaction pressure of 390 psig; M is Ti, Zr, Hf, Cr, Sc, Y, La, or a lanthanide; Cp A and Cp B independently are a cyclopentadienyl, indenyl, or fluorenyl group; each R A and R B independently is a hydrocarbyl, hydrocarbylsilyl, hydrocarbylamino, or hydrocarbyloxide group having up to 18 carbon atoms; E is a bridging chain of 3 to 8 carbon atoms or 2 to 8 silicon, germanium, or tin atoms, wherein any substituents on atoms of the bridging chain independently are H or a hydrocarbyl group having up to 18 carbon atoms; each X independently is F; Cl; Br; I; methyl; benzyl; phenyl; H; BH 4 ; OBR 2 or SO 3 R, wherein R is an alkyl or aryl group having up to 18 carbon atoms; or a hydrocarbyloxide group, a hydrocarbylamino group, or a hydrocarbylsilyl group, any of which having up to 18 carbon atoms; m is 0, 1, 2, 3, or 4; n is 0, 1, 2, 3, or 4; q is 2 when M is Ti, Zr, or Hf; and q is 1 when M is Cr, Sc, Y, La, or a lanthanide.