| abstract |
The invention relates to a process for producing an ethylene polymer comprising: contacting ethylene with a catalyst system, comprising: silylchromate, a silica-containing support, dehydrated at 400 to 860°C, comprising silica selected from silica having: (a) a pore volume of 1.1 to 1.8 cm 3 /g and a surface area of 245 to 375 m 2 /g, (b) a pore volume of about 2.4 to 3.7 cm 3 /g and a surface area of 410 to 620 m 2 /g, and (c) a pore volume of 0.9 to 1.4 cm 3 /g and a surface area of about 390 to 590 m 2 /g; and an alkyl aluminum alkoxide compound; and adding an alkyl aluminum compound to the polymerization reactor in an amount to effect a final ratio of equivalents of aluminum to equivalents of chromium of from 0.1:1 to 10:1. |