| 摘要 |
<p>The invention provides a process for the preparation of a polyethylene, which comprises polymerizing ethylene and, optionally an ethylenically unsaturated comonomer copolymerizable therewith, in the presence of a catalyst comprising a first silica-supported chromium catalyst having a pore volume of at least 2 mL/g, a surface area of at least 350 m2/g and a chromium content of 0.1 to 1.0 % by weight and a second silica-supported chromium catalyst having a pore volume of at least 2 mL/g, a surface area of at least 450 m2/g and a chromium content of 0.1 to 1.0 % by weight, wherein the silica support of said first catalyst also comprises alumina and the silica support of said second catalyst also comprises titanium, and preferably a co-catalyst.</p> |
