Activation of Titanium-Based Single-Site Catalysts for Ethylene Polymerization Using Supports of Type MgCl2/AlRn(OEt)3–n

✍ Scribed by John R. Severn; John C. Chadwick

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 158 KB
• Volume: 205
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200400270

✦ Synopsis

Abstract

Summary: Easy and effective immobilization and activation of a range of Ti‐based single‐site catalysts for ethylene polymerization has been achieved, without methylaluminoxane or borate activators, using MgCl~2~/AlR~n~(OEt)~3–n~ supports obtained by reaction of AlR~3~ with adducts of magnesium chloride and ethanol. The use of relatively low catalyst loadings leads to efficient uptake by the support and gives high catalyst activity. Catalyst immobilization using these MgCl~2~‐based supports also leads to stable polymerization kinetics, with negligible decay in catalyst activity during polymerization. Metallocene, half‐metallocene, and non‐metallocene catalysts have been used, particularly high activities being obtained using cyclopentadienyl titanium trichloride and its analogues. The polyethylenes obtained have narrow molecular weight distribution, with $\overline M _{\rm w} /\overline M _{\rm n}$ generally in the range 2–3, indicating retention of single‐site catalyst characteristics after immobilization. Spherical polymer particle morphology was achieved, without reactor fouling.

Temperature profile of ethylene polymerization using [(Indenyl)TiCl~3~] immobilized on a MgCl~2~/AlEt~n~(OEt)~3–n~ support (▴: internal temperature; ▪: cooling mantle temperature).

magnified imageTemperature profile of ethylene polymerization using [(Indenyl)TiCl~3~] immobilized on a MgCl~2~/AlEt~n~(OEt)~3–n~ support (▴: internal temperature; ▪: cooling mantle temperature).