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Supported propene polymerization catalysts, 2. Supports derived from dialkylmagnesium/dibutyl butylphosphonate complexes

1989; Wiley; Volume: 190; Issue: 9 Linguagem: Inglês

10.1002/macp.1989.021900901

0025-116X

Nicholas M. Karayannis, John S. Skryantz, Bryce V. Johnson, Charles R. Hoppin, Habet M. Khelghatian,

Organometallic Complex Synthesis and Catalysis

Abstract Following the earlier development of highly active supported propene polymerization catalysts prepared by activating supports derived from Mg dialkyl complexes with the rare and very expensive ethyl esters of 2,6‐dimethyl‐ ( 1 ) or 2,4,6‐trimethylbenzoic acid ( 2 ), research was undertaken to uncover low‐cost and commercially available substitutes for 1 and 2 . Several phosphonate, phosphate, and phosphite alkyl esters, as well as ethers and amines, were investigated. Dibutyl butylphosphonate ( 5b ) adducts with Mg dialkyl were found to produce catalysts with comparable activity, improved, narrower particle size distribution, and only slightly lower stereospecificity and polymer powder bulk density relative to catalysts made using MgR 2 adducts with 1 or 2 as starting materials (R = n ‐C 4 H 9 ). Optimized catalysts based on MgR 2 · 5b adducts, prepared by precipitating the support by reaction of a solution of the adduct with SiCl 4 and subsequent activation by treatment of the support with TiCl 4 and diisobutyl phthalate in chlorobenzene, realize yields of 16–17 kg polypropylene/g catalyst in 2‐h hexane slurry polymerizations at 70°C, 10,2 atm, with 1,2–1,5 wt.‐% boiling hexane extractables and 0,40–0,41 g/ml polymer powder bulk density. The cocatalyst‐external modifier package used consists of Al(C 2 H 5 ) 3 ‐dimethoxydiphenylsilane. The narrow particle size distribution of the polymer powder produced renders the new catalysts suitable for use in both slurry and solventless propene polymerization processes, while the low cost and ready availability of 5b make the catalyst preparation commercially feasible.