Hiroyoshi Nakajima

Propylene polymerization using various metal-containing MCM-41 as cocatalyst

Polymerizations of propylene were conducted with rac -ethylene(bisindenyl)zirconium dichloride ( rac -Et(Ind) 2 ZrCl 2 ) with triisobutylaluminum (Al( i -C 4 H 9 ) 3 ) using various metal-containing MCM-41(Metal-MCM-41). The catalyst system gave selectively isotactic polypropylene. The order of the cocatalytic activity of Metal-MCM-41 (Si/Metal=ca. 13) was as follows: GaMCM-41>ZnMCM-41>AlMCM-41≫TiMCM-41. The linear relationship between the polymer yield and the number of strong Lewis acid sites was observed. This strongly suggests that not weak Lewis acid sites but strong Lewis acid sites generated on Metal-MCM-41 can activate the metallocene compound effectively, resulting in the formation of active sites for propylene polymerization.

Isospecific polymerization of propylene with Metal-MCM-41

Abstract Polymerizations of propylene were conducted using various Metal-MCM-41 prepared by the post-synthesis method. Ti-, Zr-, Hf-, Mn- and Zn-MCM-41 combined with alkylaluminiums were found to give isotactic polypropylenes with wide molecular mass distributions.

Propylene polymerization behavior of Ti-containing mesoporous silicas

Ti-containing mesoporous silicas (Ti-MCM-41, Ti-MCM-48 and Ti-SBA-15) were prepared by the post-synthesis with Ti(OC 4 H 9 ) 4 and their propylene polymerization behavior was investigated. It was found that these Ti-containing mesoporous silicas combined with Al( i -C 4 H 9 ) 3 provide the isotactic polypropylene. Polypropylenes outside and inside the mesopores of Ti-containing mesoporous silicas had different characteristics despite being polymerized concurrently. The crystallization of polypropylenes confined in the mesopores was considerably depressed due to the limited space.