Supported hafnium and titanium catalysts were prepared under the same conditions starting from the corresponding tetrakisbutanolates, which were supported on MgCl2 by reaction of a suspension of Hf/Mg catalyst with aluminum alkyl chlorides. The systems were employed in the copolymerization of 1-hexene with 4-methyl-1-pentene. The extent of polymerization, as well as the copolymer composition, sequence distribution, stereoregularity, and molecular weight were evaluated. The hafnium catalysts gave higher molecular weights and better isotactic stereoregularity but displayed lower activity than the titanium catalysts, but the co-monomer distributions were similar for the two systems. These results are discussed in terms of the number and type of active sites.
Comparative behaviour of Hafnium and Titanium catalysts in the a-olefins copolymerization
ALTOMARE, ANGELINA;SOLARO, ROBERTO;CIARDELLI, FRANCESCO;
1991
Abstract
Supported hafnium and titanium catalysts were prepared under the same conditions starting from the corresponding tetrakisbutanolates, which were supported on MgCl2 by reaction of a suspension of Hf/Mg catalyst with aluminum alkyl chlorides. The systems were employed in the copolymerization of 1-hexene with 4-methyl-1-pentene. The extent of polymerization, as well as the copolymer composition, sequence distribution, stereoregularity, and molecular weight were evaluated. The hafnium catalysts gave higher molecular weights and better isotactic stereoregularity but displayed lower activity than the titanium catalysts, but the co-monomer distributions were similar for the two systems. These results are discussed in terms of the number and type of active sites.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
