Journal of Molecular Catalysis A: Chemical

Autor: Basso, Nara Regina de Souza, Greco, Paula P., Carone, Carlos L. P., Livotto, Paolo R., Simplício, Lílian M. T., Rocha, Zênis N. da, Galland, Griselda B., Santos, João Henrique Zimnoch dos
Jazyk: angličtina
Rok vydání: 2007
Předmět:
Zdroj: Repositório Institucional da UFBA
Universidade Federal da Bahia (UFBA)
instacron:UFBA
ISSN: 1381-1169
DOI: 10.1016/j.molcata.2006.11.027
Popis: Texto completo: acesso restrito. p. 129-136 Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2014-01-28T17:04:33Z No. of bitstreams: 1 1-s2.0-S1381116906013859-main.pdf: 792382 bytes, checksum: ea828a8616f7f3346df0f8ed180dda1d (MD5) Made available in DSpace on 2014-01-28T17:04:33Z (GMT). No. of bitstreams: 1 1-s2.0-S1381116906013859-main.pdf: 792382 bytes, checksum: ea828a8616f7f3346df0f8ed180dda1d (MD5) Previous issue date: 2007 The catalyst activity of zirconium and titanium complexes bearing bidentade ligands was evaluated in ethylene polymerization at different experimental conditions with methylaluminoxane (MAO) as the cocatalyst. The best activity was achieved for dichlorobis(3-hydroxy-2-methyl-4-pyrone)zirconium(IV) at Al/Zr = 2500 at 60 °C. Conversely, dichlorobis(3-hydroxy-2-methyl-4-pyrone)titanium(IV) exhibited a higher catalyst activity at lower Al/Ti ratio and temperature. According to 1H NMR analysis, two stereoisomers are present for the zirconium complex. Electrochemical analyses evidenced a higher stability in the reduction of Zr(IV) in comparison to the analogous Ti(IV) complex. The cyclic voltammogram of the Ti complex in the presence of MAO and ethylene shows a potential shift to lower values, suggesting the formation of the Ti cationic species, which might be stabilized by ClMAO−. For the Zr complex in the presence of MAO, stabilization of the active species takes place only in the presence of an ethylene atmosphere.
Databáze: OpenAIRE
Externí odkaz: