Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Correlation between catalyst surface structure and polypropylene tacticityin Ziegler-Natta polymerization system
Autore:
Kim, SH; Somorjai, GA;
Indirizzi:
Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA Univ Calif Berkeley Berkeley CA USA 94720 pt Chem, Berkeley, CA 94720 USA Lawrence Berkeley Lab, Div Mat Sci, Berkeley, CA 94720 USA Lawrence Berkeley Lab Berkeley CA USA 94720 t Sci, Berkeley, CA 94720 USA
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 18, volume: 105, anno: 2001,
pagine: 3922 - 3927
SICI:
1520-6106(20010510)105:18<3922:CBCSSA>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
ELECTRON-PARAMAGNETIC RESONANCE; OLEFIN POLYMERIZATION; MOLECULAR-WEIGHT; MECHANICAL-PROPERTIES; TITANIUM CHLORIDE; OXIDATION-STATES; SPIN-RESONANCE; ACTIVE-SITES; THIN-FILMS; GROWTH;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
47
Recensione:
Indirizzi per estratti:
Indirizzo: Somorjai, GA Univ Calif Berkeley, Dept Chem, Berkeley, CA 94720 USA Univ Calif Berkeley Berkeley CA USA 94720 eley, CA 94720 USA
Citazione:
S.H. Kim e G.A. Somorjai, "Correlation between catalyst surface structure and polypropylene tacticityin Ziegler-Natta polymerization system", J PHYS CH B, 105(18), 2001, pp. 3922-3927

Abstract

correlation between the surface structure of the Ziegler-Natta catalysts and the stereospecificity in propylene polymerization was shown experimentally using model catalysts and temperature-programmed desorption (TPD) of mesitylene as a nondestructive surface probe. Two types of titanium chloride model catalysts, with MgCl2 support (TiClx/MgCl2) and without MgCl2 (TiCly),were fabricated on an Au substrate in ultrahigh vacuum. Once activated with AIEt(3) vapor, both catalysts were active for propylene polymerization inthe absence of excess ALEt(3) during polymerization. The TiClx/MgCl2 catalyst produced both atactic and isotactic polypropylene, while the TiCly catalyst without the MgCl2 support produced exclusively isotactic polypropylene. For the same catalysts, the mesitylene TPD revealed that TiClx/MgCl2 had two adsorption site structures, a basal plane structure and a nonbasal plane structure, while TICly had only the latter structure. To our knowledge, this was the first direct experimental evidence revealing the structural difference of the catalyst surfaces that exhibit different stereospecificity in propylene polymerization.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 13/08/20 alle ore 13:23:37