Metallocene catalyst supported on chemically modified silica for production of ethylene–propylene copolymers

✍ Scribed by Mônica C Haag; Jairton Dupont; Fernanda C Stedile; João H.Z dos Santos

• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 296 KB
• Volume: 197
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(02)00625-8

✦ Synopsis

In the present work Et(IndH 4 ) 2 ZrCl 2 was immobilized on silica previously modified with different chemical compounds, namely VOCl 3 , SnCl 4 , Bu 3 SnH, Me 2 SiHCl, polymethylhydrosiloxane (PMHS) and such systems were compared to methylaluminoxane (MAO) pretreated systems. Bu 3 SnH-modified silica led to the highest zirconocene grafted content. Zr 3d 5/2 binding energy determined by X-ray spectroscopy (XPS) was shown to increase for Et(IndH 4 ) 2 ZrCl 2 supported on silica modified with VOCl 3 , MAO and Bu 3 SnH, suggesting the generation of more electron deficient surface species. All systems were shown to be active in ethylene-propylene copolymerization, presenting higher activity than those prepared by grafting the zirconocene on bare silica. Aging test with MAO-mediated systems showed that the catalyst bearing 2.0 wt.% Al/SiO 2 kept its catalyst activity at least for 3 months after preparation.