Ethylene polymerization catalysis over chromium oxide

✍ Scribed by Hogan, J. P.

• Book ID: 104535457
• Publisher: Wiley (John Wiley & Sons)
• Year: 1970
• Tongue: English
• Weight: 833 KB
• Volume: 8
• Category: Article
• ISSN: 0449-296X
• DOI: 10.1002/pol.1970.150080929

✦ Synopsis

Abstract

A study of the nature of polymerization catalysis over CrO~3~–silica and of the nature of the polyethylene obtained is presented. A fixed surface chromate (or possibly dichromate) species was shown to be activated for polymerization by an oxidation–reduction reaction with the monomer or with other reactive compounds such as CO. A change in catalyst color from orange to blue occurred simultaneously, and an indigoblue color was present only during ethylene addition, indicating involvement of Cr d orbitals. A spectacular chemiluminescence, due to excitation of oxygen, occurred when CO‐treated catalyst was exposed to air. Active site population and the rate at which each site produced polymer molecules were calculated. A reaction mechanism compatible with the experimental data is depicted.