AN FTIR SPECTROSCOPIC VIEW OF THE INITIATION OF ETHYLENE POLYMERIZATION ON CR/SIO2 CATALYST

The onset of polymerization of ethylene on Cr/SiO2 catalyst activated by high-temperature treatment was studied at room temperature using fast-scanning FTIR spectral measurements. Initial rapid adsorption of molecular ethylene on the pre-activated catalyst preceded the onset of polymerization. A time-delay between adsorption and polymerization was observed. The experimental evidence suggests that initiation of polymerization follows dissociation of ethylene, presumably on two Cr sites. Propagation and other mechanistic steps then follow as suggested earlier. © 1992.