IR study of the interaction of hydroxyl groups of silica gel with Cr species of Phillips' type catalysts
Abstract
Spectroscopic evidence for the interaction of hydroxyl groups and chromium ions was obtained using a catalyst prepared from chromyl chloride. A new OH peak, observed at 3705 cm−1 after pumping away CO gas, is attributed to the direct interaction of OH with the low-valent chromium. This peak shifts to 3590 cm−1 on contact with O2 at room temperature and it is assigned to a hydroxyl interacting with the oxidized chromium. New assignments are also proposed for IR bands of CO presorbed on the catalyst. The peak due to CO at 2188 cm−1 decreases as the OH intensity at 3705 cm−1 increases, suggesting that the former peak arises from adsorption on Cr(II) species to which two oxygen atoms are attached.
Keywords
Cr/SiO2 ethylene polymerization surface hydroxyl groups FTIR Phillips catalyst CO adsorptionPreview
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