The study of active centers of ethylene polymerization over chromium catalysts prepared from tri- and bivalent chromium compounds

摘要: Abstract The catalysts prepared from the trivalent and divalent chromium compounds under conditions that prevented their oxidation were investigated in reaction of ethylene polymerization. Also reduced chromia catalyst by standard method sexivalent compound was investigated. valence coordinate states ions determined EPR reflectance optical spectroscopy. In all cases, had a large activity; whereas no activity. reduction into state sharply decreased activity also reduction. It is concluded exposed Cr 3+ low coordination are responsible for catalytic catalysts.