X-RAY-ABSORPTION STUDIES OF SUPPORTED CHROMOCENE ETHYLENE POLYMERIZATION CATALYSTS

We studied the structure of two supported chromocene high density poly ethylene catalysts, CrCp2/SiO2 and CrCp2 /AlPO4, by means of X-ray abs orption spectroscopy using synchrotron radiation. Here Cp stands for t he cyclopentadienyl group. Our results indicate that the Cr surface sp ecies of the CrCp2/SiO2 and CrCp2/AlPO4 catalysts have similar structu res around the Cr atoms regardless of the different supports. When chr omocene is supported, CrCP2 loses one Cp group and anchors to the supp ort through two Cr-O-Si (in the case of CrCp2/SiO2) or Cr-O-P (in the case of CrCP2/AlPO4) bridges.