Catalizzatori di Phillips Cr/SiO2: influenza del supporto SiO2 sulle proprietà dei siti attivi e sulle proprietà catalitiche​

The Phillips supported chromium catalyst is used to produce 4050% of the worlds high-density polyethylene. In contrast to its great commercial success, the chemistry of this system has not been fully understood yet. The structure and porosity of Cr/silica catalysts has been shown to have a strong influence on ethylene polymerization and on the character of the polymer. In this study, the effect of varying physical structure on the catalyst chemistry and on the produced polymer has been investigated by analyzing four different supports. In the first part of the work the academic progress on this subject is reviewed. Then, the catalyst synthesis and activation is described along with a description of the instruments which were used to obtain the data. The second section consists of spectroscopical studies(IR, UV-vis) of the catalyst and of their interaction with probe molecules. The polymer production was achieved in the CPE Lyon laboratories and a brief history of the various trials in a more industrial-like enviroment is also provided. In the end, kinetic data for a low pressure reaction and the resulting polymer analysis(SEC,DSC) are presented.​