Preparation of 1,3,5-tribenzylhexahydro-1,3,5-triazine-CrCl3 catalyst supported on SiO2 and activity studies in ethylene polymerization

In the present work, 1,3,5-tribenzylhexahydro-1,3,5-triazine-CrCl₃ (TAC-CrCl₃) complex was supported on Stöber silica and on commercial porous SiO₂. Ethylene polymerization and copolymerization were carried with methylaluminoxane (MAO) as co-catalyst. In the polymerization of ethylene, the silica-supported TAC-CrCl₃ catalysts exhibit activity values from 200 to 374 kg/molCr/h with Stöber silica being the best. In the co-polymerization of ethylene with 1-hexene, the yields of polymer are 34–117 kg/molCr/h; the highest value is again obtained with Stöber silica as a support. The polymers were characterized by X-ray diffraction, solid-state ¹³C NMR, viscosimetric analysis and differential scanning calorimeter (DSC). The polymers have molecular weights of 23,000–40,000 g/mol; crystallinity varies from 60 to 68% and melting points in the range 125–131 °C.