Preparation of LLDPE through tandem ethylene polymerization using novel chromium catalyst

Tandem ethylene polymerization to preparation of LLDPE has been done by using a system based on two Catalysts: a highly selective, aluminoxane-activated SBA-15-lig/CrCl3 catalyst (catalyst 1) for the trimerization of ethylene to 1-hexene and Philips polymerization catalyst (catalyst 2 that was supported on SiO2), for the same time copolymerization of ethylene and 1-hexene. The tandem action was carried out at ethylene pressure 23 bar, temperature of 90 oC and in the presence of methylaluminoxane (MAO) as a cocatalyst in n-hexane as solvent. The effect of Cr/Al molar ratio for Phillips and trimerization catalysts on the activity were examined. Analysis by means of DSC and 1H-NMR suggests that copolymer of 1-hexene. DSC curve shows the decrease in the crystalinity of the structure which revealed the copolymer formation. 1H NMR analysis shows that the synthesized polymer was branched.

Keywords:

Ethylene-Trimerization , Philips Catalyst , Tandem-LLDPE