Study on the catalytic performance of hydroxy ortho-tridentate [OSO] bisphenol titanium complex catalyst for ethylene polymerization.

Four kinds of tridentate [OSO] bisphenol titanium complex catalysts [S (2-CH2-4-tBu-6-R-C6H2O)2]TiCl2(R1 = CMe3, R2 = CPhMe2, R3 = CPh2Me, R4 = CPh3) were prepared from 4-tert-butyl phenol through bromination, nucleophilic substitution and metal complexation reaction by changing the ortho-substituent of hydroxyl. The reaction performance of ethylene polymerization was investigated under the conditions of 30, 50, 70 °C, and pressure of 0.6 MPa. Polyolefin products under different conditions were obtained by changing the Al/Ti ratio of the catalyst and the reaction time. The products were characterized and analyzed by gel chromatogram phy (GPC). The four catalysts under different reaction conditions were compared. Due to the effect of R group steric hindrance, the larger the steric hindrance, the higher the activity of the catalyst. Based on the experimental results, it was concluded that the activity of the [S(2-CH2-4-tBu-6-CMePh2-C6H2O)2]TiCl2 catalyst at 50 °C was up to 6.7 x 106 g PE/(mol Ti ⋅ h), and the obtained polyolefin product Mw was 1.68 x 105, with a molecular weight distribution of 3.2. [ABSTRACT FROM AUTHOR]