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-t Bu-6-R-C6 H2 O)2]TiCl2(R1 = CMe3,R2 = CPhMe2,R3 = CPh2 Me,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℃,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 charac-terized and analyzed by gel chromatogram phy(GPC).The four catalysts under different reaction condi-tions 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-t Bu-6-CMePh2-C6 H2 O)2]TiCl2 catalyst at 50℃was up to6.7×106 g PE/(mol Ti·h),and the obtained polyolefin product MW was 1.68×105,with a molecular weight distribution of 3.2.
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维普
