Design And Synthesis Of Dendritic Pnp Catalysts And The FT-IR Performance Of Ethylene Oligomerization

Series of dendritic PNP ligands were synthetized with 1.0G dendritic polyammidoamine(PAMAM)which used ethylamine,1-butylamine and1-hexylamine as cores and chlorodiphenylphosphine.Series of dendritic PNP chromium complexes were synthesized with chromium(?)chloride tetrahydrofuran complex as material in the paper.The structures of series of dendrimers and its correspongding chromium complexes were characterized by FT-IR,1H NMR,13 C NMR,31 P NMR,ESI-MSand elemental analysis characterization means.On the basis of the systhesis and characterization,the effects of the reaction solvent and co-catalyst of the dendritic PNP chromium complex C1 was evaluated in catalysis of ethylene oligomerization under dendritic PNP chromium complex C1 as precatalysts.The oligomerization results showed the best conditions of this catalytic system were as follows: MAO as co-catalyst,2 ?mol precatalyst,30 min,25 ?,0.9MPa and Al/Cr ratio of 500.Futhermore,under these catalysis conditions,three kinds of chromium complexes have reached best catalytic performance,and the catalyst with ethylamine as core had the highest catalytic performance.the catalytic activities of three kinds of catalysts were 2.15×105 g/(mol Cr·h)-1,1.45×105 g/(mol Cr·h)-1 and0.79×105g/(mol Cr·h)-1,respectively.And the amount of C6 and C8 were followed by22.22% and 21.58%?32.49% and 17.27%?45.84% and 35.16%.Furthermore,the effects of the reaction solvent on the catalystic activities of the dendritic PNP chromium complex C1 were evaluated in catalysis of ethylene polymerization under dendritic PNP chromium complex C1 as precatalysts.The polymerization results showed the best conditions of this catalytic system were as follows: Et Al Cl2 as co-catalyst,2 ?mol precatalyst,30 min,45 ?,4.0 MPa and Al/Cr ratio of 500.Under these catalysis conditions,three kinds of chromium complexes have reached best catalytic performance.A comparison of the series of chromium complexes showed that the complex C1 exhibited the highest catalytic performance.Under these conditions,the catalytic activities of three kinds of catalysts were followed by 1.50×106 g/(mol Cr·h),1.32×106 g/(mol Cr·h)and 1.17×106 g/(mol Cr·h),and the amount of polyethylene was followed by 95%,90% and 87%.