Research On Late Transition Metal Complexes With MgCl₂/SiO₂/THF Support For Ethylene Polymerization

polyethylene is the biggest output variety of the world general synthetic resin,holding the pivotal status in the plastics industry.In many polyethylene catalysts,late transition metal olefin polymerization catalysts are new-type catalysts,which have been attracted much attention in recent years.Late transition metal catalysts possess high catalytic activity for olefin polymerization,with single active center and wonderful molecular tailoring properties.Now,the aim of research and development of late transition metal catalysts catalyst is not only on high activity,but also on its high performance and morphology structure.Before the reference spray-drying technology of Ziegler-Natta supported catalyst,in this paper we prepared late transition metal catalysts of MgCl2/SiO2/THF complex support by spray-drying technology.The supported catalyst for ethylene polymerization characteristics,the polymerization conditions and the type of cocatalyst on the catalytic performance are studied in this paper.Two different late transition metal catalysts were synthesized here.We prepared late transition metal catalysts of MgCl2/SiO2/THF complex support by spray-drying technology in order to alter the nature of the catalyst’s active sites.The catalyst systems were investigate by SEM,BET and XRD analysis,for determining catalyst element content,particles morphology,surface area,hole and catalyst internal structure,also investigated the effects of the temperature in polymerization,Al/Ni mole ratio,Al/Fe mole ratio,THF residual influence on the performance of the content of catalyst.The iron content the supported iron catalyst is 0.25%,nickel content of the nickel supported catalyst is 0.126%.The ethylene poilmerization results show that,the best reaction temperature for iron,nickel supported catalyst was 30℃.Three methyl aluminium was the best cocatalyst for iron supported catalyst.In general,when the Al/Fe ratio was about 600,the iron supported catalyst shows the best activity.ACDA was the best cocatalyst for nickel supported catalyst.When the Al/Ni ratio was about 1500,the nickel supported catalyst shows the best activity.The residual THF content directly influences Catalytic properties of the catalysts.Right amount of free THF will effectively protect the activity center,the activity increased.