无机/有机复合载体负载乙酰丙酮铁/双亚胺基吡啶催化剂及其乙烯聚合

ORGANIC/INORGANIC SUPPORT FOR IMMOBILIZING IRON(Ⅲ) ACETYLACETONATE AND BIS(IMINO)PYRIDYL LIGAND CATALYST SYSTEM FOR ETHYLENE POLYMERIZATION

采用溶胶-凝胶法,将苯乙烯-丙烯酸共聚物(PSA)包覆于955 Davison硅胶上得到无机/有机复合微球载体,并在2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3均相催化剂中浸渍后得到负载型双亚胺基吡啶铁催化剂.该催化剂在生产高结晶度(72%)聚乙烯的同时,还能生产一定量的α-烯烃.考察了不同膜材料以及聚合条件(不同助催化剂,压力,温度,Al/Fe摩尔比)对聚合活性以及聚合产物性能的影响,发现温度对聚合产物的α-烯烃与聚乙烯的质量比影响最大,助催化剂类型既影响催化剂的活性,也对最终产物的性质有着很大的影响.氯化镁处理的PSA作为膜材料时,负载2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3所得到聚乙烯分子量较低(Mw=11.9×104),结晶度较大(72%),熔融指数MI较高(2.35 g/10min),可作为双峰聚乙烯中的低分子量部分加以利用.

An organic/inorganic support of immobilizing catalysts for ethylene polymerization was devised.The composition of the hybrid catalyst is as following： styrene and acrylic copolymer（PSA） is the organic part for binding iron（Ⅲ） acetylacetonate and bis（imino）pyridyl ligand catalyst,and SiO2（Davison 955 silical gel） is the inorganic part.The inorganic part is coated by the organic part（PSA） by sol-gel method.The catalyst could produce not only high crystallinity（72%） polyethylene,but also α-olefin.We considered the impact of different membrane materials and polymerization conditions（different cocatalyst,pressure,temperature,Al/Fe molar ratio） to the polymerization activity and properties of polymers and found that temperature had the greatest impact to the weight ratio of oligomer to PE.Because of the poor thermal stability of catalyst,the catalytic activity significantly attenuated with increasing temperature.When pressure increased,catalytic activity would increase too.The relationship of pressure and catalytic activity met the cossee catalytic reaction mechanism,which was widely accepted in Ziegler-Natta catalyst＇s ethylene polymerization mechanism.Different membrane materials would affect the final polyethylene product performance,the pure PSA as organic part would increase the molecular weight significantly.Cocatalysts affect not only the catalytic performance,but also the property of the final product.The alkylaluminium as cocatalyst tended to decrease the molecular weight.The iron catalyst system binding on the PSA after the treatment of magnesium chloride could produce the polyethylene of lower molecular weight（Mw=11.9×104） and higher crystallinity（72%）.And the polyethylene＇s melt index MI（2.35 g/10min） was higher than the iron catalyst binding on other membrane materials.The polyethylene can be used as the low molecular weight part of bimodal polyethylene.