共查询到16条相似文献,搜索用时 109 毫秒
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介绍了茂金属化合物及其他活性中心催化剂负载于SiO2、MgCl2、沸石、高分子材料等多种不同的载体上合成载体催化剂的研究,以及茂金属催化剂用于烯烃聚合反应的特征。 相似文献
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介绍了茂金属化合物及其他单活性中心催化剂负载于SiO_2、MgCl_2、沸石、高分子材料等多种不同的载体上合成载体催化剂的研究,以及茂金属催化剂用于烯烃聚合反应的特征。 相似文献
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茂金属催化剂硅胶载体研究进展 总被引:4,自引:0,他引:4
综述了近年来经甲基铝氧烷(MAO)化学处理后硅胶载体负载茂金属催化剂的一些研究进展,指出硅胶的化学活化是茂金属催化剂负载化的关键,单组分化学处理剂处理硅胶载体不能完全满足人们对负载型茂金属催化剂烯烃聚合的需求,采用含MAO的多组分化学处理剂化学活化硅胶后负载催化剂是该领域发展的趋势。 相似文献
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综述了近年来硅胶载体经甲基铝氧烷(MAO)化学处理后负载茂金属催化剂的一些研究进展,指出硅胶的化学活化是茂金属催化剂负载化的关键,单组分化学处理剂处理硅胶载体不能完全满足人们对负载型茂金属催化剂烯烃聚合的需求,采用含MAO的多组分化学处理剂化学活化硅胶后负载催化剂是该领域发展的趋势。 相似文献
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Dramatic changes occur during the initial stages of olefin polymerization over heterogenous catalysts. As polymer accumulates, the catalyst fragments and the void space within the growing particle becomes filled with polymer. The changing monomer transport rate to the active sites, dissipation of heat and stress with the particle, and eventually, dispersion of catalyst fragments within the growing particle can control the polymerization. We focus on the changes in, and influence of, polymer, catalyst and void morphology during the nascent polymerization for silica supported chromium oxide catalysts. We find that the course of the polymerization depends on the initial stages yet is seldom considered in polymerization models. We review several years of morphological characterization that identify the important physical phenomena which occur during nascent heterogeneous olefin polymerization. 相似文献
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Supported metallocene polymerization catalysis 总被引:2,自引:0,他引:2
Zirconocene supported on alumina or magnesium chloride exhibits modest olefin polymerization activity but not when it is supported
directly on silica. The surface silanol as well as siloxane groups must be passivated with appropriate reagents. A very active
and stereospecific supported catalyst was obtained by first reacting silica with methylalumoxane and bisphenol A before the
impregnation of the ansa-zirconocene precursor. The main difference between a homogeneous and supported catalyst is that at
the same gross amount of metallocene, the net concentration of it in the pores of a support material is several orders of
magnitude greater than it exists in solution thus the rate of deactivation in the former case is correspondingly faster than
in the latter. Most other supported metallocene catalysts based on supports such as zeolites, cyclodextrin, polymeric MAO,
synthetic polymers, etc., are poor in olefin polymerization for this and other reasons discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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