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采用X射线光电子能谱(XPS)技术研究了二氧化碳与环氧丙烷共聚反应的稀土三元催化剂,探讨了中心金属的X射线光电子能谱与催化活性间的关系,指出稀土三元催化剂的活性中心在于配位活化后的锌氧键,稀土盐通过与烷氧基锌形成双金属桥键,改变了活性中心的电子云分布,从而提高了反应活性.  相似文献   
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Ethylene/1-hexene was copolymerized by an unbridged zirconocene, (2-PhInd)2ZrCl2/MAO (methyl aluminoxane) at 0°C and 50°C respectively. High copolymerization activity and 1-hexene incorporation were observed at 0°C, with the copolymer formed having random sequence distribution and narrow molecular weight distribution. Ethylene polymerization at 50°C showed high activity, but copolymerization at 50°C showed much lower activity, which decreased sharply with increasing 1-hexene concentration in the monomer feed. Copolymer formed at 50°C showed blocky sequence distribution and broad molecular weight distribution. A mechanism model based on ligand rotation hindered by the propagation chain has been proposed to qualitatively explain the observed phenomena. Project (Nos. 29734144 and 20274037) supported by the National Natural Science Foundation of China  相似文献   
3.
Ethylene/1-hexene was copolymerized by an unbridged zirconocene, (2-PhInd)2ZrCl2/MAO (methyl aluminoxane) at 0 ℃ and 50 ℃ respectively. High copolymerization activity and 1-hexene incorporation were observed at 0 ℃, with the copolymer formed having random sequence distribution and narrow molecular weight distribution. Ethylene polymerization at 50 ℃showed high activity, but copolymerization at 50 ℃ showed much lower activity, which decreased sharply with increasing 1-hexene concentration in the monomer feed. Copolymer formed at 50 ℃ showed blocky sequence distribution and broad molecular weight distribution. A mechanism model based on ligand rotation hindered by the propagation chain has been proposed to qualitatively explain the observed phenomena.  相似文献   
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