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Z-N催化剂生产宽/双峰MWD聚乙烯的研究进展 总被引:5,自引:0,他引:5
介绍了Ziegler-Natta(Z-N)催化剂在单反应器中生产宽,双峰相对分子质量分布(MWD)聚乙烯(PE)的最新研究进展,概括了Z-N催化剂制备宽/双峰MWDPE的主要方法及特点,即传统的Ti系催化体系生产的双峰PE的MWD较窄,改进的Ti-V双金属催化体系活性高,可以调节MWD,但反应操作难度大。通过加入不同的配合物,调节并改进PE的MWD,取得了较好的实验结果。宽/双峰MWDPE的生产和开发是PE工业发展的一个重要方向。 相似文献
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世界聚乙烯催化剂研究新进展 总被引:4,自引:0,他引:4
综述了国内外聚乙烯齐格勒-纳塔催化剂、茂金属催化剂、非茂金属催化剂、双功能催化剂、双峰或宽峰分子量分布聚乙烯复合催化剂等的研究开发新进展。 相似文献
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采用相同的工艺制备了两种不同的MgCl2/SiO2复合载体型Ziegler-Natta催化剂,考察了SiO2粒径对催化剂的形态结构及其催化乙烯聚合性能的影响,并利用BET测试仪和扫描电子显微镜(SEM)等对催化剂的形态和物性进行了表征。结果表明:加入小颗粒SiO2可以改善催化剂的颗粒形态和均匀程度,而且小颗粒SiO2制备的复合载体催化剂不仅具有较高的催化剂活性,还可使聚合产品的颗粒变得均匀,提高聚合物的堆密度,降低细粉含量,增强氢调敏感性。 相似文献
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TiCl4/SiO2负载型催化剂用于丁二烯聚合Ⅱ.聚合条件及聚合动力学 总被引:1,自引:1,他引:0
使用以球磨法制备的 SiO2负载 TiCl4催化剂进行丁二烯溶液聚合,考察了聚合条件对催化效率的影响以及在 20~ 60℃下的聚合动力学。确定了适宜的聚合条件:以加氢汽油为溶剂, Al/Ti摩尔比为 20, Ti/Bd摩尔比为 2× 10- 4, 50℃聚合 10 h以上。溶液聚合动力学研究结果表明,本体系在低转化率下为稳态聚合,其稳态聚合速率方程为 Rp=kpf[Ti]0[Bd],聚合的表观活化能为 11.4 kJ/mol。 相似文献
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Naeimeh Bahri‐Laleh Mehrdad Seifali Abbas‐Abadi Mehdi Nekoomanesh Haghighi Zahra Akbari Mohamad Reza Tavasoli Seyed Heydar Mirjahanmardi 《应用聚合物科学杂志》2010,117(3):1780-1786
In our previous study we found that addition of proper amount of halocarbons (HC) including chlorocyclohexane (CHC), chlorocyclopentane (CHP), butylchloride (BC), 1,4‐dichlorobutane (DCB), and chloroform (C) to the MgCl2 (Ethoxide type)/TiCl4/AlEt3 catalytic system leads to a strong productivity improvement. In this study, the effect of these halocarbons on the properties of resulting polymers was investigated using H2 as chain transfer agent at optimum HC/Ti molar ratio. The nature of halocarbon compound had a strong effect on polymer properties as well as on development of polymerization activity. Effect of halocarbon promoters on the polymer melt flow index (MFI), melt flow ratio (MFR), particle size distribution (PSD), bulk density, wax amount, crystallinity, and thermal properties of the polymers were studied. Results showed that, in the presence of halocarbons, polyethylenes with higher MFI and bulk density, broader MFR and lower wax amount have been obtained. Also, sieve analysis showed that, in the presence of halocarbons as promoter, polymers had better particle size distribution (PSD). DSC analysis showed that the Tm of PEs prepared with the different promoters were in the region commonly reported for HDPE and was not affected substantially by halocarbons, but, the crystallinity of the polymers has been improved using halocarbon promoters. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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The polymerization of ethylene over metal chloride-exchanged silica-gel has been studied. Basic, amphoteric and electropositive metals on the surface of the silica-gel were found to promote the polymerization reaction. I.r., e.s.r. and kinetic studies suggest that the active sites were highly dispersed in a solid solution of TiCl3 and MCl2 formed from the supporting TiCl4. The influence of polymerization time, temperature and pressure on the polymerization rate were also investigated. 相似文献
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Ethylene-propylene copolymers have been prepared by using Ziegler-Natta catalysts based on TiCl4, MgCl2, PCl3 and (n-Bu)3PO4. The catalysts TiCl4/MgCl2/PCl3 and TiCl4/MgCl2/(n-Bu)3PO4 were prepared by reacting TiCl4 with pretreated MgCl2. The support was prepared by ball milling of MgCl2 with varied amounts of PCl3 or (n-Bu)3PO4. The addition of PCl3 has remarkably increased the MgCl2 surface area in comparison with (n-Bu)3PO4. The effects of PCl3 and (n-Bu)3PO4 on ethylene homopolymerization, ethylene-propylene copolymerization and on copolymer properties were evaluated. The catalyst
system containing PCl3 permitted to synthesize propylene-ethylene copolymers with up to 75% (w/w) of propylene and provided control of copolymer
crystallinity. The reduction of the copolymer molecular weight distribution suggested that PCl3 acted as an internal donor, poisoning some active catalytic sites.
Received: 2 April 1997/Revised: 6 June 1997/Accepted: 18 June 1997 相似文献
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To investigate the influence of support porosity parameters e.g., average pore volume (APV), pore diameter (PD), and pore surface area distribution (PSAD) on activity‐profile of catalyst and comonomer incorporation, a series of silica‐supports with different porosity were prepared through sol–gel method and used to synthesize corresponding (SiO2/MgCl2/TEOS/TiCl4) catalysts. Polymerization of ethylene/butene‐1 showed that increasing of APV from 0.75 to 2.2 cm3 g increase initial activity from 120 to 400 (gpoly/gcat.bar.hr) followed by appearance of secondary peaks in activity‐profile which could be attributed to the variation of PSAD. It is found that the effect of support in polymerization is a complicated issue which depends not only on the porosity parameters also on the comonomer concentration. The catalyst with PD of 300 Å gives higher comonomer incorporation and polymers with 15–20% lower crystallinity in contrast to catalyst with PD of 100 Å. Porosity effect was quantitatively studied by modifying of conventional Z‐N catalyst polymerization mechanism through introducing fragmentation term to achieve a new tool in designing and developing of polyolefin catalysts. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献