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高分子化Si桥联茂金属催化剂的合成及其催化乙烯聚合反应 总被引:2,自引:0,他引:2
合成了硅桥上含乙烯基团的硅桥联茂金属催化剂[(CH_2=CH)CH_3Si(C_5H_4) _2]ZrCl_2 (3),并通过IR, ~1H NMR对化合物进行了表征,3在AIBN的引发下与苯 乙烯共聚形成高分子化的茂金属催化剂4。研究了3和4对乙烯聚合的能力,考察了 n(Al)/n(Zr)'温度对催化剂活性的影响。 相似文献
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新型聚合物载体茂金属催化剂 总被引:4,自引:0,他引:4
均相茂金属催化剂虽然有许多优点和特点,但也存在着某些不足之处,例如,不适于现在通用的气相和淤浆聚合工艺;要想达到足够的聚合活性需大量价格昂贵的MAO;相当多的均相茂金属催化剂不适于高温聚合(活性降低,分子极低),不能很好地控制聚合物的形态,为了在工业上得到实际应用,必须将它们载体(非均相)化。通常采用的载体都是无机物,如SiO2、MgCl2、Al2O3等。由于无机载体表面具有酸性,负载茂金属催化剂活性有所降低,用聚合和作茂金属催化剂的载体很少有报道,我们研制了一种新型的聚合物载体茂金属催化剂,即可保持均相茂金属催化特点和优点,又能克服其缺点。其合成路线如下。 相似文献
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Guang Qian YU* De Ze ZHANG Fu SHUN Li Jun QIAO Tao TANG Bao Tong HUANG State Key Laboratory of Polymer Physics Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Polymer Chemistry Laboratory Chemistry Academy of S 《中国化学快报》2001,(3)
Although homogeneous metallocene catalysts show some specific characteristics, such as single site, extremely high catalytic activity, high ability to incorporate monomers, narrow molecular weight and comonomer distribution, and excellent control of stereoregularity, but they also suffer some drawbacks, a very large amount of MAO requirement, inability to be used in slurry or gas phase processes, and poor control of polymer morphology. Therefore, it is necessary to modify the catalysts for the… 相似文献
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Mostafa Ahmadi Roghieh Jamjah Mehdi Nekoomanesh Gholam Hossein Zohuri Hassan Arabi 《大分子反应工程》2007,1(6):604-610
A Ziegler‐Natta/metallocene hybrid catalyst was produced and utilized in the polymerization of ethylene with the aim of producing bimodal polyethylene. The MgCl2 adduct was prepared by a melt quenching method and Cp2ZrCl2 and TiCl4 catalysts were loaded, respectively, after treating the surface with TiBAl. The polymerization kinetics involved an induction period, followed by fragmentation and expansion of particles. SEM micrographs revealed that the spherical morphology was retained through the initial mild reaction conditions of induction period. The polymers produced showed bimodal molecular weight distribution patterns, suggesting that both components of the hybrid catalyst were active over the support.
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以SiO2为载体,制备了负载的双核茂金属[(η5-C5H5)Zr Cl2]2[μ,μ-(SiMe2)2(η5-allyl C5H2)2]/MAO/SiO2催化剂,以己烷为溶剂进行了淤浆条件下乙烯聚合反应,研究了扩散因素、乙烯聚合压力和聚合温度对乙烯淤浆聚合动力学参数的影响,测定了聚合反应级数和表观活化能,采用动力学和相对分子质量法计算了负载催化剂的活性中心浓度,并对链增长速率常数等动力学参数进行了计算.结果表明,以负载双核茂金属催化剂催化乙烯淤浆聚合反应速率对单体浓度呈1.11级依赖,反应活化能Ea为72.47 kJ/mol,活性中心浓度C*为0.33 mol/mol,链增长速率常数Kp为1.06×106L.(mol.h)-1. 相似文献
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The solution polymerization of ethylene using rac-Et(Ind)2ZrCl2/MAO and (Dimethylsilyl(tert-butylamido)(tetramethyl- cyclopentadienyl)titanium Dichloride)(CGC-Ti)/MAO was studied in a semi-batch reactor at 120 °C under different monomer pressures and catalyst concentrations. The kinetics of ethylene polymerization with rac-Et(Ind)2ZrCl2/MAO can be described with first order reactions for polymerization and catalyst deactivation. When (CGC-Ti)/MAO is used, however, second order kinetics are observed for catalyst decay and the order of polymerization changes from 2 to 1 with increasing ethylene pressure. 相似文献
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Sung Chul Hong Ursula Rief Marc Oliver Kristen 《Macromolecular rapid communications》2001,22(17):1447-1454
Gel‐type poly(styrene‐co‐divinylbenzene) beads (PS bead) were used as a carrier to encapsulate metallocene catalysts through a simple swelling‐shrinking procedure. The catalytic species were homogeneously distributed in the PS bead particle. The catalyst exhibited high and stable ethylene polymerization and ethylene/1‐hexene copolymerization activity affording uniform spherical polymer particles (1 mm). Polymerization rate profiles exhibited slow initiation and stable increase in polymerization activity with time. 相似文献
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Karunakaran Radhakrishnan Henri Cramail Alain Deffieux Philippe Franois Ardchir Momtaz 《Macromolecular rapid communications》2002,23(14):829-833
A facile nonaqueous synthetic route to methylaluminoxane (MAO) by heating a mixture of benzophenone and trimethylaluminium (TMA) is described. The MAO prepared such reveals to be an efficient activator of metallocenes and late transition metal complexes for ethylene polymerization. The [TMA]/[benzophenone] ratio used for the preparation of MAO is shown to have a dramatic effect on the catalytic activity as well as the molecular weight distribution of the resulting polyethylenes. 相似文献
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Dialkylzinc compounds (ZnR2) with the alkyl groups of different steric hindrance were used as chain transfer agents in ethylene and propylene polymerizations catalyzed by two conventional metallocene catalysts including rac-Et(Ind)2ZrCl2 and rac-Me2Si[2-Me-4-Ph-Ind]2ZrCl2. In general, catalyst activities for ethylene polymerizations are barely affected by chain transfer agents, regardless of the R type; however, there are significant activity reductions in propylene polymerizations when the R in ZnR2 is less hindered, and as R becomes bulkier, catalyst activities are gradually restored. ZnR2 and metallocene catalyst active site tend to form a reversible and catalytically inactive complex, thus the geometry congested ZnR2 would reduce complex formation tendency and hence decreased its negative effect on catalyst activities. 相似文献
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IntroductionItiswellknownthatmetallocenesactivatedwithmethylaluminoxane (MAO)arehighlyactivehomogeneousZiegler Nattacatalyststhatproducepolyolefinwithcon trolledstereoregularityandnarrowmolecularweightdistri bution ,1 4 however,themolecularweightofthepolym… 相似文献
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Jovita Moreno Rafael van Grieken Alicia Carrero Beatriz Paredes 《Macromolecular Symposia》2011,302(1):198-207
Summary: As known, the pore structure of the catalytic support plays a decisive role during the polymerization reactions determining intra-particle mass and heat transport phenomena. In this work, several ethylene polymerizations have been carried out by using as catalytic support different mesostructured materials with unimodal and bimodal pore size distributions in order to evaluate the influence of this pore size distribution on the catalytic behavior. Calcined mesoporous materials were impregnated with the catalytic system MAO/(nBuCp)2ZrCl2 and used for ethylene polymerization and ethylene/1-hexene copolymerizations, at 70 °C and 5 bar of ethylene pressure. Polyethylenes obtained were characterized by GPC, DSC and Crystaf. Results indicate that porous structure of the support has a significant influence on polymerization activity and polymer properties. Despite the catalyst bimodal pore size distribution, only ethylene/1-hexene copolymers presented a bimodal chemical composition distribution. 相似文献
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Fernando Silveira Denise Santos de Sá Zênis Novais da Rocha João Henrique Zimnoch dos Santos 《大分子反应工程》2008,2(3):253-264
A series of metallocenes, namely [Cp2ZrCl2], [(MeCp)2ZrCl2], [(nBuCp)2ZrCl2], [(iBuCp)2ZrCl2], [(tBuCp)2ZrCl2], [Cp2TiCl2], [Et(Ind)2ZrCl2], [Et(IndH4)2ZrCl2] and [MeSi2(Ind)2ZrCl2)], were combined in a 1:1 molar ratio within a reactor for ethylene polymerization, with MAO as the cocatalyst. The catalysts were characterized by cyclic and differential pulse voltammetry. The combined systems that showed the highest and lowest activities were combined in 1:3 and 3:1 molar ratios. The catalyst activity in the ethylene polymerization reaction is discussed in terms of the estimated consumption rate, decomposition rate constant and half‐life of the metallocene species formed with MAO in an ethylene atmosphere.
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Dialkylzinc compounds (ZnR2) with the alkyl groups of different steric hindrance were used as chain transfer agents in ethylene and propylene polymerizations catalyzed by two conventional metallocene catalysts including rac-Et(Ind)2ZrCl2 and rac-Me2Si[2-Me-4-Ph-Ind]2ZrCl2. In general, catalyst activities for ethylene polymerizations are barely affected by chain transfer agents, regardless of the R type; however, there are significant activity reductions in propylene polymerizations when the R in ZnR2 is less hindered, and as R becomes bulkier, catalyst activities are gradually restored. ZnR2 and metallocene catalyst active sites tend to form a reversible and catalytically inactive complex, thus, the geometry congested ZnR2 would reduce complex formation tendency and hence, decrease its negative effect on catalyst activities. 相似文献