茂金属催化剂的负载化

茂金属催化剂是继齐格勒-纳塔催化剂之后的新一代烯烃聚合催化剂,与多活性中心催化剂相比,这种单一活性中心类型的催化剂具有聚合活性较高、聚合物分子量分布较窄等特点。其中,负载化是茂金属催化剂实用化的重要课题,它克服了均相催化体系中聚合物形貌不可控的缺点,降低了助催化剂的用量。近些年来茂金属负载化的研究仍很活跃。本文总结了近十年来茂金属负载化的研究进展,主要对载体的形貌、载体的改性处理、茂金属催化剂的负载方法和负载化茂金属催化剂的应用进行了评述并展望了茂金属催化剂负载化的发展趋势。     

负载型茂金属烯烃聚合催化剂有机载体研究进展

综述了近年来各种有机载体负载茂金属催化剂的负载方法,介绍了有机载体型茂金属催化剂的特点、负载方式、负载化对催化烯烃聚合性能和聚合物性能的影响。目前还不能完全解释清楚有机载体对聚烯烃形态以及聚合活性的影响效果。在有机载体合成方面,可以通过高分子工程,进行有机载体的设计,将茂金属催化剂负载到有机载体上,进一步提高有机载体型茂金属催化剂的活性、改善有机载体的形态和结构,将会推进有机载体负载型茂金属催化剂的工业化开发。     

新型聚合物载体茂金属催化剂

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。     

二氧化硅负载[C5Me5]2SmMe(THF)引发甲基丙烯酸甲酯聚合

近年来 ,有许多文献报道茂金属催化剂的负载化及其在烯烃聚合中的应用 ,这对发展新型茂金属催化剂和开发新型高分子材料有重要意义 [1,2 ] .我们 [3]曾报道壳聚糖负载稀土催化剂用于甲基丙烯酸甲酯的配位聚合有优良性能 .以五甲基环戊二烯为配体的有机稀土配合物 ,如 [Sm H( C5Me5) ]2 ,[C5Me5]Ln Me( THF) ( Ln=Sm,Yb)等在甲苯中单组分引发甲基丙烯酸甲酯聚合及内酯开环聚合具有许多优异性能[4 ,5] ,但是经负载化的该类催化剂的聚合性能尚未见报道 .本文报道将 [C5Me5]2 Sm Me·( THF)负载于二氧化硅 ,引发甲基丙烯酸甲酯聚合的结…     

有机/无机复合载体负载茂金属催化剂的制备和乙烯聚合

苯乙烯/丙烯酰胺共聚物;SiO2载体;有机/无机复合载体负载茂金属催化剂的制备和乙烯聚合     

负载型烯烃聚合催化剂合成的新方法

介绍了负载型烯烃聚合催化剂合成的新方法,探讨了不同载体负载的Ziegler- Natta催化剂各组分之间的相互作用机理及活性中心的形成途径。对负载茂金属催 化剂的新型载体及新的负载方法进行了评述。     

双核茂金属催化剂的研究

双核茂金属催化剂是近年来茂金属催化剂研究的一个重要方向。综述了双核茂金属化合物的研究进展及其在烯烃聚合方面的应用;分别叙述了同核型双核茂金属化合物和异核型双核茂金属化合物的合成及性能研究;对双核茂金催化剂的作用机理也进行了介绍。     

茂金属催化乙酸与丁醇酯化反应

以二茂铁、二茂钛、二茂锆和取代茂锆为催化剂用于催化酯化合成乙酸丁酯, 探讨了不同茂金属、反应时间和催化剂用量对反应性能的影响. 结果表明, 低含量的茂金属就可高效催化酯化反应. 当催化剂为二茂钛, 其含量为 0.049%(摩尔比)时, 反应 30 min 产物乙酸丁酯的分离收率达到 90%, 纯度达到 98%. 以 400 目不同温度活化的硅胶为载体, 考察了负载二茂锆催化剂的性能. 当硅胶在 400 ℃ 焙烧 4.0 h, 负载二茂锆催化剂用量为 Zr/丁醇 = 0.487% (摩尔比), 反应后乙酸丁酯收率为 90.6%, TOF = 318 h-1. 该反应的产物后处理不需要用水洗涤, 无废水排出, 催化剂易回收利用, 是一个绿色的反应过程.     

修饰Al2O3负载的烯基取代茂金属催化体系催化乙烯聚合的研究

经过十几年的研究和开发,茂金属催化剂已经有了很大的发展,部分已经工业化,同时新的茂金催化体系仍然在不断地开发出来［１～４］．均相烯烃聚合催化剂经负载后能有效地改善所得聚合物的颗粒形态,并可用于气相聚合,同时也出现了许多新的聚合特征,这方面的研究一直是烯烃聚合催化剂研究领域的一个热点［５～８］．在负载型催化剂的制备时,通常用ＭＡＯ先对载体进行处理,然后再负载茂金属,这样ＭＡＯ的用量就很大．茂环上的取代基对聚合有较大的影响,许多聚合规律仍在探索之中．尽管硼化合物作为助催化剂的茂金属催化体系已经被应用…     

茂金属催化丙烯间规聚合的研究进展

间规聚丙烯的结构独特新颖,具有良好的透明性、透气性以及耐辐射性等性能。由间规聚丙烯制成的共混材料,在医疗产品、包装和汽车配件等方面具有巨大的潜在用途。要得到性能优异的商品化间规聚丙烯,就需要在催化剂的选择性、催化剂负载化和聚合工艺等方面做深入研究。本文综述了间规选择性茂金属催化剂及其聚丙烯产品的研发进展,着重介绍了间规选择性茂金属催化剂的发展及其影响催化性能的因素,同时涉及间规聚丙烯的生产工艺以及间规聚丙烯产品的加工应用等方面。     

Recent progress on olefin polymerization catalysts

Recent progress on metallocene catalysts is reviewed. This consists for the main part of research activities in metallocene catalysts and their polymerization performances (ethylene polymerization, propylene polymerization, styrene polymerization). In addi-tion, the computational design of metallocene catalysts and the commercial status of metallocene technologies in Japan are described.     

双核茂金属催化剂催化聚合反应进展

综述了双核茂金属化合物的研究进展及其在烯烃和极性单体聚合方面的应用及双核茂金属化合物的合成及性能研究；并对双核催化剂的作用机理、催化剂结构与性能的关系也做了介绍。     

等规-无规立体嵌段聚丙烯链增长机理

综述了各种催化剂催化丙烯聚合合成等规-无规嵌段聚丙烯的链增长机理,这些催化剂包括非桥联摇摆型茂金属催化剂、C1对称茂金属催化剂、C1对称和C2v对称双组分茂金属催化剂及后茂金属催化剂。     

C1桥联的茂金属化合物(Cp)CR1R2(Flu)MCl2的合成及其催化烯烃聚合活性

合成了6种单碳桥联的含芴(Flu)茂(Cp)基B族茂金属催化剂,研究了它们催化烯烃聚合的能力.通过IR,¹HNMR,EI-MS和元素分析对化合物进行了表征.用所合成的茂金属化合物与MAO所组成的催化体系对乙烯、丙烯的聚合进行了研究.其中金属为Ti的催化剂没有聚合活性或活性极低.金属为Zr的催化剂有一定的催化活性,用不同的催化剂得到的聚合物性质有一定的差异.     

A New Zirconocene Complex and Its Catalytic Properties for Olefin Polymerization

As metallocene olefin polymerization catalysts,unbridged metallocenecomplexeshave re-ceived much attention because they are relatively easy to be synthesized and can produce notonly polyethylene butalso oligo-or polypropylenes with differentstereoregularities and prop-erties depending on their structures[1 ,2 ] .It has been known that a rather small structuralchange for a metallocene compound may cause a remarkable effect on its catalytic properties,such as catalytic activity,polymer molecule w…     

AlR2Cl/MgR2 combinations as universal cocatalysts for Ziegler–Natta,metallocene, and post‐metallocene catalysts

Combinations of dialkylaluminum chlorides and dialkylmagnesium compounds, when used at molar [AlR₂Cl]:[MgR₂] ratios ≥ 2, act as universal cocatalysts for all three presently known types of alkene polymerization catalysts—Ziegler–Natta, metallocene, and post‐metallocene. When these cocatalysts are used with supported Ti‐based Ziegler–Natta catalysts, they produce catalyst systems which are 1.5–2 times more active than the systems utilizing AlR₃ compounds as cocatalysts. Combinations of AlR₂Cl/MgR₂ cocatalysts and various metallocene complexes produce single‐center catalyst systems similar to those formed in the presence of MAO. The same cocatalysts activate numerous post‐metallocene Ti complexes containing bidentate ligands of a different nature and produce multicenter systems of very high activity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3271–3285, 2009     

Activation Energy and Transition State Determination of the Olefin Insertion Process of Metallocene Catalysts Using a Semiempirical Molecular Orbital Calculation

The transition state of the olefin insertion process of metallocene catalysts can be determined by adopting the semiempirical PM3 model. In computational chemistry, the computational methods most employed are the ab initio method and density functional theory, which are very time consuming. The semiempirical molecular orbital method requires much less computational resources than the above methods. However, the accuracy and reliability of the semiempirical molecular orbital method remains to be determined. The PM3 model is the most recently developed the semiempirical molecular orbital method and can also be applied to transition metal calculations. This study is intended to investigate the reliability of computational results determined using semiempirical PM3 model on metallocene catalysts through comparison with published results on the density functional theory (DFT). The saddle point finding procedure is adopted to find the transition state of the ethylene insertion process of metallocene catalysts. Results on the geometry and energy trends of the ethylene insertion process of metallocene catalysts determined using the PM3 model are in good agreement with the DFT results. In addition, the saddle point of the potential energy surface of ethylene insertion is verified in accordance with the eigenvalue of the vibrational frequency spectrum. Correct eigenvalues indicate that the correct saddle point of the potential energy surface of ethylene insertion has been successfully located. Hence, the eigenvalue of the vibrational frequency spectrum is a valuable reference in terms of saddle point justification. Computational results and vibrational frequency spectrum analysis demonstrate that the PM3 model can be used to locate the correct saddle point of the potential energy surface. The results obtained using the PM3 model confirm that the eigenvalue of the transition state lies nearly on the vibrational frequency spectrum. The eigenvalues are also analyzed, providing a valuable reference for further studies of the transition state of olefin insertion of metallocene catalysts. The activation energies for the olefin insertion reaction are also studied for evaluation of the catalyst.     

Self-immobilizing catalysts and cocatalysts for olefin polymerization

Homogeneous catalysts for olefin polymerization such as metallocene or half-sandwich complexes containing the metals titanium, zirconium and hafnium, or other transition-metal coordination complexes can be functionalized with alkenyl groups and have then the potential to copolymerize with olefins to give heterogeneous catalysts. In a similar manner metallacyclic metallocene complexes with a metal-carbon sigma bond allow the catalytic insertion of olefins into this bond and produce heterogeneous catalysts. It is also possible to functionalize the active species of the cocatalyst methylalumoxane (MAO) and use it for self-immobilization processes. The high excess of MAO that is necessary in homogeneous solution can be reduced by more than 90% with this method.     

环烯烃加成聚合研究开发进展

综述了环烯烃加成聚合的催化剂体系及其聚合物的研究和开发状况。主要介绍了催化剂种类,包括传统的齐格勒－纳塔（Ziegler-Natta)催化剂、茂金属催化剂、钯、镍等后过渡金属催化剂,及其催化环烯烃均聚合以及与α-烯烃共聚合的特性,也描述了用不同催化体系进行环烯烃聚合的机理以及环烯烃加成聚合物及其与α-烯烃共聚物的性能及应用前景。     

Immobilized organometallic catalysts in the catalytic polymerization of olefins

Studies in the field of supported Ziegler-Natta catalysts employed for the polymerization of olefins that were begun by works performed under the guidance of Prof. Chirkov are reviewed in brief. The development of immobilization procedure for metallocene catalysts including the synthesis of alkylaluminoxanes heterogenized on the support surface via the partial hydrolysis of AlR₃ by water contained in the support and subsequent supporting of a metallocene is described. It is revealed how the immobilization of various metallocenes on the solid surface affects the activity of the catalysts and the structure and molecular mass of the polymers. The use of immobilized organometallic catalysts for the polymerization filling of polyolefin matrices aimed at the design of new polymer composites with special characteristics and preparation of polyolefin nanocomposites is considered.