【作者】 王临才；

【导师】 孙俊全；

【作者基本信息】 浙江大学 ， 化学工程与技术， 2007， 博士

【摘要】 迄今为止，对后过渡金属催化剂的研究主要集中在单核方面，有关双核后过渡金属催化剂方面的报道较少。双核聚烯烃催化剂内的两个金属中心之间存在特殊的协同效应，使得双核催化剂表现出与相应单核催化剂不同的催化性能，例如提高催化活性和聚合物的分子量，加宽聚合物分子量分布等。本文系统研究了双核后过渡金属催化剂结构和聚合条件对催化活性以及聚合产物性质的影响规律。具体工作如下：1、亚甲桥联吡啶二亚胺双核铁系催化剂成功合成了3个亚甲桥联吡啶二亚胺双核铁化合物{[2,6-R₂-C₆H₃N=C（CH₃）C₅H₃N（CH₃）C=N（3，5-R’₂）C₆H₂-CH₂-（3，5-R’₂）C₆H₂N=C（CH₃）C₅H₃N（CH₃）C=N（2，6-R₂）C₆H₃][FeCl₂]₂（R，R’=i-C₃H₇（Fe4）；R=i-C₃H₇，R’=CH₃（Fe5）；R，R’=CH₃）（Fe6）}，由于化合物为顺磁性，NMR表征不易得到，故采用FAB-MS及元素分析对F4-Fe6作了表征。同时合成了单核吡啶二亚胺铁化合物{[ArN=C（Me）C₅H3_N（Me）C=NAr’)]FeCl₂（Ar，Ar’=2,6-C₆H₃-i-Pr（Fe1）；Ar=2,6-C₆H₃-i-Pr₂，Ar’=2,6-C₆H₃-Me₂（Fe2）；Ar,Ar’=2,6-C₆H₃-Me₂（Fe3））}作为参考，考察了催化剂结构、聚合反应条件及不同助催化剂对乙烯聚合反应的影响，对所得聚乙烯进行了DSC、高温GPC和¹³C NMR表征。结果表明：吡啶二亚胺铁系催化剂的结构对催化活性和所得聚乙烯的分子量及其分布具有重要的影响，除Fe4／Al（i-Bu）₃催化体系外，其他双核吡啶二亚胺铁催化化体系的催化活性及所得聚乙烯分子量，均高于相应的单核吡啶二亚胺铁催化体系。所得聚乙烯分子量分布均较宽，呈宽峰／双峰分布。2、Fe（acac）₃-吡啶二亚胺／MAO（Al（i-Bu）₃）催化体系1)、Fe（acac）₃-吡啶二亚胺在MAO的作用下原位产生活性中心，可用于催化乙烯聚合，显示出较高的催化活性，得到高分子量聚乙烯。系统的探讨了催化剂组成、聚合反应条件、加料顺序等对乙烯聚合的影响，并对所得聚乙烯进行了DSC、高温GPC及乃¹³C NMR表征。结果显示：所得聚乙烯分子量呈双峰分布，且具有较高线性和结晶度。亚甲桥联吡啶二亚胺（L4-L6）体系催化活性高于吡啶二亚胺（L1-L3）体系。2)、Fe（acac）₃-吡啶二亚胺与Al（i-Bu）₃组成了新的催化体系，考察了温度及铝铁摩尔比两个重要因素对乙烯聚合反应的影响。发现Fe（acac）₃-吡啶二亚胺／Al（i-Bu）₃体系催化活性低于Fe（acac）₃-吡啶二亚胺／MAO体系。由于不能发生向Al（i-Bu）₃的链转移反应，所得聚乙烯分子量分布较窄，在3．54-4．26之间。3、亚甲桥联α-苊二亚胺双核镍系催化剂成功合成了3个亚甲桥联α-苊二亚胺双核镍系化合物{[2,6-R₂-C₆H₃N=C(C₁₀H₆)C=N-（3，5-R’₂）C₆H₂（CH₂），（3,5-R’₂）C₆H₂-N=C(C₁₀H₆)C=N（2，6-R₂）C₆H₃]（NiCl₂）₂（R，R’=i-C₃H₇（Ni3）；R=i-C₃H₇，R’=CH₃（Ni4）；R,R’=CH₃（Ni5））}，以FT-IR、FAB-MS及元素分析进行表征。同时合成了两个单核α-苊二亚胺镍化合物2，6-（i-Pr）₂C₆H₃-N=C(C₁₀H₅)C=N-2，6-（i-Pr）₂C₆H₃NiCl₂（Ni1）和2,6-Me₂C₆H₃-N=C(C₁₀H₅)C=N-2,6-Me₂C₆H₃NiCl₂（Ni₂）作为比较，考察了以MAO为助催化剂时，催化剂结构，聚合反应条件对催化活性、聚乙烯的分子量及其分布和聚乙烯为结构的影响。研究发现：催化剂结构与聚合条件一样，对催化剂催化性能及聚乙烯结构具有重要的影响。5个镍催化剂的活性顺序为Ni3>Ni1>Ni2>Ni4>Ni5，所得聚乙烯分子量大小顺序为Ni3>Ni4>Ni1>Ni5>Ni2。此外，改变催化剂结构及聚合条件，可以控制乙烯聚合，获得具有不同支化度聚乙烯。4、亚甲桥联中性水杨醛亚胺双核镍系催化剂成功合成了中性水杨醛亚胺双核镍化合物{[O-（3-Cyclopentenyl）-（5-Me）C₆H₂-o-C（H）=N-2，6-（i-Pr）₂C₆H₂]₂CH₂}[Ni（Ph₃P）（Ph）]₂（Ni6），经元素分析，¹H NMR确认了其结构。以Ni（COD）₂为瞵攫取剂，该双核中性水杨醛亚胺镍化合物对乙烯聚合显示出较高的催化活性，并考察了聚合反应条件对其催化性能的影响。值得注意的是，该化合物可以作为单组份催化剂催化乙烯聚合。可能是亚甲基桥的引入，改变了金属中心周围的微化学环境，使得三苯基瞵基团能够自动离去，形成活性中心而引发乙烯聚合。更多还原

【Abstract】 To date, the researches on late transitional metal catalysts are mainly aimed at mononuclear catalysts. Only a few researches are reported on binuclear late transitional metal catalysts. There is cooperative effect between two metal centers in binuclear polyolefin catalysts, which makes binuclear catalysts display different catalytic performance from correspondent mononuclear catalysts （such as, enhancing catalytic activity and the molecular weight of polymer obtained and broadening the molecular weight distribution）. The dissertation systematically studied the influences of modification on binuclear catalyst structures and polymerization conditions on catalytic activity and properties of polymer obtained. The detailed work is as follows:1. Methylene bridged binuclear bis（imino）pyridine iron catalystsThree methylene bridged binuclear bis（imino）pyridine iron complexes（{[2,6-R₂-C₆H₃N=C（CH₃）C₅H₃N（CH₃）C=N（3,5-R’₂）C₆H₂-CH₂-（3,5-R’₂）C₆H₂N=C（CH₃）C₅H₃N （CH₃）C=N（2,6 -R₂）C₆H₃][FeCl₂]₂ （R,R’=i-C₃H₇ （Fe4）; R=i-C₃H₇, R’=CH₃ （Fe5）; R,R’=CH₃ （Fe6））}） have been synthesized. The paramagnetic character of the iron catalyst makes NMR analysis impossible. So fast atom impact （FAB-MS）, FT-IR and elemental analysis were used to confirm the binuclear nickel complexes. In addition, three mononuclear bis（imino）pyridine iron complexes （{[ArN=C（Me）C₅H₃N（Me） C=NAr’）]FeCl₂ （Ar,Ar’=2,6-C₆H₃-i-Pr （Fel）;Ar =2,6-C₆H₃-i-Pr₂, Ar’= 2,6-C₆H₃-Me₂ （Fe2）;Ar,Ar’= 2,6-C₆H₃-Me₂（Fe3））}) have been synthesized as comparison. Influences of catalyst structure, polymerization conditions and different cocatalysts on ethylene polymerization were investigated to study the catalytic potential of these binuclear iron catalysts. The PE obtained were characterized by DSC, GPC and ¹³C NMR. It was found that modifying the catalyst structure has a great effect on catalytic activity, PE molecular weight and its distribution. Except for Fe4/Al（i-Bu）3 catalytic system, the other binuclear iron catalytic system displayed higher catalytic activity and produced higher molecular weight PE than their corresponding mononuclear iron catalytic system. The molecular weight distribution of PE produced by binuclear iron catalytic systems is broad, even bimodal.2. Fe（acac）3-bis（imino）pyridine/MAO（Al（i-Bu）3） catalytic systemsIn the presence of MAO, Fe（acac）₃ and bis（imino）pyridine will generate active catalytic species in one pot"（in situ） in which ethylene polymerization takes place. These catalytic systems displayed very high catalytic activity and produced high molecular weight. Effects of catalyst composites, polymerization conditions, addition order etc on the polymerization of ethylene. The PE obtained is characterized by DSC, High Temperature GPC and ¹³C NMR spectrum. The results indicate that the polymer are highly linear and crystalline PE with bimodal molecular weight distribution.L4-L6 systems displayed higher catalytic activity than L1-L3 systems.New catalytic systems formed by Fe（acac）₃, bis（imino）pyridine and Al（i-Bu）₃ were used for the polymerization of ethylene. The influences of key factors, such as reaction temperature and Al/Fe molar ratio, on ethylene polymerization were investigated. It was found that Fe（acac）₃-bis（imino）pyridine/Al（i-Bu）₃ system displayed lower catalytic activity than Fe（acac）₃-bis（imino）pyridine/MAO system. The molecular weight distribution of PE obtained are relatively narrow and in the range 3.54-4.26 due to the absence of chain transfer to Al（i-Bu）₃ reaction.3. Methylene bridged binuclearα-Acenaphthenediimine nickel catalystsThree Methylene bridged binuclearα-Acenaphthenediimine nickel complexes ({[2,6-R2-C₆H₃N=C(C₁₀H₆)C=N-（3,5-R’₂）C₆H₂（CH₂）（3,5-R’₂）C₆H₂-N=C(C₁₀H₆)C=N （2,6-R₂）C₆H₃]（NiCl₂）₂ （R,R’=i-C₃H₇ （Ni3）; R=i-C₃H₇, R’=CH₃ （Ni4）;R,R’=CH₃ （Ni5））}) have been synthesized and characterized by FT-IR, elemental analysis and FAB-MS. In addition, two mononuclearα-Acenaphthenediimine nickel complexes (2,6-（i-Pr）₂C₆H₃-N=C(C₁₀H₅)C=N-2,6-（i-Pr）₂C₆H₃NiCl₂（Ni1） and 2,6-Me₂C₆H₃-N=C (C₁₀H₅)C= N-2,6-Me₂C₆H₃NiCl₂ （Ni2）) have been synthesized as comparison. In the presence of MAO, effects of catalyst structure and polymerization conditions on the catalytic activity of these binuclear nickel complexes, PE molecular weight, molecular weight distribution and PE microstructure. The results indicate that catalyst structure have great influence on catalytic activity and PE microstructure like polymerization conditions. The catalytic: activity and PE molecular weight of these five nickel catalysts obey the order of Ni3>Ni1>Ni2>Ni4>Ni5 and Ni3>Ni4>Ni1>Ni5>Ni2 respectively. Furthermore, tuning catalyst structure and polymerization conditions could control the polymerization of ethylene to give PE with different degree of branches.4. Methylene bridged binuclear neural salicylaldimine nickel catalystsOne binuclear neutral salicylaldimnie nickel complex （{[O-（3-Cyclopentenyl）-（5-Me）C₆H₂-o-C（H）=N-2,6-（i-Pr）₂C₆H₂]₂CH₂}[Ni（Ph₃P）（Ph）]₂） （Ni6） have been synthesized and confirmed by elemental analysis and ¹HNMR. In combination with Ni（COD）₂ as phosphate scavenger, binuclear nickel complex displayed high catalytic activity for the polymerization of ethylene. It is noted to that this binuclear nickel complex is able to catalyze ethylene polymerization as single-component catalyst. It maybe due to that micro-chemical environment around the nickel center were changed by the involvement of methylene bridge into catalyst structure, which makes tri-phenylphosphine group easier to leave, resulting in active species to initiate the polymerization of ethylene.更多还原