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综述了烯烃聚合钯催化剂的研究进展,烯烃聚合钯催化剂的配体类型有膦配体、氮配体、碳配体、氧配体、氮-氧配体、膦-氧配体、氮-膦配体等。与齐格勒-纳塔催化剂和茂金属催化剂相比,烯烃聚合钯催化剂具有高催化活性、单活性中心和良好的分子剪裁性等优点,可在分子层次上实现烯烃聚合的分子设计与组装;与铁、钴、镍等后过渡金属催化剂相比,烯烃聚合钯催化剂具有反应条件较温和、催化活性和立体选择性较高的优势。 相似文献
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简要介绍了新型的烯烃聚合催化剂-Ni(Ⅱ)、Pd(Ⅱ)、Fe(Ⅱ)、Co(Ⅱ)类后过渡金属催化剂的发展,特点及催化乙烯聚合机理,并就它们的组成结构、聚合条件和配体体积对聚合产物结构,分子量等的影响根据配体不同分类进行了讨论。 相似文献
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后过渡金属烯烃聚合催化剂研究进展 总被引:5,自引:0,他引:5
烯烃在催化剂的作用下形成聚合物 .改变催化剂的结构 ,可以得到特定分子结构和特定性能的聚烯烃产物 ,因而催化剂的研究开发是聚烯烃升级换代的核心 .烯烃聚合催化剂的发展大致经历了 3个阶段 :Ziegler- Natta催化剂 -茂金属催化剂 -后过渡金属催化剂 .Ziegler[1]和 Natta[2 ]发现了用于各种 α-烯烃聚合的催化剂 ,并已作为主导技术应用于工业化大生产 . 2 0世纪 80年代初 ,Kaminsky等 [3~ 5] 发现 ,二氯二茂锆与烷基铝氧烷组成的体系(茂金属催化剂 )是一种高催化活性、高立体选择性、长寿命的催化剂 .茂金属催化剂的设计、合成和应用 ,… 相似文献
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Oligomerization and Polymerization of Ethylene Initiated by a Novel Ni(Ⅱ)-Based Acetyliminopyridine Complexes as Single-Site Catalysts 下载免费PDF全文
Baojun Zhang Yanji Wang Gang Wang Jun Cao Shukun Sun Lihua Xing Yongcheng Sun Yunguang Han 《天然气化学杂志》2007,16(1)
Novel Ni(Ⅱ)-based acetyliminopyridine complexes 1b, 2b, 3b (1-3b), which are synthesized from ligands 1a, 2a, 3a (1-3a) and [NiCl2(DME)], are suitable precursors for the catalysts that are necessary for ethylene oligomerization and polymerization reactions, activated by methylaluminoxane (MAO).The MAO-treated 1-3b presents an active catalytic center, which may oligomerize and polymerize ethylene to produce linear α-olefins and polyethylene, respectively. The molecular weight distributions of oligomers that are obtained are in good agreement with the Schulz-Flory rules for oligomers>C4. The activity of oligomers show significant reliance on the structures of catalyst precursors. 相似文献
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以β-二酮锆为唯一主催化剂, 以AlEt2Cl和MAO为助催化剂, 使之分别与主催化剂作用形成两种不同功能的催化活性中心, 考察乙烯原位共聚合成支化聚乙烯. 相似文献
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Dr. Wen‐jie Tao Ryo Nakano Dr. Shingo Ito Prof. Kyoko Nozaki 《Angewandte Chemie (International ed. in English)》2016,55(8):2835-2839
The replacement of precious metals in catalysis by earth‐abundant metals is currently one of the urgent challenges for chemists. Whereas palladium‐catalyzed copolymerization of ethylene and polar monomers is a valuable method for the straightforward synthesis of functionalized polyolefins, the corresponding nickel‐based catalysts have suffered from poor thermal tolerance and low molecular weight of the polymers formed. Herein, we report a series of neutral nickel complexes bearing imidazo[1,5‐a]quinolin‐9‐olate‐1‐ylidene (IzQO) ligands. The Ni/IzQO system can catalyze ethylene polymerization at 50–100 °C with reasonable activity in the absence of any cocatalyst, whereas most known nickel‐based catalysts are deactivated at this temperature range. The Ni/IzQO catalyst was successfully applied to the copolymerization of ethylene with allyl monomers to obtain the corresponding copolymers with the highest molecular weight reported for a Ni‐catalyzed system. 相似文献
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A series of new nickel(Ⅱ)complexes with 2-aminomethylpyridine ligands,(2-PyCH_2NHAr)_2NiBr_2(Ar=2,6- dimethylphenyl 2a;2,6-diisopropylphenyl 2b,2,6-difluorophenyl 2c),have been synthesized and used as catalyst precursors for ethylene polymerization in the presence of methylaluminoxane(MAO).The catalysts containing ortho-alkyl-substituents afford high molecular weight branched polyethylenes as well as a certain amount of oligomers.Enhancing the steric bulk of the alkyl substituent of the catalyst resulted... 相似文献
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Ding-Ding Zhao Yan-Hui Hou Ke-Ning Zong Mi-Mi Cui Bin-Yuan Liu Min Yang 《高分子科学》2021,39(12):1581-1589
In order to promote development of linear/branched block polyethylenes based on new catalytic systems,we synthesized a novel α-diimine nickel(Ⅱ) complex with isopropyl substituents on ortho-N-aryl and hydroxymethyl phenyl substituents on para-N-aryl structures.The activity of α-diimine nickel(Ⅱ) catalyst was 3.02×106 g·molNi-1·h-1 at 70 ℃,and resultant polyethylene possessed 135/1000C branches.The linear/branched block polyethylenes were synthesized from ethylene polymerization catalyzed by the α-diimine nickel(Ⅱ) complex/bis(phenoxy-imine) zirconium in the presence of diethyl zinc.With the addition of ZnEt2 (from 0 to 400),the melting peak of resultant polyethylene changed from a single melting peak to bimodal melting peaks.The molecular weights of resultant polyethylene ranging from 26.8 kg/mol to 17.1 kg/mol and PDI values varying gradually from 24.4 to 15.2 were obtained via adjusting ZnEt2 equiv.and molar ratio of two catalysts.In addition,the branching degree of the polyethylene increased from 13/1000C to 56/1000C with the increase of the proportion of α-diimine nickel(Ⅱ) catalyst.Using this binary catalyst system,the reaction temperature of chain shuttling polymerization can be carried out at 70 ℃,which is more conducive to industrial application. 相似文献
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乙烯齐聚合成线性α-烯烃镍系催化剂 总被引:5,自引:0,他引:5
利用SHOP型工艺由乙烯齐聚制备线性α-烯烃不仅具有工业应用价值,而且具有很高的学术意义。SHOP型工艺的工业化引起了人们对基于P∩O配位型及其他配位型镍催化剂的广泛的研究兴趣。镍系催化剂具有活性高、选择性好、产品分布可调、反应条件温和等优良性能。本文介绍了镍系催化剂的类型和性能等,并对影响催化性能的因素进行了分析。 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14864-14868
The transition‐metal‐catalyzed copolymerization of olefins with polar functionalized co‐monomers represents a major challenge in the field of olefin polymerization. It is extremely difficult to simultaneously achieve improvements in catalytic activity, polar monomer incorporation, and copolymer molecular weight through ligand modifications. Herein we introduce a polyethylene glycol unit to some phosphine‐sulfonate palladium and nickel catalysts, and its influence on ethylene polymerization and copolymerization is investigated. In ethylene polymerization, this strategy leads to enhanced activity, catalyst stability, and increased polyethylene molecular weight. In ethylene copolymerization with polar monomers, improvements in all copolymerization parameters are realized. This effect is most significant for polar monomers with hydrogen‐bond‐donating abilities. 相似文献
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Stefan Mecking 《Macromolecular rapid communications》1999,20(3):139-143
Ethylene is polymerized by heterobimetallic combinations of early and late transition metal catalysts. Dual combinations of zirconocenes and cationic nickel and iron catalysts with multidentate nitrogen‐donor ligands are described. Reactor blends of linear and branched ethylene homopolymers are obtained. With zirconocene / nickel complex catalyst combinations, addition of hydrogen selectively reduces the molecular weight of the linear polyethylene formed by the metallocene catalyst. 相似文献
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Timo V. Laine Kristian Lappalainen Jonas Liimatta Erkki Aitola Barbro Lfgren Markku Leskel 《Macromolecular rapid communications》1999,20(9):487-491
Three pyridylimine based complexes of NiII and CoII were reacted with methylaluminoxane (MAO) and tested as catalysts in ethylene polymerization. The two nickel catalysts produced mainly methyl branched polymers with good to moderate activity, while the cobalt compound showed only marginal activity. Reaction conditions strongly affect the polymer properties, such as molecular weight, melting temperature, degree of branching, and chain end unsaturation type. 相似文献
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JianjunYi XugengHuang WeiZhang XiaoyuHong ZhenhuaJing 《天然气化学杂志》2003,12(2):98-104
Several nickel complexes [N,N]NiBr2, in which IN,N] indicates bidentate nitrogen-containing ligands (1: [N,N]=N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine (Cl8H22N2); 2: N-(2,6-diisopropylphenyl)-6-methylpyridine-2-carboxaldimine (C19H24N2); 3: N-(2,4,6-trimethylphenyl)pyridine-2-carboxaldimine(Cl5Hl6N2); 4: N-(2,4,6-trimethylphenyl)-6-methylpyridine-2-carboxaldlmlne (Cl6Hl8N2) were synthesized. Some of the nickel complexes exhibit high activity for ethylene oligomerization in the presence of an organoaluminum activator. The main factor affecting the activity and the structure of oligomers is the steric effect of substituents on [N,N] ligands. Methylaluminoxane (MAO) -activated catalysts showed higher activities and produced oligomers with higher molecular weight than Et2AlCl-activated ones. The oligomerization in toluene rather than hexane results in much higher activity, and the oligomers produced in toluene have relatively high molecular weight. With activation of MAO or Et2AlCl,the [N,N]NiBr2 system tended to produce highly branched oligomers with low α-olefin content, but the α-olefin content could be increased by changing the reaction conditions. 相似文献