SiO2负载二亚胺镍/TiCl4催化乙烯聚合

合成了配合物N,N'-二[4-(4-氨基-3,5-二乙基苄基)-2,6-二乙基苯基]苊二亚胺二氯化镍(NiLCl2),将其与TiCl4复合负载在SiO2/MgCl2上制得负载催化剂.研究了该负载催化剂对乙烯聚合的催化活性, 考察了聚合条件对聚合反应及产物结构的影响.结果表明,负载的NiLCl2/TiCl4较之未负载的NiLCl2催化活性高,最高催化活性达到552 kg/(mol·h),而聚合需要的n(Al)/n(Ni)也较相应的NiLCl2低.     

含［N,O］配体的镍配合物/烷基铝催化甲基丙烯酸甲酯的聚合

制备了两种镍配合物二［N-(2-氧基-1-萘甲醛)缩-2,6-二异丙基苯胺］合镍［Ni(L₁)₂］和二［N-(2-氧基-1-萘甲醛)缩-邻甲基苯胺］合镍［Ni(L₂)₂］。研究了它们以普通烷基铝为助催化剂催化甲基丙烯酸甲酯(MMA)的聚合。结果表明,镍配合物的结构、聚合条件如单体浓度、Al与Ni物质的量比、聚合温度和聚合时间等对甲基丙烯酸甲酯聚合反应活性有很大的影响，当甲基丙烯酸甲酯浓度为0.8 mol·L^-1、n(Al)∶n(Ni)=400、温度为0 ℃时,催化活性达到110.7 kg-PMMA·(mol-Ni·h)^-1。随着聚合时间的延长，催化活性下降，而转化率则随着聚合时间的延长而缓慢增加。     

乙烯/1-己烯共聚合用苊二亚胺镍/TiCl4催化体系

合成了一种苊二亚胺镍配合物,以不同比例与TiCl4复合负载在SiO2/MgCl2载体上,制得4种催化剂,研究了它们对乙烯/1-己烯共聚合的催化性能.结果发现,复合负载催化剂对共聚合催化活性可达到78.2 kg/mol·h.催化乙烯共聚合可制得含不同长度支链的聚乙烯,其中以丁基支链为主,占45.3%,长支链占18.7%,这有利于改善聚乙烯的加工性能.     

α-二亚胺镍催化剂催化乙烯合成中黏度聚乙烯油的研究

为了合成高黏温性能和低温流动性的中黏度聚乙烯油,本研究以α-二亚胺镍配合物为主催化剂,催化乙烯齐聚反应合成聚乙烯油,主要研究了在一氯二乙基铝为助催化剂作用下,主催化剂用量、反应温度、反应压力、铝镍比等条件对催化性能及产品物性的影响,并采用了核磁碳谱、氢谱分别对聚乙烯油进行了表证,结果表明：聚乙烯油的长支链(>C₆)含量达到14%,倾点可以达到-36℃,同时催化剂用量的增加导致催化剂活性的降低,聚乙烯油的黏度和倾点也同样降低,压力的增加导致催化剂活性升高,当压力在0.15 MPa时,活性达到最高0.12×10⁶ g/(mol-cat·h),当聚乙烯油合成由1 L放大至20 L时,催化剂的活性,聚乙烯油黏度均与小试存在一定的差距,表明在放大过程中存在一定的放大效应。     

镍二亚胺配合物催化乙烯与丙烯酸甲酯共聚合

合成了一种新型后过渡金属络合物——镍二亚胺配合物,并以蒙脱土为载体,制备了蒙脱土载体镍催化剂,在甲基铝氧烷(MAO)、三乙基铝(TEA)和三正辛基铝(TNOA)对丙烯酸甲酯分子中的极性基团保护下,用MAO和TEA作助催化剂催化乙烯-丙烯酸甲酯(E-MA)共聚合,考察了催化剂配体、载体化、聚合条件等对催化剂催化E-MA共聚合的影响。结果表明:随保护剂的不同,催化剂的活性从大到小依次为TEA,MAO,TNOA;适宜条件下,该络合物催化活性可达576kg/(mol·h),负载后的催化剂改善了共聚物形态。     

合成弹性体的α-二亚胺镍配合物研究进展

α-二亚胺镍催化剂作为一种后过渡金属配合物,具有独特的“链行走”机理,不仅可以将乙烯转化为高度支化的聚烯烃弹性体,而且只需改变配体结构和反应条件就能有效控制聚合物的微观结构。本综述以合成聚烯烃弹性体为目的,介绍了α-二亚胺镍配合物近五年的最新进展。     

α-二亚胺氯化镍/mMAO/AlR3制备支化聚乙烯

介绍了用2,6-二异丙基苯基苊二亚胺氯化镍／改性甲基铝氧烷(mMAO）催化乙烯制备支化聚乙烯(PE),讨论了mMAO中三甲基铝(TMA)含量、外加三异丁基铝(TIBA)以及铝镍摩尔比对催化活性,PE相对分子质量、熔点、支化度及支链类型的影响。PE的核磁共振碳谱表明,当mMAO中TMA摩尔分数小于20％时,产物的支链绝大多数为甲基支链;TMA摩尔分数增大,PE支化度增大,长支链增多;外加TIBA导致产物的长支链(支链长度大于或等于6)增多。     

新型双核α-苊二亚胺镍催化剂合成及其催化乙烯聚合

通过控制schiff碱缩合反应合成了三个桥联的α-苊二亚胺,进一步与无水氯化镍反应得到了新型双核桥联α-苊二亚胺镍催化剂,配体与催化剂经过1HNMR和质谱表征。在甲基铝氧烷(MAO)的存在下,显示出较高的催化活性,所得聚合物经GPC,DSC,13CNMR表征,结果显示聚合物具有较高的分子量,较低的熔点,以及较高的支化度。     

水杨醛亚胺镍配合物的合成及其催化双环戊二烯聚合的研究

近年来,用含电负性杂原子的配体代替茂基来稳定过渡金属离子活性中心的研究取得较大进展,其中含(N,O)螯合配体的后过渡金属催化剂与前过渡金属催化剂相比,具有易于制备、对极性物质的耐受性好和能催化烯烃与极性单体的共聚等特点,因此,含(N,O)螯合配体的后过渡金属催化剂的研究已成为聚烯烃领域的一大热点[1-6].     

烯烃聚合用耐热型(α-二亚胺)镍催化剂的进展

(α-二亚胺)镍催化剂可以高效地催化乙烯聚合得到高相对分子质量及不同拓扑结构的聚乙烯,但其耐热性能差,在温度不高于60.0℃时会迅速分解,而且随着聚合温度的升高,聚乙烯的相对分子质量通常会下降,限制了该催化剂在工业生产中的应用。通过对与N相连的苯环或者α-二亚胺的骨架结构进行修饰,制备了一系列耐热型(α-二亚胺)镍催化剂。(α-二亚胺)镍催化剂的热稳定性不仅受苯环上取代基及α-二亚胺骨架位阻的影响,也与金属中心周围的空间结构有关。     

Preparation of highly branched polyethylene using (α‐diimine) nickel complex covalently supported on modified SiO2

Bis(4‐(4‐amine‐3,5‐diisopropylbenzyl)‐2,6‐diisopropylphenylimino) acenaphthene NiBr₂ (Catalyst I) was synthesized. The complex covalently supported on Et₃Al‐treated silica (SC) and used for ethylene polymerization was produced with cocatalyst of common inexpensive alkylaluminum compounds. Polyethylenes (PEs) with branching numbers of 12.94 (1000C) to 116.02 (1000C) were prepared in heptane. The polymerization conditions, such as the cocatalyst, Al/Ni ratio, and temperature, had significant effects on catalytic activity and properties of polyethylenes. Confirmed by high‐temperature ¹³C NMR, the polyethylenes synthesized contain significant amounts of not only methyl but also ethyl, propyl, butyl, pentyl, and other long branches (longer than six carbons). The branching degree of polyethylenes increased with temperature, while their molecular weight and melting point decreased correspondingly, resulting in linear semicrystalline to totally amorphous polymers. The formation of the branches could be illustrated by the chain walking mechanism, which controlled their specific spacing and conformational arrangements with one another. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 103: 1483–1489, 2007     

Synthesis of branched polyethylene by ethylene homopolymerization with a novel (α‐diimine)nickel complex in the presence of methylaluminoxane

Branched polyethylene (PE) was prepared with a novel (α‐diimine)nickel(II) complex of 2,3‐bis(2,6‐dimethylphenyl)‐butanediimine nickel dichloride {[2,6‐(CH₃)₂C₆H₃? N?C(CH₃)C(CH₃)?N? 2,6‐(CH₃)₂C₆H₃]NiCl₂} activated by methylaluminoxane in the presence of a single ethylene monomer. The influences of various polymerization conditions, including the temperature, Al/Ni molar ratio, Ni catalyst concentration, and time, on the catalytic activity, molecular weight, degree of branching, and branch length of PE were investigated. According to gel permeation chromatography, the weight‐average molecular weights of the polymers obtained ranged from 1.7 × 10⁵ to 6.0 × 10⁵, with narrow molecular weight distributions of 2.0–3.5. The degree of branching in the polymers rapidly increased with the polymerization temperature increasing; this led to highly crystalline to totally amorphous polymers, but it was independent of the Al/Ni molar ratio and catalyst concentration. At polymerization temperatures greater than 20°C, the resultant PE was confirmed by ¹³C‐NMR to contain significant amounts of not only methyl but also ethyl, propyl, butyl, amyl, and long branches (longer than six carbons). The formation of the branches could be illustrated by the chain walking mechanism, which controlled their specific spacing and conformational arrangements with one another. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1123–1132, 2002; DOI 10.1002/app.10398     

Ethylene polymerization with hybrid nickel diimine/Cp2TiCl2 catalyst: a new method to prepare blends of linear and branched polyethylene

Blends of linear polyethylene (LPE) and branched polyethylene (BPE) display very good mechanic properties that can be beneficial for various applications such as shear thinning and melt elasticity. LPE, BPE and amorphous polyethylene can be produced using nickel diimine (DMN) catalyst under various polymerization conditions, while LPE can be obtained using metallocene catalyst. Thus, LPE/BPE blends can be achieved by in situ polymerization using a hybrid DMN/metallocene catalyst. A novel hybrid catalyst made of DMN and Cp₂TiCl₂ was designed and used for ethylene polymerization. A synergistic effect of the two active sites in the hybrid DMN/metallocene catalyst was observed. Blends of linear and low branched polyethylene were synthesized when polymerization was conducted at low temperature (0 °C), while blends of linear and highly branched polyethylene were obtained at high temperature (50 °C). However, the miscibility of the polymers obtained at 50 °C was dramatically reduced as compared to those obtained at 0 °C. Mesoporous particles (MCM‐41) consisting of aluminosilicate with cylindrical pores were used to support the hybrid catalyst, in which MCM‐41 provides sufficient nanoscale pores to facilitate the polymerization in well‐controlled confined spaces. Blends of LPE and BPE were synthesized by in situ polymerization without adding comonomer and characterized. The miscibility of the polymer blends can be improved by supporting the hybrid catalyst on MCM‐41. Copyright © 2009 Society of Chemical Industry     

Ethylene polymerization with iron‐based diimine catalyst supported on MCM‐41

A mesoporous molecular sieve MCM‐41 supported iron‐based diimine catalyst ( MC ) was prepared for the first time. The kinetic behavior of ethylene polymerization with MC was studied. The effects of Al/Fe molar ratio and various cocatalysts on the catalytic activity and properties of the polyethylene obtained were investigated. The results showed that good catalytic activities can be reached with cocatalyst methylaluminoxane (MAO) and triethylaluminium (TEA). Ethylene polymerization with MC gave polymers with higher molecular weight, melting temperature and onset temperatures of decomposition (T_onset) and better morphology than those obtained with the corresponding homogeneous catalyst. Copyright © 2004 Society of Chemical Industry     

二氧化碳和丙烯直接合成甲基丙烯酸Ni2(OCH3)2/SiO2催化剂的研究

采用表面改性法制备了负载型Ni2(OCH3)2／SiO2双核金属甲氧基配合物催化剂，利用IR、DSC、TPD和微反技术对催化剂的表面结构、化学吸附性质和催化活性进行了研究。结果表明，负载型双核金属甲氧基配合物Ni2(OCH3)2／SiO2中Ni^2 与载体SiO2表面O^2-以双齿配位形式键合；二氧化碳在催化剂表面存在桥式吸附态和甲氧碳酸酯基物种两种吸附态，丙烯则只有一种吸附态；在适宜反应条件下，CO2和丙烯在Ni2(OCH3)2／SiO2催化剂上可以高选择性地合成甲基丙烯酸，反应物分子共吸附于催化剂表面同一活性单元以及羧酸根与丙烯解离吸附态的形成是反应顺利进行关键因素．     

Unsymmetrical α‐diimine nickel (II) complex with rigid bicyclic ring ligand: Synthesis,characterization, and ethylene polymerization in the presence of AlEt2Cl

Unsymmetrical α‐diimine ligand 1 was successfully synthesized via condensation of trimethylaluminum (TMA) metalated 2‐methyl‐6‐isopropyl‐aniline with rigid bicyclic aliphatic diketone camphorquinone. Syn‐ and anti‐stereoisomers were detected by ¹³C NMR in the condensation product. The corresponding α‐diimine nickel (II) complex 1 was prepared from the exchange reaction of (DME)NiBr₂ with the ligand 1 , and displayed high activity for ethylene polymerization in the presence of diethylaluminum chloride (AlEt₂Cl). The resultant polymers were confirmed by gel permeation chromatography and ¹³C NMR characterization to be broad molecular weight distribution polyethylene with various branches, and high degree of branching, even at low polymerization temperature ?10°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The influence of the preparing conditions of SiO2 supported Cp2ZrCl2 catalyst on ethylene polymerization

In this work, ethylene was polymerized by using Cp₂ZrCl₂ supported on silica pretreated with methylaluminoxane (MAO) as the catalyst system. The influence of the conditions for the preparation of the heterogeneous catalyst, such as temperature, washing method of the catalytic solid, MAO and metallocene concentration in the support treatment, time of MAO, and metallocene immobilization on the support, type of alkylaluminum used in the support pretreatment, and calcination temperature of the support were investigated. Aluminum and zirconium content fixed on the silica surface were determined by inductively coupled plasma emission spectroscopy. Polymer characteristics were determined by gel permeation chromatography and differential scanning calorimetry. According to the results, the activity of some supported catalysts were far higher than with the homogeneous system. Moreover, polyethylene with very high molecular weights were also obtained and with molecular weight distribution larger than those produced with the homogeneous precursor. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2054–2061, 2002     

复合ZrO_2载体负载Pt催化剂催化燃烧VOCs性能

采用共沉淀法制备复合ZrO_2载体,然后负载Pt制得催化剂,用于催化燃烧处理VOCs。采用BET、XRD和H2-TPD等对制备的复合ZrO_2载体和催化剂进行表征。结果表明,ZrO_2掺杂后有利于提高载体比表面积,改善载体结构。对甲苯进行催化燃烧实验,反应温度230℃时,甲苯转化率大于99.5%。考察制备的催化剂对鞋厂尾气催化处理能力,转化率均大于99.5%。     

超细镍基负载型催化剂成型工艺条件研究

以正硅酸乙酯、钛酸丁酯、硝酸镍为主要原料,采用溶胶-凝胶法(Sol-gel)实验室放大制备10 kg工业中试用催化剂粉料，加胶粘剂A进行挤条成型。催化剂前躯体的物化性能用BET、XRD、TG-DTA、TEM及强度测试仪进行表征，用固定床连续流动微反装置，考察催化剂苯加氢生成环己烷的催化性能。研究结果表明，催化剂的强度随胶粘剂的含量增大而增大，当胶粘剂含量达到13％时，NiO/SiO₂-TiO₂体系产生了新的晶相。胶粘剂的含量对催化剂的催化性能影响很小，该催化剂应用于苯加氢制环己烷实验中，苯转化率均为100％，环己烷的选择性均达到99.0％以上。     

Ethylene polymerization using a novel MgCl2/SiO2‐supported Ziegler–Natta catalyst

A novel MgCl₂/SiO₂‐supported Ziegler–Natta catalyst was prepared using a new one‐pot ball milling method. Using this catalyst, polyethylenes with different molecular weight distributions were synthesized. The effects of the [Si]/[Mg] ratio, polymerization temperature and [Al]/[Ti] ratio on the catalytic activity, the kinetic behaviour and the molecular weight and the polydispersity of the resultant polymer were studied. It was found that the polydispersity index of the polymer could be adjusted over a wide range of 5–30 through regulating the [Si]/[Mg] ratio and polymerization temperature, and especially when the [Si]/[Mg] ratio was 1.70, the polydispersity index could reach over 25. This novel bi‐supported Ziegler–Natta catalyst is thus useful for preparing polyethylene with a required molecular weight distribution using current equipment and technological processes. Copyright © 2005 Society of Chemical Industry