新型多核苊二亚胺镍配合物复合负载催化剂催化乙烯聚合

制备了两种多核苊二亚胺镍配合物N imL1C l2m和N imL2C l2m,并将其负载于M gC l2和S iO2上制备复合载体催化剂,与通用烷基铝组成新的催化体系催化乙烯聚合。研究结果表明,在A lE t2C l为助催化剂的条件下,两种多核苊二亚胺镍配合物能高效催化乙烯进行聚合,制得不同支链的各种支化聚乙烯;聚合条件对乙烯聚合活性和产物性能有较大的影响。制得产物的支链使聚乙烯的熔融峰变宽,并且支化度越高,熔融峰越宽。     

Synthesis of stereoblock poly(methyl methacrylate) via transformation of isotactic-specific living polymer anion to syndiotactic-specific anion

Polymerization of methyl methacrylate (MMA) by isotactic poly(methyl methacrylate) (PMMA) living anion, prepared with t-C₄H₉MgBr in toluene at ?60°C, was carried out at ?78°C in the presence of trialkylaluminiums (R₃Al; R = CH₃, C₂H₅, and n-C₄H₉) to obtain a stereoblock PMMA, isotactic PMMA-block-syndiotactic PMMA. Among the R₃Als, (CH₃)₃Al gave most effectively the steroblock PMMA with narrow molecular weight distribution. The fraction of rr triad in the syndiotactic PMMA block increased with increase in the ratio of Al/Mg and reached about 76% at a ratio of Al/Mg ≥ 6. The method was also used to prepare stereoblock copolymer comprising isotactic PMMA block and syndiotactic block of butyl methacrylate. Stereocomplex formation and solution viscosity of the stereoblock PMMA were also studied.     

Active sites deterioration of MgCl2‐supported catalyst induced by the electron donor extraction by alkylaluminium

To investigate the role of the internal donor in a Ziegler–Natta catalyst, the nature and existing states of the internal donor were intentionally varied by alkylaluminium treatment before polymerization, and the catalytic properties during propene polymerization were accurately evaluated using the stopped‐flow method. A significant decrease in the amount of the remaining internal donor was observed during the initial stage of the extraction. The polymerization results show a gradual decrease in the polymer isotacticity with an increase in the extraction time. These different patterns, as a function of the extraction time, indicate that the amount of the remaining internal donor is not directly related to the isotacticity of the produced polymer. © 2002 Society of Chemical Industry     

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。     

烷基铝在独山子石化公司装置中的应用

结合中国石油独山子石化公司聚乙烯(PE)、聚丙烯(PP)和顺丁橡胶(BR)装置的实际工况和工艺特点,介绍了三正辛基铝(TNOA)、三乙基铝(TEA)和三异丁基铝(TIBA)在相应的PE,PP和BR装置上的工业应用情况、经验及注意事项,并对烷基铝质量以及使用中的安全问题进行了讨论,为烷基铝在工业上安全、高效地应用提供了参考。     

烷基铝对TiCl_x/MgCl_2/THF催化剂作用的研究 Ⅰ.催化中间体的研究及烷基铝对催化剂结构的影响

制备了MgCl2/THF(THF为四氢呋喃)催化中间体及一系列不同烷基铝处理的TiClx/MgCl2/THF体系Ziegler-Natta催化剂,并采用XRD,SEM,XPS等手段对试样的晶相、形貌、化学结构进行了表征,初步探讨了烷基铝种类对催化剂结构的影响。实验结果表明,由于烷基铝的作用,催化剂的表面形态、晶相结构及化学结构均发生了明显的改变,特别是烷基铝预还原过程对催化剂的结构影响较大。烷基铝破坏了Mg(OC4H8)xCly的晶相结构,致使催化剂表面细小粒子数增多;另一方面,催化剂中Mg 2p结合能的增幅较大,说明Mg周围的电子云密度降低,进一步佐证了烷基铝破坏MgCl2与给电子体THF的结合。