共查询到18条相似文献,搜索用时 78 毫秒
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采用相同的工艺,制备了含有不同内给电子体[2-甲基-2-丙基-1,3-二甲氧基丙烷、2,2-二异丁基-1,3-二甲氧基丙烷(BIBIMP)、邻苯二甲酸二异丁酯]以及不含内给电子体的MgCl2负载型Ziegler-Natta催化剂,研究了给电子体结构对催化剂活性的影响以及用该催化剂合成的聚1-丁烯(PB)的等规指数、熔点、相对分子质量及其分布。结果表明:未加入外给电子体时,加入BIBIMP的催化剂活性最高,用其所制PB的等规指数最高,分别为539 g/g和84%;加入氢气可进一步提高催化剂活性和PB等规指数;加入外给电子体后,催化剂的活性均降低,二醚类Z-N催化剂活性降低最多,而使用二异丙基二甲氧基硅烷为外给电子体更有助于提高PB的等规指数。 相似文献
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制备和分析了不同粒径催化剂及其催化聚合物,研究了球形MgCl_2载体催化剂在乙烯聚合过程中的催化性能和动力学行为。结果表明:大颗粒催化剂的聚合过程中明显存在传热和传质阻力;一定的预聚合可以改善聚合物的形态和堆密度。 相似文献
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MgCl2-supported CoBr2 catalysts were prepared from mixture of MgCl2 and CoBr2L2 (L = triphenylphosphine or pyridine) in toluene. Polymerization of 1,3-butadiene was conducted over the catalysts combined with ordinary alkylaluminums as cocatalyst. The CoBr2(PPh3)2/MgCl2 catalyst gave polybutadiene with approximately 80% of 1,2 units, whereas cis-1,4-poly-butadiene was obtained with the CoBr2(C5H5N)2/MgCl2 catalyst. Addition of triphenylphospine to the latter catalyst caused a marked increase in the content of 1,2 units. The content of 1,2 units could be thus controlled in the range from 0 to 80% by changing the amount of triphenylphosphine. On the other hand, the CoBr2(PPh3)2/MgCl2 catalyst with very low content of CoBr2(PPh3)2 hardly displayed any activity. Addition of dimethoxydiphenylsilane to the catalyst gave polybutadiene containing 90 % of 1,2 units with a fairly high activity. 相似文献
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A novel MgCl_2-supported Ziegler-Natta catalyst containing diethyl diisopropylsuccinate donor was pre- pared and propylene polymerizations with the combination of such catalyst and four external donors were inves- tigated in detail.The catalyst was compared with a commercial one with phthalate as internal donor in terms of catalytic activity,hydrogen sensitivity and stereospecificity in propylene polymerization.The molecular weight, molecular weight distribution and microstructure of the produced polypropylenes were compared also.It was found that the novel catalyst containing succinate internal donor showed higher activity and higher stereospecificity than those with phthalate as internal donor.Consequently,polypropylenes obtained by the succinate-based catalyst showed high molecular weight,high melting temperature,high isotactic index and broad molecular weight distribu- tion than those obtained with the commercial catalyst. 相似文献
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The influence of different aluminum alkyls (diethylaluminum chloride, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum and isoprenylaluminum) on the ethylene polymerization activity of a laboratory prepared high-activity SiO2/MgCl2-supported TiCl4 catalyst has been investigated. A slurry reactor (decane diluent) was used for measuring rates of polymerization. The average molar mass, the breadth of the molar mass distribution, the polymerization activity, and the shapes of the activity-time profiles, were strongly dependent on the nature of the aluminum alkyl. For several of the cocatalysts used, the catalytic activity approached a constant value after a certain amount of time under reaction conditions. In this constant activity region, a first-order dependence of the polymerization rate on the monomer concentration was found for all of the systems examined. However, the activation energy of the polymerization reaction was found to depend strongly on the type of cocatalyst which was used. 相似文献
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Summary The MgCl2 supported TiCl3 catalyst was prepared by grinding the mixture of TiCl3·3Py and MgCl2 in a ball mill. The catalyst was treated either i.vac. at 50–200°C or with alkylaluminum halides to remove the residual pyridine, and propylene polymerization was conducted at 65°C using the resulting catalysts combined with triethylaluminum. The catalyst treated with diethylaluminum chloride showed an extremely high activity for the polymerization. 相似文献
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球形氯化镁载体是氯化镁基齐格勒-纳塔催化剂的一种高效载体,尤其适用于丙烯聚合催化剂的制备,对于催化剂及聚合物的形态和性能有重要影响。球形氯化镁载体制备技术是此类催化剂开发过程中的核心技术之一。本文论述了氯化镁作为催化剂载体的优势,分析了研磨活化和化学活化对氯化镁性能的影响,并详细介绍了高速搅拌法、细管挤出法、喷雾成型法、剪切乳化法和超重力法等球形氯化镁载体制备技术的特点,指出在氯化镁载体制备过程中的关键控制因素是对乳液混合过程的强化,良好的乳液混合是制备形貌规整、粒径分布窄的氯化镁球形载体的先决条件。 相似文献
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TiCl4/SiO2负载型催化剂用于丁二烯聚合Ⅱ.聚合条件及聚合动力学 总被引:1,自引:1,他引:0
使用以球磨法制备的 SiO2负载 TiCl4催化剂进行丁二烯溶液聚合,考察了聚合条件对催化效率的影响以及在 20~ 60℃下的聚合动力学。确定了适宜的聚合条件:以加氢汽油为溶剂, Al/Ti摩尔比为 20, Ti/Bd摩尔比为 2× 10- 4, 50℃聚合 10 h以上。溶液聚合动力学研究结果表明,本体系在低转化率下为稳态聚合,其稳态聚合速率方程为 Rp=kpf[Ti]0[Bd],聚合的表观活化能为 11.4 kJ/mol。 相似文献
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研究开发了一种新型非茂负载聚烯烃催化剂——CpTi(dbm)Cl2/MgCl2/THF,分析了该催化剂的结构特征,研究了该催化剂的乙烯聚合活性与催化剂的组成和结构间的关系。结果表明,用共沉淀方法制备的MgCl2具有较大的比表面积和孔体积。CpTi(dbm)Cl2同MgCl2作用后,催化剂中的CpTi(dbm)Cl2仍保持了原来的化学结构,而活化了的MgCl2也仍然基本保持原有的晶型;载体型催化剂的孔体积和比表面积随着Mg/Ti比的增加而增加;Mg/Ti比影响栽体型催化剂粒子形态、分散性以及催化活性随着Mg/Ti比增加,催化剂的粒子形态和分散性提高,催化活性线性地增加,MgCl2对Ti生成活性中心起良好的化学改性作用。 相似文献