乙烯四聚制1-辛烯催化剂研究进展

介绍了传统乙烯齐聚生产1-辛烯工艺,分析了乙烯四聚反应制1-辛烯机理,叙述了乙烯四聚制1-辛烯铬系催化体系中配体、助催化剂和促进剂的国内外最新进展。认为目前研究热点集中在PNP配体上N原子取代和助催化剂及促进剂的筛选等方面,国内急需解决聚乙烯共聚单体1-己烯和1-辛烯的工业化生产问题。     

乙烯选择性四聚制1-辛烯催化剂及工艺技术研究进展

综述了近年来乙烯选择性四聚制1-辛烯技术的发展现状。介绍了乙烯选择性四聚制1-辛烯催化剂研究的最新进展及发展趋势;重点阐述了影响乙烯选择性四聚制1-辛烯催化体系中的两个重要组分,即助催化剂和配体;从技术和经济方面对比了现有技术制1-辛烯的可行性。     

聚二甲基硅氧烷改性乙烯-1-辛烯共聚物微孔发泡

针对乙烯-1-辛烯共聚物(POE)发泡过程中泡孔易破裂的问题,提出将马来酸酐(MAH)接枝到POE上、然后与多氨基硅油(PDMS-NH2)反应的方法,形成具有支化结构并部分交联的改性POE(POE-PDMS),并以超临界二氧化碳为发泡剂进行微孔发泡,系统考察了上述改性POE的发泡行为及发泡材料压缩性能,结果表明,PDM...     

世界辛烯-1及辛烯-1共聚产品生产现状

概述了全球辛烯-1供需现状及生产技术,介绍了Dow、Nova、DSM等国外大公司以辛烯-1为共聚单体的聚乙烯生产工艺,并较详细地阐述了包括线型低密度聚乙烯(LLDPE)、中密度的耐热增强聚乙烯(PE-RT)、塑性体(POP)和弹性体(POE)等的辛烯-1共聚产品的性能和功能,提出了发展我国辛烯-1及辛烯-1共聚产品研发生产的建议.     

助催化剂在Cr催化剂催化乙烯四聚中的作用

主催化剂铬盐与配体、助催化剂组成的三元催化体系能够较高活性的催化乙烯四聚合成1-辛烯。主要研究了助催化剂种类、用量等对催化活性和1-辛烯选择性的影响,采用合适的助催化剂,1-辛烯的选择性达到70.1%,催化活性达到2.62×106 g/(mol Cr)·h。     

红外光谱在马来酸酐接枝乙烯-1-辛烯共聚物研究中的应用

运用傅里叶红外光谱仪对马来酸酐接枝乙烯-1-辛烯共聚物的结构特征进行测定，并且用半定量法测定了共聚物中马来酸酐的接枝率，有助于指导接枝共聚工艺过程。     

聚丙烯/乙烯-辛烯-1共聚物共混体系流变性能研究

采用高级流变扩展系统(ARES)研究了聚丙烯(PP)/乙烯-辛烯共聚物共混体系的流变性能,探讨了乙烯-辛烯共聚物含量和 PP 种类对共混体系储能模量、剪切黏度和零切黏度的影响。实验结果显示,PP 结构和 POE 含量对 PP/POE 共混体系的剪切流变性能有显著影响,随着 POE 含量的增加,PP1/POE 共混体系的储能模量和剪切黏度增加的幅度明显小于 PP2/POE 共混体系,PP1/POE 共混体系和 PP2/POE 共混体系的储能模量和剪切黏度增加幅度较大分别发生在 POE 含量为20%～30%和10%～20%,即共混体系发生"脆—韧"转变阶段。PP/POE 共混体系中存在界面滑移现象,且 PP 和 POE 的界面相容性对界面滑移现象影响较大,其中 PP1/POE 的界面滑移比PP2/POE 的界面滑移更加明显。     

乙烯四聚用Cr(Ⅲ)系催化剂配体的研究进展

综述了乙烯四聚用Cr(Ⅲ)系催化剂所用的不同类型配体的最新研究进展。其中,效果最好的催化剂的选择性可达91%,活性最高的可达2.94×107 g/(mol·h)。分析了PNP型配体骨架上的N及P原子上所带取代基的种类、位置、空间体积及给电子或吸电子性能对催化剂活性及选择性的影响。介绍了PN-(CH2)n-NP,PNN,NNO,NPN等类型的配体在乙烯四聚研究中的应用情况及特点,指出了乙烯四聚用催化剂实现工业化所需解决的问题。     

乙烯四聚催化体系双膦胺配体的结构与性能

简述了乙烯四聚反应制备1-辛烯催化体系的最新研究进展.指出乙烯四聚制1-辛烯催化体系中配体的结构和电子性是影响催化体系的活性和目的产物1-辛烯的选择性的主要因素.PNP配体中N取代基和P取代基的空间位阻和给电子效应都会对催化体系的活性和1-辛烯选择性产生影响.分析了由于取代基空间体积的增大和电负性的增强均使乙烯的进一步...     

双膦胺配体氮原子上取代基的空间和电子效应对于乙烯四聚催化体系的影响

在乙酰丙酮铬、甲基铝氧烷（MAO）、配体三元催化体系中,以乙烯为原料在高压下齐聚生成1-辛烯．主要考察N原子上取代基不同的PNP配体对催化荆活性及1-辛烯选择性的影响结果表明．苯环取代基为3．5-二甲基的配体效果较为理想,其活性达到4990kg／（mol·h）．对1-辛烯选择性为72．31％。PNP配体中苯环取代基上间、对位给电子基团有助于提高催化活性和1-辛烯选择性．而空间位阻较大的基团和吸电子基团则不利于催化反应。     

Investigation of ethylene/1-octene copolymerization models by carbon-13 NMR

Statistical reaction models have been used to fit C-NMR spectra for ethylene/1-octene copolymers and to describe the polymerization reaction probabilities. Ten models ranging in complexity from a one-site Bernoulli probability to multiple site second-order Markov systems were studied. Model parameters were determined by fitting the experimental integrations of replicated spectra using a maximum likelihood method. The best fit to the experimental NMR spectra was obtained with a two-site model, one site producing mainly high-density polymer following a Bernoulli probability model, while the second site allows more incorporation of octene following a chain-end controlled probability described by first-order Markov statistics. © 1994 John Wiley & Sons, Inc.     

Copolymerization of ethylene and 1-octene by homogeneous and different supported metallocenic catalysts

In this work, the performance of the homogeneous catalyst system based on Et(Flu)₂ZrCl₂/MAO was evaluated on the copolymerization of ethylene and 1-octene. Characteristics of some of the produced polymers were also investigated. A study was performed to compare this system with that of Cp₂ZrCl₂/MAO. The influence of different support materials for the Cp₂ZrCl₂ was also evaluated, using silica, MgCl₂, and the zeolite sodic mordenite NaM. An increase in activity was observed in relation to the comonomer addition for the two homogeneous catalysts. The copolymers produced by the Et(Flu)₂ZrCl₂/MAO system showed higher molecular weight and narrower molecular weight distribution. We verified that the catalyst supported on SiO₂ was the most active one, although the copolymers produced with the catalyst supported on NaM showed higher molecular weight and lower molecular weight distribution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 724–730, 2001     

Solubility of ethylene in 2,2,4-trimethylpentane and 1-octene mixture

With a static type equilibrium cell and the pressure decaying method, the solubility of ethylene in a mixture of 2,2,4-trimethylpentane and 1-octene was measured in the temperature range of 323.15-423.15 K, pressure range of 5-25 bar, and 1-octene concentration from 0 to 85 wt%. The experimental results show that the solubility of ethylene in a 2,2,4-trimethylpentane and 1-octane mixture increases with system pressure but decreases with system temperature.The experimental solubility data were also expressed in the vapor-liquid equilibrium relationship and correlated by the bubble pressure calculation using the Peng-Robinson equation of state (PR EOS) incorporated with the van der Waals one-fluid and the Zhong-Masuoka mixing rules. Among the deviations between the experimental and correlated results, the largest value of average absolute relative deviation is 1.73% for pressure at 423.15 K and that of average absolute deviation is 0.0024 mol fraction for vapor composition at 373.15 K by the Zhong-Masuoka mixing rule.     

序列分布导向的CGC催化乙烯与1-辛烯共聚过程建模

限制几何构型催化剂(constrained geometry catalyst,CGC)特别适用于乙烯与α-烯烃溶液聚合法制备高性能聚烯烃弹性体POE(polyolefin elastomer)。基于CGC催化乙烯与1-辛烯共聚反应机理,建立了乙烯与1-辛烯共聚反应动力学模型并确定了动力学参数。采用前期实验获得的乙烯消耗速率曲线与催化剂平均活性验证了动力学模型的准确性。基于动力学模型和面向序列结构的共聚机理,建立了乙烯与1-辛烯共聚过程序列分布模型。模型可准确预测序列分布与短支链含量及其随反应条件的变化趋势。结果表明,随着1-辛烯浓度的增加,乙烯序列长度逐渐减小,其平均序列长度线性降低,而1-辛烯平均序列平均长度呈线性增加的趋势。所建模型可为从聚合过程角度调控POE链结构提供理论参考。     

小角光散射研究PP／EOC增韧体系

以乙烯 -1-辛烯共聚物 (EOC)对聚丙烯 (PP)进行增韧改性 ,通过小角光散射测取到不同配比的共混物的相关距离 αc、积分不变量Q ,进一步求得分散相粒子表面间距 τ和过渡层厚度d ,研究 τ与材料冲击性能之间的关系 ,发现存在一个临界值 τc与材料的脆韧转变点相对应。当 τ≤τc 时 ,材料是韧性的 ;当 τ>τc 时 ,材料呈脆性。在共混过程中 ,τ随共混时间增加逐渐减小 ,在共混的中后期趋于稳定 ;随 τ值的减小 ,材料冲击强度增加。过渡层厚度d随EOC含量的递增逐渐增大 ,对应材料的冲击强度增加。     

13C-NMR study of ethylene/1-hexene and ethylene/1-octene copolymers obtained using homogeneous catalysts

Summary This study employed the ¹³C-NMR spectroscopy to investigate the influence of the increase of the comonomer concentration on the microstruture of ethylene/1-hexene and ethylene/1-octene copolymers obtained by the use of MeSiCp₂ZrCl₂, Cp₂ZrCl₂, Et[Ind]₂ZrCl₂ and [Ind]₂ZrCl₂ catalysts. For both comonomers butyl or hexyl branches were isolated between ethylene blocks. As the -olefin concentration in the copolymer increased, butyl or hexyl branches became closer, some of them, separated by only one or two ethylene units. Incorporation of -olefin in the copolymer was higher for the bridged catalysts, MeSiCp₂ZrCl₂, and Et[Ind]₂ZrCl₂ than for the unbridged ones. The -olefin size did not seem to effect its reactivity towards ethylene.     

With different structure ligands heterogeneous Ziegler-Natta catalysts for the preparation of copolymer of ethylene and 1-octene with high comonomer incorporation

Comparison with the conventional Ziegler-Natta catalyst TiCl₄/MgCl₂ (I), the modified supported Ziegler-Natta catalysts (iso-PentylO)TiCl₃/MgCl₂ (II) and (BzO)TiCl₃/MgCl₂ (III) were prepared as efficient catalysts for copolymerization of ethylene with 1-octene. The complexes (II) and (III) were desirable for the production of random ethylene/1-octene copolymers coupled with higher molecular weight, higher comonomer incorporation within copolymer chain and good yield even at high temperature 80 ^°C and fairly low Al/Ti molar ratio of 100. The effects of catalysts ligands, Al/Ti molar ratio, polymerization temperature, as well as concentration of 1-octene on the catalytic activity, molecular weight and microstructure of the copolymer were investigated in detail. The structure and properties of the copolymers were characterized with ¹³C NMR, GPC, DSC and WAXD. The kinetic results also indicate that these catalysts (II) and (III) show higher catalytic activity and the produced polymers feature higher molecular weight, because of lower ratio of K_trm/K_p and K_tra/K_p, and higher ratio of K_tra/K_trm which indicates that chain transfer to cocatalyst is predominant.     

The effect of the ethylene pressure on its reaction with 1-hexene, 1-octene and 4-methyl-1-pentene

Summary Copolymers of ethylene and 1-hexexe, 1-octene and 4-methyl-1-pentene were obtained using Et[In]₂ZrCl₂/MAO catalyst at various pressures. The increase of 1-hexene and 1-octene concentration in the feed increases catalyst activity(g/nZr.h.bar) and productivity(g/nZr.h). For 4-methyl-1-pentene the activity is independent on comonomer concentration. Increasing the ethylene pressure the productivity of the copolymerization increases and the activity shows a weak decay. Characterization of the copolymer shows that at higher pressure the cristallinity of the copolymers is higher due to lower comonomer incorporation. There is a good linear correlation of cristallinity with comonomer concentration in the feed for 1-hexene and 1-octene at a fixed pressure, but not for 4-methyl-1-pentene.