茂金属／Z—N复合型聚乙烯催化剂

茂金属催化剂和Z—N催化剂结合在一起制成的新型复合催化剂具有双活性中心,用于乙烯聚合可得到双峰分子量分布的聚乙烯,并且聚乙烯具有优良的综合物理性能和加工性能。新型复合催化剂以氯化镁为载体,以茂金属化合物和四氯化钛为双活性中心,解决了茂金属载体化后聚合活性大幅度下降的难题,相对地减少了助催化剂甲基铝氧烷的用量,克服了由茂金属催化剂制备的聚合物分子量分布窄、加工困难的弱点,为茂金属催化剂的开发应用开辟了新途径。     

茂锆金属催化剂催化乙烯聚合研究

主要考察了含锆的茂金属催化剂中催化乙烯反应条件优化研究,在最优条件下催化聚合反应所得的产物与吉林石化公司聚乙烯厂聚乙烯产品进行分析对比.对茂锆金属催化剂催化乙烯聚合反应条件研究表明,适宜的助催化剂[Al]与主催化剂[Cat]的摩尔比在1 500左右,适宜的主催化剂浓度在1.5×10-4 mol/L左右,最佳聚合温度60℃,此时催化剂的活性可达到106 gPE/(molCat·h).从物理性能、热性能、相对支化度、相对分子质量及其分布分析可知,制备出的负载茂锆金属催化剂在最优反应条件下催化乙烯聚合所得的产物与吉林石化公司聚乙烯产品性质基本一致,符合产品的指标,支链分布均匀,分子量分布更窄.同时对茂锆金属催化剂主、助催化剂催化乙烯聚合的作用和机理进行了探讨.     

制备宽/双峰分子量分布聚乙烯的催化体系

利用茂金属加合物和1种Ziegler-Natta(Z-N)催化剂的混合催化体系,制备宽/双峰分子量分布的聚乙烯.考察混合催化体系中茂金属加合物和Z-N催化剂的配比对聚合物分子量、分子量分布以及结构性能的影响.     

乙烯气相聚合过程中氢气振荡操作制备双峰聚乙烯

在单一气相反应器中,采用国产APE-1G(Cp*₂ZrCl₂·2LiCl·THF)型茂金属催化剂,通过强制振荡反应器内的氢气浓度制备双峰聚乙烯。实验考察了氢气浓度、振荡时间分配和振荡周期对聚乙烯分子量分布的影响。实验结果表明,氢气的加入使得催化剂活性降低,产物分子量也减小。通过强制振荡氢气的浓度可以得到双峰分布的聚乙烯,M_w/M_n达到11.2～34.2。研究表明,通过调节氢气振荡操作的实验条件,尤其是调节振荡时间分配,可以很好地控制双峰聚乙烯的分子量分布。     

茂金属双峰聚乙烯的研究进展

概述了用复合茂金属催化体系法和工艺法制备双峰聚乙烯的研究进展，讨论了２组分比例，及聚合温度、聚合压力、氢气用量对茂金属双峰聚乙烯制备的影响规律。     

单活性中心乙烯聚合催化剂的研究进展

单活性中心乙烯聚合催化剂是近年来国内外研究的热点,也是开发聚乙烯新产品的重要手段。本文综述了近年来单活性中心催化剂用于制备功能性聚乙烯材料的研究进展,包括茂金属催化剂、非茂金属催化剂的开发应用。通过对单活性中心催化剂结构的调控,可以得到分子量及分子量分布、分子结构、构象等精确可控的功能性乙烯共聚物,或具有特殊性能的聚乙烯产品。     

分子量宽峰分布聚乙烯茂金属催化剂的研究

以复合茂金属催化剂和双载体茂金属催化剂乙烯聚合、考察聚乙烯（ＰＥ）分子量分布变化情况。结果发现两者都使ＰＥ分子量分布加宽,其中复合茂金属催化剂Ｃｐ２ＺｒＣｌ２／ＹＢ３使分子量分布从２．３７增至９．１８。分子量分布增加幅度与不同复合茂经剂、催化剂配比、２载体量之比负载催化剂用量有关。     

茂金属聚乙烯催化剂工业应用研究

北京化工研究院合成了50余种新型茂金属化合物,在茂金属催化剂均相乙烯聚合的系统研究基础上,深入研究了载体茂金属催化剂的制备方法和制备条件等因素与载体催化剂性能的关系,研制出性能优异的载体茂金属催化剂。采用载体茂金属催化剂进行了浆液法和气相法乙烯聚合中试研究,还进行了茂金属聚乙烯树脂的加工应用研究,树脂性能与国外同类产品相当。     

聚乙烯技术新进展

评述了双峰聚乙烯技术,茂金属催化剂和采用液态冷凝技术的乙烯气相聚合工艺的新进展。介绍了生产双峰聚乙烯产品的各种双反应器工艺和单反应器工艺,指出双反应器工艺是目前国际上采用最广泛的工艺,而单反应器工艺目前仍处于开发试验中,是生产双峰聚乙烯产品未来发展方向。液态冷凝气相聚乙烯工艺利用冷凝液体的蒸发潜热及时移走反应热,极大地缓和了反应器散热问题,使得反应器单位体积的聚乙烯产量得到大幅度提高。将液态冷凝技术与超高活性的茂金属催化剂配合使用是当今研究的一个热点。     

负载型茂金属催化剂用于乙烯淤浆聚合的研究

在烯烃催化聚合领域,茂金属催化剂显示出比传统Ziegler-Natta催化剂更高的活性。以苯甲酸催化三甲基铝（TMA）受控水解生成甲基铝氧烷（MAO）,经热解过程后合成了一种不溶形式的固体聚甲基铝氧烷（sMAO）。以合成的sMAO为载体负载茂金属催化剂,并将该催化剂应用于乙烯淤浆聚合反应中,系统探究了聚合条件对催化行为的影响,同时对聚乙烯产品mPE的粒度、堆密度、分子量及分布和熔体流动速率等基本理化性能进行了分析表征。实验结果表明,制备的催化剂颗粒形态较好,粒子分布均匀,在5 L釜中催化淤浆反应,乙烯/1-己烯共聚活性最高可达15 302.6 g·g^-1,并得到了相对分子质量分布均匀的中、高密度聚乙烯产品。     

限定几何构型茂金属催化剂催化乙烯/1-己烯共聚研究

以自制的限定几何构型茂金属催化剂为主催化剂,甲基铝氧烷为助催化剂,对乙烯/1-己烯共聚性能进行研究,考察溶剂、Al与Zr物质的量比、聚合温度、聚合压力和共聚单体浓度等工艺条件对催化剂活性以及聚合物性能的影响。确定乙烯/1-己烯共聚合的工艺条件为:以正庚烷为溶剂,Al与Zr物质的量比为700~1 000,聚合温度(100~120)℃,聚合压力(1.2~2.0)MPa,优选1-己烯浓度为(0.8~1.8)mol·L~(-1)。     

Polymerization of ethylene and ethylene/1-hexene over Ziegler–Natta/metallocene hybrid catalysts supported on MgCl2 prepared by a recrystallization method

MgCl₂ for use as a catalyst support was prepared by dissolution in methanol and recrystallization in n-decane, followed by vacuum-drying at 2,000 rpm. The prepared support was modified by treatment with alkylaluminum compounds. The activity profile of ethylene over the supported catalysts persisted for periods up to 1 h during the polymerization. The prepared Ziegler–Natta/metallocene hybrid catalysts exhibited the characteristics of both metallocene and Ziegler–Natta catalysts. The polymer produced by the hybrid catalysts gave bimodal peaks in differential scanning calorimetry analysis for ethylene and ethylene/1-hexene polymerization, suggesting that the polymer was composed of two different lamellar structures that were polymerized by each catalyst. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1707–1715, 1998     

Development of novel chromium oxide/metallocene hybrid catalysts for bimodal polyethylene

The investigation of a multicomponent catalyst in polyolefin field came up as an alternative for synthesizing bimodal polymers in only one step process under constant reaction conditions.In the present work, new bifunctional catalysts were prepared by combining chromium and metallocene species on the same solid and tested in ethylene polymerization in order to evaluate the possibility of producing bimodal polyethylene. The catalytic system methylaluminoxane (MAO)/(nBuCp)₂ZrCl₂ was immobilized on activated chromium catalysts supported onto several inorganic carriers (silica, silica-alumina, aluminophosphate and mesostructured SBA-15-type materials). The reaction results showed a clear influence of the physicochemical properties of the support on the relative contribution of metallocene and chromium centers as well as on polymers molecular weight distribution. A bimodal polyethylene was obtained by supporting the MAO/metallocene system on a mesostructured chromium catalyst prepared by direct synthesis.     

Supported hybrid early and late transition metal catalysts for the synthesis of polyethylene with tailored molecular weight and chemical composition distributions

Supported hybrid catalysts using metallocenes and a nickel diimine catalyst were synthesized and used for ethylene slurry polymerization and ethylene/1-hexene copolymerization. Two types of metallocenes, together with a nickel diimine catalyst were supported onto SiO₂ through chemical bonding, and a borate compound was physisorbed for the activation of the catalysts. These supported hybrid catalysts had high catalyst activities and made free-flowing polymer particles. The chemical composition distribution, molecular weight averages and distributions of resultant polymers were controlled by catalyst structure and polymerization conditions such as reaction temperature and the use of α-olefin. According to GPC-IR, ¹³C NMR and CEF characterization results of some polymers, more 1-hexene was incorporated in the high molecular weight region, short chain branches were generated by the chain walking mechanism in low molecular weight region. The morphologies of the resulting particles were investigated by SEM.     

铬钒双金属催化剂乙烯聚合反应动力学模型化

双金属催化剂可催化乙烯聚合在单个反应器内制备双峰聚乙烯。考察了新型Cr-iV双金属催化剂及相应的单金属S-2和iV催化剂在不同实验条件下的乙烯均聚反应动力学。通过对Cr-iV催化剂聚合产物分子量分布曲线的解析发现铬钒活性中心之间存在相互作用,铬中心活性受到抑制,钒中心活性得到增强;聚合温度基本不改变铬钒活性中心生成的聚合物的质量分数。采用简化的单中心乙烯均聚动力学模型分别描述铬钒双活性中心的动力学行为,结合双金属催化剂的聚合实验结果确定了各个活性中心的动力学参数。相比单金属催化剂,Cr-iV催化剂中铬活性中心链增长速率常数降低,说明其聚合活性降低;而钒活性中心链失活速率常数减小,稳定性增强,活性提高。     

Copolymerization of ethylene/5‐ethylidene‐2‐norbornene with bis (2‐phenylindenyl) zirconium dichloride catalyst: I. Optimization of the operating conditions by response surface methodology

In this study, the copolymerization of ethylene with nonconjugated diene (5‐ethylidene‐2‐norbornene) was carried out with a bis(2‐PhInd) ZrCl₂ metallocene catalyst. Some polymerization factors that were considered affective on the catalyst activity, including comonomer content in the feed, ethylene pressure, and polymerization temperature, were investigated via response surface methodology to determine the optimum polymerization conditions. We found that the comonomer content in the feedstock had no enormous effect on the catalyst activity depression. Also, the polymerization temperature increment through the scrutinized range decreased the copolymerization activity. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

丙烯-1-己烯无规共聚物的制备及表征

以CS-2为催化剂,利用2 L本体聚合装置制备了丙烯-1-己烯无规共聚物,考察了共聚单体加入方式及加入量对催化剂活性、共聚物形态和性能的影响,采用差示扫描量热仪、傅里叶变换红外光谱仪,核磁共振质谱仪等表征了共聚物结构.结果表明:加入1-己烯,催化剂活性显著增加;控制1-己烯的加入方式,随着1-己烯加入量的增加,共聚物中...     

宽或双峰分子量分布HDPE的研制：Ⅰ双金属复合催化剂的制备？…

将Ｃｐ２ＺｒＣｌ２以一定方式负载于ＢＣＨ催化剂上制备了双金属复合催化剂,了ＢＣＨ／Ｃｐ２ＺｒＣｌ２对载锆量的影响以及负载温度对双金属复合催化剂催化性能的影响,并用Ｘ射线光电子能谱法证实了藏金属催化剂确已载到了ＢＣＨ催化剂上。催化乙烯聚合的动力学研究表明,双金属复合催化剂的动力学曲线与ＢＣＨ催化剂一样均属衰减型;由于双金属中心的存在,其动力学曲线出现了２个峰值。