Mathematical Model and Advanced Control for Gas-phase Olefin Polymerization in Fluidized-bed Catalytic Reactors

In this study, the developments in modeling gas-phase catalyzed olefin polymerization fluidized-bed reactors （FBR） using Ziegler-Natta catalyst is presented. The modified mathematical model to account for mass and heat transfer between the solid particles and the surrounding gas in the emulsion phase is developed in this work to include site activation reaction. This model developed in the present study is subsequently compared with well-known models, namely, the bubble-growth, well-mixed and the constant bubble size models for porous and non porous catalyst. The results we obtained from the model was very close to the constant bubble size model, well-mixed model and bubble growth model at the beginning of the reaction but its overall behavior changed and is closer to the well-mixed model compared with the bubble growth model and constant bubble size model after half an hour of operation. Neural-network based predictive controller are implemented to control the system and compared with the conventional PID controller, giving acceptable results.

A Sterically Hindered Zirconocene Complex (1,2-Ph_2C_5H_3)_2ZrCl_2:Synthesis,Structure and Properties as Olefin Polymerization Catalyst

An unbridged zirconocene complex bis(1,2-diphenylcyclopentadienyl)zirconium dichloride [(1,2-Ph2-C5H3)2ZrCl2] 1 has been synthesized and structurally characterized. When activated by MAO, 1 produces ultra-high molecular weight polyethylene with high melting transition temperature, as well as atactic oligopropylene with average molecular weight of ~1150 g mol-1.

NdCl_3/MgCl_2 BISUPPORTED CATALYST FOR OLEFIN POLYMERIZATION

The NdCl_3/MgCl_2 bisupported catalyst was prepared by using NdCl_3 ,MgCl_2, (CH_3)_2(CH_2)_2 OH and TiCl_4. It is shown that the structure of bisupported catalyst was different from those of either NdCl_3 or MgCl_2 single supported catalyst. A peculiar type of kinetic curve for ethylene polymerization was found.

Development of Olefin Polymerization Catalysts and Their Commercialization

As one of the most important products in petrochemical industry, polyolefin, including mainly polyethylene, polypropylene and α\|olefin polymers, is also a major raw material for plastics industry. The market demand for polyolefin in 2002 reached 88 Mt, making two thirds of the demand for thermoplastics. The growth rate of demand will be 5%-7 % in the next five years\+\{\\}. Because of its close relation to nations economy and its peoples daily life, the output of polyolefin becomes an important index of the nations industria lization and modernization level.

Recent Progress on Transition Metal （Fe, Co, Ni, Ti and V） Complex Catalysts in Olefin Polymerization with High Thermal Stability

The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial application.This review focuses on the transition metal complex catalyst with high thermal stability containing different structures,including the backbone of bis（imino）pyridine,a-diimine and other types of ligands.Besides the catalytic activity,the influence of reaction temperature on the molecular weight and molecular weight distribution of the obtained polymer was also described.The plausible mechanism on the stability of catalysts at high temperature was proposed,which may give guidance to design catalyst with good thermal stability.

Benzosuberyl Substituents as a"Sandwich-like"Function in Olefin Polymerization Catalysis

For the rational design of metal catalyst in olefin polymerization catalysis,various strategies were applied to suppress the chain transfer by bulking up the axial positions of the metal center,among which the"sandwich"type turned out to be an eficient category in achieving high molecular weight polyolefin.In the a-dimine system,the"sandwich"type catalysts were built using the typical 8-aryl-naphthyI framework.In this contribution,by introducing the rotationally restrained benzosuberyl substituent into the ortho-position of N-aryl rings,a new class of "sandwich-like"a-diimine nickel catalysts was constructed and fully identified.The rotationally restrained benzosuberyl substituents played a"sandwich-like"function by capping the nickel center from two axial sites.Compared to the nickel catalyst Ni1 bearing freely rotated benzhydryl substituent,Ni2 featuring benzosubery|substituent enabled the increase(8 times)of polymer molecular weights from 8 kDa to 65 kDa in the polymerization of ethylene.By further increasing the steric bulk of another ortho-site of the N-aryl ring,the polymer molecular weight even reached an ultrahigh level of 833 kDa(Mw=1857 kDa)using the optimized Ni3.Notably,these nickel catalysts could also mediate the copolymerization of ethylene with methyl 10-undecenoate,with Ni3 giving the highest copolymer molecular weight(88 kDa)and the highest incorporation of comonmer(2.0 mol1%),along with high activity of up to 10^(5)g·mol^(-1)·h^(-1).

Synthesis of High Performance Cyclic Olefin Polymers Using Highly Efficient WCl6-based Catalyst System

Cyclic olefin polymers（COPs） with high glass transition temperature, high transparency（higher than 80%） in the visible light range, excellent thermal stability and outstanding mechanical properties have been synthesized by effective ring opening metathesis polymerization（ROMP） of exo-1,4,4 a,9,9 a,10-hexahydro-9,10（1′,2′）-benzeno-l,4-methanoanthracene（HBM） and dicyclopentadiene（DCPD） or norbornene（NBE） using WCl6/i-Bu3Al/ethanol/1-hexene catalyst system, followed by hydrogenation of double bonds. 1-Hexene acted as a molecular weight controller in the polymerization reaction, tuning the number-average molecular weight（Mn） of P-HBM from 5.8 × 10^4 to 41.1 × 10^4. The monomer composition and thermal properties of the copolymers were characterized by nuclear magnetic resonance（NMR）, differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA）. The saturated polymers exhibited high decomposition temperatures（Td） around 340 ℃ and glass transition temperatures（Tg） in the range from 117.5 ℃ to 219.7 ℃. What is more, tensile tests indicated that the mechanical properties of the COPs could be effectively tuned in a wide range by introducing varying amount of small cyclic olefin such as DCPD or NBE.

Recent progress in immobilization of late-transition-metal complexes with diimine ligands for olefin polymerization

Late-transition-metal(LTM) catalysts are a family of very flexible ethylene polymerization catalysts because their catalytic performance can be easily adjusted by modifying the ligand structure.Their less oxyphilicity character,which may promote the production of copolymers from ethylene and polar comonomers,is another aspect that attracts much attention in both academic and industrial fields.The immobilization of LTM catalysts on spherical supports is a crucial step prior to their use in the industrial processes of gas-phase or slurry polymerizations.This paper reviews recent developments in supported LTM catalysts for olefin polymerization,and summarizes loading methods and mechanisms of the immobilization of LTM catalysts on inorganic,organic,and inorganic-organic materials,and the effects of immobilization on catalytic activity,polymerization mechanism,and polymer morphology.

Ligand Steric Effects on Naphthyl-α-diimine Nickel Catalyzed α-Olefin Polymerization

Naphthyl-α-diimine nickel complexes with systematically varied ligand sterics, activated by modified methylaluminoxane（MMAO）, were tested in the polymerization of higher α-olefin（1-hexene, 1-decene and 1-hexadecene） under suitable conditions. The polymerization results indicated the possibility of precise microstructure control, depending on catalyst structure, polymerization temperature, monomer concentration and types of monomers, which in turn strongly affects the resultant polymer properties. Naphthyl-α-diimine nickel complex bearing chiral bulky sec-phenethyl groups in the o-naphthyl position showed good catalytic activity, and resulted in branched polymers（42-88/1000 C） with high molecular weights（Mn：（4.3-15.2） × 10^4 g·mol^-1） and narrow molecular weight distribution（Mw/Mn = 1.13-1.29, RT）, which suggested a living polymerization. The increasing steric hindrance of catalyst leads to enhance insertion for 2,1-insertion of α-olefin and the chain-walking reaction.

STUDY ON HIGHLY ACTIVE ZIEGLERNATTA CATALYSTS FOR POLYMERIZATION OF OLEFINS

In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can beobtained. Plausible structure model and mechanism were proposed.

烯烃聚合用二亚胺催化剂的研究进展

综述了近几年烯烃聚合用α-二亚胺催化剂的研究进展,聚焦于配体结构的修饰,包括空间效应和电子效应的调控策略,以及配体结构变化对催化剂活性和热稳定性的影响。调控α-二亚胺配体的轴向位阻可达到提高催化剂活性、热稳定性,聚合物相对分子质量,以及调节支化度的目的。在适当的空间位阻下,引入不同电子效应的取代基对配体进行结构修饰同样也可提高α-二亚胺催化剂的性能。

α-二亚胺镍/钯催化剂体系用于乙烯聚合研究进展

带有大位阻基团的二亚胺催化体系在烯烃聚合中已经有着非常广泛的应用,它的结构中具有的诸多调控位点可实现催化剂性能及所制备聚合物性能的调整。介绍了近年来Brookhart催化体系的研究进展,综述了该催化体系的改进方法,主要包括改变配体骨架、N-芳基对位基团修饰、N-芳基取代基修饰及其他类型的修饰等,并分析了催化体系的改进对催化剂活性以及聚合物性能的影响。

烯烃聚合用茂金属催化剂研究进展

综述了主流的非桥联型、桥联型、限定几何构型和吡啶氨基型中典型的6个茂金属催化剂在乙烯与α-烯烃高温溶液聚合方面的应用。为了探究桥联型茂金属催化剂微观结构与烯烃聚合活性的内在关系,着重分析了4个茂金属催化剂的几何结构参数,揭示了该类催化剂通过改变配位空间以提高聚合性能的方向。

单电子转移活性自由基聚合法制备表面活性聚合物及性能

以丙烯酰胺(AM)和α-烯基磺酸钠(AOS)为功能单体,2-氯丙酰胺(CPA)为引发剂,采用单电子转移自由基聚合方法,制备无规二元共聚物PAM-co-PAOS。结果表明,最佳工艺条件为c(单体)=2.5 mol/L,n(单体)∶n(CPA)∶n(CuBr)∶n(Me_(6)TREN)=769∶1.2∶1∶3.8;m(AOS)∶m(AM+AOS)=3.5%。对表面活性聚合物PAM-co-PAOS进行性能研究,在大庆模拟盐水中具有较好的增黏性及表面活性。

链穿梭聚合制备烯烃多嵌段共聚物的研究进展

通过链穿梭聚合技术可制备烯烃多嵌段共聚物(OBC),极大地提高了催化剂的使用效率。OBC的链结构可以集每一个链段的各自优势于一体,表现出区别于均聚物、无规共聚物或共混物的独特性质。通过调控催化剂和链穿梭剂的结构、配比及反应条件,可以调控OBC的链结构和性能。介绍了链穿梭聚合的原理,综述了链穿梭聚合用于制备OBC的最新研究进展,包括不同单体的共聚、新型链穿梭剂的开发、OBC结构与性能的表征研究,提出了目前链穿梭聚合的问题与挑战,对未来的发展进行了展望。

丙烯齐聚合成低碳烯烃研究进展

文中介绍了目前丙烯的低聚合成即丙烯的二聚、三聚和四聚的研究进展。丙烯二聚反应和丙烯三四聚反应研究的主要区别在于它们的目标产物不同。丙烯二聚反应主要选择性的制备特定结构丙烯二聚体,而丙烯三四聚反应则产生更高碳数的聚合物,且由于对于高碳数烯烃同分异构体分析手段的缺乏,无法对高聚物的结构具体分析从而对催化剂选择性进行有目的的调整。未来对丙烯齐聚工艺的研究方向包括进一步提高催化剂的选择性和稳定性,降低反应温度和压力,开发更高效的催化剂以及分析检测方法的同步。

环烯烃开环易位聚合物的合成

采用MoCl_(5)为核心的齐格勒-纳塔催化剂合成降冰片烯-四环十二烯的开环易位聚合物,实现稳定的100%单体转化率,凝胶率0%。并采用Al_(2)O_(3)负载的Ru催化剂和SiO 2/Al_(2)O_(3)负载的Ni金属催化剂对相同的降冰片烯-四环十二烯开环易位聚合物进行非均相加氢,可实现100%的加氢率,且简单过滤即可将催化剂与聚合物溶液完全分离。两种加氢催化剂的产品具有不同的性质,Ni负载催化剂最佳反应条件:催化剂含量10%、反应温度190℃、初始氢气压力4 MPa、反应时间2 h,加氢产物的熔融指数76 g·min^(-1),玻璃化转变温度126℃;Ru负载催化剂最佳反应条件:催化剂含量2%、反应温度180℃、初始氢气压力4 MPa、反应时间2 h,加氢产物的熔融指数10 g·min^(-1),玻璃化转变温度131℃。

链穿梭聚合制备的烯烃多嵌段共聚物

烯烃多嵌段共聚物因其独特的分子结构和优异的物理性能,在材料科学中展现出重要的应用前景。链穿梭聚合技术有效地实现了烯烃多嵌段共聚物的合成,简化了工业化生产并显著提升了聚合物的性能。文中介绍了烯烃多嵌段共聚物的结构,性能和应用,综述了烯烃多嵌段共聚物的链穿梭聚合制备技术和其它新型单体烯烃多嵌段共聚物的研究进展。