Ethylene and Propylene Polymerization Using In Situ Supported Me2Si(Ind)2ZrCl2 Catalyst: Experimental and Theoretical Study

Summary: Me₂Si(Ind)₂ZrCl₂ was in situ immobilized onto SMAO and used for ethylene and propylene polymerization in the presence of TEA or TIBA as cocatalyst. The catalytic system Me₂Si(Ind)₂ZrCl₂/SMAO exhibited different behavior depending on the amount and nature of the alkylaluminum employed and on the monomer type. The catalyst activity was nearly 0.4 kg polymer · g cat^?1 · h^?1 with both cocatalysts for propylene polymerization. Similar activities were observed for ethylene polymerization in the presence of TIBA. When ethylene was polymerized using TEA at an Al/Zr molar ratio of 250, the activity was 10 times higher. Polyethylenes made by in situ supported or homogeneous catalyst systems had practically the same melting point (T_m). On the other hand, poly(propylenes) made using in situ supported catalyst systems had a slightly lower T_m than poly(propylenes) made using homogeneous catalyst systems. The nature and amount of the alkylaluminum also influenced the molar mass. The poly(propylene) molar mass was higher when TIBA was the cocatalyst. The opposite behavior was observed for the polyethylenes. Concerning the alkylaluminum concentration, the molar mass of the polymers decreased as the amount of TEA increased. In the presence of TIBA, the polyethylene's molar mass was almost the same, independent of the alkylaluminum concentration, and the poly(propylene) molar mass increased with increasing amounts of cocatalyst. The deconvolution of the GPC curves showed 2 peaks for the homogeneous system and 3 peaks for the heterogeneous in situ supported system. The only exception was observed when TEA was used at an Al/Zr molar ratio of 500, where the best fit was obtained with 2 peaks. Based on the GPC deconvolution results and on the theoretical modeling, a proposal for the active site structure was made.

Molar mass distribution deconvolution of polyethylene prepared with the system Me₂Si(Ind)₂ZrCl₂/SMAO/TIBA with 500 mol/mol of alkylaluminum as cocatalyst.     

Polymerization of propylene with highly active MgCl2-supported TiCl3 catalyst

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.     

Ethylene slurry polymerization using nickel diimine catalysts covalently-attached onto MgCl2-based supports

MgCl₂/alcohol adducts were recrystallized with alkyl aluminums and used as catalysts supports for nickel diimine complexes functionalized with amine groups. These supported catalysts were used to polymerize ethylene in a slurry reactor. The MgCl₂-based supported nickel diimine catalysts had higher activities than the equivalent SiO₂-supported nickel diimine catalysts, even without the use of activators. These catalysts made polyethylene with melting temperatures and molecular weights higher than those made with the equivalent homogeneous catalysts. Interestingly, the catalyst activity and polymer molecular weight could be controlled by changing the support composition. In addition, covalent chemical bonds between the functionalized nickel diimine complex and the MgCl₂-based supports avoided catalyst leaching during polymerization, leading to the production of polymer particles with good morphology. The mechanical strength of the resulting polymer particles, however, was lower than those made with SiO₂-supported nickel diimine catalysts.     

On the topology of highly branched polyethylenes prepared by amine−imine nickel and palladium complexes: the effect of ortho‐aryl substituents

Series of nickel and palladium complexes bearing amine?imine ligands in various ortho‐aryl and backbone positions were prepared and investigated in ethene polymerization. Ethene polymerization initiated by symmetrically ortho‐substituted nickel and palladium amine?imine catalysts is controlled. Mono‐substitution in the ortho‐aryl positions of nickel complexes is not as efficient in protecting centers from chain transfer as di‐substitution. Both the central metal and the size of the ortho‐aryl substituent have a significant effect on the polyethylene (PE) topology. Based on detailed characterization by high temperature SEC‐IR‐η, SEC with multi‐angle laser light scattering and ¹³C NMR data, PEs prepared by nickel amine?imine complexes have a linear rather than dendritic topology. In contrast, palladium amine?imine complexes with small ortho‐aryl substituents at low ethene pressure were shown for the first time to form dendritic PEs with topology comparable to PEs formed by α‐diimine palladium catalyst. © 2018 Society of Chemical Industry     

一种新型非茂负载催化剂应用于乙烯聚合催化的研究

研究开发了一种新型非茂聚烯烃催化剂CpTi(dbm)Cl2，考察了该催化剂在均相以及负载条件下对乙烯聚合的催化行为。此催化剂在均相条件下对乙烯聚合的催化活性较低，但用MgCl2和MgCl2／高岭土复合双载体对催化剂进行负载后，催化乙烯聚合具有非常好的催化活性。MgCl2和MgCl2／高岭土双载体用甲基铝氧烷（MAO）预处理后，可以在铝钛摩尔比较低时发挥出高的催化活性，也可以用烷基铝代谢MAO做助催化剂。采用负载催化剂后，不仅提高了催化活性，而且也提高了聚合物的堆密度。用BET法测孔结构，发现当非茂催化剂负载到经MAO处理的双载体上，催化剂的比表面积增加了3．5倍，孔体积增加了4倍，大孔所占比例较负载前有显著提高。     

α-二亚胺镍溴化物/凹凸棒黏土负载催化剂催化乙烯聚合研究

A nickel-diimine catalyst [N, N'-bis(2,6-diisopropylphenyl)-1,4-diaza-2,3-dimethyl-1, 3-butadiene nickel dibromide, DMN] was supported on palygorskite clay for ethylene slurry polymerization. The effect of supporting methods on the catalyst impregnation was studied and compared. Pretreatment of the support with methylalumi-noxane (MAO) followed by DMN impregnation gave higher catalyst loading and catalytic activity than the direct impregnation of DMN. Catalyst activity as high as 5.42×105g PE·molNi-1·h-1 was achieved at ethylene pressure of 6.87×105 Pa and polymerization temperature of 20℃. In particular, the morphological change of the support during MAO treatment was characterized and analyzed. It was found that nano-fiber clusters formed during the support pretreatment, which increased the surface area of the support and favored the impregnation of the catalyst. The investigation of polymerization behavior of supported catalyst revealed that the polymerization rate could be kept at a relatively h     

低碳烯烃聚合催化剂的研究新进展

介绍了近来来烯烃聚合催化剂研究所取得的一些新进展,它们包括Ziegler-Natta催化剂、茂金属催化剂、非茂金属催剂、某些亚胺类后过渡金属(Ni、Pd、Fe、Co)配合物催化剂以及其它用于烯烃聚合的新型催化剂等。对世界一些主要石化公司生产PE及PP所采用的催化剂近况也作了简单表述。目前世界茂金属催化剂发展迅速,对于烯烃聚合新品种的开发具有潜在而广阔的工业应用前景和重要价值。     

Olefin homopolymerization catalyzed over asymmetric and symmetric ni(II) diimine complexes

Symmetric and asymmetric Ni(II) diimine complexes such as 2-[(2,6-diisopropylphenylimino)methyl]pyridine nickel(II) dibromide (a), 2-[1-(2,6-diisopropylphenylimino)ethyl]pyridine nickel(II) dibromide (b) and [1,2-bis(2,6-diisopropylphenylimino)] acenaphthene nickel(II) dibromide (c) were synthesized. For olefin homopolymerization, asymmetric Ni(II) diimine complexes [(a) & (b)] were compared with symmetric system (c). Asymmetric Ni(II) diimine complexes exhibited less catalytic activity and thermal stability as well as more b-hydride elimination than a symmetric diimine complex (c). The activity of (a) was larger than that of (b), which indicates that methyl group has a contribution to the instability of catalyst by s bond vibration rather than the stabilization of the active site by electron releasing property. This paper is dedicated to Professor Wha Young Lee on the occasion of his retirement from Seoul National University.     

Copolymerization of ethylene with unsaturated alcohols and methylmethacrylate using a silylated α‐diimine nickel catalyst: Molecular modeling and photodegradation studies

In this article, the experimental results obtained in the copolymerization of ethylene with polar monomers using a silylated α‐diimine nickel catalyst are described and compared with those obtained with a non‐silylate similar one. The results show that the introduction of a siliyl group in the para‐position of the imine moiety turns the catalyst less sensitive toward polar functionalities. However, the reactivity observed in copolymerization reactions was found to be reduced both the global polymerization and incorporation rates. Molecular modeling calculation allowed us to understand both the preferred insertion mode and the intermediate product structures for E/MMA copolymerization. Photodegradation studies showed that the presence of polar groups in the copolymers increases their rate of oxidation and turn them more easily degradable. The stabilization performed by Tinuvin 770 showed that for long‐exposure times, it is not very effective regardless it is only mixed or grafted to the copolymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of alkylaluminum structure on Ziegler-Natta catalyst systems based on neodymium for producing high-cis polybutadiene

Summary  In this work, a laboratory scale process for producing polybutadiene with high content of cis-1,4 repeating units was studied. A Ziegler-Natta catalyst system constituted of neodymium versatate (catalyst), an alkylaluminum compound (alkylating agent and cocatalyst) and tert-butyl chloride (chlorinating agent) was used. The solvent employed was a mixture of hexane and cyclohexane (80/20 v/v). The objective of this work was to evaluate the effect of alkylaluminum structure and the influence of Al/Nd (5 to 15) molar ratio of long chain alkylaluminium compound (tri(n-hexyl)aluminum) on catalyst activity and polybutadiene characteristics. The alkylaluminum compounds employed in this study were tri(i-butyl)aluminum, tri(n-hexyl)aluminum, tri(n-octyl)aluminum and di(i-butyl)aluminum hydride. The polybutadienes molar masses obtained were strongly influenced by the alkylaluminum structure. Polymers with the highest molar masses were obtained when tri(i-butyl)aluminum, tri(n-hexyl)aluminum and tri(n-octyl)aluminum were employed. However, polymers with the highest contents of cis-1,4 units and the lowest molar masses were produced when di(i-butyl)aluminum hydride was employed.     

新型高性能Ziegler-Natta催化剂用于乙烯淤浆聚合

A novel high performance MgCl2/TiCl4 catalyst with tetrabutyloxsilicane as electron donor was prepared for ethylene slurry polymerization process. The properties of the catalyst such as particle size distribution, catalytic activity, hydrogen responsibility and copolymerization performance were investigated and compared with commercial catalyst (imported catalyst). Copolymerization of ethylene and 1-butylene using the catalyst was stud-ied in a pilot plant. The composition, structure and property of the copolymer were characterized by 13C nuclear magnetic resonance (13C NMR) and gel permeation chromatography-Infrared (GPC-IR), and compared with those of the copolymer obtained from a commercial catalyst. In comparison with the commercial catalyst, the novel cata-lyst had a higher activity (up to 34.6 kg•g－1) and a better particle size distribution (PSD), and produced polymers having higher bulk density (up to 0.37 g•cm－3) with less fine resin. Meanwhile, the novel catalyst showed a higher hydrogen responsibility and better copolymerization performance. The results indicated that the copolymer obtained from the novel catalyst has a higher branch in the high molecular weight fraction and lower branch in the low mo-lecular weight fraction.     

烷基铝对齐格勒-纳塔催化剂催化1-丁烯聚合性能的影响

采用5种烷基铝,在2 L不锈钢高压反应釜中对齐格勒-纳塔催化剂催化1-丁烯液相本体聚合反应进行研究。结果表明,与单一烷基铝相比,复配烷基铝使1-丁烯聚合活性明显提高,当n(三乙基铝)∶n（三异丁基铝）=100∶100时,活性最高,为13.5 kg·g^-1,且以复配烷基铝为助催化剂,高氢气量时,催化剂的氢调敏感性较强。     

一种新型丙烯聚合催化剂的研究

阐述在一定的条件下制备了一种新型的用于丙烯聚合的负载型Ziegler/Natta催化剂,在此催化剂体系中添加了一种新的内给电子体BN,结果表明:此种催化剂具有催化活性高,粒度非常集中,聚合得到的聚丙烯细粉少,此催化剂氢调敏感,等规度可调,聚合物性能好等特点.     

Catalysis of ethylene to linear low‐density polyethylene with iron‐based diimine complex immobilized on calcosilicate and silica‐supported rac‐Et(Ind)2ZrCl2

Iron‐based diimine complex was immobilized on calcosilicate (CAS‐1) to form heterogeneous precatalyst, which oligomerized ethylene to α‐olefins even without the use of aluminum alkyl compounds as activators. The α‐olefins, upon the catalysis of another catalyst, i.e., silica‐supported rac‐Et(Ind)₂ZrCl₂, copolymerized with ethylene to produce linear low‐density polyethylene (LLDPE). The copolymerization reactions could be performed with the addition of triethylaluminum alone because of the introduction of methylaluminoxane to CAS‐1 and silica during the supporting process. In addition to the formation of more α‐olefins with lower molar mass, the layered structure of CAS‐1 acted well in the controlled release of α‐olefins in the copolymerization process. The simultaneous employment of the aforementioned two catalysts hence resulted in high catalytic activities, smooth kinetic process, well‐regulated branching degree, higher molecular weights (M_n), improved thermal stability, and better morphology of the LLDPE obtained. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Enantioselective Cyanosilylation of Ketones with Amino Acid/BINAP/Ruthenium(II)‐Lithium Phenoxide Catalyst Systems

Enantioselective reactions of simple ketones, α,α‐ and β,β‐dialkoxy ketones, and α‐alkoxy ketones with trimethylsilyl cyanide catalyzed by the bimetallic systems of amino acid/BINAP/ruthenium(II) complexes and lithium phenoxide have been studied [BINAP=2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl]. The Ru(PhGly)₂(BINAP)‐lithium phenoxide system showed high enantioselectivity for the reaction of acetophenone derivatives to afford the cyanated products in up to 90% ee [PhGly=phenylglycinate]. For the cyanosilylation of dialkoxy ketones and α‐alkoxy ketones, the Ru(t‐Leu)₂(BINAP)‐lithium phenoxide system exhibited the best catalyst performance to produce the cyanohydrin derivatives in up to 99% ee and 98% ee, respectively [t‐Leu=tert‐leucinate]. The excellent catalytic activity resulted in complete conversion in the reaction with a substrate‐to‐catalyst molar ratio (S/C) of 10,000 in the best cases.     

Catalyst impregnation and ethylene polymerization with mesoporous particle supported nickel-diimine catalyst

A nickel-diimine catalyst (1,4-bis(2,6-diisopropylphenyl) acenaphthene diimine nickel(II) dibromide, DMN) was supported on mesoporous particles having parallel hexagonal nanotube pore structure (MCM-41 and MSF) for ethylene polymerization. The effects of supporting methods and particle morphological parameters, such as pore size and length, on the catalyst impregnation were systematically investigated. Pretreating the supports with methylaluminoxane (MAO) followed by DMN impregnation gave much higher catalyst loading and higher catalytic activity than the direct impregnation of DMN. The particle structure significantly affected the catalyst impregnation and this effect was explained with a semi-quantitative molecular diffusion model. Compared to homogeneous catalysts, significant reduction in activity was observed with the supported systems in ethylene polymerization. Extraction of active sites from the supports during polymerization was observed. The mesoporous supports exerted steric effects on unleached active sites, lowering chain walking ability, and producing polymers having lower short chain branch density. Replication of the particle morphology was observed in some polymer samples.     

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     

工业CS—2型高效催化剂丙烯聚合试验

系统地研究了CS-2型高效催化剂的性能，探讨了反应条件（如：铝/钛摩尔比，铝/硅摩尔比，反应温度，反应时间，氢气试验等）对CS-2型高效催化剂的影响，使用户对CS-2型高效催化剂有一个更深刻的了解，利于CS-2型高效催化剂在环管工艺上更好地发挥其优良性能。     

DMC催化剂催化环氧丙烷聚合反应的研究

研究了使用DMC催化剂制备环氧丙烷聚醚时 ,聚合温度、催化剂浓度、加料速度对聚醚相对分子质量和相对分子质量分布的影响规律。采用连续加起始剂的操作方式可窄化聚醚的相对分子质量分布 ,调节引发体系的酸度可以缩短聚合反应的诱导期     

Friedel–Crafts Reaction of Indoles with Isatin‐Derived β,γ‐Unsaturated α‐Keto Esters Using a BINOL‐Derived Bisoxazoline (BOX)/Copper(II) Complex as Catalyst

Several chiral BINOL‐derived bisoxazoline (BOX)/copper(II) complexes were synthesized and evaluated as catalysts for the Friedel–Crafts reaction of indoles with isatin‐derived β,γ‐unsaturated α‐keto esters. The resulting bis‐indole products bearing a quaternary stereocenter were obtained in excellent yields and enantioselectivities. Additionally, the desired products were practically transformed to α‐amino esters, α‐hydroxy esters and α‐keto amides. It is noteworthy that this catalytic procedure was conducted with a catalyst loading of 0.5 mol% without any discernible decrease in the reactivity or enantioselectivity.