Study of the ethylene polymerization over homogeneous and supported catalysts based on 2,6-bis(imino)pyridyl complexes of Fe(II) and Co(II)

Semikolenova, Nina V.; Захаров, В. А.; Talsi, Evgenii P.; Babushkin, Dmitrii E.; Sobolev, Anatoly P.; Echevskaya, L. G.; Khysniyarov, M.M

doi:10.1016/s1381-1169(01)00476-9

Cited by 75 publications

(65 citation statements)

References 7 publications

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“…In our earlier studies, [7,11,14] it was shown that for catalysts prepared by the anchoring of LFeCl 2 on different supports (SiO 2 , Al 2 O 3 and MgCl 2 ), the rate of polymerization as a function of time is very stable. The activity of LFeCl 2 , fixed on the oxide supports (SiO 2 , Al 2 O 3 ) was very close, whereas when MgCl 2 was used as a support, the activity of the corresponding catalysts was almost two times higher.…”

Section: Polymerization Kineticsmentioning

confidence: 96%

“…Using 1 H and 2 H NMR spectroscopy, data on the composition and structure of the intermediate structures, formed in these homogeneous systems, were obtained. [6,7] The supported catalytic systems are of most interest in applications in slurry and gas-phase industrial processes. Data on the polymerization of ethylene using iron complexes with different substitutes in bis(imino)pyridil ligands, grafted onto the oxide (SiO 2 , Al 2 O 3 ) and modified (SiO 2 /MAO, SiO 2 /AlR 3 , where R Me, i-Bu) supports are presented in ref.…”

Section: Introductionmentioning

confidence: 99%

“…Data on the polymerization of ethylene using iron complexes with different substitutes in bis(imino)pyridil ligands, grafted onto the oxide (SiO 2 , Al 2 O 3 ) and modified (SiO 2 /MAO, SiO 2 /AlR 3 , where R Me, i-Bu) supports are presented in ref. [7][8][9][10][11][12] These supported catalysts exhibit high activity during ethylene polymerization (1 000 to 5 000 kg PE Á (mol Fe Á h Á bar) À1 at 70 to 90 8C) and produce PE with good morphology. According to diffuse reflection infrared Fourier transform spectroscopy (DRIFTS), [11] the complex LFeCl 2 is fixed onto the oxide supports via both its interaction with the surface hydroxyl groups and the Lewis acidic sites (in case of Al 2 O 3 ).…”

Section: Introductionmentioning

confidence: 99%

“…[14] All of the LFeCl 2 -based supported catalysts exhibit rather stable activity over the 1 to 2 h of polymerization, whereas corresponding homogeneous catalysts show very high starting activity (%1 Â 10 5 kg of PE Á (mol Fe Á h Á bar) À1 at 35 8C) but completely deactivate within 30 to 40 min of polymerization. [7,15] In spite of the great interest in supported catalysts with bis(imino)pyridyl iron (II) complexes as the active component, there is no data in the literature about the fraction of the active component involved in the polymerization, and about the reactivity of the active sites formed in the systems. In the present work we have determined the number of active centers (C P ) and propagation rate constants (k P ) for ethylene polymerization with LFeCl 2 (L ¼ 2,6-(2,6-(Me) 2 C 6 H 3 N CMe) 2 C 5 H 3 N) complex, supported on different supports (SiO 2 , Al 2 O 3 , MgCl 2 ), with Al(i-Bu) 3 , as a co-catalyst.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Study of Ethylene Polymerization Over Supported Bis(imino)pyridine Iron (II) Catalysts

Барабанов

Букатов

Захаров

et al. 2006

Macro Chemistry & Physics

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Summary: The number of active centers (CP) and propagation rate constants (kP) for polymerization of ethylene with supported catalysts LFeCl2/SiO2, LFeCl2/Al2O3 and LFeCl2/MgCl2 (L = 2,6‐(2,6‐(Me)2C6H3NCMe)2C5H3N), activated by an Al(i‐Bu)3 co‐catalyst, were determined by a method of polymerization inhibition with radioactive 14CO. In contrast to homogeneous systems based on LFeCl2, the supported catalysts are highly active and stable in ethylene polymerization at 70–80 °C. In the presence of hydrogen, the activity of the supported catalysts substantially increases (2–4 fold). The data obtained on the effect of hydrogen on the calculated CP and kP values suggests that for ethylene polymerization without hydrogen, the “dormant” active centers are formed in the catalytic systems. A scheme for the formation of these “dormant” centers and their reactivation in presence of hydrogen is suggested. For the investigated supported catalysts the CP values were found to be only 2 to 4% of the total iron complex content in the catalysts. The kP value for the catalysts prepared using different supports (SiO2, Al2O3 and MgCl2) were close (3.2 × 104 to 4.5 × 104 L · (mol · s)−1 at 70 °C). The support composition affects neither the molecular mass (MM) nor the molecular mass distribution (MMD) of the polymers produced. The obtained CP and kP values and data on the polymer MM and MMD lead to conclusion that the nature of the support has almost no effect on the structure of the active centers and the distribution of their reactivity.Effect of support on the MMD of PE produced over supported LFeCl2 catalysts.magnified imageEffect of support on the MMD of PE produced over supported LFeCl2 catalysts.

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Section: Polymerization Kineticsmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetic Study of Ethylene Polymerization Over Supported Bis(imino)pyridine Iron (II) Catalysts

Барабанов

Букатов

Захаров

et al. 2006

Macro Chemistry & Physics

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“…The bis(imino)pyridine cobalt precatalyst/co-catalyst systems have also been examined with regard to co-catalyst variation. For example, 6b /AlMe 3 shows similar activities to MAO-based systems whereas 6b /Al( i -Bu) 3 was almost inactive at a molar ratio Al:Co = 500 [119] . As a general feature, the activities exhibited by these cobalt systems are less than their iron counterparts.…”

Section: Other Co-catalysts/activatorsmentioning

confidence: 99%

Iron-Based and Cobalt-Based Olefin Polymerisation Catalysts

Gibson¹,

Solan²

2008

Topics in Organometallic Chemistry

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This chapter describes the brief history of iron or cobalt catalysts for olefin polymerisation and oligomerisation. Since the discovery in 1998 that 2,6-bis(imino)pyridine iron and cobalt halides, on activation with MAO, can convert ethylene to highly linear polyethylene, numerous reports have been concerned with ligand modification, mechanisms for precatalyst activation, identifying the active species and understanding the mode of propagation/chain transfer. In addition, heterogenisation of this class of catalysts, their incorporation into macrocycles/ polymers and their use in reactor blending/tandem catalysis has seen some important developments; alternative ligand architectures that can support active iron and cobalt catalysts are also discussed as are different types of olefinic monomer.

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Olefin Oligomerizations and Polymerizations Catalyzed by Iron and Cobalt Complexes Bearing Bis(imino)pyridine Ligands

Gibson

Solan

2010

Catalysis Without Precious Metals

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IntroductionThe capacity of 2,6 -bis(arylimino)pyridine -iron(II) and -cobalt(II) halide complexes, on activation with methylalumoxane ( MAO ), to act as exceptionally active catalysts (comparable with Group 4 metallocenes) for the conversion of ethylene to high density polyethylene ( HDPE ) was fi rst disclosed independently by Brookhart, Bennett and ourselves in 1998 ( Figure 5.1 ) [1 -7] . The signifi cance of this discovery was further highlighted by the complete absence at the time of examples of iron and cobalt complexes in olefi n polymerization applications. In comparison with early transition metal -based catalysts such as metallocenes, these late transition metal systems offer some distinct advantages which range from their relative ease of handling and manipulation, their reduced oxophilicity, to the cost -effectiveness and low toxicity of the metal centers employed. Moreover, by simple modifi cation of the 2,6 -bis(arylimino)pyridine ligand frame, exceedingly effi cient iron and cobalt oligomerization catalysts can also be generated, facilitating the formation of highly linear α -olefi ns with near ideal Schulz -Flory distributions. Since these initial fi ndings the past decade has witnessed a dramatic growth in reports associated with this class of late transition metal catalysts, and clear structure -activity relationships have emerged.This chapter is concerned with highlighting some of the more notable advances that have come to light as a result of identifying key factors that infl uence catalyst performance, particularly those related to precatalyst structure. The importance of the initiator and the role played in chain transfer is probed. Current mechanistic understanding is examined from both a spectroscopic and a computational viewpoint while efforts to prepare well -defi ned iron or cobalt alkyl catalysts are discussed. Efforts to heterogenize these homogeneous catalysts are briefl y reviewed, as is their use in multi -component catalysis.The reader is referred to a series of reviews for more general overviews of postmetallocene α -olefi n polymerization catalysts [8 -12] , while recent reviews relating to the versatility of 2,6 -bis(imino)pyridines and to iron -and cobalt -based catalysis itself have also been documented [13 -15] .

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Study of the ethylene polymerization over homogeneous and supported catalysts based on 2,6-bis(imino)pyridyl complexes of Fe(II) and Co(II)

Cited by 75 publications

References 7 publications

Kinetic Study of Ethylene Polymerization Over Supported Bis(imino)pyridine Iron (II) Catalysts

Kinetic Study of Ethylene Polymerization Over Supported Bis(imino)pyridine Iron (II) Catalysts

Iron-Based and Cobalt-Based Olefin Polymerisation Catalysts

Olefin Oligomerizations and Polymerizations Catalyzed by Iron and Cobalt Complexes Bearing Bis(imino)pyridine Ligands

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