Oligomerisation of Ethylene by Bis(imino)pyridyliron and -cobalt Complexes

Britovsek, Gjp; Migliore, Sergio; Solan, Ga; Baugh, Spd; Redshaw, Carl; Gibson, VC; White, Ajp; Williams, DJ; Elsegood, Mark R. J.

doi:10.1002/1521-3765(20000616)6:12<2221::aid-chem2221>3.3.co;2-l

Cited by 73 publications

(136 citation statements)

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“…The ligand, ortho ‐methyl and para ‐methoxy substituted bis(imino)pyridine (L, see Scheme 1 ), was synthesized by following the established literature procedure and its characterizations with 1 H NMR, MS, and elemental analyses can be referred to our previous work . It is employed herein based on the rationale that an electron‐donating group at para ‐ or meta ‐position is beneficial for better stabilizing the corresponding iron complexes, resulting in the enhancement of the activity while with little effect on the product distribution …”

Section: Methodsmentioning

confidence: 99%

“…These complexes exhibit very high catalytic activity and their substituents on the aryl rings and skeleton of the ligand can be modified to regulate molecular weight of the oligomerization products. It is now known that those complexes bearing a single ortho ‐alkyl substituent (especially methyl) on the aryl rings, upon activation by methylaluminoxane (MAO), exhibit the highest activity, to the best of our knowledge, in affording α‐olefins with the Schulz–Flory distribution . However, the resulting α‐olefins are usually featured with a very broad distribution ranging from C 4 to C 40+ , and almost inevitably, accompanied by undesirable insoluble polyethylene with a content as high as 40% or more .…”

Section: Introductionmentioning

confidence: 99%

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Tuning Bis(imino)pyridyl Iron‐Catalyzed Ethylene Oligomerization by Modification of MAO with p‐BrPhOH

Zhang

Jiang

et al. 2018

Macro Reaction Engineering

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To reduce the simultaneous production of insoluble polymers during the bis(imino)pyridyl iron‐catalyzed ethylene oligomerization, in this study, p‐BrPhOH (4‐bromophenol) has been chosen as the most optimal modifier for the production of linear α‐olefins. It is found that the polymer share in the total products is largely reduced with the use of p‐BrPhOH as the modifier. The catalytic system also possesses a high activity with the liquid production maintained high level of linearity. Moreover, the introduction of p‐BrPhOH promoted the high‐temperature stability of the catalytic system, leading to the enhanced oligomerization activity as the catalytic system can catalyze ethylene oligomerization at higher temperatures. A characterization of the catalytic system with electron paramagnetic resonance shows that introduction of p‐BrPhOH significantly inhibits the formation of ferric ions, which can be the main active centers responsible for generating undesired insoluble polymers, thus this can largely retard the production of insoluble polymers during ethylene oligomerization.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tuning Bis(imino)pyridyl Iron‐Catalyzed Ethylene Oligomerization by Modification of MAO with p‐BrPhOH

Zhang

Jiang

et al. 2018

Macro Reaction Engineering

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“…However, in practice, this makes little difference because is typically determined by taking natural logarithms to each side of Eq. 5a, plotting ln(mol(n) %) vs. n, performing a linear regression analysis to find the gradient lnα and then exponentiating the result as a power of e [20]. The value for determined in this way will be the same in both cases.…”

Section: 3 For Derivation)mentioning

confidence: 99%

The Mathematics of Ethylene Oligomerisation and Polymerisation

et al. 2020

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Linear α-olefins or LAOs are produced by the catalytic oligomerisation of ethylene on a multimillion ton scale annually. A range of LAOs is typically obtained with varying chain lengths which follow a distribution. Depending on the catalyst, various types of distributions have been identified, such as Schulz-Flory, Poisson, alternating and selective oligomerisations such as ethylene trimerisation to 1-hexene and tetramerisation to 1-octene. A comprehensive mathematical analysis for all oligomer distributions is presented, showing the relations between the various distributions and with ethylene polymerisation, as well as providing mechanistic insight into the underlying chemical processes.

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“…Above 20 o C, the activity steadily decreased reaching its lowest value of 0.75 × 10 5 g(PE) mol -1 (Cr) h -1 at 60 o C (entry 5, Table 4) which can be accredited to the onset of catalyst deactivation [48,62,[65][66][67]. In terms of molecular weight, the corresponding polymers followed a similar downward trend (Mw: from 106.6 to 21.9 kg mol -1 ) on increasing temperature which can be ascribed to chain transfer occurring faster than chain propagation under these conditions [43,50,[68][69]. As a general observation, the molecular weight distributions for the polymers were narrow to broad (Mw/Mn = 2.8 -10.3) (Figure 2a).…”

Section: <Table 3>mentioning

confidence: 98%