2-Benzimidazol-6-pyrazol-pyridine Chromium(III) Trichlorides: Synthesis, Characterization, and Application for Ethylene Oligomerization and Polymerization

Luo, Wenlong; Li, Antai; Liu, Shaofeng; Ye, Hongqi; Li, Zhibo

doi:10.1021/acs.organomet.6b00573

Cited by 25 publications

(18 citation statements)

References 54 publications

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“…1 and 2. In addition, a number of alternating LAO distributions with chromiumbased systems have been reported in the literature [11][12][13][14][15][16][17]. These four types of ethylene product distribution are depicted in Fig.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

The Mathematics of Ethylene Oligomerisation and Polymerisation

et al. 2020

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“…With increasing of the Al/Cr molar ratio from 300 to 1300, the trend for oligomerization activity was the same as that for the influence of the reaction temperature ( Table , entries 2 and 6 – 9). The highest activity was observed with an Al/Cr molar ratio of 500, indicating that the active species formed on ethylene oligomerization required an optimum amount of alkylaluminium reagent, but that either lower or higher ratios were detrimental to the ethylene oligomerization . The content of C 6 and C 8 oligomer reached up to 26.71% at Al/Cr molar ratio of 1300.…”

Section: Resultsmentioning

confidence: 98%

“…The highest activity was observed with an Al/Cr molar ratio of 500, indicating that the active species formed on ethylene oligomerization required an optimum amount of alkylaluminium reagent, but that either lower or higher ratios were detrimental to the ethylene oligomerization. [24] The content of C 6 and C 8 oligomer reached up to 26.71% at Al/Cr molar ratio of 1300. This was probably because the rate of chain propagation was higher than that of chain transfer and b-hydrogen elimination.…”

Section: Ethylene Oligomerizationmentioning

confidence: 96%

Novel Dendritic PNP Chromium Complexes: Synthesis, Characterization, and Performance on Ethylene Oligomerization

Wang

Gao

Zhang

et al. 2017

Helvetica Chimica Acta

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Three dendritic PNP ligands with ethylenediamine, 1,4‐butanediamine, 1,6‐diaminohexane as bridged groups are synthesized in good yields, respectively. Three dendritic PNP chromium complexes (C1 – C3) are prepared with the ligands and chromium(III) chloride tetrahydrofuran complex (CrCl3(THF)3) as materials. The dendritic PNP ligands and the synthetic chromium complexes are fully characterized by spectroscopic and analytical methods. All chromium complexes activated with methylaluminoxane (MAO) exhibited moderate activities on ethylene oligomerization (7.90 × 104 – 2.15 × 105 g (mol Cr h)−1] and had better selectivity for C6 and C8 oligomer, reaching up to 81%. The chromium complex (C1) activated with diethylaluminium chloride (Et2AlCl) has higher catalytic activity than the chromium complex C1 activated with MAO, although the chromium complex (C1) activated with Et2AlCl had lower selectivity for C6 and C8 oligomer. The effects of solvent and reaction parameters on ethylene oligomerization are also studied using the chromium complex C1 as pre‐catalyst and MAO as co‐catalyst. Under optimized conditions ([complex] = 2 μmol, Al/Cr = 500, 25 °C, 0.9 MPa ethylene, 30 min), the catalytic activity of complex C1 in toluene is 2.15 × 105 g (mol Cr h)−1 and the selectivity for C6 and C8 oligomer is 36.76%. In addition, the structure of complexes significantly affects both the catalytic activity and the selectivity on ethylene oligomerization.

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“…A series of chromium(III) chlorides bearing 2-benzimidazol-6-pyrazol-pyridines, 8a -8d ( Figure 3), displayed high activities for both ethylene oligomerization (2.17 × 10 6 g (mol Cr) -1 h -) and polymerization (6.78 × 10 5 g (mol Cr) -1 h -1 ) when treated with MAO [74]. Moreover, the resultant oligomers showed high selectivity for α-olefins (>99%).…”

Section: N^n^n and N^n^n^n Ligands And Their Cr Precatalystsmentioning

confidence: 99%

Recent advances in homogeneous chromium catalyst design for ethylene tri-, tetra-, oligo- and polymerization

Bariashir

Huang

Solan

et al. 2019

Coordination Chemistry Reviews

114

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This review focuses on recent progress made using well-defined molecular chromium complexes that, upon suitable activation, can catalyze the tri-, tetra, oligo-and/or polymerization of ethylene. In particular, emphasis will be placed on the tuning of the performance characteristics of these homogeneous catalysts through structural modifications made to the multidentate ligand manifold (e.g., donor atoms, charge, backbone and strain) and the effects these changes have on the resulting ethylene derivatives. While the ability of these catalysts to mediate the formation of high molecular weight linear polyethylene continues to see many developments, their capacity to form polyethylene waxes and oligomers has witnessed some major advances. Moreover, the impressive selectivity of some chromium systems to generate commercially important 1-hexene and more recently 1-octene has seen the implementation of this technology at the industrial level. The types of precatalysts to be discussed will be divided broadly on the basis of their ability to generate either polymers/oligomers or short chain αolefins; the effects of co-catalyst and reaction conditions (e.g., temperature, pressure, solvent) on catalytic activity and selectivity, will be also developed. In addition, current proposals as to the mechanistic details displayed by these versatile chromium catalysts will be highlighted.

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2-Benzimidazol-6-pyrazol-pyridine Chromium(III) Trichlorides: Synthesis, Characterization, and Application for Ethylene Oligomerization and Polymerization

Cited by 25 publications

References 54 publications

The Mathematics of Ethylene Oligomerisation and Polymerisation

The Mathematics of Ethylene Oligomerisation and Polymerisation

Novel Dendritic PNP Chromium Complexes: Synthesis, Characterization, and Performance on Ethylene Oligomerization

Recent advances in homogeneous chromium catalyst design for ethylene tri-, tetra-, oligo- and polymerization

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