Selective Ethylene Oligomerization with Chromium-Based Metal–Organic Framework MIL-100 Evacuated under Different Temperatures

Liu, Suyan; Zhang, Ying; Yang, Han; Feng, Guangliang; Gao, Fei; Wang, Hui; Qiu, Ping

doi:10.1021/acs.organomet.6b00834

Cited by 45 publications

(42 citation statements)

References 39 publications

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“…Figure shows XRD results for three types of synthesized polymers. By observing this figure, we can see two sharp peaks which are associated with orthorhombic crystal phase (OR110 and OR200) reflection of UHMWPE at angles of 2θ = 21.4° and 2θ = 23.9°, respectively …”

Section: Resultsmentioning

confidence: 95%

Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene

Amini

Ramazani

Varjouy

et al. 2018

Polymers for Advanced Techs

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The aim of this work is to investigate the effect of molybdenum disulfide on tribological properties of Ultra-high-molecular-weight polyethylene (UHMWPE). UHMWPE/ MoS 2 nano-composites were prepared using in-situ polymerization and Ziegler-Natta catalytic system. Studies showed that, in order to obtain the optimum tribological properties, interlayer distance between nanosheets should be as high as possible.Therefore, the nanosheets were subjected to oxidation using the required oxidants followed by thermal shock and ultrasound. Fourier-transform infrared spectroscopy (FTIR) analysis was used to determine the formation of functional groups which indicate the formation of S═O bond in the molybdenum disulfide oxide. Then, in order to exfoliate and increase the interlayer distance of nanosheets, thermal shock and ultrasonic were conducted Field Emission Scanning Electron Microscopy (FESEM) analyses. Finally, the obtained sample was used as the second support of catalyst in in-situ polymerization process. Then, under specified and constant operational conditions, the synthesis of samples containing 0.5%, 1%, and 2% nanoparticles were conducted. The results of the morphological study with FESEM indicate that the filler is uniformly distributed in the matrix, and X-ray Powder Diffraction (XRD) analysis showed that completely exfoliated nanocomposites were resulted and in low nanoparticle content. Addition of MoS 2 as reinforcing agent had a significant effect on friction coefficient of the nanocomposites. With the addition of 0.5 wt% of MoS 2 , the friction coefficient declined by approximately 35%. Furthermore, negligible decrease in sample's weight after the wear test is an indication of a strong interaction between MoS 2 and the matrix. Scratch resistance test revealed that with the addition of filler, the resistance increased from 23 to 60 MPa.

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Section: Resultsmentioning

confidence: 95%

Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene

Amini

Ramazani

Varjouy

et al. 2018

Polymers for Advanced Techs

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“…In the binuclear metallacyclic mechanism, the metal vacancy was first coordinated with two ethylene molecules to give the transition state of five‐membered organometallic ring, and then the two adjacent rings were coupled to form C 8 olefins. This mechanism required a relatively short distance between the active metal sites, and it could only take place in Fe‐L , as some metal centers in 3D disordered packing might be close enough with each other to cooperate synergistically . Therefore, it was deduced that both the coordination steric hindrance and the binuclear metallacyclic mechanism probably worked simultaneously and limited the ethylene dimerization selectivity of Fe‐L .…”

Section: Resultsmentioning

confidence: 99%

Metal–Organic Gels Derived from Iron(III) and Pyridine Ligands: Morphology, Self‐Healing and Catalysis for Ethylene Selective Dimerization

Zhou

Liu

et al. 2019

Chemistry An Asian Journal

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Metal‐organic gels showing potential application in catalysis have received much concern. In this work, we designed and synthesized two metal‐organic gels based on coordination between FeIII and pyridine ligands at room temperature. The gels were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to reveal their assembly structures and morphologies, and it was found the metal‐organic gel derived from di‐topic ligand was composed of three‐dimensional network of nanofibers, while the gel derived from tri‐topic ligand was constituted of sponge‐like structure with amorphous phase. Rheological analysis showed the gel consisting of nanofiber networks displayed self‐healing property. The gels were used as catalysts for selective ethylene dimerization, and the optimum catalysis results of the gel with nanofibers reached the maximal catalytic activity of 1.48×105 g/(mol Fe⋅h) with C4 yield more than 90 %, whereas the sponge‐like gel only gave 38 % C4 products at the same condition. The higher dimerization selectivity of the former FeIII gel was attributed to its regular assembly structure and lower steric hindrance of the surface metal sites. Due to its catalytic activity, high selectivity and preparation simplicity, the FeIII gel might be potentially applicable for the preparation of C4 α‐olefins.

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“…Herein, we report another type of MAO‐free and extremely active catalytic system, whose activity is more than 10 times that of the original MAO‐based Sasol system. Catalyst development for ethylene oligomerization is still an active research topic in both academia and industry …”

Section: Introductionmentioning

confidence: 99%

MAO‐free and extremely active catalytic system for ethylene tetramerization

Kim

Lee

Park

et al. 2019

Applied Organom Chemis

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The original Sasol catalytic system for ethylene tetramerization is composed of a Cr source, a PNP ligand, and MAO (methylaluminoxane). The use of expensive MAO in excess has been a critical concern in commercial operation. Many efforts have been made to replace MAO with non‐coordinating anions (e.g., [B(C6F5)4]−); however, most of such attempts were unsuccessful. Herein, an extremely active catalytic system that avoids the use of MAO is presented. The successive addition of two equivalent [H(OEt2)2]+[B(C6F5)4]− and one equivalent CrCl3(THF)3 to (acac)AlEt2 and subsequent treatment with a PNP ligand [CH3(CH2)16]2C(H)N(PPh2)2 (1) yielded a complex presumably formulated as [1‐CrAl (acac)Cl3(THF)]2+[B(C6F5)4]−2, which exhibited high activity when combined with iBu3Al (1120 kg/g‐Cr/h; ~4 times that of the original Sasol system composed of Cr (acac)3, iPrN(PPh2)2, and MAO). Via the introduction of bulky trialkylsilyl substituents such as –SiMe3, –Si(nBu)3, or –SiMe2(CH2)7CH3 at the para‐position of phenyl groups in 1 (i.e., by using [CH3(CH2)16]2C(H)N[P(C6H4‐p‐SiR3)2]2 instead of 1), the activities were dramatically improved, i.e., tripled (2960–3340 kg/g‐Cr/h; more than 10 times that of the original Sasol system). The generation of significantly less PE (<0.2 wt%) even at a high temperature is another advantage achieved by the introduction of bulky trialkylsilyl substituents. NMR studies and DFT calculations suggest that increase of the steric bulkiness on the alkyl‐N and P‐aryl moieties restrict the free rotation around (alkyl)N–P (aryl) bonds, which may cause the generation of more robust active species in higher proportion, leading to extremely high activity along with the generation of a smaller amount of PE.

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Selective Ethylene Oligomerization with Chromium-Based Metal–Organic Framework MIL-100 Evacuated under Different Temperatures

Cited by 45 publications

References 39 publications

Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene

Effect of exfoliated molybdenum disulfide oxide on friction and wear properties of ultra high molecular weight polyethylene

Metal–Organic Gels Derived from Iron(III) and Pyridine Ligands: Morphology, Self‐Healing and Catalysis for Ethylene Selective Dimerization

MAO‐free and extremely active catalytic system for ethylene tetramerization

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