Supported hafnium catalysts for ethylene polymerization

Masi, Francesco; Malquori, Stefano; Barazzoni, Lia; Invernizzi, Renzo; Altomare, Angelina; Ciardelli, Francesco

doi:10.1016/0304-5102(89)80179-8

Cited by 11 publications

(3 citation statements)

References 10 publications

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“…A variety of supported metallocene/metallocene-like catalysts, including zirconium hydrocarbyls (Chart ), have been prepared by chemisorption on various metal oxide surfaces. − These catalysts can exhibit remarkable activity for ethylene homopolymerization and arene hydrogenation. ,,− However, despite the extensive knowledge of supported organozirconium catalysis, information on the analogous supported Hf compounds is curiously sparse. − Empirically, hafnium complexes are typically less reactive than their zirconium congeners, although their properties are similar from both steric and electronic perspectives. , …”

Section: Introductionmentioning

confidence: 99%

Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

et al. 2018

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Here we report the combined application of high-resolution solid-state 13C–CPMAS-NMR and FT-IR spectroscopy, elemental analysis, kinetic poisoning/active site counting, variable dielectric constant medium, and DFT computation to characterize the surface chemistry of a pyridylamido hafnium complex (Cat1, L1-HfMe2, L1 = 2,6-diisopropyl-N-{(2-isopropylphenyl)[6-(naphthalen-1-yl)pyridin-2-yl]methyl}aniline) adsorbed on Brønsted acidic sulfated zirconia (ZrS). The spectroscopic and DFT results indicate protonolytic formation of organohafnium cations having a largely electrostatic pyridylamido-Hf-CH3 +···ZrS– interaction with elongated Hf···OZrS distances of ∼2.14 Å. High-molecular-weight polyethylenes and ethylene/1-octene copolymers are obtained with this supported catalyst without an activator/cocatalyst. The DFT calculations reveal that the first ethylene insertion into the Hf-methyl bond has a lower barrier than the corresponding insertion into the Hf-aryl bond of this single-site heterogeneous catalyst.

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Section: Introductionmentioning

confidence: 99%

Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

et al. 2018

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“…The polymerization of 4MP was investigated in the presence of a MgCl2 supported Titanium catalyst (Table III) (21 ). By using DBAS as cocatalyst, independent of the Al/Ti molar ratio, very low conversions to polymeric products were observed at 25°C.…”

Section: (Dpoas) or With The Heterogeneous Slurries Tbas And Tpoas Omentioning

confidence: 99%

“…Magnesium-supported hafnium and titanium catalysts were prepared according to procedures similar to those previously described (21). (Tables I and II).…”

Section: Al-cl + Ch 3 -0-s-o-ch^-• Al-o-s-o-almentioning

confidence: 99%

Polymerization of C₂—C₆ α-Olefins in the Presence of Modified Ziegler—Natta Catalysts Based on Titanium Halides and Organoaluminum Sulfates

Chiellini

D’Antone

Solaro

et al. 1992

ACS Symposium Series

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Enichem S.p.A., via Maritano 26, S. Donato Milanese, ItalyThe preparation of unconventional Ziegler-Natta catalysts is reported and their catalytic activity in the polymerization of ethylene, propylene and 4-methyl-1-pentene is compared with that of the corresponding conventional counterparts. The catalysts were obtained by reacting monomeric or oligomeric alkylaluminum sulfates with transition metal halides, either as such or supported on magnesium dichloride. In spite of their high oxygen content and saline features, the prepared unconventional catalysts were found comparably active as conventional systems in the polymerization of C2-C6 olefins. Essentially linear poly(ethylene) of fairly high molecular weight was obtained. Poly(propylene) and poly(4-methyl-1-pentene) with high isotacticity and molecular weight were also obtained.In recent years a great relaunch of interest in fundamental and applied investigations of anionic coordinate polymerization of α-olefins is taking place (1,2). The demand for high efficiency catalytic systems suitable to provide polyolefins with properties tailored to specific application and economically competitive with catalysts of the most recent generation is behind this new research and development impulse (3,4). In this context, modified Ziegler-Natta catalysts less chemically and thermally vulnerable appear exciting for the several implications connected with the polymerization of olefins containing functional groups and polymerization of hybrid comonomer mixtures. In previous papers we described the catalytic activity displayed in the polymerization of alkyl vinyl ethers by soluble stechiometrically defined organoaluminum sulfates or by their insoluble counterparts attained by addition of sulfuric acid to trialkylaluminum or trialkoxyaluminum derivatives (5,6).Indeed organoaluminum sulfates are structurally reminiscent of alumoxane derivatives that recently have been widely investigated and found to be active alone in the polymerization of lactones and epoxides (7,8) and of olefins when combined with transition metal halides (9,10).As a part of our continuing interest in the stereospecific polymerization of functional monomers (11-14) and in the chemical modification of reactive polymers (15-18), in the present contribution we report on the investigation of the catalytic activity of unconventional Ziegler-Natta catalysts based on the use of monomelic and oligomeric organoaluminum sulfates in combination with transition metal halides in the

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Structural features of 4‐methyl‐1‐pentene polymers prepared with different transition metal catalysts

Altomare

Solaro

Ciardelli

et al. 1992

Makromolekulare Chemie. Macromolecular Symposia

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Homopolymerization of 4-methyl-1-pentene carried out in the presence of catalysts containing variable relative amounts of Ti, Hf and Mg indicates that molecular weight and stereoregularity can be varied to an appreciable extent depending on catalyst nature and composition. A distinct behaviour of the various catalytic systems is also observed during the copolymerization of 4-methyl-1-pentene with monoalkenes such as propylene, 1-butene and 1-hexene. These data are discussed by underlining the important role of the transition metal in determining the features of polyolefins materials

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Supported hafnium catalysts for ethylene polymerization

Cited by 11 publications

References 10 publications

Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

Polymerization of C₂—C₆ α-Olefins in the Presence of Modified Ziegler—Natta Catalysts Based on Titanium Halides and Organoaluminum Sulfates

Structural features of 4‐methyl‐1‐pentene polymers prepared with different transition metal catalysts

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Supported hafnium catalysts for ethylene polymerization

Cited by 11 publications

References 10 publications

Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

Cationic Pyridylamido Adsorbate on Brønsted Acidic Sulfated Zirconia: A Molecular Supported Organohafnium Catalyst for Olefin Homo- and Co-Polymerization

Polymerization of C2—C6 α-Olefins in the Presence of Modified Ziegler—Natta Catalysts Based on Titanium Halides and Organoaluminum Sulfates

Structural features of 4‐methyl‐1‐pentene polymers prepared with different transition metal catalysts

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Polymerization of C₂—C₆ α-Olefins in the Presence of Modified Ziegler—Natta Catalysts Based on Titanium Halides and Organoaluminum Sulfates