Ethylene polymerization studies with supported cyclopentadienyl, arene, and allyl chromium catalysts

Karol, Frederick J.; Johnson, Robert N.

doi:10.1002/pol.1975.170130713

Cited by 58 publications

(13 citation statements)

References 10 publications

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“…Examples include Ziegler catalysts based on titanium or vanadium, Ballard-type catalysts [219][220][221][222][223][224][225][282][283][284][285][286] based on zirconium, titanium, yttrium, or scandium, certain nickel catalysts [287], divalent and zerovalent organotitanium compounds [222,288], chromocene [226][227][228][229][230][231] common underlying mechanistic principles behind all these systems. They too produce linear polymer with first-order kinetics, exhibit very similar activity, transfer primarily to monomer, respond to H 2 , insert comonomer in a 1,2-orientation with accompanying acceleration of chain transfer, produce vinyl and methyl end-groups and exhibit other behavioral similarities.…”

Section: Polymerization Mechanismmentioning

confidence: 99%

Review of the Phillips Chromium Catalyst for Ethylene Polymerization

McDaniel

2008

Handbook of Heterogeneous Catalysis

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The year 2001 marked the 50th anniversary of the discovery of the Phillips chromium catalyst, from which today's worldwide high‐density polyethylene industry sprang. Appropriately, during that year the discoverers of this catalyst system, J. Paul Hogan and Robert L. Banks, were inducted into the National Inventors Hall of Fame, in Akron, OH, to join other distinguished inventors spanning two centuries who have shaped our world. This chapter reviews our understanding of the chemistry associated with that catalyst system, which is used globally to produce perhaps half of the world's high‐density polyethylene, and it provides examples of how that chemistry is exploited commercially.

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Section: Polymerization Mechanismmentioning

confidence: 99%

Review of the Phillips Chromium Catalyst for Ethylene Polymerization

McDaniel

2008

Handbook of Heterogeneous Catalysis

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“…In another, less common, variation of the catalyst, lower valent organochromium compounds can be deposited onto an already calcined support to produce very active catalysts (43)(44)(45)(46)(47)(48)(49)(50)(51). These compounds react with surface hydroxyls to become attached to the support, often losing one or more ligands.…”

Section: Oxidizedmentioning

confidence: 99%

Ethylene Polymers,HDPE

Benham

McDaniel

2001

Encyclopedia of Polymer Science and Technology

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History of PEEarly Work. The history of HDPE (and polyolefins in general) actually began in the 1890s with the synthesis of "polymethylene" from the decomposition of diazomethane. Between 1897 and 1938, numerous reports of such polymers appeared in the literature (1-6). Catalysts such as unglazed china, amorphous boron, and boric acid esters were used for the decomposition. The empirical formula of such products was found to be CH 2 . Later reproductions of work (3,6) established Encyclopedia of Polymer Science and Technology.

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“…For example, both Cr(allyl)3 and Cr2(allyl)4 are rapidly adsorbed on silica and silica-alumina and have afforded active catalysts (86). There has been an extensive study of the use of chromium derivatives as precursors to alkene polymerisation catalysts.…”

Section: Transition Metal Hydrocarbyl Complexesmentioning

confidence: 99%

“…The catalysts derived from chromocene are more thermally stable than those formed from chromium allyls, and this may explain their greater observed catalytic activity [86]. It appears though that having closely spaced (vicinal or geminal) silanols has a deleterious effect on the catalytic performance.…”

Section: Transition Metal Hydrocarbyl Complexesmentioning

confidence: 99%

Reaction of Organometallics with Surfaces of Metal Oxides

Evans

1988

Surface Organometallic Chemistry: Molecular Approaches to Surface Catalysis

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Organometallic complexes can be introduced onto metal oxide supports either by direct bonding or via an intervening ligand. The former method uses the diverse reaction sites available on oxide surfaces. The chemisorption processes may be considered in the same way as reactions of organometallic complexes in solution. For example, interaction of Rh(allyl)3 with silica causes an electrophilic cleavage of one metal-allyl bond to generate a new metal centre, viz.[Si]-ORh(allyl)2' Alternatively, interaction of RU3(CO)12 with silica proceeds via an oxidative addition reaction of a silanol group across one of the metal-metal bonds. Nuclearity is not always maintained during anchoring procedures, as in the case of the interaction of Rh4(CO)12 with alumina, in which mononuclear metal centres are produced. Some of the coordination centres derived from these grafted organometallic complexes have close analogues in mainstream organometallic chemistry; others appear to have no discrete counterpart at present and offer a challenge to the synthetic chemist. Organometallics also provide alternative routes to supported metal particles. In some instances these may be formed under much milder conditions than conventional reductions of metal salts. By virtue of the differing kinetics involved, different (often smaller) particle sizes, compositions, and size distributions become available. Ligandtethered complexes may be synthesised with high specificity. However, subsequent surface reactions occur to give new coordination centres. If the aim is to anchor a known homogeneous catalyst, then precautions must be taken to avoid these, either by protective silylation or by design of a stabilising tethering ligand. But the original tethered complex may be used as a catalyst precursor, and so these surface reactions may be of interest. Many new catalysts have been prepared by supporting organometallic complexes on oxide supports. Establishing the metal coordination site requires a combination of total product analysis and direct spectroscopic measurements characterizing the supported complex, preferably aided by reference to close model compounds. This is now considerably easier with the range of techniques presently available. For a high proportion of materials, the oxide surface binding site is not understood. Progress in this is necessary 47

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Ethylene polymerization studies with supported cyclopentadienyl, arene, and allyl chromium catalysts

Cited by 58 publications

References 10 publications

Review of the Phillips Chromium Catalyst for Ethylene Polymerization

Review of the Phillips Chromium Catalyst for Ethylene Polymerization

Ethylene Polymers,HDPE

Reaction of Organometallics with Surfaces of Metal Oxides

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