Novel supported catalysts for ethylene polymerization based on aluminohydride-zirconocene complexes

Charles, R. Malcolm; Gonzalez-Hernandez, Rebeca; Morales, Elsa; Revilla, J.; Elizalde, Luis E.; Cadenas, Gregorio; Pérez‐Camacho, Odilia; Collins, Scott

doi:10.1016/j.molcata.2009.03.018

Cited by 12 publications

(10 citation statements)

References 36 publications

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“…Ethylene Polymerization with Clathrates : Ethylene polymerizations were conducted in a 600 mL Parr reactor equipped with Ar and ethylene inlets, temperature control and mechanical agitation, as described in several reports for aluminohydride zirconocenes, using MMAO‐7 as scavenger.…”

Section: Methodsmentioning

confidence: 99%

“…Since 2006 we reported the use of this kind of complex, as catalytic systems in coordination polymerizations and copolymerizations of olefins and alfa‐olefins in homogeneous phase using different activators (MAO or boron compounds) . As with most metallocenes, the zirconocene aluminohydrides were supported on porous silica, in order to obtain polyolefins of useful morphology in slurry polymerization processes . Different zirconocene aluminohydrides supported on silica produced very active systems (50–90 ton PE/molZr‐hr), using MAO as co‐catalyst, however the leaching of the catalysts was very evident because fine particles produced in the reactors caused fouling .…”

Section: Introductionmentioning

confidence: 99%

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Zirconocene Aluminohydride‐Methylaluminoxane Clathrates for Ethylene Polymerization in Slurry

Padilla‐Gutiérrez

Ventura‐Hunter²,

García-Zamora³

et al. 2017

Macromolecular Symposia

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The main aim of this work is to obtain heterogeneous, zirconocene aluminohydride/methylaluminoxane (MAO) polymerization catalysts, without using inorganic carriers like silica. The syntheses of zirconocenium ion‐based clathrates, formed from aluminohydride zirconocene complexes activated with MAO, are reported here. Several different approaches were examined for the synthesis of these clathrate compositions; in one approach the catalyst (nBuCp2ZrH3AlH2/MAO) was first prepared in toluene solution, and the clathrate phase then generated by addition of silicone oil. An alternate approach involved reaction of silicone oil or another clathrate‐forming additive (e.g. KCl) with MAO to form a solidified clathrate, and then introducing the zirconocene aluminohydride complex (nBuCp2ZrH3AlH2). The clathrate catalysts were probed in the polymerization of ethylene in hydrocarbon slurry, without using additional co‐catalyst (MAO), or at very low concentrations of modified MAO (MMAO 7, 13 wt‐% in iso‐octane). The catalytic activities of the solid clathrate catalysts were compared as well as the morphology and properties of the polyethylene synthesized in slurry.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Zirconocene Aluminohydride‐Methylaluminoxane Clathrates for Ethylene Polymerization in Slurry

Padilla‐Gutiérrez

Ventura‐Hunter²,

García-Zamora³

et al. 2017

Macromolecular Symposia

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“…As regards another generation of ethylene polymerization organometallic catalysts, i.e., metallocene catalysts, silica was a dominating support for those systems initially 15–18. Effective immobilization of such systems on a magnesium support became possible much later.…”

Section: Introductionmentioning

confidence: 99%

The influence of body mass index on lumbar disc degeneration: Comment on the article by Samartzis et al

Alexiou¹,

Voulgaris²

2012

Arthritis & Rheumatism

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suggestion that MCH might be a better indicator than MCV in the identification of IDA in these patients.Furthermore, we would like to mention additional features that may support the preferred use of Hgb content parameters (as opposed to MCH and MCV) in the management of iron deficiency in this patient population. The difference between Ret-Hgb and RBC-Hgb, expressed as ⌬Hgb, provides information on the current iron availability and short-term iron incorporation for erythropoiesis owing to the long life span of mature erythrocytes compared to reticulocytes (3). As a consequence, in the presence of absolute iron deficiency, iron supplementation is expected to substantially raise the Ret-Hgb and ⌬Hgb within several days (4-6), while no effect, or only limited effect, is expected in the pure functional iron deficiency of the inflammatory state (patients with ACD). The combined use of Ret-Hgb and RBC-Hgb might thus prove an indicator of the effectiveness of oral iron supplementation in these patients, and as such, these parameters are promising additional markers for the management of anemia in patients with rheumatoid arthritis; we are currently investigating this hypothesis.We agree with Dr. Jolobe that laboratories lacking the facilities to assess Hgb content parameters could use MCH (or MCV) in addition to serum hepcidin to diagnose iron deficiency in patients with anemia and chronic inflammation. However, our findings, and the findings of others, suggest that Hgb content parameters can provide added value in the management of patients with rheumatoid arthritis; more studies are needed to confirm this.

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“…Some years ago, we reported the use of zirconocene aluminohydride complexes for ethylene polymerizations, comparing their performance with the corresponding zirconocene dichloride, under the same polymerization conditions. Zirconocene aluminohydride showed activities 30–40% higher than zirconocene dichloride, when were activated with MAO in solution, under the same polymerization conditions 6…”

Section: Introductionmentioning

confidence: 59%

Heterogeneous Ethylene and Alpha‐Olefin Copolymerization Using Zirconocene Aluminohydride Complexes

Pérez¹,

Soares

García³

et al. 2013

Macromolecular Symposia

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Summary: In this work we studied the copolymerization of ethylene and different alpha-olefins (propylene, 1-butene, 1-hexene, and 1-octene) using aluminohydride zirconocene systems supported on modified silica. The copolymerization reactions were carried out in hexanes, at different Al/Zr ratios, using two different comonomer concentrations. The effect of comonomer type on catalyst activity and polymer molecular weight and chemical composition distributions (MWD and CCD) was compared. Average comonomer incorporation was determined by 13 C NMR and the CCD by crystallization elution fractionation (CEF). Most of the copolymerizations showed very high catalytic activity (up to 4000 Kg PE/mol Zr), and the molecular weight was higher for the copolymers containing 1-octene, demonstrating that aluminohydride zirconocene systems can copolymerize ethylene and alpha-olefins effectively.

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Novel supported catalysts for ethylene polymerization based on aluminohydride-zirconocene complexes

Cited by 12 publications

References 36 publications

Zirconocene Aluminohydride‐Methylaluminoxane Clathrates for Ethylene Polymerization in Slurry

Zirconocene Aluminohydride‐Methylaluminoxane Clathrates for Ethylene Polymerization in Slurry

The influence of body mass index on lumbar disc degeneration: Comment on the article by Samartzis et al

Heterogeneous Ethylene and Alpha‐Olefin Copolymerization Using Zirconocene Aluminohydride Complexes

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