New Catalysis and Process for Ethylene Polymerization

Karol, Frederick J.; Wagner, Burkhard E.; Levine, I. J.; Goeke, G. L.; Noshay, Allen

doi:10.1007/978-1-4757-9095-5_24

Cited by 7 publications

(2 citation statements)

References 10 publications

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“…Whereas the simplest amide ligand NH 2 - plays an increasing role in the chemistry of late-main-group-metal complexes, complexes of the early-main-group metals are only known as polymeric salts [M(NH 2 ) x ] ∞ . The calcium amide [Ca(NH 2 ) 2 ] ∞ has been used in polymerization catalysis . In combination with its thermal decomposition product, the related imide CaNH, it also receives attention in hydrogen-storage research …”

Section: Resultsmentioning

confidence: 99%

Big Ligands for Stabilization of Small Functionalities in Calcium Chemistry

Ruspic

Harder

2007

Inorg. Chem.

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Reaction of (DIPP-nacnac)CaN(SiMe3)2.THF (DIPP-nacnac=CH{(CMe)(2,6-iPr2C6H3N)}2) with NH3 gave the heteroleptic complex (DIPP-nacnac)CaNH2.(NH3)2 which crystallized as a dimer with bridging NH2- ions. In contrast to other heteroleptic (DIPP-nacnac)calcium amides, (DIPP-nacnac)CaNH2.(NH3)2 is remarkably stable toward ligand exchange. Reaction of (DIPP-nacnac)CaH.THF with Me3SiCN gave the heteroleptic complex (DIPP-nacnac)CaCN.THF that crystallized as a trimer. The CN- ions bridge in a linear fashion between the Ca2+ ions. In a new synthetic route (DIPP-nacnac)CaN(SiMe3)2.THF reacted with Et3NH+Cl- to give (DIPP-nacnac)CaCl.THF, which crystallized as a dimer with bridging Cl- ions. The exceptional stability of these aggregates toward ligand-exchange reactions, which would give insoluble homoleptic Ca(NH2)2, Ca(CN)2, or CaCl2, is remarkable and likely due to their multinuclear nature.

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Section: Resultsmentioning

confidence: 99%

Big Ligands for Stabilization of Small Functionalities in Calcium Chemistry

Ruspic

Harder

2007

Inorg. Chem.

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“…9 -13 If requirements for shape replication are not fulfilled, growing polymer particles can suffer from morphological deformations and particle rupturing could result, causing a complete loss of the original shape. 14 In general, catalyst fragmentation depends mainly on two factors: hydraulic pressure generated by the formed polymer inside the catalyst pores and the rigidity of the support material. 15 The support must have a mechanical strength great enough to withstand handling and low enough to break down during polymerization.…”

Section: Introductionmentioning

confidence: 99%

Study of the morphology and kinetics of novel Ziegler–Natta catalysts for propylene polymerization

Abboud

Denifl

Reichert

2005

J of Applied Polymer Sci

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ABSTRACT:The morphological and kinetic characteristics of novel Ziegler-Natta catalysts were studied. Catalysts were prepared by Borealis Polymers Oy using a new synthesis technique (emulsion technology). Video microscopy was used to study the growth of single catalyst particles during polymerization in the gas and liquid phases. The distribution of single particle activity was very narrow in the catalyst without external support and was rather broad in the the silica-supported catalyst. Video microscopy of molten polymer particles allowed observation of the process and degree of fragmentation of the catalyst particles. A correlation between the activation period during the initial stage of polymerization and catalyst fragmentation was found. Fragmentation was faster and more uniform with the catalyst without external support than with the silica-supported catalyst. Scanning electron microscopy provided information on morphology evolution and shape replication of the catalyst particles. With the catalyst without external support, good shape replication was observed, and compact and spherical particles were formed. With the silica-supported catalyst, shape replication was poor, and nonspherical porous polymer particle were formed. Modeling of the kinetics of propylene polymerization was done using a simple threestep reaction scheme neglecting mass and heat transport effects.

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Investigation on the particle growth mechanism in propylene polymerization with MgCl₂‐supported ziegler–natta catalysts

Noristi

Marchetti

Baruzzi

et al. 1994

J. Polym. Sci. A Polym. Chem.

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To elucidate the particle growth mechanism in propylene polymerization with high‐yield MgCl2‐supported Ziegler‐Natta catalysts, observations have been carried out by electron microscopy on a series of samples having different degrees of polymer growth (from 0.1 to 1000 g/g of catalyst). Topics such as surface and bulk morphology, catalyst fragmentation, as well as distribution of the catalyst residues in the polymer have been investigated. The experimental data suggest that if the site distribution in the catalyst is uniform and the polymerization conditions are mild, the polymer growth starts uniformly throughout the catalyst particle, which then undergoes an even and progressive fragmentation into very fine units homeogeneously dispersed in the polymer matrix. The above results thus provide further experimental support to the particle growth mechanism outlined in the multigrain or polymeric flow models. © 1994 John Wiley & Sons, Inc.

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New Catalysis and Process for Ethylene Polymerization

Cited by 7 publications

References 10 publications

Big Ligands for Stabilization of Small Functionalities in Calcium Chemistry

Big Ligands for Stabilization of Small Functionalities in Calcium Chemistry

Study of the morphology and kinetics of novel Ziegler–Natta catalysts for propylene polymerization

Investigation on the particle growth mechanism in propylene polymerization with MgCl₂‐supported ziegler–natta catalysts

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New Catalysis and Process for Ethylene Polymerization

Cited by 7 publications

References 10 publications

Big Ligands for Stabilization of Small Functionalities in Calcium Chemistry

Big Ligands for Stabilization of Small Functionalities in Calcium Chemistry

Study of the morphology and kinetics of novel Ziegler–Natta catalysts for propylene polymerization

Investigation on the particle growth mechanism in propylene polymerization with MgCl2‐supported ziegler–natta catalysts

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Investigation on the particle growth mechanism in propylene polymerization with MgCl₂‐supported ziegler–natta catalysts