The activation of MgCl2-supported ziegler-natta catalysts: A structural investigation

Galli, Paolo; Barbè, Pier Camillo; Guidetti, G.; Zannetti, Roberto; Martorana, Antonino; Marigo, Antonio; Bergozza, M.; Fichera, A.M.

doi:10.1016/0014-3057(83)90096-4

Cited by 88 publications

(27 citation statements)

References 10 publications

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“…On the other hand, in the case of supporting the active transition metal on MgCl 2 with low surface area, the resulting catalyst gives very low activity. Thus MgCl 2 is modified to increase the specific surface areas for high activity [12][13][14][15][16] , contrary to SiO 2 support 17) . From this point, the rate enhancement in the present supported catalyst is probably due to the formation of the increased surface areas.…”

Section: Resultsmentioning

confidence: 99%

Highly active MgCl2-supported CpMCl3 (M = Ti, Zr) catalysts for ethylene polymerization

Kang¹,

Jeong

et al. 1999

Macromol. Rapid Commun.

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SUMMARY: Monocyclopentadienyl compounds, CpMCl 3 (M = Ti, Zr) supported on activated MgCl 2 were used for the polymerizations of ethylene in the presence of methylaluminoxane (MAO) or a common alkylaluminium as a cocatalyst. By supporting CpMCl 3 on MgCl 2 , the catalyst activity was increased drastically to show high activity similar to MgCl 2 -supported TiCl 4 catalysts. The activity of the CpZrCl 3 /MgCl 2 catalyst was higher than that of the CpTiCl 3 /MgCl 2 one. Both catalysts gave polymers with high molecular weight (M

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Section: Resultsmentioning

confidence: 99%

Highly active MgCl2-supported CpMCl3 (M = Ti, Zr) catalysts for ethylene polymerization

Kang¹,

Jeong

et al. 1999

Macromol. Rapid Commun.

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“…2. (a) Scheme of the stacking sequence of pentasil layers, drawn according to Kokotailo & Meier (1980). Bergozza & Fichera, 1983;Giunchi & Allegra, 1984), all the layers within one crystal will be assumed to have the same rectangular shape and size, in order to optimize their packing energy. Furthermore, to minimize the lateral crystal surface, no significant shift between distant layers will be admitted parallel to the layer plane.…”

Section: Stacking Of the Layersmentioning

confidence: 99%

Ordered and disordered structures in borosilicates with a pentasil-type framework

Perego¹,

Cesari²,

Allegra³

1984

J Appl Cryst

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X-ray diffraction patterns of two different zeolite-like borosilicates, BOR-C and BOR-D, are subjected to investigation. The structure of BOR-C is interpreted in terms of a regular stacking of 'pentasil' layers correlated by inversion centres (/-type stacking). Conversely, the structure of BOR-D may only be described as a layer sequence in which the prevailing /-type stacking is interrupted by faults consisting of mirrorrelated layers (a-type stacking). A statistical model where both the crystal surfaces and the stacking faults (with a 25% probability) are randomly distributed (Bernoullian model) leads to Lorentzian profiles and the resulting calculations show a good fit with experiment. In view of the very strong X-ray similarity among BOR-D, the ZSM-11 aluminosilicate and the pure silica analogue silicalite-2, the same statistical model is proposed for the two latter structures.

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“…As concerns a possible comparison between the disorder affecting /?-MgCl 2 and the one introduced by ball milling in the α-form, it can be observed that, while in /?-MgCl 2 each structural layer affects the relative position of the first and second neighbouring layers, in the ground α-form the sphere of influence extends only to the first neighbours (Galli et al, 1983). It is rather difficult to go beyond this remark in order to find a satisfactory explanation: probably an accurate study of such a difference among the statistical models describing the two forms should involve both cohesive energy calculations and the investigation of the growth kinetics of /f-MgCl 2 and of the stacking faults introduced by ball milling into a-MgCl 2 .…”

Section: Resultsmentioning

confidence: 99%

“…MgCl 2 is normally used as support in the crystalline a-modification (Montedison, 1969;Galli, 1983), but recently a new ß-form has been described as concerns both its structure and the activity in some catalytic processes (Montedison, 1977;Spitz et al, 1984). As pointed out in recent works (Makhtarulin et al, 1978;Gerbasi et al, 1984) the support structure is of prime importance in determining the catalyst performance.…”

Section: Introductionmentioning

confidence: 99%

Stacking faults in the β-form of magnesium dichloride

Martorana¹,

Mango²,

Toniolo³

et al. 1986

Zeitschrift Für Kristallographie - Crystalline Materials

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The structure of /?-MgCl 2 has been studied by powder X-ray diffraction methods.An accurate investigation of the diffraction profiles shows that the structure is strongly perturbed by stacking faults.A statistical model is proposed for the sequences of the CI-Mg-CI layers and is checked by fitting the calculated pattern to the experimental one.A mathematical treatment for simulation of texture effects is also proposed.

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The activation of MgCl2-supported ziegler-natta catalysts: A structural investigation

Cited by 88 publications

References 10 publications

Highly active MgCl2-supported CpMCl3 (M = Ti, Zr) catalysts for ethylene polymerization

Highly active MgCl2-supported CpMCl3 (M = Ti, Zr) catalysts for ethylene polymerization

Ordered and disordered structures in borosilicates with a pentasil-type framework

Stacking faults in the β-form of magnesium dichloride

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