Propylene polymerization with catalysts containing divalent titanium

Albizzati, Enrico; Giannini, U.; Balbontin, Giulio; Camurati, Isabella; Chadwick, John C.; Dall'Occo, Tiziano; Dubitsky, Y.; Galimberti, Maurizio; Morini, Giampiero; Maldotti, Andrea

doi:10.1002/(sici)1099-0518(19970930)35:13<2645::aid-pola11>3.0.co;2-b

Cited by 32 publications

(28 citation statements)

References 5 publications

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“…Finally, our computations unambiguously reveal that Ti(IV) is the most active species in Ziegler-Natta catalyst system although existence of other Ti oxidation states have been shown by several studies [14][15][16][17]23,25].…”

Section: Discussionmentioning

confidence: 53%

“…It is well known that in the real Ti catalyzed ZieglerNatta (ZN) polymerization, Ti exists in several oxidation states of +2, +3, +4 [15][16][17]23]. Our studies explored the effect of variation of these metal oxidation states on Ziegler-Natta catalyst activity in order to investigate which Ti oxidation states lead to most promising olefin polymerization activities.…”

Section: Discussionmentioning

confidence: 99%

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Role of titanium oxidation states in polymerization activity of Ziegler–Natta catalyst: A density functional study

Bhaduri

Mukhopadhyay²,

Kulkarni³

2006

Journal of Organometallic Chemistry

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Section: Discussionmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 99%

Role of titanium oxidation states in polymerization activity of Ziegler–Natta catalyst: A density functional study

Bhaduri

Mukhopadhyay²,

Kulkarni³

2006

Journal of Organometallic Chemistry

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“…On the contrary, Albizzati et al reported that a MgCl 2 -supported η 6 -benzeneTi(II)Al 2 Cl 8 complex was quite active for propylene polymerization. 6 Though the supported complex including benzene and Al 2 Cl 8 might not be a good active site model for real Ti 2+ species produced by the over-reduction of TiCl 4 , the over-reduction of the Ti species must not be the sole reason of the deactivation. Another source of the active sites deactivation is aggregation of Ti species which proceeds in parallel with the reduction during polymerization, leading to a decrease in the active site concentration.…”

Section: Introductionmentioning

confidence: 99%

Role of dispersion state of ti species in deactivation of MgCl2-supported Ziegler-Natta catalysts

et al. 2010

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The deactivation behaviors of TiCl 3 /MgCl 2 model catalysts with molecularly dispersed TiCl 3 were investigated to clarify the role of the dispersion state of the Ti species in the deactivation of MgCl 2 -supported ZieglerNatta (ZN) catalysts for propylene and ethylene polymerization. The propylene and ethylene polymerization activities of clustered Ti species supported on MgCl 2 were approximately one tenth of those of isolated Ti species, which is indicative of the significance of the aggregation of Ti species in the deactivation of ZN catalysts for olefin polymerization. Moreover, the time-course depression of monomer consumption for the clustered Ti species was slower than that for the isolated Ti species in propylene polymerization, whereas the dispersion state barely affected the depression rate in ethylene polymerization. The reduction rate of the Ti species was concluded to be important for the time-course depression of propylene consumption, whereas ethylene polymerization was insensitive to the oxidation state of the Ti species.

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“…The comparison of a catalyst of the type g 6 -arene-TiAl 2 Cl 3 with MgCl 2 /TiCl 4 led to the conclusion that the aging of Ziegler -Natta catalysts cannot be explained by reduction to the divalent state but by clustering [20].…”

Section: Polymerization By Transition Metal Complexesmentioning

confidence: 99%