Kinetic behavior of ethylene polymerization in the presence of highly active titanium-magnesium catalysts

Захаров, В. А.; Makhtarulin, S. I.; Yermakov, Yu. I.

doi:10.1007/bf02068913

Cited by 17 publications

(3 citation statements)

References 5 publications

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“…Table IV lists the data on the effect of AlEt 3 concentration on the polymer yield, MW and MWD of the PE produced, and the content of terminal vinyl groups. As seen from these data, a certain decrease in the polymer yield is observed with AlEt 3 concentration increasing, which was earlier noted in works 17, 25. The MW of the resultant PE decreases and the MWD broadens as AlEt 3 concentration increases (Table IV, Fig.…”

Section: Resultssupporting

confidence: 79%

Ethylene polymerization over supported titanium‐magnesium catalysts: Effect of polymerization parameters on the molecular weight distribution of polyethylene

Nikolaeva¹,

Mikenas²,

Matsko³

et al. 2011

J of Applied Polymer Sci

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ABSTRACT:The data on the effects of polymerization duration, cocatalyst, and monomer concentrations upon ethylene polymerization in the absence of hydrogen, and the effect of an additional chain transfer agent (hydrogen) on the molecular weight (MW), molecular weight distribution (MWD), and content of vinyl terminal groups for polyethylene (PE) produced over the supported titanium-magnesium catalyst (TMC) are obtained. The effects of these parameters on nonuniformity of active sites for different chain transfer reactions are analyzed by deconvolution of the experimental MWD curves into Flory components. It has been shown that the polymer MW grows, the MWD becomes narrower and the content of vinyl terminal groups in PE increases with increasing polymerization duration. It is assumed to occur due to the reduction of the rate of chain transfer with AlEt 3 with increasing polymerization duration. The polydispersity of PE is found to rise with increasing AlEt 3 concentration and decreasing monomer concentration due to the emergence of additional low molecular weight Flory components. The ratios of the individual rate constants of chain transfer with AlEt 3 , monomer and hydrogen to the propagation rate constant have been calculated.

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Section: Resultssupporting

confidence: 79%

Ethylene polymerization over supported titanium‐magnesium catalysts: Effect of polymerization parameters on the molecular weight distribution of polyethylene

Nikolaeva¹,

Mikenas²,

Matsko³

et al. 2011

J of Applied Polymer Sci

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“…( 1967) reported that propagation• rate is proportional to the active-site concentration and amount of monomer adsorbed on the catalyst. Zakharov and co-workers (Zakharov, 1978;Zakharov et al, 1976aZakharov et al, ,b, 1977Zakharov et al, , 1978 and Bukatov et al (1977) also concluded that the propagation step on an active site involved the monomer adsorbed. These kinetic data suggested that propagation occurred in two steps including the coordination of monomer to titanium ion and a subsequent insertion into the active titanium-carbon bond.…”

Section: Introductionmentioning

confidence: 99%

Computer simulation study of ethylene polymerization rate profile catalyzed over highly active Ziegler-Natta catalysts

Kim¹,

Kim²,

Woo³

1991

Ind. Eng. Chem. Res.

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“…Although slurry reactors have been extensively used in the laboratory, the majority of earlier studies have involved Ziegler−Natta type catalysts. − Fewer results , are available concerning slurry reactor studies with Phillips type catalysts (Cr/silica). Too often, these earlier studies fail to present important details concerning the reactor construction, its operation, or the conditions of the measurements being made.…”

Section: Introductionmentioning

confidence: 99%

A Novel Laboratory Slurry Reactor for Ethylene Polymerization Studies

et al. 1996

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A novel laboratory slurry reactor useful for studies of polymerization of olefins with solid catalysts such as Cr/silica is described. The operation of this reactor, in which gaseous impurities are minimized by purification of incoming gases and by in situ activation of the catalyst, has enabled the early stages of the homopolymerization of ethylene to be studied without interference from catalyst deactivation effects. By standardizing the conditions for the experimental runs, the reactor demonstrated its usefulness in isolating and assessing the relative physical roles of different silica supports. Four catalysts supported on different silica supports were compared, and their differences in promoting the polymerization were interpreted in terms of porosity, average particle size, and changes in specific surface area. During early polymerization, the fracturing of catalysts prepared by impregnation of the porous silica support ensures access to these original Cr sites, in the absence of additional concealed sites. At low yields, the polymerization process is clearly affected by the physical character of the silica support; however, at higher yields, the evidence suggests that other causes such as chemical effects are responsible for the continuing acceleration in rate. The porous Cr/silica catalyst tested did not fracture instantaneously; hence, current models of nascent polymer do not describe this process. The "hardcore" model of nascent polymer seems applicable to polymerization on the nonporous Cr/Cab-O-Sil catalyst tested.

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Kinetic behavior of ethylene polymerization in the presence of highly active titanium-magnesium catalysts

Cited by 17 publications

References 5 publications

Ethylene polymerization over supported titanium‐magnesium catalysts: Effect of polymerization parameters on the molecular weight distribution of polyethylene

Ethylene polymerization over supported titanium‐magnesium catalysts: Effect of polymerization parameters on the molecular weight distribution of polyethylene

Computer simulation study of ethylene polymerization rate profile catalyzed over highly active Ziegler-Natta catalysts

A Novel Laboratory Slurry Reactor for Ethylene Polymerization Studies

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