Comparison of catalytic ethylene polymerization in slurry and gas phase

Daftari‐Besheli, Majid

doi:10.3990/1.9789036528382

Cited by 8 publications

(8 citation statements)

References 81 publications

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“…On the other hand, for precontacting times longer than the optimum value the catalyst activity decreases. This is in full accordance with the previous published results and literature findings [4,5,13].…”

Section: Resultssupporting

confidence: 83%

“…When comparing our results with experiments of Daftaribesheli [4] and Di Martino et al [5] on precontacting with heterogeneous Z-N system in slurry-phase, similar results are obtained despite the fact that different solvents were used (i.e., hexane and heptane, resp.). Han-Adebekun and Ray [13], studied the effect of long precontacting times in a gasphase olefin polymerization system.…”

Section: Resultssupporting

confidence: 71%

“…The catalyst activation prior to the main polymerization process plays an important role towards reaching the maximum potential of a catalyst system in terms of productivity. It has been shown that pretreatment of the catalyst can increase the activity of the catalyst system [4][5][6]. Prepolymerization is already a wide explored field for catalyst tuning/optimization and morphology control [7,8].…”

Section: Introductionmentioning

confidence: 99%

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Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

Aigner

Paulik

Krallis

et al. 2016

Journal of Polymers

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In industrial-scale catalytic olefin copolymerization processes, catalyst and cocatalyst precontacting before being introduced in the polymerization reactor is of profound significance in terms of catalyst kinetics and morphology control. The precontacting process takes place under either well-mixing (e.g., static mixers) or plug-flow (e.g., pipes) conditions. The scope of this work is to study the influence of mixing on catalyst/cocatalyst precontacting for a heterogeneous Ziegler-Natta catalyst system under different polymerization conditions. Slurry ethylene homopolymerization and ethylene copolymerization experiments with 1-butene are performed in a 0.5 L reactor. In addition, the effect of several key parameters (e.g., precontacting time, and ethylene/hydrogen concentration) on catalyst activity is analyzed. Moreover, a comprehensive mass transfer model is employed to provide insight on the mass transfer process and support the experimental findings. The model is capable of assessing the external and internal mass transfer limitations during catalyst/cocatalyst precontacting process. It is shown that catalyst/cocatalyst precontacting is very important for the catalyst activation as well as for the overall catalyst kinetic behavior. The study reveals that there is an optimum precontacting time before and after which the catalyst activity decreases, while this optimum time depends on the precontacting mixing conditions.

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Section: Resultssupporting

confidence: 83%

Section: Resultssupporting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

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Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

Aigner

Paulik

Krallis

et al. 2016

Journal of Polymers

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“…For instance, Naderpour et al studied ethylene polymerization kinetics with a heterogeneous Ziegler‐Natta (ZN) catalyst, and concluded that process variables as temperature, pressure and hydrogen concentration have different effects on the kinetic parameters and rate of polymerization of ethylene in slurry and gas phases. Daftaribesheli studied mass transfer resistances in gas and slurry processes, and determined that transport of gaseous monomer over a gas‐liquid boundary can become the rate limiting step when highly active catalysts are used. Diffusion in the gas phase is obviously much faster than in a liquid hydrocarbon, and as consequence the reaction starts more quickly in gas, and particles in the gas‐phase suffer more easily from overheating than in slurry phase.…”

Section: Introductionmentioning

confidence: 99%

A Comparison of the Influence of Temperature During Slurry and Gas Phase Propylene Polymerization on Ziegler‐Natta Catalyst

Cancelas

Hongmanee

Andrade

et al. 2016

Macromolecular Symposia

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Summary Semi‐batch propylene polymerizations were performed in slurry and gas phase using a supported Ziegler‐Natta catalyst. The obtained instantaneous reaction rates were fitted with a kinetic model, and the influence of bulk temperature and reaction phase on kinetic parameters was studied. The estimated propagation constant increased with increasing reaction temperature up to 90 °C in slurry phase polymerizations, but reached a maximum at 60 °C when propylene was polymerized in the gas phase. Gas phase stopped flow reactions were done at 60 and 70 °C to investigate the strong influence of temperature during the initial instants of reaction and to evidence thermal degradation at particle level. These results and those from autoclave reactor were well consistent and could explain the effects of temperature.

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“…the same concept is used in the thesis of M. Daftaribesheli[31] in the same research group who focused on the comparison of slurry and gas phase PO processes in 2009 too…”

mentioning

confidence: 99%

Fragmentation and disintegration of polymerizing PE particles

Ramamoorthy¹,

Narayanan²

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Morphology control is an important issue in the field of polyolefins as well as catalyst development. New generations of supported catalysts often show complex fragmentation behaviour. Ideally, with stable skin formation, one polymer particle results from one catalyst particle. However, a combination of thermal and growth / mechanical stress can lead to so called particle disintegration ("external fragmentation") -the particle cracks into a number of smaller particles that polymerize and grow, leading to smaller than expected polymer grains which are referred to as "fines". Generation of fines has been a major problem in olefin (ethylene) polymerizations for a long time now. Production of fines in industrial processes leads to a multitude of problems like-wall sheeting, bad heat transfer characteristics, non-homogeneous polymerization, off-spec products, disturbances in downstream processes, and so on and so forth.The main objective of this thesis was to develop a semi-quantitative method for characterization of fines generation in ethylene polymerization using MgCl2supported Ziegler-Natta catalysts based on a detailed analysis of the polymerization kinetics, molecular weight, crystallinity, particle growth and particle size distribution, pre-polymerization and catalyst pretreatment and their individual and combined impact on internal and external fragmentation.

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Comparison of catalytic ethylene polymerization in slurry and gas phase

Cited by 8 publications

References 81 publications

Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

Optimal Catalyst and Cocatalyst Precontacting in Industrial Ethylene Copolymerization Processes

A Comparison of the Influence of Temperature During Slurry and Gas Phase Propylene Polymerization on Ziegler‐Natta Catalyst

Fragmentation and disintegration of polymerizing PE particles

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