Observation on different reducing power of cocatalysts on the Ziegler–Natta catalyst containing alkoxide species for ethylene polymerization

Hongmanee, Goond; Sripothongnak, Saovalak; Jongsomjit, Bunjerd; Praserthdam, Piyasan

doi:10.1002/app.40884

Cited by 6 publications

(8 citation statements)

References 25 publications

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“…Finally, the reactor was pressurized with the total pressure of 8 bars with ethylene at 75°C. The polymerization time was 1 h. The obtained polymer was dried at room temperature overnight …”

Section: Methodsmentioning

confidence: 99%

Influence of Hydrogen on Catalytic Properties of Ziegler‐Natta Catalysts Prepared by Different Methods in Ethylene Polymerization

et al. 2016

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Ethylene homopolymerization by two types of Ziegler-Natta catalyst including ZN-THF and ZN-EtOH catalysts was compared. The influences of hydrogen pressure and reaction time on catalytic activity using different types of catalyst were investigated. The EDX analysis and surface area measurement confirmed that ZN-EtOH catalyst had better active center distribution than that of ZN-THF. Thus, the ZN-EtOH catalyst could retard the effect of hydrogen and show higher activity with increased hydrogen pressures. However, catalytic activity was lower with high hydrogen pressure. Moreover, polymerization time also has an influence on activity. Both catalysts showed the similar result where an increase in polymerization time can improve yield of polymer, but it decreased activity. In addition, it is seen that the increase in hydrogen pressure leads to decrease the melting temperature for polyethylenes, but it increases the crystallinity.

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Section: Methodsmentioning

confidence: 99%

Influence of Hydrogen on Catalytic Properties of Ziegler‐Natta Catalysts Prepared by Different Methods in Ethylene Polymerization

et al. 2016

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“…In addition, the g-value of 1.95 appeared to increase with the activation time indicating the presence of Ti 3+ ions. For quantitative analysis of Ti 3+ species, ESR peak area relating to the relative amounts with activation time of Ti 3+ species was calculated by double integration [15]. In addition, the ESR results obtained from Figure 1 were further calculated by double integration technique and normalized peak areas of interval time to compare with the data at initial time (no activation) to obtain the plot of relative area (corresponding to the amount of changes in Ti 3+ ) with time in Figure 2.…”

Section: Catalytic Activitymentioning

confidence: 99%

“…They showed that TEA exhibited the highest activity and the activity enhanced with increased Al/Ti molar ratios (from 2 to 5). They concluded that an increase in Al/Ti molar ratios can alter the catalytic activity [15]. Later, other researchers suggested that different activators likely increased the insertion of 1-hexene in polyethylene.…”

Section: Introductionmentioning

confidence: 99%

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Facile Investigation of Ti3+ State in Ti-based Ziegler-Natta Catalyst with A Combination of Cocatalysts Using Electron Spin Resonance (ESR)

Pongchan

Praserthdam

Jongsomjit

2019

Bull. Chem. React. Eng. Catal.

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This study aims to investigate the influences of a combination of cocatalysts including triethylaluminum (TEA) and tri-n-octylaluminum (TnOA) for activation of a commercial Ti-based Ziegler-Natta catalyst during ethylene polymerization and ethylene/1-hexene copolymerization on the change in Ti3+ during polymerization. Thus, electron spin resonance (ESR) technique was performed to monitor the change in Ti3+ depending on the catalyst activation by a single and combination of cocatalyst. It revealed that the amount of Ti3+ played a crucial role on both ethylene polymerization and ethylene/1-hexene copolymerization. For ethylene polymerization, the activation with TEA apparently resulted in the highest catalytic activity. The activation with TEA+TnOA combination exhibited a moderate activity, whereas TnOA activation gave the lowest activity. In case of ethylene/1-hexene copolymerization, it revealed that the presence of 1-hexene decreased activity. The effect of different cocatalysts tended to be similar to the one in the absence of 1-hexene. The decrease of temperature from 80 to 70 °C in ethylene/1-hexene copolymerization tended to lower catalytic activity for TnOA and TEA+TnOA, whereas only slight effect was observed for TEA system. The effect of different cocatalyst activation on the change of Ti3+ state of catalyst was elucidated by ESR measurement. It appeared that the activation of catalyst with TEA+TnOA combination essentially inhibited the reduction of Ti3+ to Ti2+ leading to lower activity. Furthermore, the polymer properties such as morphology and crystallinity can be altered by different cocatalysts. Copyright © 2020 BCREC Group. All rights reserved

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“…The brown slurry mixture was observed. The catalyst slurry was purified by washing with n-hexane for seven times and dried under vacuum [82].…”

Section: Preparation Of Magnesium Powder Supported Catalystmentioning

confidence: 99%

Effect of cocatalyst combination in titanium-based ziegler-natta catalyst on olefin polymerization

Pongchan¹

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This research focused on effect of cocatalyst types (TEA, TnOA, and TEA+TnOA) on titanium-based Ziegler-Natta catalyst in olefin polymerization both in slurry and gas-phase systems. This study has been divided into four sections. The commercial titanium-based catalyst was selected to investigate effect of reaction temperature and oxidation state of titanium from ESR measurement on slurry ethylene and propylene polymerization in the first and the second parts, respectively. The commercial catalyst with TEA exhibited the highest activity in ethylene polymerization. However, divalent, and trivalent of titanium (Ti2+ and Ti3+) was active in ethylene polymerization to produce more polymer. Stability of Ti3+ was demonstrated to assist insertion of 1-hexene. Hence, propylene polymerization under different reaction temperatures was conducted to evaluate the titanium oxidation state (Ti3+). The ESR results revealed that TEA+TnOA at 50oC can stabilize titanium (III) state. Regarding to the third and fourth parts, different magnesium sources supported-catalyst; MgCl2 (Cat A), MgO (Cat B), and Mg(OEt)2 (Cat C); were compared in gas-phase ethylene polymerization. The modification of supported catalyst could improve the performance of catalyst and polymer. The results presented that Cat C or Mg(OEt)2 reacting with TEA showed the highest catalytic activity for both homo- and co-polymerization of ethylene. The addition of 1-hexene as comonomer could improve the activity and higher comonomer response called as “comonomer effect”. Moreover, the polymer obtained in gas-phase process exhibited remarkably better morphology than in slurry process.

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Observation on different reducing power of cocatalysts on the Ziegler–Natta catalyst containing alkoxide species for ethylene polymerization

Cited by 6 publications

References 25 publications

Influence of Hydrogen on Catalytic Properties of Ziegler‐Natta Catalysts Prepared by Different Methods in Ethylene Polymerization

Influence of Hydrogen on Catalytic Properties of Ziegler‐Natta Catalysts Prepared by Different Methods in Ethylene Polymerization

Facile Investigation of Ti3+ State in Ti-based Ziegler-Natta Catalyst with A Combination of Cocatalysts Using Electron Spin Resonance (ESR)

Effect of cocatalyst combination in titanium-based ziegler-natta catalyst on olefin polymerization

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