The influence of magnesium dichloride as support on molecular weights of the polyethylenes produced by Ziegler-Natta catalyst

Document Type : Original research

Authors

Boreskov Institute of Catalysis SB RAS, pr. Akademika Lavrentieva, 5, 630090 Novosibirsk, Russia

Abstract

The paper presents data on the effect exerted by magnesium dichloride in Ziegler-Natta catalysts on the activity and molecular weight of polyethylene (PE) produced by ethylene polymerization in the absence or presence of hydrogen. It was found that ethylene polymerization in the absence of hydrogen over titanium-magnesium catalysts (TMCs) with different ratio of titanium chloride and magnesium dichloride (Ti/Mg = 0.5 and 0.07), oxidation state of titanium (TiCl3 or TiCl4) and structural characteristics of the catalysts leads to the formation of PE with a close molecular weight. At the same time, PE obtained over a δ-TiCl3 catalyst has a much (threefold) higher molecular weight. The introduction of hydrogen during polymerization for decreasing the molecular weight of PE is accompanied by a sharp drop in activity of the δ-TiCl3 catalyst, in distinction to the highly active supported TMC containing 3 wt. % Ti. Data about the effect of hydrogen content during polymerization on the molecular weight of PE were used to calculate the ratio of rate constants for polymer chain transfer with hydrogen (KtrH) and polymer chain propagation reaction (Кр). This value was close for TMCs of different composition containing magnesium dichloride. In the case of δ-TiCl3, the KtrH/Кр value was approximately two times lower compared to TMCs.

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References

  1. Spalding MA, Chatterjee AM (eds) (2017) Handbook of industrial polyethylene and technology: definitive guide to manufacturing, properties, processing, applications and markets. Scrivener Publishing LLC, Beverly, MA, USA [CrossRef]
  2. Paulik C, Spiegel G, Jeremic D (2019) Bimodal polyethylene: Controlling polymer properties by molecular design. In: Multimodal polymers with supported catalysts, Albunia AR, Prades F, Jeremic D (eds), Springer, Cham [CrossRef]
  3. Nowlin TE (2014) Business and technology of the global polyethylene industry: An in-depth look at the history, technology, catalysts, and modern commercial manufacture of polyethylene and its products, Wiley-Scrivener Publishing, Salem, MA, USA
  4. Sauter DW, Taoufik M, Boisson C (2017) Polyolefins, a success story. Polymers 9: 185 [CrossRef]
  5. Plastics Europe: Plastics-The Facts (2020) Available online: https://plasticseurope.org/de/wp content/uploads/sites/3/2021/11/Plastics_the_facts-WEB-2020 version Jun21_final.pdf. Accessed 27 June 2022
  6. Zakharov VA, Chumayevskii NB, Makhtarulin SI, Bukatov GD, Yermakov YI (1975) Determination of the number of propagation centers and the propagation rate constant for ethylene polymerization on supported titanium catalysts. React Kinet Catal Lett 2: 329-335 [CrossRef]
  7. Zakharov VA, Bukatov GD, Chumayevskii NB, Yermakov YI (1977) Study of the mechanism of propagation and transfer reactions in the polymerization of olefins by Ziegler-Natta catalysts, 4. The kinetic scheme for propagation and chain transfer reactions. Macromol Chem 178: 967-980 [CrossRef]
  8. Zakharov VA, Bukatov GD, Yermakov YI (1983) On the mechanism of olefin polymerization by Ziegler-Natta catalysts. Industrial Developments. Berlin, Heidelberg: Springer Berlin Heidelberg, 61-100 [CrossRef]
  9. Zakharov VA, Bukatova ZK, Makhtarulin SI, Chumaevsky NB, Ermakov YI (1979) Chain transfer in polymerization of ethylene by highly active titanium-magnesium catalysts. Polym Sci 21: 544-550 [CrossRef]
  10. Bukatov GD, Zakharov VA, Barabanov AA (2005) Mechanism of olefin polymerization on supported Ziegler-Natta catalysts based on data on the number of active centers and propagation rate constants. Kinet Catal 46: 166-176 [CrossRef]
  11. Mikenas TB, Koshevoy EI, Cherepanova SV, Zakharov VA (2016) Study of the Composition and Morphology of New Modifications of Titanium-Magnesium Catalysts with Improved Properties in Ethylene Polymerization. J Polym Sci Pol Chem 54: 2545-2558 [CrossRef]
  12. Mikenas TB, Koshevoy EI, Zakharov VA (2017) Effect of the structure of titanium–magnesium catalysts on the morphology of polyethylene produced. J Polym Sci Pol Chem 55: 2298-2308 [CrossRef]
  13. Shams A, Mehdizadeh M, Teimoury H-R, Emami M, Mirmohammadi SA, Sadjadi S, Bardají E, Poater A, Bahri-Laleh N (2022) Effect of the Pore Architecture of Ziegler-Natta Catalyst on Its Behavior in Propylene/1-Hexene Copolymerization. J Ind Eng Chem 116: 359-370 [CrossRef]
  14. Masoori M, Rashedi R, Sepahi A, Jandaghian MH, Nikzinat E, Houshmandmoayed S (2022) Structure–Performance Relationship (SPR) of Ziegler Natta catalysts (TiCl4/MgCl2‑based) in ethylene/1‑butene and ethylene/1‑hexene copolymerization. J Polym Res 29: 317 [CrossRef]
  15. Zakharov VA, Makhtarulin SI, Poluboyarov VA, Anufrienko VF (1984) Study of the state of titanium ions and the composition of the active component in titanium-magnesium catalysts for ethylene polymerization. Macromol Chem 185: 1781-1793 [CrossRef]
  16. Mikenas TB, Koshevoy EI, Zakharov VA, Nikolaeva MI (2014) Formation of isolated titanium (II) ions as active sites of supported titanium-magnesium catalyst for polymerization of olefins in supported Ziegler-Natta. Macromol Chem Phys 215: 1707-1720 [CrossRef]
  17. Sukulova VV, Barabanov AA, Mikenas TB, Matsko MA, Zakharov VA (2018) Effect of hydrogen on the number of active centers and the propagation rate constant at ethylene polymerization over titanium-magnesium Ziegler-Natta catalysts. Mol Catal 445: 299–306 [CrossRef]
  18. Natta G, Pasquon I (1959) The kinetics of the stereospecific polymerization of α-olefins. Adv Catal 11: 1-66 [CrossRef]
  19. Echevskaya LG, Matsko MA, Mikenas TB, Nikitin VE, Zakharov VA (2006) Supported titanium–magnesium catalysts with different titanium content: Kinetic peculiarities at ethylene homopolymerization and copolymerization and molecular weight characteristics of polyethylene. J Appl Polym Sci 102: 5436-5442 [CrossRef]
  20. Nikolaeva MI, Mikenas TB, Matsko MA, Echevskaya LG, Zakharov VA (2010) Heterogeneity of Active Sites of Ziegler-Natta Catalysts: The Effect of Catalyst Composition on the MWD of Polyethylene. J Appl Polym Sci 115: 2432-2439 [CrossRef]
  21. Mikenas TB, Zakharov VA, Echevskaya LG, Matsko MA (2001) Ethylene Polymerization with Supported Vanadium-Magnesium Catalyst: Hydrogen Effect.Macromol Chem Phys 202: 75-481 [CrossRef]
Polyolefins Journal
Volume 11, Issue 4 - Serial Number 26
December 2024
Pages 235-242

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History

  • Receive Date: 11 October 2024
  • Revise Date: 02 November 2024
  • Accept Date: 02 November 2024
  • First Publish Date: 02 November 2024

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