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

Thanyaporn Pongchan  -  Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Thailand
Piyasan Praserthdam  -  Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Thailand
*Bunjerd Jongsomjit scopus  -  Center of Excellence on Catalysis and Catalytic Reaction Engineering, Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Thailand
Received: 21 Jun 2019; Revised: 28 Aug 2019; Accepted: 3 Sep 2019; Published: 1 Apr 2020; Available online: 28 Feb 2020.
Open Access Copyright (c) 2020 Bulletin of Chemical Reaction Engineering & Catalysis
License URL: http://creativecommons.org/licenses/by-sa/4.0

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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

Keywords: Ethylene polymerization; Ziegler-Natta catalyst; Cocatalysts; Titanium oxidation state; Electron spin resonance

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  1. Lee, T., Kim, W.-K., Lee, Y., Ryou, M.-H., Lee, Y. M. (2014). Effect of Al2O3 coatings prepared by RF sputtering on polyethylene separators for high-power lithium ion batteries. Macromolecular Research, 22: 1190-1195.
  2. Jeon, M., Han, C. J., Kim, S. Y. (2006). Polymerizations of propylene with unsymmetrical (α-diimine) nickel (II) catalysts. Macromolecular Research, 14: 306-311.
  3. Chien, J. C., He, D. (1991). Olefin copolymerization with metallocene catalysts. III. Supported metallocene/methylaluminoxane catalyst for olefin copolymerization. J. Polymer Sci. Part A: Polymer Chem., 29: 1603-1607.
  4. Chien, J. C., He, D. (1991). Olefin copolymerization with metallocene catalysts. I. Comparison of catalysts. J. Polym. Sci. Part A: Polym. Chem., 29: 1585-1593.
  5. Kaminsky, W. (1996). New polymers by metallocene catalysis. Macromol. Chem. Phys., 197: 3907-3945.
  6. Kaivalchatchawal, P., Samingprai, S., Shiono, T., Praserthdam, P., Jongsomjit, B. (2012). Effect of Ga-and BCl3-modified silica-supported [t-BuNSiMe2 (2,7-t-Bu2Flu)] TiMe2/MAO catalyst on ethylene/1-hexene copolymerization. Eur. Polym. J., 48: 1304-1312.
  7. Lee, S., Choi, K.Y. (2017). Ethylene polymerization over metallocene catalysts supported on highly fibrous silica nanoparticles. Macromol. Reac. Eng., 11: 1600027.
  8. Mohamadnia, Z., Ahmadi, E., Haghighi, M.N., Farandpour, A., Rezazadah, Z., Fallahi, M. (2015). Preparation of LLDPE through tandem ethylene polymerization using chromium and zirconium catalysts. Iran. Polym. J., 24: 621-628.
  9. Gagieva, S.C., Tuskaev, V.A., Fedyanin, I.V., Buzin, M.I., Vasil’ev, V.G., Nikiforova, G.G., Afanas’ev, E.S., Zubkevich, S.V., Kurmaev, D.A., Kolosov, N.A., Mikhaylik, E.S. (2017). Novel titanium (IV) diolate complexes: Synthesis, structure and catalytic activities in ultra-high molecular weight polyethylene production. J. Organometal. Chem., 828: 89-95.
  10. Kaminsky, W. (2012). Discovery of methylaluminoxane as cocatalyst for olefin polymerization. Macromolecules, 45: 3289-3297.
  11. Noristi, L., Barbè, P.C., Baruzzi, G. (1991). Effect of the internal/external donor pair in high‐yield catalysts for propylene polymerization, 1. Catalyst‐cocatalyst interactions. Die Makromolekulare Chemie: Macromol. Chem. Phys., 192: 1115-1127.
  12. Mori, H., Iguchi, H., Hasebe, K., Terano, M. (1997). Kinetic study of isospecific active sites formed by various alkylaluminiums on MgCl2‐supported Ziegler catalyst at the initial stage of propene polymerization. Macromol. Chem. Phys., 198: 1249-1255.
  13. Senso, N., Praserthdam, P., Jongsomjit, B., Taniike, T., Terano, M. (2011). Effects of Ti oxidation state on ethylene, 1-hexene comonomer polymerization by MgCl 2-supported Ziegler–Natta catalysts. Polymer Bulletin., 67: 1979-1989.
  14. Garoff, T., Mannonen, L., Väänänen, M., Eriksson, V., Kallio, K., Waldvogel, P. (2010). Chemical composition distribution study in ethylene/1‐hexene copolymerization to produce LLDPE material using MgCl2‐TiCl4‐based Ziegler‐Natta catalysts. J. Appl. Polym. Sci., 115: 826-836.
  15. Hongmanee, G., Sripothongnak, S., Jongsomjit, B., Praserthdam, P. (2014). Observation on different reducing power of cocatalysts on the Ziegler–Natta catalyst containing alkoxide species for ethylene polymerization. J. Appl. Polym. Sci., 131: 40884(1-5).
  16. Nooijen, G. (1994). On the importance of diffusion of cocatalyst molecules through heterogeneous ziegler/natta catalysts. Eur. Polym. J., 30: 11-15.
  17. Shan, C.L.P., Chu, K.J., Soares, J., Penlidis, A. (2000). Using alkylaluminium activators to tailor short chain branching distributions of ethylene/1‐hexene copolymers produced with in‐situ supported metallocene catalysts. Macromol. Chem. Phys., 201: 2195-2202.
  18. Senso, N., Khaubunsongserm, S., Jongsomjit, B., Praserthdam, P. (2010). The influence of mixed activators on ethylene polymerization and ethylene/1-hexene copolymerization with silica-supported Ziegler-Natta catalyst. Molecules, 15: 9323-9339.
  19. Pinyocheep, J., Ayudhya, S.K.N., Jongsomjit, B., Praserthdam, P. (2012). Observation on inhibition of Ti3+ reduction by fumed silica addition in Ziegler-Natta catalyst with in situ ESR. Journal of Industrial and Engineering Chemistry, 18: 1888-1892.
  20. Risse, T., Schmidt, J., Hamann, H., Freund, H.J. (2002). Direct Observation of Radicals in the Activation of Ziegler–Natta Catalysts. Angewandte Chemie International Edition, 41: 1517-1520.
  21. Xiong, L.-B., Li, J.-L., Yang, B., Yu, Y. (2012). Ti3+ in the surface of titanium dioxide: generation, properties and photocatalytic application. J. Nanomater., 2012, 1-13.
  22. Koshevoy, E.I., Mikenas, T.B., Zakharov, V. A., Shubin, A.A., Barabanov, A.A. (2016). Electron Paramagnetic Resonance Study of the Interaction of Surface Titanium Species with AlR3 Cocatalyst in Supported Ziegler–Natta Catalysts with a Low Titanium Content. J. Physical Chem. C., 120: 1121-1129.
  23. Brant, P., Speca, A.N. (1987). Electron spin resonance, titanium oxidation state, and ethylene polymerization studies of a model supported Ziegler-Natta catalyst. Spectroscopic detection of titanium tetrachloride. Macromolecules, 20: 2740-2744.
  24. Chu, K.-J., Chang, H.-S., Ihm, S.-K. (1994). Effects of diethyl aluminum chloride (DEAC) addition to the catalysts prepared by reduction of TiCl4 with EtMgCl on ethylene-propylene copolymerization. Eur. Polym. J., 30: 1467-1472.
  25. Křižan, M., Honzíček, J., Vinklárek, J., Růžičková, Z., Erben, M. (2015). Titanocene (III) pseudohalides: an ESR and structural study. New J. Chem., 39: 576-588.
  26. Stukalov, D.V., Zilberberg, I.L., Zakharov, V.A. (2009). Surface species of titanium (IV) and titanium(III) in MgCl2-supported Ziegler-Natta catalysts. A periodic density functional theory study. Macromolecules, 42: 8165-8171.
  27. Han‐Adebekun, G., Ray, W. (1997). Polymerization of olefins through heterogeneous catalysis. XVII. Experimental study and model interpretation of some aspects of olefin polymerization over a
  28. TiCl4/MgCl2 catalyst. J. Appl. Polym. Sci., 65: 1037-1052.
  29. Ludlum, D., Anderson, A., Ashby, C. (1958). The Polymerization of Ethylene by Lower Valent Compounds of Titanium. J. American Chemical Society., 80: 1380-1384.
  30. Kageyama, K., Tamazawa, J.-i., Aida, T. (1999). Extrusion polymerization: catalyzed synthesis of crystalline linear polyethylene nanofibers within a mesoporous silica. Science., 285: 2113-2115.

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