Insights into the effect of vanadium on chromium-vanadium Phillips catalysts for the ethylene polymerization

Document Type: Original research


1 State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Meilong Road 130, Shanghai 200237, China

2 Daqing Petrochemical Research Center, CNPC, NO.2 Chengxiang Road, Daqing, Heilongjiang 163000, China

3 College of Materials and Energy, South China Agricultural University, Wushan Road 4 83, Guangzhou 510642, China



The chromium/vanadium bimetallic Phillips catalysts developed by our research group have been proved to be a promising process to produce bimodal polyethylene using a single-reactor process. The vanadium loading of CrV-1/1, CrV-1/2, and CrV-1/3 has a significant effect on the polymerization activity, product molecular weight (MW), as well as the molecular weight distribution (MWD). Due to the unstable and easy deactivation of vanadium active centers at atmospheric or low (0.4 MPa) reaction pressure [Macromol. React. Eng. 2015, 9, 462–472], the reaction is carried out at 1.0 MPa to strength the V active center on the activities of ethylene homopolymerization, ethylene/1-hexene copolymerization, and the H2 responds properties. The reaction carried out at higher pressure promotes the polymerization activities. With the same amount of cocatalyst, the highest activity of the three Cr-V bimetallic catalysts CrV-1/1, CrV-1/2 and CrV-1/3 decreases with the increase of vanadium loading. The Cr-V bimetallic catalysts require more cocatalyst than the single metal Cr cat. It was found two obvious peaks in the GPC curves of homopolyethylen and ethylene/1-hexene copolymer. It means that the higher reaction pressure benefits the promotion of the active center of catalyst for higher MW. By increasing the loading from 0.48 wt.% (CrV-1/1) to 0.96 wt.% (CrV-1/2), the molecular weight increases by nearly 30%. Besides, according to the deconvolutions of the GPC curves of homopolymers, ethylene/1-hexene copolymers, and the homopolymers with H2 modulation, the synergetic effect between Cr and V center is presented. As the vanadium loading increases, the active site accounted for the high molecular weight portion increases, and the Cr-V catalyst presents better hydrogen responds. When the partial pressure of hydrogen is 0.1 MPa, the molecular weight is reduced by nearly half. Specifically, the high molecular weight peak is weakened, while the low molecular weight peak is strengthened. The peak position does not change significantly. The higher vanadium content and the greater sensitivity of hydrogen modulation indicate that the vanadium active center has better hydrogen responds than the chromium active center does. The homopolymerization product of the Cr/V-1/1 catalysts exhibits higher tensile strength and elongation-at-break. The tensile properties of the copolymerized product of CrV-1/1 are further improved.


  1. McDaniel MP (2010) A review of the phillips supported chromium catalyst and its commercial use for ethylene polymerization. Adv Catal 53: 123-606
  2. Ruff M, Paulik C (2012) Controlling polyolefin properties by in-reactor blending, 1-Polymerization process, precise kinetics, and molecular properties of UHMW- PE polymers. Macromol React Eng 6: 302-317
  3. Ushakova TM, Starchak EE, Krasheninnikov VG, Grinev VG, Ladygina TA, Novokshonova LA (2014) Influence of copolymer fraction composition in ultrahigh molecular weight polyethylene blends with ethylene/1-hexene copolymers on material physical and tensile properties. J Appl Polym Sci 131: 631-644
  4. Ruff M, Paulik C (2013) Controlling polyolefin properties by in-reactor blending: 2. Particle design. Macromol React Eng 7: 71-83
  5. Ruff M, Lang RW, Paulik C (2013) Controlling polyolefin properties by in-reactor blending, 3. Mechanical properties. Macromol React Eng 7: 328-343
  6. Han SC, Choi YH, Lee WY (2000) Characteristics of ethylene polymerization over Ziegler–Natta/ metallocene catalysts: Comparison between hybrid and mixed catalysts. Catal Today 63: 523- 530
  7. Han SC, Jin SC, Lee WY (2000) Control of molecular weight distribution for polyethylene catalyzed over Ziegler-Natta/Metallocene hybrid and mixed catalysts. J Mol Catal A-Chem 159: 203-213
  8. Jin SC, Han SC, Ko YG, Lee WY (1999) Preparation of the Ziegler–Natta/metallocene hybrid catalysts on SiO2/MgCl2 bisupport and ethylene polymerization. J Mol Catal A-Chem 144: 61-69
  9. Liu J, Dong J, Cui N, Hu Y (2004) Supporting a metallocene on functional polypropylene granules for slurry ethylene polymerization. Macromolecules 37: 6275-6282
  10. Sturzel M, Mihan S, Mulhaupt R (2016) From multisite polymerization catalysis to sustainable materials and all-polyolefin composites. Chem Rev 116: 1398-1433
  11. Ahn TO, Hong SC, Wan SH, Lee YC, Lee DH (1999) Modification of a Ziegler-Natta catalyst with a metallocene catalyst and its olefin polymerization behavior. Polym Eng Sci 39: 1257–1264
  12. Zhang S, Cheng R, Dong Q, He X, Wang Q, Tang Y, Yu Y, Xie K, Da J, Terano M, Liu B (2013) Ethylene/1-hexene copolymerization with a novel SiO2-supported inorganic and organic hybrid chromium-based catalyst. Macromol React Eng 7: 254-266
  13. Ochedzan-Siodlak W, Bihun A (2015) Direct synthesis of fibrous high molecular weight polyethylene using vanadium catalysts supported on an SiO2 ionic liquid system. Polym Int 64: 1600–1606
  14. Bialek M, Pochwala M, Spaleniak G (2014) Olefin polymerization and copolymerization by complexes bearing [ONNO]-Type salan ligands: Effect of ligand structure and metal type (titanium, zirconium, and vanadium). J of Polym Sci Pol Chem 52: 2111–2123
  15. Ghosh S (2008) Influence of supported vanadium catalyst on ethylene polymerization reactions. Polym Int 57: 262-267
  16. Hagen H, Boersma J, van Koten G (2002) Homogeneous vanadium-based catalysts for the Ziegler-Natta polymerization of α-olefins. Chem Soc Rev 31: 357-364
  17. Liu B, Tian Z, Jin Y, Zhao N, Liu B (2018) Toward the optimization of a Cr-V bimetallic catalyst for producing bimodal polyethylene: Effect of vanadium content and calcination temperature. Macromol Chem Phys 219: 11800021
  18. Zhao N, Cheng R, He X, Liu Z, Liu B, Zhang R, Gao Y, Zou E, Wang S (2014) Novel SiO2- supported silylchromate(Cr)/imido-vanadium(V) bimetallic catalysts producing polyethylene and ethylene/1-hexene copolymers with bimodal molecular-weight distribution. Macromol Chem Phys 215: 1434–1445
  19. Jin Y, Zhao N, Cheng R, Liu B (2017) Research progress of bimetallic catalysts for bimodal polyethylene synthesis. CIESC J 68: 485-495
  20. Jin Y, Zhao N, Cheng R, He X, Liu Z, Dong D, Bin Y, Chen X, Li L, Liu B (2017) One pot synthesis of bimodal UHMWPE/HDPE in-reactor blends with Cr/V bimetallic catalysts. J Polym Sci Pol Chem 55: 3404-3412
  21. Cheng R, Xue X, Liu W, Zhao N, He X, Liu Z, Liu B (2015) Novel SiO2-supported chromium oxide(Cr)/vanadium oxide(V) bimetallic catalysts for production of bimodal polyethylene. Macromol React Eng 9: 462-472
  22. Sun Q, Wang L, Cheng R, Liu Z, He X, Zhao N, Liu B (2017) A novel SiO2-supported fluorine modified chromium-vanadium bimetallic catalyst for ethylene polymerization and ethylene/1- hexene copolymerization. Macromol React Eng 11: 1600055
  23. Sun Q, Cheng R, Liu Z, He X, Zhao N, Liu B (2017) Introduction of titanium species into fluorine-modified SiO2-supported Cr-V bimetallic catalyst for ethylene polymerization and ethylene/1-hexene copolymerization. Polyolefins J 4: 221-234
  24. Zhao N (2014) Studies on novel SiO2supported Cr/V bimetallic catalysts for ethylene polymerization. PhD Thsis, East China University of Science & Technology, China
  25. Cheng R, Liu Z, Zhong L, He X, Qiu P, Terano M, Eisen M, Scott S, Liu B (2013) Phillips Cr/ Silica catalyst for ethylene polymerization. In: Polyolefins: 50 Years after Ziegler and Natta I: Polyethylene and Polypropylene, Ed. W Kaminsky, 135-202
  26. Wei X, Liu B, Fang Y, Hasebe K, Terano M (2006) Unique polymerization kinetics obtained from simultaneous interaction of Phillips Cr(VI) Ox/SiO2 catalyst with Al-alkyl cocatalyst and ethylene monomer. J Mol Catal A-Chem 256: 301-308
  27. Wei X, Tonosaki K, Taniike T, Terano M, Fujitani T, Liu B (2010) Copolymerization of ethylene and cyclopentene with the Phillips CrOx/SiO2 catalyst in the presence of an aluminum alkyl cocatalyst. J Appl Polym Sci 111: 1869-1877
  28. Zhang Z, Jiang B, Zhang B, Fu Z, Fan Z (2019) Deactivation effect caused by catalyst-cocatalyst pre-contact in propylene polymerization with MgCl2-supported Ziegler-Natta Catalyst. Chinese J Polym Sci 37: 1023-1030
  29. Jin Y, Cheng R, He X, Liu Z, Zhao N, Liu B (2017) The first vanadium-oxide-based UHMWPE catalyst supported on chemically modified silica gel. Macromol Chem Phys 218: 1600443
  30. Liu B, Tian Z, Zhao N, Liu Z, Liu B (2017) Peculiarities of ethylene polymerization kinetics with an imidovanadium /silyl-chromate bimetallic catalyst: Effect of polymerization conditions. Ind Eng Chem Res 56: 6164-6175
  31. Soares JBP,Hamielec AE (1995) Deconvolution of chain-length distributions of linear polymers made by multiple-site-type catalysts. Polymer 36: 2257-2263
  32. Niu Q, Zhang J, Peng W, Fan Z, He A (2019) Effect of alkylaluminium on the regio- and stereoselectivity in copolymerization of isoprene and butadiene using TiCl4/MgCl2 type Ziegler- Natta catalyst. Mol Catal 471: 1-8
  33. Zhang Z, Jiang B, He F, Fu Z, Xu J, Fan Z (2019) Comparative study on kinetics of ethylene and propylene polymerizations with supported Ziegler- Natta catalyst: Catalyst fragmentation promoted by polymer crystalline lamellae. Polymers 11: 15
  34. Song S, Wu P, Ye M, Feng J, Yang Y (2008) Effect of small amount of ultra high molecular weight component on the crystallization behaviors of bimodal high density polyethylene. Polymer 49: 2964-2973
  35. Andjelić S, Scogna RC (2015) Polymer crystallization rate challenges: The art of chemistry and processing. J Appl Polym Sci 132: 42006
  36. Yang Q, Jensen MD, McDaniel MP (2010) Alternative view of long chain branch formation by metallocene catalysts. Macromolecules 43: 8836-8852
  37. Wang W, Fan Z, Feng L, Li C (2005) Substituent effect of bisindenyl zirconene catalyst on ethylene/1-hexene copolymerization and propylene polymerization. Eur Polym J 41: 83-89
  38. McDaniel MP, Schwerdtfeger ED, Jensen MD (2014) The “comonomer effect” on chromium polymerization catalysts. J Catal 314: 109-116
  39. Fang Y, Liu B, Hasebe K, Terano M (2010) Ethylene and 1-hexene copolymerization with CO-prereduced phillips CrOx/SiO2 catalyst in the presence of Al-alkyl cocatalyst. J Polym Sci Pol Chem 43: 4632-4641
  40. Zhao Z, Mikenas T, Zakharov VA, Nikolaeva M, Matsko M, Bessudnova E, Wu W (2019) Copolymerization of ethylene with α-olefins over highly active supported Ziegler-Natta catalyst with vanadium active component. Polyolefins J 6: 117-126
  41. Zhao N, Cheng R, He X, Liu Z, Liu B (2014) A novel SiO2 supported Cr–V bimetallic catalyst making polyethylene and ethylene/1-hexene copolymers with bimodal molecular weight distribution. Macromol Chem Phys 215: 1753- 1766
  42. Kissin YV, Brandolini AJ (2015) Ethylene polymerization reactions with Ziegler-Natta catalysts. II. Ethylene polymerization reactions in the presence of deuterium. J Polym Sci Pol Chem 37: 4273-4280
  43. Kissin YV, Rishina LA, Vizen EI (2002) Hydrogen effects in propylene polymerization reactions with titanium-based Ziegler–Natta catalysts. II. Mechanism of the chain-transfer reaction. J Polym Sci Pol Chem 40: 1353-136