Ethylene polymerization reactions with Ziegler–Natta catalysts. I. Ethylene polymerization kinetics and kinetic mechanism

Copolymerization of ethylene with α‐olefins over supported titanium–magnesium catalysts. I. Effect of polymerization duration on comonomer content and the molecular weight distribution of copolymers

“…The increase in activity upon copolymerization over Ti-based supported catalysts as compared with that upon homopolymerization was previously noted in a number of studies. [1][2][3][4][5][6]8 Table I summarizes the data on the effect of the reaction duration on MW, MWD, and composition of the produced copolymers. The increase in the reaction duration from 5 to 60 min (exps.…”

“…Various aspects of copolymerization processes over these catalysts, including analysis of kinetic parameters of copolymerization and ascertaining the relationship between catalyst composition and the molecular structure of the resulting copolymers have been studied in numerous works. [1][2][3][4][5][6][7][8][9][10][11][12] However, many questions regarding copolymerization of ethylene and a-olefins have remained ambiguous. A number of unexpected effects were revealed for catalytic copolymerization processes; those effects have not been convincingly interpreted yet.…”

“…Among them is the effect of considerable increase in activity in the case of ethylene/a-olefins copolymerization as compared with ethylene homopolymerization. [2][3][4][5][6]8,10,12 The influence of polymerization duration (polymer yield) on copolymer composition (a-olefin content in the copolymer) at a constant ethylene/a-olefin ratio upon polymerization over Ziegler-Natta catalysts was another unexpected result. [6][7][8] The influence of the reaction duration upon ethylene/1-butene copolymerization on the titaniummagnesium catalyst of composition TiCl 4 /MgCl 2 was studied in Refs.…”

Ethylene Polymerization over MgCl2/SiO2 Bi‐Supported Ziegler–Natta Hybrid Titanium/Vanadium Catalysts

“…The presence of hydrogen could decrease both the products' MW and catalytic activity for ethylene polymerization, which is generally accepted for Ziegler-Natta catalysts. [27][28][29][30] The decreases of catalyst activities with the addition of 10 mL hydrogen for the MgTi/Si, MgTi-V/Si, MgV-Ti/Si, MgTiV/Si, and MgV/Si catalysts are 7.2%, 27.6%, 19.7%, 9.3%, and 48.7%, respectively, while the average MW of polymers reduced 38.8%, 53.0%, 37.8%, 44.5%, and 57.3%, respectively. It is obvious that the introduction of vanadium species could adjust the average MW of the polymers more efficiently by adding hydrogen but with the sacrifice of the catalytic activity.…”

“…For the MgTi/Si, MgV-Ti/Si, and MgTiV/Si catalysts, it was found that the ethylene consumption rates drastically increased with the addition of 1-hexene concentration, then decreased promptly, which have been discussed in detail in the earlier literatures. [28,[39][40][41][42][43] While the kinetic curves of ethylene/1-hexene copolymerization with the MgTi-V/Si Macromol. Chem.…”