Monomer-Isomerization polymerization. XXVIII. Catalytic activity of transition metals and alkylaluminums in monomer-isomerization polymerization of 2-butene

Monomer-isomerization polymerization of cis-2-butene (c2B) with Ziegler–Natta catalysts was studied to find a highly active catalyst. Among the transition metals [TiCl₃, TiCl₄, VCl₃, VOCl₃, and V (acac)₃] and alkylauminums used, TiCl₃? R₃Al (R = C₂H₅ and i-C₄H₉) was found to show a high-activity for monomer-isomerization polymerization of c2B. The polymer yield was low with TiCl₄? (C₂H₅)₃Al catalyst. However, when NiCl₂ was added to this catalyst, the polymer yield increased. With TiCl₃? (C₂H₅)₃Al catalyst, the effect of the Al/Ti molar ratio was observed and a maximum for the polymer yields was obtained at molar ratios of 2.0–3.0, but the isomerization increased as a function of Al/Ti molar ratio. The valence state of titanium on active sites for isomerization and polymerization is discussed.     

Monomer-isomerization polymerization. VI. Isomerizations of butene-2 with TiCl3 or Al(C2H5)3–TiCl3 catalyst

A study of the isomerization of butene-2 with TiCl₃ or Al(C₂H₅)₃–TiCl₃ catalyst in n-heptane has been investigated at 60–80°C to elucidate further the mechanism of monomer-isomerization polymerization. It was found that positional and geometrical isomerizations in the presence of these catalysts occurred concurrently with activation energies of 14–16 kcal/mole. The presence of Al(C₂H₅)₃ with TiCl₃ catalyst could accelerate the initial rates of these isomerizations and initiate the monomer-isomerization polymerization of butene-2. From the results obtained, it was concluded that the isomerization of butene-2 proceeds via an intermediate σ-complex between the transition metal hydride and butene isomers.     

Monomer-isomerization polymerization. XVII. Monomer-isomerizations copolymerizations of 2-butene with 3-heptenes and 4-methyl-2-pentenes with Ziegler-Natta catalyst

2-Butene(2B) copolymerizes with 3-heptene(3H) and 4-methyl-2-pentene(4M2P) by a monomer-isomerization copolymerization mechanism in the presence of TiCl₃–(C₂H₅)₃Al catalyst at 80°C to yield the copolymers of 1-olefin units. By comparison, the copolymerization of 1-butene(1B) with 4-methyl-1-pentene(4M1P) was also carried out under similar conditions. The composition of the copolymers obtained from these copolymerizations was determined from the ratios of optical densities D₇₂₃/D₁₃₈₀ and D₁₁₇₀/D₁₃₈₀ in their infrared (IR) spectra. The apparent monomer reactivity ratios for the monomer-isomerization copolymerization of 2B with 3H and 4M2P, in which the concentration of olefin monomer in the feed was used as 2-olefin, were determined as follows: cis-2B(M₁)/3H(M₂); r₁ = 4.00, r₂ = 0.20: trans-2B(M₁)/3H; r₁ = 3.50, r₂ = 0.20; 4M2P(M₁)-trans-2B(M₂): r₁ = 0.05, r₂ = 9.0. These results indicate that the isomerization of 2-olefins to 1-olefins was important to monomer-isomerization copolymerization.     

Monomer-isomerization polymerization. XIX. Monomer-isomerization copolymerizations of methylbutenes and 2-butene with Ziegler-Natta catalyst

The copolymerization of 3-methyl-1-butene (3M1B), 2-methyl-2-butene (2M2B), or 2-methyl-1-butene (2M1B) with trans-2-butene (2B) was attempted in the presence of a Ziegler-Natta catalyst. It was found the 3M1B underwent monomer-isomerization copolymerization with 2B to give a copolymer consisting of both 3M1B and 1-butene (1B) units, with an infrared (IR) spectrum in good agreement with that obtained from the copolymerization of 3M1B with 1B under similar conditions. When the apparent copolymerization parameters obtained by a TiCl₃–(C₂H₅)₃Al catalyst were compared, the apparent reactivity of 3M1B observed in the 3M1B-2B system was much higher than that in the 3M1B-1B system. However, 2M2B and 2M1B did not undergo monomer-isomerization copolymerization with 2B, and only the homopolymer of 1B was obtained under similar conditions.     

Monomer-isomerization polymerization. XI. Monomer-isomerization copolymerizations of 2-butene with 2-pentene and 2-hexene with Ziegler-Natta catalyst

2-Pentene and 2-hexene were found to undergo monomer-isomerization copolymerizations with 2-butene by Al(C₂H₅)₃–VCl₃ and Al(C₂H₅)₃–TiCl₃ catalysts in the presence of nickel dimethylglyoxime or transition metal acetylacetonates to yield copolymers consisting of the respective 1-olefin units. For comparison, the copolymerizations of 1-pentene with 1-butene and 1-hexene with 1-butene by Al(C₂H₅)₃–VCl₃ catalyst were also attempted. The compositions of the copolymers obtained from these copolymerizations were determined by using the calibration curves between the compositions of the respective homopolymer mixtures and the values of D₇₆₆/D₁₃₈₀ in the infrared spectra. The monomer reactivity ratios for the monomer-isomerization copolymerizations of 2-butene (M₁) with 2-pentene and 2-hexene, in which the concentrations of both 1-olefins calculated from the observed isomer distribution were used as those in the monomer feed mixture, and for the ordinary copolymerizations of 1-butene (M₁) with 1-pentene and 1-hexene by Al(C₂H₅)₃-VCl₃ catalyst were determined as follows: 2-butene (M₁)/2-pentene (M₂): r₁ = 0.14, r₂ = 0.99; 1-butene (M₁)/1-pentene (M₂): r₁ = 0.30, r₂ = 0.74; 2-butene (M₁)/2-hexene (M₂): r₁ = 0.11, r₂ = 0.62; 1-butene (M₁)/1-hexene (M₂): r₁ = 0.13, r₂ = 0.90.     

Monomer-isomerization polymerization. XVIII. Monomer-isomerization copolymerizations of 4-phenyl-2-butene with 4-methyl-2-pentene and 3-heptene with Ziegler-Natta catalyst

4-Phenyl-2-butene (4Ph2B) undergoes monomer-isomerization copolymerization with 4-methyl-2-pentene (4M2P) and 2-and 3-heptene (2H and 3H) with TiCl₃–(C₂H₅)₃Al catalyst at 80°C to produce copolymer consisting exclusively of 1-olefin units. For comparison the copolymerization of 4-phenyl-1-butene (4Ph1B) with 4-methyl-1-pentene (4M1P) and 1-heptene (1H) was carried out under similar conditions. The composition of the copolymers obtained from these copolymerizations was determined from the ratios of optical densities D₁₃₈₀ and D₁₆₀₀ of infrared (IR) spectra of their thin films. The apparent monomer reactivity ratios for the monomer-isomerization copolymerization of 4Ph2B with 4M2P, 2H, and 3H in which the concentration of olefin monomer in the feed was used as internal olefin and those for the copolymerization of 4Ph1B with 4M1P and 1H were determined as follows: 4Ph2B(M₁)-4M2P(M₂); r₁ = 0.90, r₂ = 0.20, 4Ph1B(M₁)-4M1P (M₂); r₁ = 0.40, r₂ = 0.70, 4Ph2B(M₁)-2H(M₂); r₁, = 0.45, r₂ = 1.85, 4Ph2B(M₁)-3H(M₂); r₁ = 0.50, r₂ = 1.20, 4Ph1B(M₁)-1H(M₂); r₁ = 0.55, r₂ = 0.75. The difference in monomer reactivity ratios seemed to originate from the rate of isomerization from 2- or 3-olefins to 1-oletins in these monomer-isomerization copolymerizations.     

Monomer-isomerization polymerization. XXI.. Monomer-isomerization copolymerization of 3-methyl-1-butene and 2-pentene with ziegler–natta catalyst

3-Methyl-1-butene (3M1B) was found to undergo monomer-isomerization copolymerization with 2-pentene (2P) in the presence of Ziegler–Natta catalyst to give a copolymer exclusively consisting of 3M1B and 1-pentene (1P) units, the same as that obtained from copolymerization of 3M1B and 1P. The apparent copolymerization parameters were determined. The amount of 3M1B unit incorporated in the copolymers was found to increase in the copolymerization system of 3M1B-2P more than in that of 3M1B-1P. The polymers consisting of nearly complete 3M1B units were produced at a rapid rate through monomer-isomerization copolymerization of 3M1B with 2P in the presence of TiCl₃ ? (C₂H₅)₃Al catalyst.     

Kinetic study of gas phase olefin polymerization with a TiCl4/MgCl2 catalyst I. Effect of polymerization conditions

This study focuses on the kinetics of ethylene/propylene (homo/co) polymerization reactions using a high activity TiCl₄/MgCl₂/AlEt₃ catalyst. The reactor system is a gas phase reactor equipped with an on-line composition control scheme. As such, important kinetic data such as the instantaneous reaction rate of each monomer is readily obtained. In the investigation, experiments are performed to study the effects of comonomer composition variations, temperature variations, hydrogen concentration variations, and variations in the Al/Ti ratio. It is observed that the ethylene and propylene instantaneous reaction rates show a rather peculiar pattern with the appearance of a second peak. Our work linked the existence of this peak to the Al/Ti ratio used. A theory based on the oxidation state change is proposed. This theory is also used to explain the effects of temperature changes and hydrogen concentration changes on the system. A variety of analytical techniques are employed to study the polymer properties and evidence is provided to support the existence of polymer partial melting at relatively high reaction temperatures. The resulting diffusion limitation is believed to be partially responsible for the observed activity decrease at such elevated temperatures. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2063–2074, 1997     

Distribution of active centers on TiCl4/MgCL2 catalyst for olefin polymerization

1-Octene was polymerized with TiCl₄/MgCl₂—AlEt₃ and the polymerization was quenched with CH₃COCl to introduce a CH₃CO— group onto each propagation chain. The polymer was fractionated by fractional precipitation, and the number of active centers in each fraction was determined by measuring the CH₃CO— content of the fraction. Distributions of the number and reactivity of active centers among the fractions were determined and discussed based on these experiments. The active center distributions were also studied by fitting the molecular-weight distribution (MWD) curve from GPC with multiple Schulz-Flory most-probable distributions. The uncontinuous reactivity distribution of active centers reveals that there exist limited types of active centers on the catalyst. Five types of active center were distinguished by the MWD fitting treatment. The correlations between the active center distributions and catalyst structures are discussed. © 1996 John Wiley & Sons, Inc.     

A study of polyethylene-gr-2-tert-butyl amino methacrylate-supported TiCl4 catalyst for ethylene polymerization

The use of a polyethylene-based copolymer with dual functional groups (polyethylene-gr-2-tert-butyl amino ethyl methacrylate) as the support for TiCl₄ catalyst in ethylene polymerization was studied. Different methods for treating the support were examined and treatment with BuMgCl was found to be the most effective. With the BuMgCl-modified support, a 12-run Plackett-Burman design was used to screen 11 factors in catalyst preparation. Statistical analysis of the results from this design identified significant factors with the amount of BuMgCl singled out to be the most important one for the four response variables of interest, Mg loading, Ti loading, catalyst activity per gram catalyst, and catalyst activity per gram Ti. © 1996 John Wiley & Sons, Inc.     

Monomer-isomerization polymerization. V. Effects of transition metal compounds on monomer-isomerization polymerizations of butene-2 and pentene-2

In order to clarify the correlation between polymerization and monomer isomerization in the monomer-isomerization polymerization of β-olefins, the effects of some transition metal compounds which have been known to catalyze olefin isomerizations on the polymerizations of butene-2 and pentene-2 with Al(C₂H₅)₃–TiCl₃ or Al(C₂H₅)₃–VCl₃ catalyst have been investigated. It was found that some transition metal compounds such as acetylacetonates of Fe(III), Co(II), and Cr(III) or nickel dimethylglyoxime remarkably accelerate these polymerizations with Al(C₂H₅)₃–TiCl₃ catalyst at 80°C. All the polymers from butene-2 were high molecular weight polybutene-1. With Al(C₂H₅)₃–VCl₃ catalyst, which polymerizes α-olefins but does not catalyze polymerization of β-olefins, no monomer-isomerization polymerizations of butene-2 and pentene-2 were observed. When Fe(III) acetylacetonate was added to this catalyst system, however, polymerization occurred. These results strongly indicate that two independent active centers for the olefin isomerization and the polymerizations of α-olefins were necessary for the monomer-isomerization polymerizations of β-olefins.