Correlation between the oxidation states of titanium and the polymerization activities for higher ?-olefins and diene compounds

Soga, Kazuo; Chen, Shian‐Ing; Ohnishi, Rikuo

doi:10.1007/bf00265270

Cited by 65 publications

(31 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This could be because of the fact that both Ti3+ and Ti2+ are active for ethylene polymerization, whereas only the former is thought to be active for propylene. 16 As more TEA is used, Ti2+ is formed at the expense of Ti3+ corresponding to a loss of activity for propylene (hence a maximum), but not for ethylene. Alternatively the optimum may exist at higher value of Al/Ti than those tested; however, because of mass transfer limitations (discussed later), these values were inaccessible.…”

mentioning

confidence: 99%

Gas‐phase polymerization of ethylene using MgCl₂/ethyl benzoate/TiCl₄ + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Dusseault

Hsu

1993

J of Applied Polymer Sci

View full text Add to dashboard Cite

A gas-phase reactor system was developed to polymerize ethylene using the MgC12/ethyl benzoate (EB)/TiC1, + triethylaluminum (TEA) catalyst. The reproducibility of the reactor was tested and found to be adequate for kinetic study. The effects of TEA and temperature were studied with the multisite model that assumes a multiplicity of active sites. It was found that the productivity increased with Al/Ti molar ratio while initial activity leveled off. The deactivation rate, after an initial increase, decreased with Al/Ti. This corresponded with a transition in deactivation order: below Al/Ti = 70, first-order deactivation was predominant; above A1 /Ti = 70, second-order deactivation was predominant. The secondorder deactivation reactions were made less disperse at higher Al/Ti. Molecular weight of the polyethylene was very high (> 1,000,000) indicating negligible transfer reactions. For Al/Ti > 130 a monomer sorption limitation for polymerization was found. The effect of temperature was also studied with a maximum in productivity at 55OC for Al/Ti = 98.0 and no maximum when Al/Ti = 53.0. Apparent activation energies (E,) for activity were found to be 19.5 f 3.3 kJ/mol at Al/Ti = 98.0 and 9.3 f 1.1 kJ/mol at Al/Ti = 53.0. For deactivation E, was found to be 36.6 f 5.0 kJ/mol at Al/Ti = 98.0 and -15.5 f 4.4 kJ/ mol at Al/Ti = 53.0. Temperature increased the dispersity of second-order deactivation reactions.

show abstract

mentioning

confidence: 99%

Gas‐phase polymerization of ethylene using MgCl₂/ethyl benzoate/TiCl₄ + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Dusseault

Hsu

1993

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Industrial catalysts produce Ϸ100-500 g polypropylene per g catalyst per hr⅐atm and Ϸ2,000-10,000 g polyethylene per g catalyst per hr⅐atm (9). The fact that the model catalysts exhibit activities similar to the industrial catalysts suggests that the surface properties of the model catalysts prepared in UHV are relevant to those of industrial catalysts (25,26). Single-site propylene polymerization.…”

Section: Resultsmentioning

confidence: 99%

Surface science of single-site heterogeneous olefin polymerization catalysts

Kim

Somorjai

2006

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

This article reviews the surface science of the heterogeneous olefin polymerization catalysts. The specific focus is on how to prepare and characterize stereochemically specific heterogeneous model catalysts for the Ziegler-Natta polymerization. Under clean, ultrahigh vacuum conditions, low-energy electron irradiation during the chemical vapor deposition of model Ziegler-Natta catalysts can be used to create a ''single-site'' catalyst film with a surface structure that produces only isotactic polypropylene. The polymerization activities of the ultra-high vacuum-prepared model heterogeneous catalysts compare well with those of conventional Ziegler-Natta catalysts. X-ray photoelectron spectroscopic analyses identify the oxidation states of the Ti ions at the active sites. Temperature-programmed desorption distinguishes the binding strength of a probe molecule to the active sites that produce polypropylenes having different tacticities. These findings demonstrate that a surface science approach to the preparation and characterization of model heterogeneous catalysts can improve the catalyst design and provide fundamental understanding of the single-site olefin polymerization process.Ziegler-Natta C atalysts can function by being dispersed on solid surfaces (heterogeneous catalysis) or dissolved in reaction media (homogeneous catalysis). Heterogeneous catalysts are widely used in the chemical industry because they are in general easy to handle, separate, and recycle. Homogeneous catalysts are used in synthesis of specialty chemicals, offering precise control of molecular structure and reactivity. Combining the merits of these two different catalyst systems is of great interest for production of next-generation catalysts (1). In this article, we review the surface science of the heterogeneous olefin polymerization.In the polymerization of small olefins such as ethylene and propylene, both heterogeneous and homogeneous catalytic systems are operational (Fig. 1). Heterogeneous olefin polymerization catalysts (so-called Ziegler-Natta catalysts) are used for production of more than two-thirds of the commodity polyolefins consumed in the world (2, 3). Recently, a large number of specialty polyolefins have been produced with homogeneous metallocene catalysts (4). Whereas most industrial heterogeneous catalysts producing polyethylene and polypropylene are titanium chloride-based catalysts, the homogeneous metallocene catalysts are organometallic compounds of Ti, Zn, and Hf metals in organic solvents. In both types of catalysts, the catalytic species are activated with alkyl aluminum cocatalysts to create the active sites for carbon-carbon bond formation. Triethyl aluminum (AlEt 3 ) is widely used for heterogeneous ZieglerNatta catalysts, whereas methylaluminoxane is typically used for homogeneous metallocene catalysts.The polymers produced with these catalysts can have a wide range of mechanical properties depending on how many monomers are connected (molecular weight) and how they are connected (microstructure). The mechan...

show abstract

“…16,27,28 Decreases in the T g of the copolymers obtained are probably due to increase of the ethylene content incorporated.…”

Section: ϫ3mentioning

confidence: 90%

“…19 -22 Ti ϩ2 is only active for the polymerization of ethylene and can cause homopolymerization instead of copolymerization. 23 Catalysts based on Ti-compound-supported MgCl 2 obtained from Mg(OEt) 2 combined with polydimethylsiloxane (PDMS) showed high activity. 15 Kakugo et al 24 showed that a random copolymer was produced on isotactic active centers.…”

Section: Introductionmentioning

confidence: 99%

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl₂ (ethoxide type)/EB/PDMS/TiCl₄/PMT

Zohuri

Sadegvandi²,

Jamjah

et al. 2002

J of Applied Polymer Sci

View full text Add to dashboard Cite

A high-activity Ziegler-Natta catalyst of TiCl 4 -supported MgCl 2 (ethoxide type) was prepared. Ethyl benzoate (EB) and polydimethylsiloxane (PDMS) were used as internal donors, while p-methyl toluate (MPT) and triethylaluminum (TEA) were used as the external donor and cocatalyst, respectively. Suspension copolymerization of ethylenepropylene (EPM) was carried out in n-heptane using the catalyst system. The relative pressures of 1.5 : 1 and 2 : 1 atmosphere of propylene-to-ethylene (P P /P E ) gave a polymer with elastomeric properties. The relative pressure of propylene-to-ethylene higher and lower than the above values, however, gave a homopolymer or copolymer without elastomeric properties. The effect of the TEA concentration, H 2 concentration, temperature, and pressure of P P /P E on the yield of the polymer obtained was investigated. The effects of these factors on the glass transition temperature (T g ) and ethylene content of the polymer were studied. The content of ethylene in EPM was determined using the FTIR technique. The molar ratio of Al : MPT : Ti ϭ 355 : 107 : 1 gave a polymer with an ethylene content of about 32%. However, a ratio lower than AL : MPT : Ti ϭ 355 : 107 : 1 did not give a good elastomeric polymer. The highest productivity of the catalyst was obtained at a molar ratio of AL : MPT : Ti ϭ 355 : 107 : 1. Increasing the temperature from 45 to 70°C caused a slight increase of Et % content and a decrease of the T g of the copolymer obtained, while the highest productivity of the catalyst was obtained at 55°C with good elastomeric properties using an AL : MPT : Ti ϭ 497 : 107 : 1 molar ratio. Increasing the pressure of propylene from 1.5 to 2.5 atm caused a sharp decrease in the T g and ethylene content of the polymer. When the ethylene content in the copolymer was increased, the T g value had a tendency to be closer to the polyethylene T g .

show abstract

Correlation between the oxidation states of titanium and the polymerization activities for higher ?-olefins and diene compounds

Cited by 65 publications

References 5 publications

Gas‐phase polymerization of ethylene using MgCl₂/ethyl benzoate/TiCl₄ + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Gas‐phase polymerization of ethylene using MgCl₂/ethyl benzoate/TiCl₄ + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Surface science of single-site heterogeneous olefin polymerization catalysts

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl₂ (ethoxide type)/EB/PDMS/TiCl₄/PMT

Contact Info

Product

Resources

About

Correlation between the oxidation states of titanium and the polymerization activities for higher ?-olefins and diene compounds

Cited by 65 publications

References 5 publications

Gas‐phase polymerization of ethylene using MgCl2/ethyl benzoate/TiCl4 + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Gas‐phase polymerization of ethylene using MgCl2/ethyl benzoate/TiCl4 + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Surface science of single-site heterogeneous olefin polymerization catalysts

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl2 (ethoxide type)/EB/PDMS/TiCl4/PMT

Contact Info

Product

Resources

About

Gas‐phase polymerization of ethylene using MgCl₂/ethyl benzoate/TiCl₄ + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Gas‐phase polymerization of ethylene using MgCl₂/ethyl benzoate/TiCl₄ + triethylaluminum catalyst: Effects of triethylaluminum and temperature

Copolymerization of ethylene/propylene elastomer using high‐activity Ziegler–Natta catalyst system of MgCl₂ (ethoxide type)/EB/PDMS/TiCl₄/PMT