Homo- and copolymerization of ethylene and propylene with a soluble chromium catalyst

Soga, Kazuo; Chen, Shian‐Ing; Shiono, Takeshi; Doi, Yoshiharu

doi:10.1016/0032-3861(85)90020-5

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…A similar mechanism has also been suggested by Satyanarayana and Sivaram (1993) for the formation of active sites in the case of Cp 2 TiCl 2 supported on MgCl 2 . Although directly impregnated silica-supported systems are inactive in olefin polymerization when AlR 3 is the cocatalyst, the use of MAO yields active polymerization catalysts (Soga et al, 1991;Kaminsky and Renner, 1993;Kaminsky, 1995a;Chen et al, 1995;Sacchi et al, 1995). By analogy with homogeneous metallocene/MAO systems, Kaminsky and Renner (1993), He (1991), andChen et al (1995) have suggested the formation, on silica supported catalysts, of ionic species of the type (SiO -‚Zr + ); see Scheme 2.…”

Section: Nature Of the Active Sites And Mechanism Of Formationmentioning

confidence: 99%

“…By analogy with homogeneous metallocene/MAO systems, Kaminsky and Renner (1993), He (1991), andChen et al (1995) have suggested the formation, on silica supported catalysts, of ionic species of the type (SiO -‚Zr + ); see Scheme 2. However, considering this mechanism, it is not clear why directly impregnated silica catalysts behave differently when combined with MAO and with AlR 3 (Soga et al, 1991;Soga, 1991, 1992). It can be speculated that the formation and the stabilization of Zr + cations are more difficult in the case of supports with weak Lewis acid character.…”

Section: Nature Of the Active Sites And Mechanism Of Formationmentioning

confidence: 99%

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Supported Metallocene Complexes for Ethylene and Propylene Polymerizations: Preparation and Activity

Ribeiro

Deffieux

Portela

1997

Ind. Eng. Chem. Res.

220

110

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Important research is currently underway to develop supported metallocene-based catalysts that could be widely used in the polyolefin industry. Recent developments concerning these systems are reviewed. The main preparation methods for metallocene immobilization on various supports are first systematized and described. Then, the nature and structure of active sites as well as their formation mechanism are analyzed. The performances for ethylene and propylene polymerizations of various supported metallocene systems are compared and discussed on the basis of the different catalyst preparations and of the operational polymerization conditions. Finally, the influence of metallocene heterogenization on the final polymer properties is examined.

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Section: Nature Of the Active Sites And Mechanism Of Formationmentioning

confidence: 99%

Section: Nature Of the Active Sites And Mechanism Of Formationmentioning

confidence: 99%

Supported Metallocene Complexes for Ethylene and Propylene Polymerizations: Preparation and Activity

Ribeiro

Deffieux

Portela

1997

Ind. Eng. Chem. Res.

220

110

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“…The first six workers in Table IIW9 proposed Three of the references cited in Table I1 also report sequential polymerization kinetic experiments. Soga et al 35 used a soluble Cr ( C17H35C00)3/ Et2A1C1 catalyst system that was inactive for propylene polymerization but active for ethylene homopolymerization and somewhat active for ethyl-ene /propylene simultaneous copolymerization. Soga et al Polymerized ethylene in toluene at 0°C after first adding to the reactor 1 atm of propylene for 35 min and then evacuating the propylene from the reactor.…”

Section: Rate Enhancement Effectsmentioning

confidence: 99%

Polymerization of olefins through heterogeneous catalysis XI: Gas phase sequential polymerization kinetics

Chen

Ray

1993

J of Applied Polymer Sci

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SYNOPSISA unique series of ethylene and propylene sequential polymerization experiments have been carried out in a stirred bed gas phase reactor using unsupported Stauffer AA catalyst ( TiC13 * f AlC13). Several interesting kinetic results were observed. It was found that propylene causes rate enhancement for a subsequent ethylene polymerization but that ethylene causes a rate reduction for a subsequent propylene polymerization. Furthermore, the rate enhancement /reduction effect increases with the duration of the preceding polymerization. Chemical/kinetic effects were found to be the likely causes of both the rate enhancements and the rate reductions observed during sequential polymerization. It was also shown that enhanced monomer sorption caused by the presence of a more soluble component, such as a heavier comonomer, does contribute to rate enhancement during simultaneous copolymerizations, but is not a factor for sequential polymerizations. 0 1993

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Homo- and copolymerization of ethylene and propylene using a heterogeneous chromium catalyst system

Gan

Chen

Ohnishi

et al. 1987

Polymer

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Homo- and copolymerization of ethylene and propylene with a soluble chromium catalyst

Cited by 6 publications

References 5 publications

Supported Metallocene Complexes for Ethylene and Propylene Polymerizations: Preparation and Activity

Supported Metallocene Complexes for Ethylene and Propylene Polymerizations: Preparation and Activity

Polymerization of olefins through heterogeneous catalysis XI: Gas phase sequential polymerization kinetics

Homo- and copolymerization of ethylene and propylene using a heterogeneous chromium catalyst system

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