Zeolite supported polymerization catalysts: Copolymerization of ethylene and α-olefins with metallocenes supported on HY zeolite

Michelotti, Marco; Altomare, Angelina; Ciardelli, Francesco; Roland, Eckehart

doi:10.1016/s1381-1169(97)00154-4

Cited by 41 publications

(27 citation statements)

References 26 publications

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“…Gas-phase A H of polymer-supported (n-Bu) 2 ZrCl 2 / MAO catalysts increased with support F. Lack of fracturing of the low-F catalysts during ethylene homopolymerization resulted in a strong mass-transfer limitation and low activity; the presence of 1-hexene or propylene significantly increased the activity. The magnitude of activity enhancement decreased with increasing catalyst F. High-F catalysts, which also had high A H , showed little or no activity enhancement by 1-hexene.…”

Section: Discussionmentioning

confidence: 99%

“…Polymerization activity enhancement by the comonomer decreased with increasing comonomer size due to the diffusivity and the reactivity of the comonomers. The comonomer enhancement for the polymer-supported (n-BuCp) 2 ZrCl 2 /MAO catalysts was caused by differences in the ease with which the catalyst particles fractured (F); that is, the comonomer effect was mainly due to physical effects and not due to chemical effects.…”

Section: Discussionmentioning

confidence: 99%

“…25 Briefly, the desired amount of support was placed in a three-necked flask and heated (at 70-858C) with evacuation for about 17 h. The evacuated support was cooled to room temperature, suspended in 5-10 mL of anhydrous toluene, and reacted with a predetermined amount of the MAO solution for 2-3 h at room temperature. The metallocene solution prepared by the dissolution of the desired amount of (nBuCp) 2 ZrCl 2 in 5 mL of anhydrous toluene was added to the support/MAO suspension and allowed to react for 1-2 h on a shaker at room temperature. The final suspension was dried by solvent evacuation to obtain the supported catalyst.…”

Section: Catalyst Preparationmentioning

confidence: 99%

“…The immobilization of metallocene/MAO systems on solid carriers is normally accompanied by a decrease in catalytic activity. The activity drop has been attributed to (1) geometric restrictions of monomer access to the active sites 1,2 or the limitation of metallocene-MAO interaction due to isolated confinement; 3 (2) the deactivation of metal centers during the immobilization, which results in low ratios of activeto-total transition metal centers; 4,5 and (3) a decrease in the propagation rate. 6 Occasionally, supported metallocene/MAO catalysts exhibit higher average activities than homogeneous ones due to more stable kinetic profiles.…”

Section: Introductionmentioning

confidence: 99%

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Influence of support friability and concentration of α‐olefins on gas‐phase ethylene polymerization over polymer‐supported metallocene/methylaluminoxane catalysts

Hammawa

Wanke

2007

J of Applied Polymer Sci

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The effects of support friability (F) and ethylene/comonomer ratios were investigated over supported metallocene/methylaluminoxane catalysts prepared with nine different porous polymeric supports and various comonomer concentrations with a 2-L reactor operated in the semibatch gas-phase mode at 808C and 1.4 MPa. F of the supports was measured with a newly devised method. The performance of the supported catalysts depended on support F as follows. The average homopolymerization activities varied from less than 6 t of polyethylene (PE) (mol of Zr)À1 h À1 for low-F catalysts to 10-20 t of PE (mol of Zr)À1 h À1 for moderate-F catalysts and up to 100 t of PE (mol of Zr) À1 h À1 for the high-F catalysts. The presence of 1-hexene and propylene comonomers increased the activity of the low-F catalysts by up to 20-fold and 50-fold, respectively; that is, there were very marked comonomer effects. Activity enhancement by 1-hexene was less than 3-fold for the moderate-F catalysts, whereas the high-F catalysts showed little activity enhancement. Sometimes, 1-hexene even resulted in activity reductions. Very different particle morphologies were obtained with the catalysts of different F's.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Catalyst Preparationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of support friability and concentration of α‐olefins on gas‐phase ethylene polymerization over polymer‐supported metallocene/methylaluminoxane catalysts

Hammawa

Wanke

2007

J of Applied Polymer Sci

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“…For this reason, supporting metallocene complexes on inorganic carries has been proposed as a way to introduce metallocene catalyst in the existent technology. Traditionally, the homogeneous complexes are supported on silica [3 -7], modified silica or alumina [8 -13], although other innocuous carrier based on clays [14,15], zeolites [16,17] and polymers [18 -24] have also been studied. Despite the broad use of MgCl 2 as a support for conventional heterogeneous Ziegler-Natta (Z-N) catalysts, its use for supporting metallocene-type complexes has serious drawbacks [25 -36].…”

Section: Introductionmentioning

confidence: 99%

Ethylene polymerization using metallocenes supported on MgCl2/SiCl4−n (n-C6H13O)n

Cérdán

Parada

Ibarra

et al. 2007

Designed Monomers and Polymers

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Abstract-Metallocene complexes Cp 2 TiCl 2 , Cp 2 ZrCl 2 , Cp 2 Zr(N n Bu 2 ) 2 , Cp 2 Ti(η 1 -OC(O)C 6 H 5 ) 2 and Cp 2 Zr(η 1 -OC(O)C 6 H 5 ) 2 were supported on MgCl 2 /SiCl 4−n (n-C 6 H 13 O) n carrier and used for ethylene polymerization. The supported complexes result in highly active catalysts when treated with different aluminum alkyl-based co-catalysts. These catalysts are able of tuning the final properties of the produced polyethylenes. Mixed composites of metallocenes and conventional Ziegler-Natta catalysts supported on the same carrier were also studied. A supported zirconocene Cp 2 Zr(η 1 -OC(O)C 6 H 5 ) 2 on MgCl 2 /SiCl 4−n (n-C 6 H 13 O) n resulted in a highly active catalyst that eject control on the molecular weight, crystallinity and morphology of the resultant polyethylene.

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Single‐Site Catalysts

Leino

2001

Encyclopedia of Polymer Science and Technology

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The recent rapid development of organometallic single‐site catalysts (SSCs) has revolutionized polymer synthesis and polyolefin production technologies. These well‐defined catalyst systems generally consist of a transition metal atom, such as titanium, zirconium, iron, nickel, or palladium, complexed with an organic ligand set and an initiating group(s). Activation with methylaluminoxane or other weakly coordinating anions generates the cationic active species responsible for olefin coordination and polymer chain growth. Representative examples of SSCs include the bis(cyclopentadienyl)‐type Group 4 metallocenes as well as the diimine complexes of nickel and palladium. By variation of the organic ligand and thus the steric and electronic environment of the metal center, these catalysts can be tailored to control the olefin polymerization reaction in an unprecedented fashion. Almost any vinyl monomer, irrespective of molecular weight or steric hindrance, can be polymerized by choosing the proper catalyst. Virtually all feasible poly(α‐)olefin microstructures ranging from atactic to isotactic, hemiisotactic, syndiotactic, and stereoblock polymers can be produced by rational modification of the catalyst structure. Functional monomers are readily copolymerized with the less oxophilic late transition metal catalysts. Entirely new materials, not accessible with traditional Ziegler–Natta catalysts, have emerged, including high melting syndiotactic polystyrene and cycloaliphatic polymers. This article provides a broad overview of SSCs and their application in olefin polymerization. Evolution and classification of SSCs, catalyst generation, polymerization of ethylene, propylene, cycloolefins, dienes, styrene, as well as as functional olefins, and the application of SSCs in enantioselective polymerization are covered. Finally, heterogenization of SSCs for use in industrial processes is briefly discussed.

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Zeolite supported polymerization catalysts: Copolymerization of ethylene and α-olefins with metallocenes supported on HY zeolite

Cited by 41 publications

References 26 publications

Influence of support friability and concentration of α‐olefins on gas‐phase ethylene polymerization over polymer‐supported metallocene/methylaluminoxane catalysts

Influence of support friability and concentration of α‐olefins on gas‐phase ethylene polymerization over polymer‐supported metallocene/methylaluminoxane catalysts

Ethylene polymerization using metallocenes supported on MgCl2/SiCl4−n (n-C6H13O)n

Single‐Site Catalysts

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