Porous versus novel compact Ziegler–Natta catalyst particles and their fragmentation during the early stages of bulk propylene polymerization

Vestberg, Torvald; Denifl, Peter; Wilén, Carl‐Eric

doi:10.1002/app.28411

Cited by 24 publications

(36 citation statements)

References 31 publications

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“…The catalyst looked compact and had no measurable surface area, according to BET, but evidently due to its exceptional structure the monomer did not encounter diffusion problems not even in the early stage of polymerization. 22,24 The polymerization started everywhere in the particle more or less simultaneously, typical for MgCl 2 -based ZN PP catalyst. [25][26][27][28] The fragmentation model best describing how this catalyst break up in the early stage of polymerization is the continuous bisection fragmentation model.…”

Section: Internal Morphology Of Hipp Particles Produced Withmentioning

confidence: 99%

“…These tests were performed at 30 C in a manner previously described. 22 The catalyst particles with low degree of polymerization (DP) are referred to as prepolymerized catalyst particles in the text.…”

Section: Polymerizationmentioning

confidence: 99%

“…Catalysts prepared using this technology have no measurable pore volume and a very low surface area (<5 m 2 ) according to Brunauer-Emmet-Teller (BET) analysis. 22 Catalyst B was produced with the same emulsion technology, except that SiO 2 nanoparticles (average particle size 80 nm, surface area 440 m 2 and bulk density 0.063 g/cm 3 ) were added during catalyst preparation. The preparation of the catalyst is described elsewhere.…”

Section: Catalystsmentioning

confidence: 99%

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Increased rubber content in high impact polypropylene via a sirius ziegler‐natta catalyst containing nanoparticles

Vestberg

Denifl

Wilén

2013

J. Polym. Sci. A Polym. Chem.

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High impact polypropylene was produced in a tworeactor polymerization process operating in series using two different Ziegler-Natta catalysts (referred to as catalysts A and B) that had been prepared by Sirius emulsion technology in the absence and presence of SiO 2 nanoparticles, respectively. The homo polypropylene matrix was produced in liquid bulk and the ethylene/propylene rubber in gas phase under industrial conditions. Catalyst B was prepared with the same emulsion technology as catalyst A, except that SiO 2 nanoparticles (average particles size 80 nm) were added during catalyst preparation. Scanning electron microscopy studies showed that the nanoparticles were fairly evenly distributed within catalyst B particles, although there was some agglomeration. It was shown that the nanoparticles in catalyst B increased the internal porosity in the homo polypropylene matrix particles and this enabled a significant increase in the rubber content. Maximum rubber content, before running into stickiness problems, was approximately 25 wt % for catalyst A without nanoparticles, whereas the maximum rubber content for catalyst B was almost doubled to 45 wt % due to the beneficial transformation of the internal catalyst morphology by the nanoparticles. In addition, it was also found that the reaction was not mass transfer limited during the ethylene/propylene rubber polymerization stage, even at very high rubber contents where all pores and cavities were filled with rubber.

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Section: Internal Morphology Of Hipp Particles Produced Withmentioning

confidence: 99%

Section: Polymerizationmentioning

confidence: 99%

Section: Catalystsmentioning

confidence: 99%

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Increased rubber content in high impact polypropylene via a sirius ziegler‐natta catalyst containing nanoparticles

Vestberg

Denifl

Wilén

2013

J. Polym. Sci. A Polym. Chem.

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“…Anyhow, the yield could be improved by washing the residue several times with excess of n-hexane. Another limitation of this reaction is the preparation of KC 8 . This reaction proceeds by heating (80°C) potassium metal and graphite powder for several hours along with fast stirring and requires extreme care as potassium metal becomes pyrophoric with heating [27,32].…”

Section: Ethylene Polymerization With Ti-complex 26mentioning

confidence: 99%

“…Major industrial production of these polymers primarily utilizes group-IV metal catalysts [3][4][5][6]. A revolution was initiated by Zeigler and Natta by the discovery of group-IV metal catalysts due to their enormous industrial application which also inspired intensive research and development of these catalysts for olefin polymerization [4] that ultimately led to the development of group-IV metallocene catalysts for olefins polymerization using Alalkyls as co-catalyst [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Following breakthrough occurred in 1970 with the discovery of Cp 2 TiCl 2 /AlMe 2 Cl and Cp 2 TiMe 2 /AlMe 3 catalysts, but their catalyzing abilities were low.…”

Section: Introductionmentioning

confidence: 99%

Aminopyridine stabilized group-IV metal complexes and their applications

Hafeez

Muhammad

2016

Appl Petrochem Res

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During the last two decades, group-IV metalsbased aminopyridinato complexes have attracted a tremendous research interest because of immense industrial needs for the catalyst which would be of higher activity and selectivity with lower toxicity and lower cost. Chemistry of titanium (Ti) and zirconium (Zr) complexes was more extensively explored as compared to hafnium (Hf) complexes. Direct synthesis, salt metathesis, amine elimination, alkane elimination, silyl chloride elimination, hydrogen chloride elimination and toluene elimination protocols have been used for the synthesis of group-IV metal complexes. Changes in ligand and complex design were made to optimize these catalysts for olefin polymerization. Most of these complexes have shown good catalytic activities when activated with dry methyl aluminoxane. Ligand transfer to aluminum was found in these complexes, particularly with less bulky ligands, and this ligand transfer problem was overcome by tridentate ligands but the activities of these complexes were not competitive to complexes with bidentate aminopyridinato ligands. Majority of these complexes produce high-molecularweight polymers with broader molecular weight distributions, and Hf-complexes produce longer chain polymers than their comparative Ti and Zr aminopyridinato complexes. It could be deduced that group-IV metals inherit the potential for optimal polymerizing catalysts probably, because of their almost vacant d-orbitals, these act as hard acids which on combination with soft bases carry the opportunity to design and develop polymerization catalysts which could overcome the problems associated with existing systems.

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Poly(propylene‐co‐ethylene) produced with a conventional and a self‐supported ziegler–natta catalyst: Effect of ethylene and hydrogen concentration on activity and polymer structure

Vestberg

Parkinson

Fonseca

et al. 2011

J of Applied Polymer Sci

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A novel self-supported emulsion-based catalyst and a conventional MgCl 2 -supported Ziegler-Natta catalyst were used in the copolymerization of propylene and ethylene under industrial conditions using triethyl aluminium as cocatalyst and dicyclopentyl dimethoxy silane as external donor. The effects of the concentration of ethylene and hydrogen on the polymerization behaviors and polymer properties were investigated. The combined effect of both ethylene and hydrogen increased the relative activity of the novel catalyst more than for the conventional catalyst. This trend was consistent with our earlier observed higher degree of dormancy, due to 2,1 insertions, found with the novel catalyst. More importantly, the work has uncovered that the self-supported catalyst incorporates ethylene in a more random fashion and produces copolymers with relatively narrow molecular weight distribution (MWD). These results in combination with polymer microstructure studies using Fourier transform infrared spectroscopy, 13 C-NMR spectroscopy, and differential scanning calorimetry all indicated that the novel catalyst has a narrower distribution of active site types than the conventional reference catalyst. The narrow composition of active site structures, the narrow MWD, and the random incorporation of ethylene into the polymer chain indicated that the emulsion-based catalyst possesses features that to a certain degree tend to be more indicative for a single-sitelike catalyst structure and behavior.

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Porous versus novel compact Ziegler–Natta catalyst particles and their fragmentation during the early stages of bulk propylene polymerization

Cited by 24 publications

References 31 publications

Increased rubber content in high impact polypropylene via a sirius ziegler‐natta catalyst containing nanoparticles

Increased rubber content in high impact polypropylene via a sirius ziegler‐natta catalyst containing nanoparticles

Aminopyridine stabilized group-IV metal complexes and their applications

Poly(propylene‐co‐ethylene) produced with a conventional and a self‐supported ziegler–natta catalyst: Effect of ethylene and hydrogen concentration on activity and polymer structure

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