Activity For Ethylene Polymerization Research Articles

Ethylene polymerization and ethylene/hexene copolymerization by vanadium(III) complexes bearing bidentate phenoxy-phosphine oxide ligands

A series of novel vanadium(III) complexes bearing bidentate phenoxy-phosphine oxide [O,P=O] ligands, (2-R1-4-R2-6-Ph2P=O-C6H2O)VCl2(THF)2 (2a: R1 = R2 = H; 2b: R1 = F, R2 = H; 2c: R1 = tBu, R2 = H; 2d: R1 = Ph, R2 = H; 2e: R1 = R2 = Me; 2f: R1 = R2 = tBu; 2g: R1 = R2 = CMe2Ph) have been synthesized by adding 1 equiv of the ligand to VCl3(THF)3 dropwise in the presence of excess triethylamine. Under the same conditions, the adding of VCl3(THF)3 to 2.0 equiv of the ligand afforded vanadium(III) complexes bearing two [O,P=O] ligands (3c, 3f). All the complexes were characterized by FTIR and mass spectra as well as elemental analysis. Structures of complexes 2c and 3c were further confirmed by X-ray crystallographic analysis. On activation with Et2AlCl and ethyl trichloroacetate, these complexes displayed high catalytic activities for ethylene polymerization (up to 26.4 kg PE/mmolV·h·bar) even at high reaction temperature (70 °C) indicative of high thermal stability, and produced high molecular weight polymers with unimodal molecular weight distributions. Additionally, the complexes with optimized structure exhibited high catalytic activities for ethylene/1-hexene copolymerization. Catalytic activity, comonomer incorporation, and polymer molecular weight can be controlled in a wide range via the variation of catalyst structure and the reaction parameters such as Al/V molar ratio, comonomer feed concentration, and reaction temperature. The monomer reactivity ratios rE and rH were determined according to 13C NMR spectra, which indicated these complexes preferred ethylene to 1-hexene in the copolymerization. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 5298–5306

Synthesis and Catalytic Activity of Amido-Boratabenzene Complexes of Rare-Earth Metals and Zirconium and Chromium

Amidino-boratabenzenes represent a type of L3X ligand and can be regarded as the monoanionic analogues of the linked amido-cyclopentadienyl ligands. By employment of this type of ligand, 19 constrained-geometry complexes, including Sc(III), Y(III), Lu(III), Zr(IV), and Cr(III) derivatives, have been successfully prepared, and some of them showed excellent catalytic activity for ethylene polymerization upon activation.

Borate and MAO Free Activating Supports for Metallocene Complexes

Fluorinated activating supports (AS) for metallocene complexes were prepared via treatment of silica with AlEt3 or AlEt2F followed by pyrolysis and combustion steps, and a subsequent fluorination step when AlEt3 was used. This new family of activators appears to be universal for metallocene complexes leading to catalysts displaying high activities in ethylene polymerization without the addition of MAO. A productivity of 3200 g gAS–1 was obtained in 1 h with the catalyst rac-Et(Ind)2ZrCl2/AS8/Al(iBu)3 at 80 °C under 10 bar of ethylene. An isotactic polypropylene with a melting transition at 145 °C was prepared using rac-Me2Si(2-Me-benz(e)Ind)2ZrCl2 activated by AS9 and Al(iBu)3. The spherical particle morphology of polyolefins was particularly adapted to slurry processes employed in industry.

Synthesis, structure and catalytic properties of new half-titanocene complexes bearing substituted cyclopentadienyl and aryloxide ligands

New cyclopentadienyltitanium aryloxide complexes, 1-phenyl-2,3,4,5-Me4CpTi(O-2,6-iPr2-4-nBu-C6H2)Cl2 (1) and [4,4′-biphenyl-(2,3,4,5-Me4Cp)2][Ti(O-2,6-iPr2-4-nBu-C6H2)Cl2]2 (2), have been prepared by treatment of cyclopentadienyltitanium trichloride complexes [PhMe4CpTiCl3 and 4,4′-biphenyl-(Me4CpTiCl3)2] with 1 or 2 equiv of lithium salt of 2,6-di-isopropyl-4-butylphenol. Complexes 1 and 2 have been characterized by elemental analysis, 1H and 13C NMR spectroscopy. The molecular structure of 1 has been determined by single-crystal X-ray diffraction. Upon activation with iBu3Al and Ph3CB(C6F5)4, 1 and 2 both exhibit good catalytic activity for ethylene polymerization, producing polyethylene with moderate molecular weight and melting point.

Development of a Hetero‐Bimetallic Phillips‐Type Catalyst for Ethylene Polymerization

In order to improve the ethylene polymerization activity and branching ability of Phillips catalysts, various bimetallic catalysts were synthesized on the basis of co‐impregnation of chromium and second metal salts. The activity and branching ability of the catalysts were enhanced by the introduction of zirconium, zinc, and vanadium, while deteriorated by the introduction of molybdenum and tungsten. On the other hand, the structure of metal salt precursors did not greatly affect the catalytic performances. X‐ray photoelectron spectroscopy (XPS) clarified a tendency that second metal with lower electronegativity decreased the electron density on chromium species, resulting in higher polymerization activity of the bimetallic catalysts plausibly due to enhanced ethylene activation. On the other hand, the branching ability of the catalyst improved as the catalyst activity increased due to more facile formation of α‐olefin co‐monomer.

Effect of ZnCl2‐ and SiCl4‐doped TiCl4/MgCl2/THF catalysts for ethylene polymerization

ABSTRACTIn this research, ethylene polymerization was carried out in the presence of different additives (ZnCl2, SiCl4, and the combined ZnCl2‐SiCl4) on TiCl4/MgCl2/THF catalytic system. The presence of ZnCl2‐SiCl4 mixtures showed higher activity in ethylene polymerization when compared with the catalytic activity in the presence of single Lewis acids, ZnCl2, or SiCl4. The modified catalyst with ZnCl2‐SiCl4 demonstrated the highest activity, which was more than three times the activity of the system without Lewis acid modification. The enhanced activity can be attributed to the reduction in the peak intensity of MgCl2/THF complexes with Lewis acid compounds as proven by XRD. This was reasonable because of some THF removal from the structure of MgCl2/THF by Lewis acid compounds. In addition to the effect of modification with additives on the partial elimination of THF, the catalytic activities could be increased due to the titanium atoms that have been locally concentrated on the surface as seen by energy dispersive X‐ray spectroscopy measurement. On the basis of the in situ electron spin resonance measurement, the mixed metal chlorides (ZnCl2‐SiCl4) addition could promote the amount of Ti3+after reduction with triethylaluminum. It revealed that the modification of TiCl4/MgCl2/THF catalytic system with mixed metal chlorides (ZnCl2‐SiCl4) is very useful for ethylene polymerization. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1588–1594, 2013

Syntheses, characterization and ethylene polymerization of half-sandwich group IV metal complexes with tridentate [O,N,S] ligands

A series of half-sandwich group IV metal complexes with tridentate monoanionic phenoxy-imine arylsulfide [O−NS] ligand [2-But4-Me-6-((2-(SC6H5)C6H4N=CHC6H2O)]− (La) and dianionic phenoxy-amine arylsulfide [O−N−S] ligand [2-But4-Me-6-((2-(SC6H5)C6H4N-CH2C6H2O)]2− (Lb) have been synthesized and characterized. Lb was obtained easily in high yield by reduction of ligand La with excess LiAlH4 in cool diethyl ether. Half-sandwich Group IV metal complexes CpTi[O−NS]Cl2 (1a), CpZr[O−NS]Cl2 (1b), CpTi[O−N−S]Cl (2a), CpZr[O−N−S]Cl (2b) and Cp*Zr[O−N−S]Cl (2c) were synthesized by the reactions of La and Lb with CpTiCl3, CpZrCl3 and Cp*ZrCl3, and characterized by IR, 1H-NMR, 13C-NMR and elemental analysis. In addition, an X-ray structure analysis was performed on ligand Lb. The title Group IV half-sandwich bearing tridentate [O,N,S] ligands show good catalytic activities for ethylene polymerization in the presence of methylaluminoxane (MAO) as co-catalyst up to 1.58 × 107 g-PE·mol-Zr−1·−1. The good catalytic activities can be maintained even at high temperatures such as 100 °C exhibiting the excellent thermal stability for these half-sandwich metal pre-catalysts.

Tailoring iron complexes for ethylene oligomerization and/or polymerization

Recent progress in the use of iron-based complex pre-catalysts for ethylene reactivity is reviewed, illustrating the current state-of-the-art and the potential usefulness of such systems for delivering solely ethylene oligomerization or polymerization products. The problems associated with the industrial use of late transition metal complex pre-catalysts are generally regarded as catalyst deactivation and the formation of more products of lower molecular weight at elevated temperature. These problems have been addressed for iron-based complex pre-catalysts via the fine tuning of substituents of existing ligands and/or the design of new ligand sets. Results revealed that modified bis(imino)pyridyliron dichlorides were capable of operating at elevated temperatures, and were capable of delivering highly linear polyethylene. Other new models of iron complexes have achieved high activity for ethylene oligomerization and/or polymerization. Particularly successful has been the use of the 2-iminophenanthrolyliron pre-catalyst, which have now been utilized in a 500 tonne pilot plant.

Group iv complexes containing the benzotriazole phenoxide ligand as catalysts for the ring-opening polymerization of lactides, epoxides and as precatalysts for the polymerization of ethylene

A series of Ti(IV), Zr(IV) and Hf(IV) benzotriazole phenoxide (BTP) complexes were synthesized and characterized by various spectroscopic techniques, elemental analysis and X-ray crystallography. The monosubstituted Zr(IV) BTP complexes [(μ-L)Zr(O(i)Pr)3]2 1-3 [L = (C1)BTP-H (1), (TCl)BTP-H (2), (pent)BTP-H (3)] and tetrasubstituted Zr(IV), Hf(IV) complexes ZrL4 4-6 [L = (C1)BTP-H (4), (TCl)BTP-H (5), (pent)BTP-H (6)] and HfL4 7-9 [L = (C1)BTP-H (7), (TCl)BTP-H (8), (pent)BTP-H (9)] were prepared by the reaction of Zr(O(i)Pr)4·((i)PrOH) and Hf(O(t)Bu)4 in toluene with the respective ligands in different stoichiometric proportions. The reaction between BTP and TiCl4 and ZrCl4 and HfCl4 in a 2 : 1 stoichiometric reaction resulted in the formation of disubstituted group IV chloride complexes L2MCl2 10-12 [L = (C1)BTP-H, M = Ti, Zr and Hf]. The molecular structures of complexes 1, 4, 7, 10, 11, and 12 were determined by single-crystal X-ray studies. The X-ray structure of 1 reveals a dimeric Zr(IV) complex containing a Zr2O2 core bridged through the oxygen atoms of the phenoxide groups. Each Zr atom is distorted from an octahedral symmetry. These complexes were found to be active towards the ring-opening polymerization (ROP) of L-lactide (L-LA) and rac-lactide (rac-LA). Complex 1 produced highly heterotactic poly(lactic acid) (PLA) from rac-LA under melt conditions with narrow molecular weight distributions (MWDs) and well controlled number average molecular weights (M(n)). Additionally, epoxide polymerizations using rac-cyclohexene oxide (CHO), rac-propylene oxide (PO), and rac-styrene oxide (SO) were also carried out with these complexes. The yield and molecular weight of the polymer was found to increase with the extension of reaction time. Compounds 1-12 were activated by methylaluminoxane (MAO) and show good activity for ethylene polymerization and produced high molecular weight polyethylene.

Synthesis, characterization and catalytic behavior toward ethylene of 2-[1-(4,6-dimethyl-2-benzhydrylphenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridylmetal (iron or cobalt) chlorides

A series of 2-[1-(4,6-dimethyl-2-benzhydrylphenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridines was synthesized and used to prepare the iron(II) and cobalt(II) chloride complexes thereof. All organic compounds were fully characterized by elemental analysis, IR and NMR ((1)H/(13)C) spectroscopy, whilst the metal complexes were characterized by elemental analysis and IR spectroscopy as well as by single-crystal X-ray diffraction studies (for two representative cobalt complexes), which revealed that the geometry at the metal was either pseudo-square-pyramidal or trigonal bipyramidal. Upon activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all metal complex pre-catalysts exhibited high activities for ethylene polymerization. The iron pre-catalysts show much higher activity than did their cobalt analogues; however, the iron catalytic systems generally produced polyethylene of wide molecular weight polydispersity. At elevated reaction temperature, the polyethylene was of lower molecular weight, but revealed narrow polydispersity.

Ethylene Polymerization by Monochloro Non-Bridged Half-Metallocene-type Zirconium Complexes Containing Phosphine Oxide-(thio)phenolate Chelating Ligands as Catalyst at High Temperature

Ethylene polymerizations were explored by monochloro half-zirconocene complexes containing phosphine oxide-(thio) phenolate chelating ligands of the type,ClCp'Zr[X-2-R1-4-R2-6-((Ph2P=O) C6H2]2(Cp' = C5H5,a:X = O,R1= Ph,R2= H;b:X = O,R1= F,R2= H;c:X = O,R1=tBu,R2= H;d:X =O,R1= R2=tBu;e:X = O,R1= SiMe3,R2= H;f:X = S,R1= SiMe3,R2= H;Cp' = C5Me5,g:X = O,R1= SiMe3,R2= H) in the presence of Ph3CB(C6F5)4/iBu3Al as co-catalyst at high temperature(50 ~125 ℃).As reveled by the polymerization results,under optimized reaction temperature of 75 ℃,complexes a ~ d were efficient ethylene polymerization catalysts under high temperature(50 ~ 100 ℃).Catalytic activity was improved by increasing the steric bulk of R1substituent or the introduction of electron withdrawing groups at the same position.The occurrence of trimethylsilyl rendered a greatly improved temperature resistance for catalyst e than those of catalysts a ~ d,exhibiting an ethylene polymerization activity of 5628 kg /(mol Zr·h)under 100 ℃ optimized reaction temperature.The variation of coordinated atom or the substituents at the Cp moiety had certain influences upon the catalytic activity and the PDI of the resulting polymer material.

Isospecific polymerization of propene by new indolyl-pyridylamido Zr(IV) catalysts

New zirconium complexes bearing indolyl-pyridylamido ligands [−NNN−] have been synthesized and used as catalysts in ethylene and propene polymerization in the presence of AliBu2H/MAO as cocatalytic system. Complexes 1 and 2, bearing ligands with a different steric hindrance on the carbon bridging the pyridine and the aniline moieties, exhibited remarkable catalytic activity for ethylene and propene polymerization, affording ultrahigh molecular weight polymers with monomodal molecular weight distributions. Moreover, the presence of the 2-isopropyl phenyl substituent on the bridging carbon (complex 2) resulted in higher stereoselectivity and regioselectivity providing a polypropylene sample with an [mmmm] content up to 96% and 1.3% of regioinversion. On the other hand, the change of the substituents of the aniline moiety (complex 3) gave a zirconium complex which resulted completely inactive both in the ethylene and propene polymerization.

Preparation of new FI-type catalyst for polymerization of ethylene

AbstractA new FI-type Zr-based catalyst of bis[N-(3,5-dicumylsalicylidene)- anthracylaminato]zirconium(IV) dichloride was found to display a moderate ethylene polymerization activity of 42×104 g PE/mmol Zr. h with a viscosity average molecular weight (Mv) of 56×104 at the monomer pressure of 4 bars and temperature of 30 °C. HOMO (the highest occupied molecular orbital) and LUMO (the lowest unoccupied molecular orbital) energy level of the anionic phenoxyimine ligands, were calculated using HF/6-31G method. Plurality of the fused aromatic rings on the catalyst structure decreased the energy gap between the HOMO and LUMO, but could not increase the activity. The highest activity of the catalyst was obtained at about 30 °C following a sharp decrease at higher temperature. The catalyst showed the high activity at about [Al]:[Zr]=80000:1 molar ratio and further addition did not affect the activity of the catalyst. Experimental results revealed that low HOMO energy level is not a necessity to reach high activity of the catalyst. Despite low HOMO energy level, the prepared catalyst displayed moderate polymerization activity. Either the activity of the catalyst or the viscosity average molecular weight of the obtained polymer was affected by the hydrogen concentration slightly. However, activity of the catalyst showed higher sensitivity to amount of hydrogen and increased with increasing the hydrogen concentration. Higher monomer pressure increased productivity, crystallinity and the Mv values of the resulting polymer. Some specification of the obtained polymer was studied.

Binuclear zirconium complexes with bidentate N-(ortho-dimethylaminobenzyl)anilide ligands: Synthesis, characterization, and catalytic properties for ethylene polymerization and copolymerization with 1-hexene

A series of binuclear zirconium complexes of the type [ortho-(Me2N)C6H4CH2NArZrCl2(μ-Cl)]2 [Ar=2,6-Me2C6H3 (1), 2,6-Et2C6H3 (2), 2,6-iPr2C6H3 (3)] were synthesized by reactions of ZrCl4 with corresponding ortho-(Me2N)C6H4CH2NArLi. All new zirconium complexes were characterized by 1H and 13C NMR spectroscopy and elemental analyses. The molecular structures of complexes 1 and 2 were determined by single crystal X-ray diffraction analysis. Upon activation with AliBu3 and Ph3CB(C6F5)4, complexes 1–3 exhibit moderate catalytic activity for ethylene polymerization and copolymerization with 1-hexene, producing high or ultra high molecular weight polyethylene or relatively high molecular weight poly(ethylene-co-1-hexene) with reasonable 1-hexene incorporation.

PE/clay nanocomposites produced via in situ polymerization by highly active clay-supported Ziegler–Natta catalyst

The synthesis of polyethylene/clay (PE/clay) nanocomposites by means of in situ polymerization was achieved using the clay/BOM/chloroform/EtOH/TiCl4/TEA catalyst system where butyl octyl magnesium (BOM) and triethyl aluminum (TEA) were a modifier for the clay and cocatalyst, respectively. It was found that the catalyst had high activity in ethylene polymerization. The microstructure of the resulting PE/clay nanocomposites was characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The examinations evidenced the nanocomposite formation with exfoliated clay in the PE matrix. The thermal properties of the produced nanocomposites were studied by differential scanning calorimetry, oxidation induction time, and thermal gravimetric analysis. Furthermore, the mechanical properties of the nanocomposites were evaluated by the impact and tensile tests. The examinations indicated the improved thermal stability and mechanical properties. Meanwhile, a wide range of molecular weights were produced in the presence of hydrogen.

(“Ferrocene-salaldiminato”)zirconium Complexes for Ethylene Polymerization Catalysis: The Role of the Bulky Substituents

We prepared the 2-hydroxy-5-trimethylsilylferrocenecarbaldimine systems 13 enantioselectively by a short synthetic route starting from the chiral ferrocene carbaldehyde acetal 5. The imines 13a–c were used to synthesize the zwitterionic (“ferrocene-salaldiminato”)2ZrCl4 complexes 14a–c. Activation with MAO gave homogeneous Ziegler–Natta catalysts, which showed only a moderate ethylene polymerization activity, similar to the unsubstituted parent “ferrocene-salaldiminato” zirconium systems. Consequently, a synthetic route was devised and carried out to make the corresponding 2-hydroxy-3,5-bis(trimethylsilyl)ferrocenecarbaldimines (21) available. The enantiomerically highly enriched ligands (pS)-21a and -d derived from the aldehyde and aniline or cyclohexylamine, respectively, were used to synthesize the corresponding (“ferrocene-salaldiminato”)2ZrCl4 complexes 22a,d. Both gave highly active homogeneous Ziegler–Natta catalysts upon activation with MAO for the formation of linear low molecular weight polyethylene. Complex 22d and many ligand precusors from both sequences were characterized by X-ray diffraction.

Syntheses and structures of titanium complexes having O,N,O-tridentate ligands and their catalytic ability for ethylene polymerization

O,N,O-tridentate ligands 2-H2 based on a 2,6-substituted pyridine structure and their dichlorotitanium complexes 3 were synthesized and structurally characterized. The complexes have five-coordinated, trigonal bipyramidal structure, in which one chlorine atom was located at trans-position to the nitrogen atom of the pyridine ring and the other was at cis-position. NMR spectroscopy indicated their fluxional structure in solution. The complexes showed low to modest catalytic activity for ethylene polymerization in the presence of methylaluminoxane (MAO) as a co-catalyst.

Titanium and zirconium compounds stabilized by coordination of heteroscorpionate [N,N,O]-donor ligands. Synthesis, characterization and polymerization activity

The bis(pyrazol-1-yl)methane compounds [(2-hydroxyphenyl)bis(pyrazol-1-yl)methane (4) bpzmpH, (3,5-di-tert-butyl-2-hydroxyphenyl)bis(pyrazol-1-yl)methane (5) bpzmtBu2pH, (2-hydroxyphenyl)bis(3,5-dimethyl-pyrazol-1-yl)methane (6) Me2bpzmpH, (3,5-di-tert-butyl-2-hydroxyphenyl)bis(3,5-dimethyl-pyrazolyl)methane (7) Me2bpzmtBu2pH, (2-hydroxyphenyl)bis(4-methyl-pyrazolyl)methane (8) MebpzmpH and (3,5-di-tert-butyl-2-hydroxyphenyl)bis(4-methyl-pyrazolyl)methane (9) MebpzmtBu2pH] as heteroscorpionate precursor ligands have been prepared by reaction of the corresponding bis(pyrazol-1-yl)ketone (1), bis(3,5-dimethylpyrazol-1-yl)ketone (2) and bis(4-methylpyrazol-1-yl)ketone (3) with the appropriate salicylaldehyde derivative. The coordination of these molecules to titanium and zirconium compounds containing a cyclopentadienyl ligand has been studied. TiCpRCl3 (CpR = η5-C5H5 (Cp); η5-C5H4SiMe3 (Cp′); η5-C5Me5 (Cp*)) reacts with 4–9 in the presence of 2.5 equiv of NEt3, in toluene at room temperature, through an alcoholysis process to give the monocyclopentadienyl heteroscorpionate dichloro complexes TiCpRLCl2 [CpR = Cp, L = bpzmp (10), Me2bpzmtBu2p (11), MebpzmtBu2p (12); CpR = Cp′, L = Me2bpzmtBu2p (13); CpR = Cp*, L = bpzmp (14), Me2bpzmtBu2p (15)] (Scheme 2). Treatment of TiCp*Me3 with 4, 6 and 8 affords the dimethyl complexes TiCp*LMe2 [L = bpzmp (16), Me2bpzmp (17), Mebpzmp (18)]. Analogous dichloro ZrCpLCl2 [L = bpzmp (19), bpzmtBu2p (20), Me2bpzmp (21), MebpztBu2p (22)] and dibenzyl ZrCpLBz2 [L = bpzmp (23), bpzmtBu2p (24), Me2bpzmp (25), MebpzmtBu2p (26)] zirconium complexes have also been prepared by reaction of ZrCpCl3 in THF or ZrCpBz3 in toluene with 4, 5, 6 and 8 at room temperature. From spectroscopic data tetrahedral structures in solution with a κ1-O coordination mode are suggested for the titanium complexes, while distorted octahedral geometries with a κ3-N,N,O coordination are proposed for the zirconium derivatives. Fluxional exchange between coordinated and non-coordinated pyrazolate rings is concluded in some zirconium compounds, depending on the electronic and steric effects imposed by the substituents of the heteroscorpionate ligands. Preliminary studies of catalytic activity for ethylene polymerization using sMAO as cocatalyst were performed. The complexes proved to be moderate catalysts due to loss of the scorpionate ligand.

ChemInform Abstract: (Imido)vanadium(V)‐Alkyl, Alkylidene Complexes Exhibiting Unique Reactivities Towards Olefins, Phenols, and Benzene via 1,2‐C—H Bond Activation

AbstractReview: 119 refs.

High activity and good hydrogen response silica-supported Ziegler-Natta catalyst for ethylene polymerization

A silica-supported Ziegler-Natta catalyst with dimethyldichlorosilane (DMDS) as modifier and small silica as support was successfully prepared and characterized. Results from pilot screen showed that the new catalyst exhibited higher catalytic activity, better hydrogen response ability and better copolymerization ability than the commercial M catalyst. Pilot screen in ethylene gas phase fluidized bed polymerization, the catalytic activity of the new catalyst was up to 8000 g PE/g cat, which was twice of that of the commercial M catalyst. The bulk density of polyethylene obtained with the new catalyst was 0.38 g/cm3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.