Preparation of functionalized montmorillonites and their application in supported zirconocene catalysts for ethylene polymerization

Ethylene polymerization was carried out with zirconocene catalysts supported on montmorillonite (or functionalized montmorillonite). The functionalized montmorillonite was from simple ion exchange of [CH3O2CCH2NH3](+) (MeGlyH(+)) ions with interlamellar cations of layered montmorillonites. The functionalized montmorillonlites [high-purity montmorillonite (MMT)-MeGlyH(+)] had larger interlayer spacing (12.69 Angstrom) than montmorillonites without treatment (9.65 Angstrom). The zirconocene catalyst system [Cp2ZrCl2/methylaluminoxane (MAO)/MMT-MeGlyH(+)] had much higher Zr loading and higher activities than those of' other zirconocene catalyst systems (Cp2ZrCl2/MMT, Cp2ZrCl2/MMT-MeGlyH(+), Cp2ZrCl2/MAO/MMT, [CP2ZrCl](+)[BF4]/MMT, [Cp2ZrCl][BF4](-)/MMT-MeGlyH(+), [CP2ZrCl](+)[BF4](-)/MAO/MMT-MeGlyH(+), and [Cp2ZrCl](+)[BF4](-)/MAO/MMT). The polyethylenes with good bulk density were obtained from the catalyst systems, particularly (CP2ZrCl2/MAO/MMT-MeGlyH(1)). MeGlyH(+) and MAO seemed to play important roles for preparation of the supported zirconocenes and polymerization of ethylene. The difference in Zr loading and catalytic activity among the supported zirconocene catalysts is discussed.

Cyclization in situ of isoprene polymerization catalyzed by Nd-Al bimetallic complex

Function of chloride and effect of various alkylaluminiums, C1/A1 molar ratio, solvents on cyclization in situ of isoprene polymerization catalyzed by Nd-Al bimetallic complex were studied. The structure of cyclized products was characterized by means of IR and H-1 NMR, The results indicated that in the course of isoprene polymerization with rare earth catalytic system, the function of alkylchloride introduced is terminating cis-polymerization and generating cationic species with alkyl-aluminums to initiate cyclization in situ. Soluble cyclized polyisoprene was obtained with fragments of cyclopolyisoprene.

Preparation of poly(4-vinylpyridine)/silica hybrids supported cyclopentadienyltitanium trichloride (CpTiCl3) catalyst and styrene polymerization

Poly(4 - vinylpyridine)/silica( PVP/SiO2) organic - inorganic nanoscale hybrid was prepared using sol - gel method, in which PVP was used as an organic component and TEOS as a SiO2 precusor, This hybrid was used as CpTiCl3 support. The XPS and IR measurements showed that two kinds of catalytic active site were formed through analyzing the interaction mode between support and CpTiCl3. The results of styrene polymerization showed that syndiotactic was the highest at 50 degreesC. The catalytic activity was 1.09 x 10(6) g PS/ (mol Ti . h) at 70 degreesC when n(Al)/n(Ti) = 1500. GPC results showed a bimodal molecular weight distribution.

Polymerization of methyl methacrylate with organolanthanides as single-component catalysts

It was first found that Ind(2)Y(mu -Et)(2)AlEt2 and Ind(2)LnN(i-Pr)(2) (Ln = Y, Yb) exhibit extremely high catalytic activity in the polymerization of methyl methacrylate. The reactions can be carried out over a quite broad range of polymerization temperatures from -30 to 50 degreesC. PMMA with high molecular weight (7.8 x 10(-5)) and high isotacticity (94%) can be obtained by using Ind(2)Y(mu -Et)(2)AlEt2, and narrow molecular weight distribution (M-w/M-n < 1.5) can be obtained by using Ind(2)LnN(i-Pr)(2) (Ln = Y, Yb).

Polymerization of acrylonitrile with organolanthanides as single-component catalysts

Ind(2)Y(mu -Et)(2)AlEt2 and Ind(2)LnN(i-Pr)(2) (Ln = Y, Yb) were used as a single-component catalyst for the polymerization of acrylonitrile (AN) respectively. The regularity of polymerization of AN and stereoregularity of polyacrylonitrile (PAN) were also studied in both cases. Both catalysts can produce PAN with molecular weight from 10,000 to 30,000. In addition, the catalytic activity and molecular weights were increased by the addition of PhONa.

Preparation of polymer-supported zirconocene catalysts and olefin polymerization

A novel polymer-supported metallocene catalyst with crosslinked poly(styrene-co-acrylamide) (PSAm) as the support has been prepared and characterized. The probability of long sequences of acrylamide (Am) in PSAm is still low even at an Am amount of 32.8 mol %, implying the relatively homogeneous distribution of Am. The infrared spectra of PSAm and the supported catalyst substantiate that an amide group in PSAm coordinates with methylaluminoxane through both oxygen and nitrogen atoms. Ethylene/alpha-octene copolymerization showed that the catalytic activity is not markedly affected by adding alpha-octene. C-13 NMR analysis of the ethylene/alpha-octene copolymer indicated that the composition distribution of the copolymer is uniform. (C) 1999 John Wiley & Sons, Inc.

Polymer-supported zirconocene catalyst for ethylene polymerization

The use of crosslinked poly(styrene-co-4-vinylpyridine) having functional groups as the support for zirconocene catalysts in ethylene polymerization was studied. Several factors affecting the activity of the catalysts were examined. Conditions like time, temperature, Al/N (molar ratio), Al/Zr (molar ratio), and the mode of feeding were found having no significant influence on the activity of the catalysts, while the state of the supports had a great effect on the catalytic behavior. The activity of the catalysts sharply increased with either the degree of crosslinking or the content of 4-vinylpyridine in the support. Via aluminum compounds, AlR3 or methylaluminoxane (MAO), zirconocene was attached on the surface of the support. IR spectra showed an intensified and shifted absorption bands of C-N in the pyridine ring, and a new absorption band appeared at about 730 cm(-1) indicating a stable bond Al-N formed in the polymer-supported catalysts. The formation of cationic active centers was hypothesized and the performance of the polymer-supported zirconocene was discussed as well. (C) 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 37-46, 1999.

Synthesis, characterisation and catalytic activity of propionamide complexes of rare earth chlorides

Propionamide complexes of rare earth chlorides were synthesized, Formula of the complexes is LnCl(3). 3BA. The ligand is shown to behave as a normal amide donor With the oxygen of the carbonyl group coordinated to the metal ions. Binary system composed Elf propionamide and aluminum alkyl shows higher activity and stereospecificity for butadiene polymerization. The cis-1,4 content of polybutadiene is more than 98%.

Identification of o-phenylenediamine polymerization product catalyzed by cytochrome c

The hydrogen peroxide (H2O2) and cytochrome c-dependent oxidation of o-phenylenediamine (o-PD) was investigated by spectrophotometry and electrochemistry. The results indicated that o-PD underwent facile catalytic oxidation in the presence of cytochrome c, and that the degradation of cytochrome c by hydrogen peroxide can also be partly prevented in the presence of o-PD. The hydroxyl radical scavengers (mannitol and sodium benzoate) and oxo-heme species scavenger (uric acid) do not inhibit the oxidation, which implies that the hydroxylation of o-PD may not be involved in its oxidation. Combining with the results of the mass spectrum, elemental analysis, nuclear magnetic resonance and Fourier transform infrared spectrum of the isolated product, a conceivable structure of the product was suggested. (C) 1998 Elsevier Science B.V.

Polymerization of ethylene by zirconocene-B(C6F5)(3) catalysts with aluminum compounds

Ethylene polymerization by zirconocene-B(C6F5)(3) catalysts with various aluminum compounds has been investigated. It is found that the catalytic activity depended on zirconocenes used, and especially on the type of aluminum compounds. For Et(H(4)Ind)(2)ZrCl2 (H(4)Ind : tetrahydroindenyl), the activity decreases in the following order: Me3Al > i-Bu3Al > Et3Al much greater than Et2AlCl. While for Cp2ZrCl2(Cp : cyclopentadienyl), it varies as follows: i-Bu3Al > Me3Al much greater than Et3Al. Furthermore, the activity is significantly affected by the addition mode of the catalytic components, which may imply that the formation of active centers is associated with an existing concentration of catalytic components. Results of thermal behavior of polyethylene (PE) studied by differential scanning calorimetry(DSC) show that crystallinity of the polymer prepared with Et3Al is higher than that with Me3Al or i-Bu3Al. It is also found that the number-average molecular weight ((M) over bar) of the polymers prepared with Me3Al or i-Bu3Al is much higher than that with Et3Al. H-1-NMR studies substantiate that i-Bu3Al is a more efficient alkylation agent of Cp2ZrCl2 in comparison with Me3Al. (C) 1997 John Wiley & Sons, Inc.

Stereospecific polymerization of styrene using a homogeneous lanthanide catalyst

Stereospecific polymerization of styrene was catalyzed by homogeneous neodymium phosphonate [Nd(P-507)(3)]-H2O-Al(i-Bu)(3) catalytic system. The polymer was separated into isotactic polystyrene and atactic polystyrene by extracting the latter with boiling 2-butanone. The conversion of styrene and the yield of isotactic polystyrene (IY) were influenced by the [H2O]/[Al(i-Bu)(3)] mole ratio and the solvent polarity. The reaction is first order with respect to monomer at 70 degrees C.

ESCA study of dichlorozirconocene/methylaluminoxane olefin polymerization catalyst system

An investigation has been undertaken by use of ESCA in the characterization of the central metal(Zr) of dichlorozirconocene/methylaluminoxane homogeneous olefin polymerization catalyst. The change of electron density shown by a shift in ESCA signals (181.8 - 182.7eV) indicates that the catalytic species are ''cation-like''. Within the range of detecting sensitivity of ESCA spectrometer, only a part of the new catalytic derivative was formed. The influence of complexion time and Al : Zr ratio on the formation of the catalytic zirconocene cation has also been investigated.

Polymer-supported titanium catalysts for syndiotactic polymerization of styrene

Poly(styrene-co-acrylamide) (PSAm)-titanium complexes (PSAm . Ti) were prepared and characterized. It is found that the coordination number of acrylamide (Am) to Ti in the complexes is strongly dependent on Am content in PSAm, but not on [Am]/[Ti] ratio in the feed. The infrared and x-ray photoelectron spectra suggest that the polymer-supported complexes possess the structure [GRAPHICS] The catalytic behavior of the complexes in styrene polymerization is described. The catalytic activity is markedly affected by [Al]/[Ti] ratio in the complexes. C-13 NMR, IR, and DSC data indicate that the polystyrene obtained with PSAm . Ti/MAO (MAO = methylaluminoxane) is highly syndiotactic. Use of Et(3)Al and i-Bu(3)Al in place of MAO gives atactic polystyrene. The activities of the various aluminum compounds used as the cocatalysts decrease in the order: MAO > Et(3)Al > i-Bu(3)Al. The polymer-supported complexes show relatively high activity even after the complexes had been exposed to air for 19 h or higher polymerization temperature. (C) 1996 John Wiley & Sons, Inc.

POLYMERIZATION OF ACRYLONITRILE INITIATED BY DI(2,6-DI-TERT-BUTYL-4-METHYLPHENOXO) SAMARIUM COMPLEX

The polymerization of acrylonitrile initiated by organolanthanide complexes alone is studied for the first time. The effect df polymerization conditions on catalytic activity of the title complex and molecular weight of the polymers produced have been studied.

SYNTHESIS AND CHARACTERIZATION OF POLYMER-SUPPORTED LANTHANIDE COMPLEXES AND BUTADIENE POLYMERIZATION BASED ON THEM

Poly(styrene-acrylic acid)-lanthanide (Ln.PSAA) and poly(ethylene-acrylic acid)-neodymium (NdPEAA) complexes have been prepared and characterized. The infrared and X-ray photoelectron spectra indicate that the lanthanide complexes possess the bidentate carboxylate structure Ln-O-C(R)-O (see structure B in text). The catalytic behavior of the complexes has been described. The catalytic activities of Nd.PSAA and Nd.PEAA are much greater than that of the corresponding low molecular weight catalyst for butadiene polymerization. The activities of various individual lanthanide elements are quite different from one another. Neodymium shows the highest activity. Europium, samarium and the heavy elements exhibit very low or no activities. The cis-1,4 content of the polybutadiene obtained is not affected by different lanthanide elements in the series. The complex with the intermediate content of the functional group has a higher activity than the others. The polymer-supported lanthanide complexes having different constitutions have different catalytic activities. When the molar ratio of lanthanide to the functional group is ca. 0.2, the activity of the complex is in the optimum state. The activity is influenced by the dispersion of the lanthanide metal immobilized on the polymer chain. Catalytic activity can be improved by adding other metals to the catalyst system.