Neodymium chloride isopropanol complex （NdCl3.3＇prOH） activated by modified methylaluminoxane （MMAO） was examined in isoprene polymerization in hexane, with regards to Nd compounds, aluminum （Al） compounds, [Al...Neodymium chloride isopropanol complex （NdCl3.3＇prOH） activated by modified methylaluminoxane （MMAO） was examined in isoprene polymerization in hexane, with regards to Nd compounds, aluminum （Al） compounds, [Al]/[Nd] ratio, polymerization temperature and time. NdCl3＇3iprOH exhibited high activity producing polymers feasting high cis-l,4 stereospecificity （〉 96%）, very high molecular weight （Mn 〉 1.0 × 10^6） and fairly narrow molecular weight distribution （MWD, Mw/Mn 〈 2.0） simultaneously. In comparison, neodymium isopropoxide also showed high activity providing polymers with narrow MWD （Mw/Mn = 2.07）, but somewhat low cis-1,4 content （ca. 92%）, while neodymium chloride had no activity under present polymerization conditions. The Al compounds affected the polymer yield in the order of Al（i-Bu）3 〉 MMAO 〉 Al（i-Bu）2H. MMAO as cocatalyst afforded polyisoprene with high Mn over 1.0 × 10^6, whereas as stronger chain transfer agent than MMAO, AI（i-Bu）3 and AI（i-Bu）EH yielded polymers with low Mn （1.0 × 10^5-8.0 × 10^5）. NdCl3·3＇PrOH/MMAO catalyst showed a fairly good catalytic activity even at relatively low [Al]/[Nd] ratio of 30, and the produced polymer remained high cis-1,4 content of 95.8% along with high Mn over 1.0× 10^6 even at elevated temperatures up to 70℃. The polymerization rate is of the first order with respect to the concentration of isoprene. The mechanism of active species formation was discussed preliminarily.展开更多
The formations of defective MgC12 surfaces, and subsequent adsorption of Ti species and electron donor, as well as propylene polymerization over the Ziegler-Natta catalyst have been investigated using density function...The formations of defective MgC12 surfaces, and subsequent adsorption of Ti species and electron donor, as well as propylene polymerization over the Ziegler-Natta catalyst have been investigated using density functional theory （DFT） method. Twelve possible support models of regular and defective MgC12 （110） and （100） surfaces were built. The individual adsorptions of titanium chlorides as mononuclear or dinuclear, and ethyl benzoate （EB） as electron donor, on these models were evaluated. The analysis of energies presented the cases of EB adsorption were generally more stable than titanium chlorides on both surfaces. Thus, EB as internal electron donor mainly prevented TIC14 from coordinating on the MgC12 surfaces where mostly non-stereospecific active sites could be formed. Exceptionally, A5 the site model with terminal Cl-vacancy on the MgC12 support, presented stronger adsorption of TiCl4 than that of EB on （110） surface. Since the TIC14 and ethyl benzoate （EB） would compete to adsorb on the support surface, it seems reasonable to assume that TIC14 might predominately occupy this site, which can act as the most plausible active site for propylene polymerization. The first insertion of propylene monomer into the A5 active site model showed that it exhibited good regioselectivity but poor stereospecificity in the absence of electron donor.展开更多
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 catalys...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/cm^3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.展开更多
The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high act...The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high activity and controllable selectivity. The microstructure of the resultant polymer was adjustable by variation of electron donor and/or the alkylaluminum. ^13C-NMR and thermal analysis demonstrate that the produced polybutadienes have stereo-block chain structures of cis-1,4 and trans-1,4 segments with adjustable Tm and To. The neodymium sulfonate-based catalyst is believed to be significant in regulating the chain structure of polydienes and in exploring 1,3-diene polymerization mechanism.展开更多
Several bis（trifluoromethylsulfonyl）phenylamines have been synthesized and used as internal donors for the preparation of heterogeneous Ziegler-Natta catalysts for propylene polymerization. These new cata- lysts are...Several bis（trifluoromethylsulfonyl）phenylamines have been synthesized and used as internal donors for the preparation of heterogeneous Ziegler-Natta catalysts for propylene polymerization. These new cata- lysts are highly active and stereospecific in combination with an external donor for the polymerization of propylene. The activity of these catalysts is dramatically influenced by the electronic capability of the phenyl substituents on the sulfonyl phenylamines. Therefore, the performances of the catalysts can be modified by adjusting the electronic property of the phenyl substituents of the sulfonyl phenylamines.展开更多
基金supported by the Administration of Science and Technology of Jilin Province,China (No.200505254)
文摘Neodymium chloride isopropanol complex （NdCl3.3＇prOH） activated by modified methylaluminoxane （MMAO） was examined in isoprene polymerization in hexane, with regards to Nd compounds, aluminum （Al） compounds, [Al]/[Nd] ratio, polymerization temperature and time. NdCl3＇3iprOH exhibited high activity producing polymers feasting high cis-l,4 stereospecificity （〉 96%）, very high molecular weight （Mn 〉 1.0 × 10^6） and fairly narrow molecular weight distribution （MWD, Mw/Mn 〈 2.0） simultaneously. In comparison, neodymium isopropoxide also showed high activity providing polymers with narrow MWD （Mw/Mn = 2.07）, but somewhat low cis-1,4 content （ca. 92%）, while neodymium chloride had no activity under present polymerization conditions. The Al compounds affected the polymer yield in the order of Al（i-Bu）3 〉 MMAO 〉 Al（i-Bu）2H. MMAO as cocatalyst afforded polyisoprene with high Mn over 1.0 × 10^6, whereas as stronger chain transfer agent than MMAO, AI（i-Bu）3 and AI（i-Bu）EH yielded polymers with low Mn （1.0 × 10^5-8.0 × 10^5）. NdCl3·3＇PrOH/MMAO catalyst showed a fairly good catalytic activity even at relatively low [Al]/[Nd] ratio of 30, and the produced polymer remained high cis-1,4 content of 95.8% along with high Mn over 1.0× 10^6 even at elevated temperatures up to 70℃. The polymerization rate is of the first order with respect to the concentration of isoprene. The mechanism of active species formation was discussed preliminarily.
基金supported by the Program of Introducing Talents of Discipline to Universities (B08021)Fundamental Research Funds for the Central Universities
文摘The formations of defective MgC12 surfaces, and subsequent adsorption of Ti species and electron donor, as well as propylene polymerization over the Ziegler-Natta catalyst have been investigated using density functional theory （DFT） method. Twelve possible support models of regular and defective MgC12 （110） and （100） surfaces were built. The individual adsorptions of titanium chlorides as mononuclear or dinuclear, and ethyl benzoate （EB） as electron donor, on these models were evaluated. The analysis of energies presented the cases of EB adsorption were generally more stable than titanium chlorides on both surfaces. Thus, EB as internal electron donor mainly prevented TIC14 from coordinating on the MgC12 surfaces where mostly non-stereospecific active sites could be formed. Exceptionally, A5 the site model with terminal Cl-vacancy on the MgC12 support, presented stronger adsorption of TiCl4 than that of EB on （110） surface. Since the TIC14 and ethyl benzoate （EB） would compete to adsorb on the support surface, it seems reasonable to assume that TIC14 might predominately occupy this site, which can act as the most plausible active site for propylene polymerization. The first insertion of propylene monomer into the A5 active site model showed that it exhibited good regioselectivity but poor stereospecificity in the absence of electron donor.
基金supported by the Program for New Century Excellent Talents in Universities(NCET-07-0142)the Program for New Century Excellent Talents in Heilongjiang Provincial Universities(NCET-06-010)+1 种基金the National Natural Science Foundation of China(No.20972025)the Science Foundation of Tianjin University of Science & Technology(No.20090420).
文摘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/cm^3. The new catalyst is suitable for condensed and super-condensed process in fluidized bed ethylene polymerization.
基金financially supported by the National Basic Research Program of China(No.2015CB654700(2015CB674702))The CAS Hundred Talents Program(Y220011001)+1 种基金the National Natural Science Foundation of China(Nos.51473156 and 51203147)Jilin Provincial Research Fund for Basic Research,China(No.20130102007JC)
文摘The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high activity and controllable selectivity. The microstructure of the resultant polymer was adjustable by variation of electron donor and/or the alkylaluminum. ^13C-NMR and thermal analysis demonstrate that the produced polybutadienes have stereo-block chain structures of cis-1,4 and trans-1,4 segments with adjustable Tm and To. The neodymium sulfonate-based catalyst is believed to be significant in regulating the chain structure of polydienes and in exploring 1,3-diene polymerization mechanism.
文摘Several bis（trifluoromethylsulfonyl）phenylamines have been synthesized and used as internal donors for the preparation of heterogeneous Ziegler-Natta catalysts for propylene polymerization. These new cata- lysts are highly active and stereospecific in combination with an external donor for the polymerization of propylene. The activity of these catalysts is dramatically influenced by the electronic capability of the phenyl substituents on the sulfonyl phenylamines. Therefore, the performances of the catalysts can be modified by adjusting the electronic property of the phenyl substituents of the sulfonyl phenylamines.
