A ^(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On ...A ^(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On the basis of the sequence distributions, the ethylene-1-octenecopolymerization mechanism was studied. It was found that the observed sequence distributions inethylene-1-octene copolymers are satisfactorily predicted by the two-site model M/M,in whichthe copolymerization proceeds according to first-order Markovian statistics at the two differentsites.展开更多
Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)_2ZrCl_2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of ...Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)_2ZrCl_2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of 1-octene concentration in thefeed the content of 1-octene in the copolymer increases, while the density, melting point,crystallinity and intrinsic viscosity of copolymer decrease. A copolymer with very lowdensity, containing 11.5 mol% of 1-octene (VLLDPE) can be produced with this catalystsystem. The effect of temperature and zirconium aluminum mole ratio of the catalyst onthe copolymerization was also investigated. The results of ^(13)C NMR determination of thecopolymer showed that the 1-octene units in the copolymer are principally isolated.展开更多
Two novel diphoshinoamine ligands have been synthesized. Combination of Cr（Ⅲ） and methylaluminoxane（MAO） generated active catalytic system which can catalyze tetramerization of ethylene with high catalytic activi...Two novel diphoshinoamine ligands have been synthesized. Combination of Cr（Ⅲ） and methylaluminoxane（MAO） generated active catalytic system which can catalyze tetramerization of ethylene with high catalytic activity up to 2.5×10^6 g/mol Cr.h and high selectivity to produce 1-octene （Cs in products is being 89.80 wt%）.展开更多
Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction press...Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction pressure and Al/Cr molar ratio on ethylene tetramerization were investigated in detail. Chromium was uniformly and firmly immobilized on the support and could not be leached off by methylaluminoxane. The supported catalyst, upon being activated with methylaluminoxane, exhibited catalytic activity of 1.70×107 g/(mol Cr·h) for ethylene tetramerization to form 1-octene at a reaction temperatures of 80 ℃, a pressure of 2.0 MPa and an Al/Cr molar ratio of 300. The supported catalyst presented a good tolerance to high temperature.展开更多
基金This work was supported by the National Natural Science Foundation of China
文摘A ^(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On the basis of the sequence distributions, the ethylene-1-octenecopolymerization mechanism was studied. It was found that the observed sequence distributions inethylene-1-octene copolymers are satisfactorily predicted by the two-site model M/M,in whichthe copolymerization proceeds according to first-order Markovian statistics at the two differentsites.
文摘Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)_2ZrCl_2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of 1-octene concentration in thefeed the content of 1-octene in the copolymer increases, while the density, melting point,crystallinity and intrinsic viscosity of copolymer decrease. A copolymer with very lowdensity, containing 11.5 mol% of 1-octene (VLLDPE) can be produced with this catalystsystem. The effect of temperature and zirconium aluminum mole ratio of the catalyst onthe copolymerization was also investigated. The results of ^(13)C NMR determination of thecopolymer showed that the 1-octene units in the copolymer are principally isolated.
文摘Two novel diphoshinoamine ligands have been synthesized. Combination of Cr（Ⅲ） and methylaluminoxane（MAO） generated active catalytic system which can catalyze tetramerization of ethylene with high catalytic activity up to 2.5×10^6 g/mol Cr.h and high selectivity to produce 1-octene （Cs in products is being 89.80 wt%）.
基金supported by the National Natural Science Foundation of China (U1162114)the PetroChina Innovation Foundation (2012D-5006-0501)+2 种基金the Tianjin Municipal Education Commission of China (20110505)the Natural Science Foundation of Tianjin (12JCQNJC06000)the Program for New Century Excellent Talents in University (NCET-07-0142)
文摘Chromium acetylacetonate and bis(diphenylphosphino)isopropylamine were coordinated in situ and supported on methylaluminoxane-modified silica. The catalyst structure and effects of reaction temperature, reaction pressure and Al/Cr molar ratio on ethylene tetramerization were investigated in detail. Chromium was uniformly and firmly immobilized on the support and could not be leached off by methylaluminoxane. The supported catalyst, upon being activated with methylaluminoxane, exhibited catalytic activity of 1.70×107 g/(mol Cr·h) for ethylene tetramerization to form 1-octene at a reaction temperatures of 80 ℃, a pressure of 2.0 MPa and an Al/Cr molar ratio of 300. The supported catalyst presented a good tolerance to high temperature.
