Nickel-based catalyst [N,N]NiBr2, in which [N,N] stands for N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine, shows high activity for ethylene polymerization in the presence of organoaluminum compounds under high et...Nickel-based catalyst [N,N]NiBr2, in which [N,N] stands for N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine, shows high activity for ethylene polymerization in the presence of organoaluminum compounds under high ethylene pressure to yield polyethylene characteristic of low molecular weight and highly branched chains. Toluene as the solvent is more in favor of catalyst activity, higher molecular weight and branched chains in polyethylene structure as compared to hexane solvent.展开更多
?Ethene/norbornene copolymerization by the catalyst system [Me_2Si( 3- tertBuCp)(N tertBu)]TiCl_2/MAO was investigated in detail at 30 ℃, 60℃, and 90℃. A mass flow controller was used in this work to obtain kine ...?Ethene/norbornene copolymerization by the catalyst system [Me_2Si( 3- tertBuCp)(N tertBu)]TiCl_2/MAO was investigated in detail at 30 ℃, 60℃, and 90℃. A mass flow controller was used in this work to obtain kine tic data and investigate tempera ture's effects on activity, norbornene incorporation, copolymerization parameter , microstructure, glass transition temperature, and molar masses were described. H igh copolymerization values r_E and high alternation are determined. The n umber of isotactic alternating sequences is much higher than that of the syndiot actic alter nating sequences.展开更多
N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR...N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.展开更多
文摘Nickel-based catalyst [N,N]NiBr2, in which [N,N] stands for N-(2,6-diisopropylphenyl)pyridine-2-carboxaldimine, shows high activity for ethylene polymerization in the presence of organoaluminum compounds under high ethylene pressure to yield polyethylene characteristic of low molecular weight and highly branched chains. Toluene as the solvent is more in favor of catalyst activity, higher molecular weight and branched chains in polyethylene structure as compared to hexane solvent.
文摘?Ethene/norbornene copolymerization by the catalyst system [Me_2Si( 3- tertBuCp)(N tertBu)]TiCl_2/MAO was investigated in detail at 30 ℃, 60℃, and 90℃. A mass flow controller was used in this work to obtain kine tic data and investigate tempera ture's effects on activity, norbornene incorporation, copolymerization parameter , microstructure, glass transition temperature, and molar masses were described. H igh copolymerization values r_E and high alternation are determined. The n umber of isotactic alternating sequences is much higher than that of the syndiot actic alter nating sequences.
基金Supported by National Natural Science Foundation of China (No.20476080)Tianjin Natural Science Foundation (No.07JCYBJC00600)
文摘N-valeronitrile-N'-methylimidazolium hexafluorophosphate ([C 4 CNmim]+ PF 6),as a novel ionic liquid with polar nitrile functional group,was prepared.The structure of the ionic liquid was characterized by using IR and 1 H NMR.As a medium,the ionic liquid plays an important role in copolymerization of carbon monoxide (CO) with styrene (St).Some synthetic conditions were determined,including the usage of ionic liquid,palladium composite catalyst and methanol,CO pressure,reaction time and reaction temperature.The influence of these factors on catalytic activity was analyzed.The results show that the catalytic activity has reached 1 724.1 gStCO/(gPd·h) and the catalyst could be reused 5 times under the optimal condition:composite catalyst 0.015 mmol,ionic liquid 3 mL,methanol 0.75 mL,CO pressure 2MPa,reaction time 2 h and reaction temperature 70℃.This CO/St copolymerization within [C 4 CNmim]+ PF 6 system could facilitate ionic liquids with efficient and economical applications to polymeric materials.
