A new iron based catalyst 2,6\|bis[(1\|fluorenylimino)ethyl] pyridine iron dicloride (2) was synthesized via Shiff base condensation with 2,6\|diacetylpyridine and 9\|aminofluorene hydrochloride under formic acid as c...A new iron based catalyst 2,6\|bis[(1\|fluorenylimino)ethyl] pyridine iron dicloride (2) was synthesized via Shiff base condensation with 2,6\|diacetylpyridine and 9\|aminofluorene hydrochloride under formic acid as catalyst.Ethylene oligomerizations were carried out using this new catalyst and methylaluminoxane as cocatalyst under various conditions.The effects of Al/Fe molar ratio,reaction temperature and ethylene pressure on catalytic activity and product distribution were investigated.This novel catalyst had a good activity for ethylene oligomerization (e.g. 4 21×10 6g oligomers\5mol -1 Fe·h -1 ,Al/Fe molar ratio=2000,reaction temperature=40℃,ethylene pressure=1 5?MPa).The catalytic activity increased with the increasing concentration of MAO.The tendency to produce more C 4～C 10 olefins was attributed to the more chain transfer reactions to MAO.The higher the reaction temperature,the lower catalytic activity was present.The reasonable explanation was the combination of the accelerated catalyst’s deactivation and the decrease in ethylene concentration in solvent due to the elevated temperature.Under such condition,however,the oligomerization of ethylene produced more short chain olefins which are adapted to act as comonomers for preparation of linear low density polyethylene materials.Ethylene pressure in autoclave also had an important influence on catalytic activity and carbon\|number distribution of product.The catalytic activity increased sharply with the elevated ethylene pressure.However,the proportion of C 4～C 10 olefins in product decreased in higher pressure due to the enhanced chain propagation reaction.The research work indicated that the control of catalytic activity and product distribution can be realized by the variation of oligomerization conditions such as Al/Fe molar ratio,reaction temperature and ethylene pressure.The results also showed that the ethylene oligomerization employing this novel iron\|based catalyst mainly produces the C 4～C 10 olefins with high selectivity for linear C 4～C 10 α \|olefin (>98%).展开更多
Plant growth rate (GR), contents of free polyamines (fPAs) and bound polyamines (bPAs) and activities of some key enzymes involved in polyamine (PA) metabolism in the roots of two barley (Hordeum valgare L.) cultivars...Plant growth rate (GR), contents of free polyamines (fPAs) and bound polyamines (bPAs) and activities of some key enzymes involved in polyamine (PA) metabolism in the roots of two barley (Hordeum valgare L.) cultivars differing in salt sensitivity were investigated with 0-300 mmol/L NaCl treatments. With 0-200 mmol/L NaCl treatments, activities of arginine decarboxylase (ADC) and transglutaminase (TGase) and PA oxidase (PAO) in the roots of barley seedlings all increased, while TGase and PAO activities decreased slightly at 300 mmol/L NaCl. As a result, free Put (fPut) content increased continuously with increasing concentrations of NaCl, while levels of free Spd (fSpd) and an unknown PA (fPAx) and bPAs (bPut, bSpd and bPAx), as well as (fSpd + fPAx)/fPut ratio rose at 50-200 mmol/L NaCl and reduced at 300 mmol/L NaCl. However, no significant change in the tetra-amine spermine (Spin) content was observed. Statistical analysis showed that GR was very significantly positively correlated with (fSpd + fPAx)/fPut ratios and the contents of bPAs, whereas a significant inverse correlation existed between GR and the ratios of fPA contents to bPA levels. These results showed that, under salt stress, the balance between fSpd, fPAx and fPut levels and an equipoise between fPA and bPA contents in roots were important to salt tolerance of barley seedlings.展开更多
Optimized the experimental conditions of determination of trace iodine in soil in chloramine T-Tetrabase system, and analysis the national standards material, the results showed that the measured values was to be iden...Optimized the experimental conditions of determination of trace iodine in soil in chloramine T-Tetrabase system, and analysis the national standards material, the results showed that the measured values was to be identical with recommended values with a detection limit of 0.16 μg/g, and the relative standard deviation was less than 8%, the whole process was short in time and simple, so it was applicable to the determination of trace iodine in batches.展开更多
文摘A new iron based catalyst 2,6\|bis[(1\|fluorenylimino)ethyl] pyridine iron dicloride (2) was synthesized via Shiff base condensation with 2,6\|diacetylpyridine and 9\|aminofluorene hydrochloride under formic acid as catalyst.Ethylene oligomerizations were carried out using this new catalyst and methylaluminoxane as cocatalyst under various conditions.The effects of Al/Fe molar ratio,reaction temperature and ethylene pressure on catalytic activity and product distribution were investigated.This novel catalyst had a good activity for ethylene oligomerization (e.g. 4 21×10 6g oligomers\5mol -1 Fe·h -1 ,Al/Fe molar ratio=2000,reaction temperature=40℃,ethylene pressure=1 5?MPa).The catalytic activity increased with the increasing concentration of MAO.The tendency to produce more C 4～C 10 olefins was attributed to the more chain transfer reactions to MAO.The higher the reaction temperature,the lower catalytic activity was present.The reasonable explanation was the combination of the accelerated catalyst’s deactivation and the decrease in ethylene concentration in solvent due to the elevated temperature.Under such condition,however,the oligomerization of ethylene produced more short chain olefins which are adapted to act as comonomers for preparation of linear low density polyethylene materials.Ethylene pressure in autoclave also had an important influence on catalytic activity and carbon\|number distribution of product.The catalytic activity increased sharply with the elevated ethylene pressure.However,the proportion of C 4～C 10 olefins in product decreased in higher pressure due to the enhanced chain propagation reaction.The research work indicated that the control of catalytic activity and product distribution can be realized by the variation of oligomerization conditions such as Al/Fe molar ratio,reaction temperature and ethylene pressure.The results also showed that the ethylene oligomerization employing this novel iron\|based catalyst mainly produces the C 4～C 10 olefins with high selectivity for linear C 4～C 10 α \|olefin (>98%).
文摘Plant growth rate (GR), contents of free polyamines (fPAs) and bound polyamines (bPAs) and activities of some key enzymes involved in polyamine (PA) metabolism in the roots of two barley (Hordeum valgare L.) cultivars differing in salt sensitivity were investigated with 0-300 mmol/L NaCl treatments. With 0-200 mmol/L NaCl treatments, activities of arginine decarboxylase (ADC) and transglutaminase (TGase) and PA oxidase (PAO) in the roots of barley seedlings all increased, while TGase and PAO activities decreased slightly at 300 mmol/L NaCl. As a result, free Put (fPut) content increased continuously with increasing concentrations of NaCl, while levels of free Spd (fSpd) and an unknown PA (fPAx) and bPAs (bPut, bSpd and bPAx), as well as (fSpd + fPAx)/fPut ratio rose at 50-200 mmol/L NaCl and reduced at 300 mmol/L NaCl. However, no significant change in the tetra-amine spermine (Spin) content was observed. Statistical analysis showed that GR was very significantly positively correlated with (fSpd + fPAx)/fPut ratios and the contents of bPAs, whereas a significant inverse correlation existed between GR and the ratios of fPA contents to bPA levels. These results showed that, under salt stress, the balance between fSpd, fPAx and fPut levels and an equipoise between fPA and bPA contents in roots were important to salt tolerance of barley seedlings.
文摘Optimized the experimental conditions of determination of trace iodine in soil in chloramine T-Tetrabase system, and analysis the national standards material, the results showed that the measured values was to be identical with recommended values with a detection limit of 0.16 μg/g, and the relative standard deviation was less than 8%, the whole process was short in time and simple, so it was applicable to the determination of trace iodine in batches.
