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homogeneous catalytic systems
相关语句
  均相催化体系
     STUDIES ON STYRENE SYNDIOSPECIFIC POLYMERIZATION AND PROPENE ATACTIC POLYMERIZATION WITH TITANOCENE/MAO/ AlR3 HOMOGENEOUS CATALYTIC SYSTEMS
     单茂钛化合物/MAO/AlR_3均相催化体系合成sPS与aPP研究
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  “homogeneous catalytic systems”译为未确定词的双语例句
     Homogeneous catalytic systems often have disadvantages, such as difficult separation of the products and corrosive effect of the catalyst on the reactor materials.
     均相催化剂虽然活性高但往往难以分离且有腐蚀性,而多相催化剂则易于分离、再生和回收使用。
短句来源
     Although the asymmetric catalytic reactions can be efficiently carried out in homogeneous catalytic systems with high yields and ee value, it has also some disadvantages, such as complicated purification procedures and using the expensive catalysts that are quite difficult to recover and recycle.
     虽然均相催化反应可以高产率高ee(对映体过量)值的进行,但要经过多步纯化过程,而且昂贵的催化剂也很难回收再循环利用。
短句来源
  相似匹配句对
     HOMOGENEOUS CATALYTIC HYDROGENATION OF MONOCROTALINE
     农吉利碱的均相催化氢化
短句来源
     Studies on Homogeneous Catalytic Hydrosilation of Cycloalkanonc
     脂环酮均相催化硅氢化反应的研究
短句来源
     STUDIES ON HOMOGENEOUS BIFUNCTIONAL CATALYTIC SYSTEMS FOR ETHYLENE DIMERIZATION AND COPOLYMERIZATION
     乙烯二聚共聚双功能均相催化体系的研究
短句来源
     Progress in Catalytic Hydroxylation of Aromatics in Homogeneous/Liquid Systems
     芳烃化合物液(均)相催化羟化反应研究进展
短句来源
     CATALYTIC TITRATION
     催化滴定
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  homogeneous catalytic systems
The study of the catalytic behavior of phenol oxidation by hydrogen peroxide in presence of iron has shown that both heterogeneous and homogeneous catalytic systems behave similarly.
      
The hydroesterification of propene into methyl 2-methylpropanoate by homogeneous catalytic systems consisting of palladium, copper, oxygen and acid is investigated under very mild conditions (room temperature, atmospheric pressure).
      
Coordination state of Ti3+ions formed in the homogeneous catalytic systems TiCl2(acac)2+Et2AlCl, and its changes upon interaction with ethylene, carbon monoxide and pyridine have been studied by ESR.
      
Surface immobilization of active species onto mesoporous materials is gaining importance, especially in the design of functionalized mesoporous materials as a nanocatalyst through heterogenization of homogeneous catalytic systems.
      
The polymerization and copolymerization of vinylcyclohexane with α-olefins in the presence of several heterogeneous and homogeneous catalytic systems were studied.
      
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The molecular weight distribution of cis-1,4 polybutadiene obtained by polymerization with homogeneous Ziegler catalyst (Et2AlCl-CoCl2-4C5H5N) as well as heterogeneous Ziegler catalyst (i-Bu3Al-Til4) has been determined by means of fractional precipitation. The results show that the molecular weight distribution of both types of polybutadiene is not broad. With regard to the homogeneous catalytic system, the molecular weight distribution becomes narrower when the temperature of polymerization is...

The molecular weight distribution of cis-1,4 polybutadiene obtained by polymerization with homogeneous Ziegler catalyst (Et2AlCl-CoCl2-4C5H5N) as well as heterogeneous Ziegler catalyst (i-Bu3Al-Til4) has been determined by means of fractional precipitation. The results show that the molecular weight distribution of both types of polybutadiene is not broad. With regard to the homogeneous catalytic system, the molecular weight distribution becomes narrower when the temperature of polymerization is increased, the monomer concentration lowered, the chain transfer agent added and the cobalt concentration decreased or the Al/Co ratio increased. As to the heterogeneous catalytic system, the homogeneity of molecular weight distribution increases with the lowering of the polymerization temperature and the decreasing of the Al/Ti ratio. But the monomer concentration and aging of catalyst give no evident effect.

本工作以逐步沉淀法测定了在均相(Et_2AlCl-CoCl_2·4C_5H_5N)及非均相(i-Bu_3Al-TiI_4)Ziegler型催化剂的作用下,丁二烯在各种条件下进行顺式-1,4聚合的分子量分布。结果指出,不论均相或非均相催化聚合得到的分子量分布都比较窄。对于均相体系,升高聚合温度、降低单体浓度、添加链转移剂(如乙硫醚、N-苯基-β-萘胺、庚烷)、减少催化剂钴的浓度和增加Al/Co比,均能使聚合物的分子量分布变窄;而对于非均相体系,则降低聚合温度和减少Al/Ti比均能增加分子量的均一性;单体浓度和催化剂老化对分子量分布无显著影响。 非均相聚合的分子量分布比均相聚合的更窄,前者的微分分布曲线的高峰偏于高分子量部分,而后者的偏于低分子量部分。这可能是由于非均相聚合的链终止速度依赖于链长,而均相聚合的链终止速度与链长无关。

More than twenty different transition metal catalytic systems including Fe, Ni, Mo,Zr, Cr, Pd, Pt and Ti-containing organometallic compounds have been tested, and Cp2TiCl2/2-C3H7MgBr was found to be the most active homogeneous catalytic system for the isomerization of 1,5-cyclooctadiene to 1,3-cyclooctadiene. The effects of reaction time and temperature, catalyst amount, and solvent were studied. The results of change in isomerization products with reaction time suggest that the isomerization...

More than twenty different transition metal catalytic systems including Fe, Ni, Mo,Zr, Cr, Pd, Pt and Ti-containing organometallic compounds have been tested, and Cp2TiCl2/2-C3H7MgBr was found to be the most active homogeneous catalytic system for the isomerization of 1,5-cyclooctadiene to 1,3-cyclooctadiene. The effects of reaction time and temperature, catalyst amount, and solvent were studied. The results of change in isomerization products with reaction time suggest that the isomerization of 1, 5-cyclooctadiene to 1,3-cyclooctadiene proceeds stepwisely via 1,4-cyclooctadiene. 1, 5-Cyclooctadiene was isomerized to 1,3-cyclooctadiene quantitatively with substrate/catalyst ratio as high as 200 at room temperature within 1 hour, but the conversion of 1,5-cyclooctadiene was only 5 % at - 10℃ with catalyst/substrate ratio 1:200 in 1 hour. Experiments carried out at 65℃ with the same catalyst amount, 1,5-cyclooctadiene can be isomerized quantitatively into 1,3-cyclooctadiene even in a few minutes. The isomerization proceeded well in many organic solvents, however, the reaction did not take place in halogen-containing solvents and polar solvents, such as CH2Cl2, CHCl3, CCl4, acetone and acetic acid.A mechanism of Ti-H addition to carbon-carbon double bond followed by β-H elimination is proposed for the isomerization of 1,5-cyclooctadiene (see p.166).

用20多种过渡金属络合物催化体系进行了1,5-环辛二烯的催化异构化研究,发现CP_2TiCl_2/i-C_3H_7MgBr催化体系的条件温和,催化活性高。例如,当Cp_2TiCl_2与 1,5-环辛二烯克分子比为1:200时,25℃下反应1小时,1,5-环辛二烯即可定量转化为1,3-环辛二烯。深入研究了这个催化体系,并提出了[Cp_2TiH]对双键加成,然后发生 Ti—βH消除的异构化机理。

An effective homogeneous catalytic system for hydroformylation of ethylene has been found. It involves ruthenium cluster H4Ru4(CO)12 or Ru3(CO)12,halide and alkali metal cation promoters in a basic aqueous tetrahydrofuran solution. In the range of reaction temperature 125-175C. at total pressure of ethylene, H2 and CO(1: 2- 2) of less than 75kg/cm2, the catalytic activity is proportional to reaction temperature and partial pressures of ethylene, H2 and CO. Addition of halide and alkali metal cation...

An effective homogeneous catalytic system for hydroformylation of ethylene has been found. It involves ruthenium cluster H4Ru4(CO)12 or Ru3(CO)12,halide and alkali metal cation promoters in a basic aqueous tetrahydrofuran solution. In the range of reaction temperature 125-175C. at total pressure of ethylene, H2 and CO(1: 2- 2) of less than 75kg/cm2, the catalytic activity is proportional to reaction temperature and partial pressures of ethylene, H2 and CO. Addition of halide and alkali metal cation promoters greatly increases the catalytic activity in the following sequence: NaI/NaOHcatalytic activity of Ru3(CO) 12/CsI/CsOH/THF system is observed and the turnover is 285 overall products, mol/Ru3(CO)12, mol.h.The IR spectrum of the solution after reaction indicates the presence of [HRu3(CO)H]~as a main component. When the partial pressure of H2 or CO is greater than 30kg/cm2, there is aggregation to [H3Ru4(CO) 12]-or formation of cluster Ru3(CO)12. In the above two cases, further raising of the partial pressure ol H2 or CO does not cause an increase of catalytic activity. According to the relation between the catalytic activity and IR spectrum of the reaction solution, the active catalytic species, the role of the promoters and the mechanism of catalytic cycle of [HRu3-(CO)11]- are discussed.

发现了乙烯醛化的一个有效的新催化体系,它由钌原子簇H_4Ru_4(CO)_(12)或Ru_3(CO)_(12),卤化物和碱金属阳离子促进剂组成。在碱性的四氢呋喃-水溶液中,C_2H_4,H_2和CO的分压为1:2:2(总压小于75kg/cm~2)及125~175℃的条件下,其催化活性正比于反应温度、C_2H_4、H_2和CO的分压。添加卤化物和碱金属阳离子极大地提高了催化活性并得到如下顺序:NaI/NaOH

 
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