双核钴配合物(RC_2R′)CO_2(CO)_6_n[P(OEt)_3]_n的合成与结构

PR_3可取代(RC_2R′)Co_2(CO)_6中的CO生成相应的取代配合物(RC_2R′)CO_2(CO)_(6-n)(PR_3)n: (RC_2R′)Co_2(CO)_6 +nPR_3→ (RC_2R′)Co_2(CO)_(6-n)(PR_3)n已经利用此反应合成了一系列PR_3取代配合物,但P(OEt)_3的取代配合物则未见报     

Synergistic effect between Sn and K promoters on supported platinum catalyst for isobutane dehydrogenation

Catalytic dehydrogenation of isobutane has recently received considerable attention because of the increasing demand for isobutene.In this study,the synergistic effect between Sn and K on PtSnK/γ-Al2O3 catalysts has been investigated by changing the content of Sn.It was found that with the presence of potassium,suitable addition of Sn could not only increase the metal dispersion,but also reduce the catalyst acidity.In these cases,the synergistic effect could also strengthen the interactions between the metal and support,which resulted in an increase in both catalytic activity and stability.In our experiments,Pt-0.6SnK/Al catalyst exhibited the lowest deactivation rate (12.4%) and showed a selectivity to isobutene higher than 94% at the isobutane conversion of about 45.3% after running the reaction for 6 h.However,with the excessive loading of Sn,surface property of active sites and the interactions between metal and support were changed.As a result,the initial optimal ratio between the metallic function and acid function would be destroyed,which was disadvantageous to the reaction.     

DEGREE OF BRANCHING OF THE HYPERBRANCHED POLYMERS RESULTED FROM AB_2 POLYCONDENSATION WITH SUBSTITUTION EFFECT

The analytical expressions of the various structural units and the average degree of branching for the hyperbranched polymers resulted from AB_2 polycondensation with substitution effect were derived by the kinetic mechanism.The reactivity difference between the B group in linear unit and that in terminal group has great effect on the molecular parameters of the products obtained.The concentration of terminal units has a maximum with the increase of the conversion of A groups(x).The higher the reactivity...     

THE ADSORPTION BEHAVIORS OF TOLUENE ON HYPERCROSSLINKED RESINS

1. INTRODUCTION Toluene has been widely used for many industrial purposes. Owing to their toxicity and recalcitrance, the presence of toluene in the natural environment, especially in the groundwater, has been a great concern. The removal of toluene is of…     

解偏振光法测定装置的改进及高聚物结晶速度的测定

试制成功了热平衡时间短的解偏振光强度测定装置,用该装置测定了尼龙66,尼龙6和PET的结晶动力学数据,得到了满意的结果,     

g-期望关于凸(凹)函数的Jensen不等式

在文[8]的基础上和彭实戈提出的关于g-期望的最基本的条件下,证明了g-期望关于凸(凹)函数的Jensen不等式在一般意义下成立当且仅当g是关于(y,z)的超齐次(次齐次)生成元且不依赖于y．     

THE ADSORPTION BEHAVIORS OF 2,6-DICHLOROPHENOL ONTO HYPERCROSSLINKED RESINS

1. INTRODUCTION Chlorophenolic compounds are very toxic, and many are known or suspected human carcinogens. They have been widely used for many industrial purposes. The removals of chlorophenols are of high industrial and environmental interest [1~2]. The adsorption resin is another adsorbent widely employed for isolation and purification of organic substances, treatment of wastewaters, solid phase extraction, and so on. A variety of materials has been developed and tested, such as Amber…     

The structure and magnetic properties of μ_3-oxotriiron(Ⅲ) complex [Fe_3O(OBz)_6(CH_3OH)_3](NO_3)(CH_3OH)_2

A new μ3-O triiron(Ⅲ) complex [Fe_3O(OBz)_6(CH_3OH)_3](NO_3)(CH_3OH)_2 (HOBZ = benzoic acid) has been synthesized, its structure has been determined and variable temperature magnetic susceptility has also been measured. In the molecule, three iron atoms formed an equilateral triangle with u_3-O in center. The fitting to the magnetic susceptibility showed that an intramolecular antiferromagnetic exchange interaction occurred between iron atoms with J=-25.51 cm~(-1), and a weaker intermolecular antiferromagnetic exchange interaction occurred with zJ' = -2.30cm~(-1).     

Simulation of growing GaN in vertical HVPE reactor

The paper reports the setting up of a model of fluid dynamic for GaN HVPE system and the simulation. It is found that when the direction of gravity is opposite to the direction of GaCl flow inlet,there exits a distance at which the uniformity of the deposition is optimal. Here the good uniformity of the deposition is obtained when the distance between the substrate and GaCl inlet is 5 cm. The parameters of gas flow used in growing GaN are also optimized. In addition, the influence of gravity and buoyancy on...     

树脂吸附法分离纯化桑叶总黄酮(Ⅰ)H103树脂对桑叶水提液中总黄酮的吸附性能

采用大孔吸附树脂法从桑叶水提液中分离黄酮类化合物。通过比较10种大孔吸附树脂对桑叶水提液中总黄酮的吸附特性及机理,发现H103树脂对桑叶总黄酮吸附量大、洗脱容易、吸附速度快,是一种良好的桑叶总黄酮吸附剂。实验表明,H103树脂吸附桑叶黄酮的适宜上样浓度为6.05mg/mL,吸附动力学符合Bangham模型,吸附过程符合内扩散模型。