柠檬酸络合法制备的Co/CeO2催化剂上中温乙醇水蒸气重整性能（英文）

采用柠檬酸络合法制备了Co/CeO2及其钙掺杂系列催化剂,并对催化剂进行了低温N2物理吸附、X射线衍射、H2程序升温还原、傅里叶变换红外光谱、高分辨透射电镜表征以及乙醇水蒸气重整催化性能测试.结果表明,所制Co/CeO2催化剂具有良好的乙醇水蒸气重整催化性能,500oC时乙醇能全部转化为C1,氢气产率高达85%以上.Ca掺杂减小了载体CeO2纳米颗粒尺寸,但对还原后Co0尺寸的影响较小.当Ca掺杂量大于5.0%时,催化剂氧化还原性能和乙醇水蒸气重整催化性能下降.较高的还原温度有利于体相Ce4+还原为Ce3+,并且提高了催化活性,认为金属-氧化物边界的增加提高了催化活性.初步稳定性考察结果表明,5%钙掺杂后的催化剂具有更好的抗积炭性能.     

铁铁基普鲁士蓝钠离子电池正极材料的共沉淀反应控制

铁铁基普鲁士蓝(NaFeHCF)是一种较为理想的钠离子电池(SIBs)正极材料.但是,如何有效控制合成反应参数来提升NaFeHCF电极材料的循环稳定性仍然是当前需要解决的问题.采用简单的共沉淀法,探索了合成过程中配位剂添加与否和反应温度(0～80℃)的变化对NaFeHCF沉淀产物的形貌结构和电化学性能的协同影响.结果 ...     

基于密度泛函理论研究碱性水溶液中乙内酰脲及其衍生物的结构及性质

乙内酰脲及其衍生物对多种金属离子具有良好的络合效果,是一种有望取代氰化物的绿色电镀络合剂.本文以密度泛函理论(DFT)方法对乙内酰脲及其衍生物的反应活性进行了研究.通过分子极性指数和极性表面积所占总面积百分比研究多种乙内酰脲衍生物在水中的溶解性,理论计算结果与文献报道的实验结果基本一致.通过原子电荷、表面静电势、原子对...     

EDTA-柠檬酸法合成的SrCo0.8Fe0.2O3-δ钙钛矿的结构及制氧性能研究

采用EDTA-柠檬酸联合络合法合成了钙钛矿型金属氧化物SrCo_0.8Fe_0.2O_3-δ(SCF182)粉体。通过XRD和ESEM研究了前驱体溶液不同的pH值对合成的SCF182粉体的晶体结构和微观形貌的影响。并采用固定床实验研究前驱体溶液pH值对SCF182的氧吸附/脱附性能的影响。结果表明,pH值对SCF182晶胞结构和参数影响不大,但影响SCF182的晶粒粒径和微观形貌,当pH值为8的弱碱性条件下时,能够合成蓬松多孔网状纳米结构的钙钛矿粉体。固定床实验显示,前驱体溶液的pH值影响合成的粉体SCF182的氧吸附速率;且SCF182的氧脱附性能随pH值的增大先升高后降低,pH值为8时氧脱附量达到峰值为42.2 mg/g。     

On the propagation rate constants of cationic polymerizations

The concepts employed to explain polymerizations by ionizing radiations are used for a critical examination of the concepts involved in interpreting the kinetics of chemically initiated cationic polymerizations. It is explained how the interactions of the propagating carbenium ions with the solvent, monomer, and anion can result in the formation of up to six distinct unpaired species and several kinds of ion pairs; therefore, the consumption of the monomer can be governed simultaneously by many rate constants. Only one of these can have any general theoretical use, and suggestions are made for how it can be measured. For the first time, it is shown that the ion‐pairing process must involve a ligand displacement and so resembles the amination of the Ag⁺ ion, for example, in an aqueous solution by NH₃, rather than an association of inert ions of unchanging identity. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2537–2544, 2002     

Approximate equations for the determination of complexing parameters: Applicability criteria

Quantitative critera for the applicability of several approximate equations for finding complexing parameters are analyzed using a computer simulation technique. The Benesi-Hildebrand equation has been found most suitable for this purpose. The conclusions obtained are compared with the applicability criteria already known for approximate equations. By analyzing literature data it has been shown that it is possible to determine the correctness of published values for equilibrium constants of complexing and the extinction coefficient of a complex.     

Viscosity behavior of poly(glyceryl methacrylate) in the presence of borate and phenylboronate ions

The viscosity behavior of polyelectrolyte solutions induced by borate or phenylboronate complexation with poly(glyceryl methacrylate) (PGM) has been investigated. In dilute solutions borate ions can form monodiol (1/1) complexes and didiol (2/1) intramolecular complexes. Both types of complex are anionic. Thus, the polymer is characterized by the existence of charged sites on the chain and loops formed by intramolecular complexation. On the contrary, phenylboronate can only give monodiol 1/1 complexes. In the presence of passive salt, the charges are screened. By addition of borate ion to a PGM solution, a decrease of the initial polymer viscosity due to loop formation is first observed, then the anionic charges fixed on the chain by complex formation induce an expansion of the polyelectrolyte and the viscosity of the solution increases. The situation is different for the PGM-phenyl boronate system, where no intramolecular crosslink is present. In this case the viscosity of the solution increases with phenyl boronate concentration. But for a fixed complexing ion concentration it will tend to that of the neutral polymer when NaCl is added. ©1995 John Wiley & Sons, Inc.     

Complexing of polymer-bound crown ethers with sodium salts in aqueous solution

It has been established that polymer-bound crown ethers L₁ and L₂ are effective sorbents for sodium salts in aqueous solution; the manner in which sodium salts are bound by these ligands differs. Complex compounds of immobilized macrocyclic polyether L₁ with sodium salts have been shown to have the properties of reversible anion exchangers.L. V. Pisarzhevskii Institute of Physical Chemistry, Ukrainian Academy of Sciences, 252028 Kiev. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 87–91, January, 1992.     

Phosphorus-containing podands. 9. Synthesis of oligoethylene glycol bis(diphenylphosphinylethyl) esters and their complexing properties with respect to alkali metal cations in a low-polarity solvent

The complexing ability of phosphoryl-containing monopodands with the general formula Ph₂P(O)CH₂CH₂O(CH₂CH₂O)_nCH₂CH₂P(O)Ph₂ (n=0–5, 6.4, 8.7, 13.2) with respect to alkali metal cations was investigated conductometrically in tetrahydrofuran:chloroform mixed solvent (4:1, vol.) at 25°C. It was found that ligands of this type are efficient complexing agents relative to all alkali metal cations, and the monopodand with n=0 also exhibits elevated Li/Na and Li/K selectivity. The effect of the structure, particularly the "rigidity" of the terminal fragments of the monopodands, on their complexing capacity was discussed. The method of synthesis of this type of ligand was described.See [1] for preceding communication.Institute of Physiologically Active Substances, Russian Academy of Sciences, 142432 Chernogolovka. Scientific-Research Institute of Chemical Reagents and Special-Purity Chemicals, Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1161–1167, May, 1992.     

Vibrational spectral studies of solutions at elevated temperatures and pressures. X. Raman spectral study of aqueous cadmium bromide solutions at 25 and 200°C

The Raman spectra of cadmium bromide solutions with bromide to cadmium mole ratios varying from 1.0 to 9.74 were studied at 200°C. Factor analysis revealed that three complexes contributed to the spectra. From a comparison with previous results at 25°C these species were identified as CdBr₂, CdBr ₃ ^– , and CdBr ₄ ^2– cadmium existed as the tetrabromo complex, CdBr ₄ ^2– , at mole ratios greater than 5.99. A formation constant of 7±2 was determined for CdBr ₄ ^2– at 200°C. No evidence of Cd(H₂O) ₆ ²⁺ or CdBr⁺ was found, although electroneutrality dictates that one or both of these species must exist at low mole ratios.