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41.
以互通多孔碳(IPC)为载体,水热条件下在碳表面原位反应生成纳米结构的二氧化锰(MnO2),制备互通多孔碳/二氧化锰纳米(IPC/MnO2)复合电极材料. 采用扫描电镜(SEM),透射电镜(TEM),X射线衍射(XRD),热重分析(TGA)对其结构进行表征;采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究. 结果表明:生成的MnO2均匀地负载在碳的表面,形成多层次结构,并且随着温度的升高IPC表面负载的MnO2由纳米颗粒变为纳米片状结构;MnO2纳米片具有典型的K-Birnessite 型晶体结构;复合物中MnO2的含量约为34%(w). 在100 ℃制备的IPC/MnO2复合材料在三电极系统中最高比电容达到了411 F·g-1;随着反应温度的升高,比容量先增长后基本保持不变. 以IPC/MnO2为正极,活性炭(AC)为负极,1 mol·L-1 Na2SO4溶液为电解液组装成IPC/MnO2//AC 混合超级电容器,发现IPC/MnO2电极的电容器其电位窗口从1 V扩展到1.8 V,容量可达86F·g-1,且表现出良好的电容特性和大电流放电性能. 相似文献
42.
The acylation of 2-methoxynaphthalene with acetic anhydride was carried out over zeolite beta catalysts having various Si/Al
ratios. It was found that the reaction performance is strongly dependent on the Si/Al ratio of the catalyst. The catalytic
reaction features were elucidated in terms of the acidic properties of the catalysts.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
43.
44.
IR lattice vibration spectra were used to monitor the changes in the structure of zeolite Na-Y upon its dealumination with ethylenediaminetetraacetic acid (EDTA) or with HCl. The terminal Si-O(H,Na) bonds thus formed (which are detectable by characteristic absorbance at v 900–950 cm–1) are energetically less uniform when EDTA has been used as the dealuminating agent. This inhomogeneity is connected with the local deformations of zeolite structure which result in lowering the symmetry of silicon-oxygen tetrahedra. As a consequence, two novel bands appear at v 1090 cm–1 and 1200 cm–1 in addition to the fundamental absorption bands, vas (TO4) (T = Si, Al), at 1030 cm–1 and 1145 cm–1. A mechanism of dealumination is proposed, which takes into account the topochemical peculiarities involved in the chelation of the framework aluminum ions with EDTA.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskay, No. 2, pp. 284–287, February, 1993. 相似文献
45.
A novel rapid pressure swing adsorption (RPSA) process is described for production of 25–50% oxygen enriched air. The embodiment consists of one or more pairs of adsorbent layers contained in a single adsorption vessel. The layers undergo simultaneous pressurization-adsorption and simultaneous depressurization-purge steps. A total cycle time of 6–20 seconds is used. The process yields a very large specific oxygen production rate and a reasonable oxygen recovery for production of 20–50 mole% oxygen enriched gas.It is demonstrated by a simple mathematical model of isothermal single adsorbate pressure swing ad(de)sorption concept on a single adsorbent particle that the specific production rate of a PSA process cannot be indefinitely increased by reducing the cycle time of operation when adsorbate mass transfer resistances are finite. 相似文献
46.
Wet oxidation of BPL porous carbon by H2O2 and HNO3 changes the pore structure and also increases the concentration of surface oxides. KOH uptake is increased by oxidation and is seen to be dependent on KOH concentration and to a lesser extent on inert electrolyte concentration. Enthalpy of immersion measurements have allowed the estimation of the enthalpy of hydration of the surface oxides and the enthalpy of neutralization of the easily accessible acid oxides. 相似文献
47.
Orlik S. N. Ostapyuk V. A. Alekseenko L. M. 《Theoretical and Experimental Chemistry》2002,38(3):195-198
The possibility of making products of partial oxidation, alcohols and acids in particular, by the reaction of C3-C4 alkanes with nitrogen monoxide over oxide and zeolite catalysts is demonstrated. The most effective catalysts are CeO2 and Fe-TsVK. The dependence of the rate and selectivity of the process on the reaction conditions has been established. 相似文献
48.
A correction method is proposed for the quantitative determination of stoichiometric ratios in porous materials by electron microprobe analysis. Analysis of this kind of material is complicated by an imperfect surface that can only be improved to some extent. The correction is based on a linear dependence (different for each element) of the analyses on a sum of weight concentrations of oxides. With this correction it is possible to use analyses affected by the imperfection of the surface with much better confidence compared to common normalisation. An example is presented for a series of ceramic superconductors Bi2.1(SrCa)2.9Cu2O8+. 相似文献
49.
50.
Summary The pozzolanic reactivity of thermally treated zeolites was studied on the basis of the Chapelle test combined with X-ray
diffraction (XRD) and Fourier Transform (FTIR) spectroscopy, as well as thermogravimetric analysis (TG/DTG) and differential
thermal analysis (DTA). The raw zeolite samples are from the Pentalofos area, Thrace, NE Greece. Their main mineral constituent
is 'heulandite type-II', an intermediate type of the heulandite-clinoptilolite isomorphous series. Calcination of the samples
was carried out up to 400, 500, 600, 700 and 1000°C for 15 h. The changes were recorded using the above methods. The deformation
of the zeolite crystal lattice starts at about 400°C and proceeds as the temperature of thermal treatment rises. The thermal
treatment of zeolite at 400°C improves its pozzolanic reactivity and accelerates the reaction with Ca(OH)2. 相似文献