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51.
Solubility measurements of several oxides in molten NaCl-KCl and NaCl-KCl-Na2SO4-K2SO4 were conducted in three different levels of basicity. The dissolution behavior of the oxides showed almost the same tendency as that shown by the dissolution behavior of the oxides in molten Na2SO4 in literature. In a waste incineration environment, a protective Cr2O3 film easily dissolves in molten chlorides as CrO42− because pO2− of the molten chlorides tends to have a small value due to the effect of water vapor contained in the combustion gas. From the result of the solubility measurement, the addition of molybdenum and/or silicon was expected to improve the corrosion resistance of alloys. Laboratory corrosion tests confirmed this expectation. However, the scale analysis suggested that the effect of molybdenum could not be explained completely by only the mechanism derived from the result of the solubility measurement. 相似文献
52.
Ying Chen Shuichi Iwata Tetsuo Mohri 《稀有金属(英文版)》2006,25(5):437-440
Theoretical investigation of the phase equilibria of the Fe-Ni alloy has been performed by combining the FLAPW total energy calculations and the Cluster Variation Method through the Cluster Expansion Method. The calculations have proved the stabilization of the LIE phase at 1:3 stoichiometry, which is in agreement with the experimental result, and predicted the existence of L1 0 as a stable phase below 550 K; this L1 0 phase has been missing in the conventional phase diagram. The calculations are extended to the Fe-rich region that is characterized by a wide range phase separation and has drawn considerable attention because of the intriguing Invar property associated with a Fe concentration of 65%. To reveal the origin of the phase separation, a P-V curve in an entire concentration range is derived by the second derivative of free energy functional of the disordered phase with respect to the volume. The calculation confirmed that the phase separation is caused by the breakdown of the mechanical-stability criterion. The newly calculated phase separation line combined with the L1 0 and L12Eorder-disordered phase boundaries provides phase equilibria in the wider concentration range of the system. Furthermore, a coefficient of thermal expansion (CTE) is attempted by incorporating the thermal vibration effect through harmonic approximation of the Debye-Gruneisen model. The Invar behavior has been reproduced, and the origin of this anomalous volume change has been discussed. 相似文献
53.
Sn-incorporated folded sheets mesoporous materials (Sn-FSM-16) with various contents of Sn were synthesized by using a mixture of water glass, SnCl4 and NaOH as starting materials. Hexadecyltrimethyl-ammonium chloride (surfactant) was used to intercalate into the layered silicate. The reaction process was followed by measurements of XRD patterns of intermediates. The Sn-FSM-16 was formed via the following mechanism: (1) layered silicates such as - - and -Na2Si2O5 were formed as intermediates by the calcination of the mixture of the starting materials; (2) the surfactant was intercalated into the layered silicates; (3) the surfactant-silicate complex with hexagonal structure was obtained as a precursor of Sn-FSM-16; (4) the precursor was calcined to decompose the surfactant in the interlayer and was changed to Sn-FSM-16. The structural aspect of Sn in Sn-FSM-16 was studied by XPS profiles of Sn 3d
5/2 and Si2p, 29 Si MAS NMR and FTIR. The content of Sn in Sn-FSM increased with increasing concentrations of both Sn and NaOH in the starting materials. The surface area of Sn-FSM-16 decreased with an increase of Sn content in Sn-FSM (1160–620 m2/g). 相似文献
54.
Kazuhiko Takeuchi Taka-aki Hanaoka Takehiko Matsuzaki Yoshihiro Sugi Shigeto Ogasawara Yoshimoto Abe Takahisa Misono 《Catalysis Today》1994,20(3):423-435
An in situ diffuse reflectance FT-IR technique was employed to investigate the active surface species and the reaction mechanism of the oxygenate formation in the vapor phase hydroformylation of ethene on Co/SiO2 promoted with various noble metals such as Ir, Rh, Pt, Re, Ru, and Pd. Co(A)/SiO2 and Ir(CO)/SiO2 which were derived from cobalt(II) acetate and Ir4(CO)12, respectively, were quite inactive in the reaction, and showed only quite small peaks of adsorbed CO under the conditions of 1.1 MPa of C2H4/CO/H2 at 298 K. In contrast, Co(A)-Ir(CO)/SiO2, which were very active in the reaction, exhibited strong absorption bands of linear and bridged CO species. At 423–463 K, propanal adsorbed on the catalyst and acyl species which is suggested as the intermediate for the formation of propanal were also observed on this catalyst. By exposing CO preadsorbed on this catalyst to C2H4/H2 at 289 K and 0.1 MPa, the intensity of the linear CO band decreased, and the bands of propanal and acyl species emerged simultaneously, whereas that of the bridged CO band remained constant after the initial drop. These results suggested that the oxygenates are formed via the CO insertion into adsorbed ethyl species, and linear CO species plays a major role in the CO insertion on these noble metal-promoted cobalt catalysts. 相似文献
55.
Masayuki Nogami Yoshihiro Abe Ayako Kato 《Journal of the American Ceramic Society》1995,78(4):1066-1070
Silica glasses doped with small-sized CdSx -Se1-x crystals were prepared by the sol-gel method. Gels synthesized by the hydrolysis of Si(OC2 H5 )4 , in the presence of CdSeO4 with NH4 SCN dissolved in HNO3 or NH4 OH, were heated in H2 -N2 atmosphere. The pH value of solutions for CdSeO4 and NH4 SCN primarily determined the fraction of anions in CdSx Se1-x crystals. The anion content in crystals was dependent on the pH value of the solvent and/or heat-treatment temperature, and the sulfur fraction changed from 0.1 to 0.6. The optical absorption spectra were red-shifted as the selenium content and the crystal size increased, and the emission spectra showed a sharp band near the absorption edge position and a broad tail extending into the long wavelength. The optical band gap energies increased reciprocally proportional to the square of the crystal size. 相似文献
56.
N,N'- Unsymmetrical dialkyl-3,4:9,10-perylenebis(dicarboximide)s (in which alkyl = methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl and octyl) were prepared by the condensation of N-alkyl-3,4:9,10-perylene-tetracarboxylic monoanhydride monoimide with the appropriate alkyl-amines. The properties of these derivatives as pigments were tested and their thermal stability measured. 相似文献
57.
A new Ag/Al2O3 catalyst for removing NOx in lean exhaust gas was developed. Oxidized Ag/Al2O3 catalyst is highly active for reduction of NOx with ethanol and propene, whereas reduced Ag/Al2O3 catalyst is less active for these reactions. Selectivity to N2 is also high on the oxidized Ag/Al2O3 compared to that on the reduced Ag/Al2O3. XRD and SEM studies of these two types of Ag catalysts suggest that oxidation induces an interaction between Ag and the
support, where the particles are grown in large size. In contrast, the metallic Ag particles are finely dispersed by the reduction
process. Although dispersion of Ag particles is decreased by the oxidation process, the catalytic activity is increased. This
suggests that the Ag-alumina sites created in the high temperature oxidizing environment are active in catalytic reduction
of NOx.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
58.
Carbon materials are often used as catalyst supports, and for catalysts in electrodes of a polymer electrolyte fuel cell, carbon black has been used. Recently, it was found, however, that activated carbon could replace carbon black and besides, significantly improve the activity of the electrode catalyst layer for oxygen reduction. In the present study, to optimize the pore structure of activated carbon for further activity improvement, the influence of the pore structure on the activity was investigated using activated carbon of various specific surface areas and mean pore diameters. A catalyst layer was formed from activated carbon loaded with platinum and a polymer electrolyte. The activity of the layer was measured in an oxygen-saturated perchloric acid solution, supporting the layer on a rotating glassy carbon disk electrode. We found that increases in the specific surface area and mean pore diameter increased the activity and that the latter was more effective than the former mainly due to the enhanced mass-transfer in the pores; the catalyst layer formed from activated carbon with the largest mean pore diameter was the most active. Unless pores excessively develop and lose connections between particles, a large pore diameter is therefore desired for the fuel cell electrodes. 相似文献
59.
A commercially available, densely sintered alpha silicon carbide was tested in air from room temperature to 1700°C using a modified instrumented pendulum unit and standard Charpy size test specimens. The resistance heated silicon carbide specimens exhibited only elastic behavior, even at 1700°C. A compliance analysis of the test revealed a linear elastic decrease of the absorbed impact energy and also a decrease of the fracture stress of the silicon carbide with increasing temperature. 相似文献
60.
Sudip Adhikari Sunil Adhikary Ashraf M.M. Omer Mohamad Rusop Hideo Uchida Tetsuo Soga Masayoshi Umeno 《Diamond and Related Materials》2005,14(11-12):1824
Nitrogenated diamond-like (DLC:N) carbon thin films have been deposited by microwave surface wave plasma chemical vapor deposition on silicon and quartz substrates, using argon gas, camphor dissolved in ethyl alcohol composition and nitrogen as plasma source. The deposited DLC:N films were characterized for their chemical, optical, structural and electrical properties through X-ray photoelectron spectroscopy, UV/VIS/NIR spectroscopy, Raman spectroscopy, atomic force microscope and current–voltage characteristics. Optical band gap decreased (2.7 to 2.4 eV) with increasing Ar gas flow rate. The photovoltaic measurements of DLC:N / p-Si structure show that the open-circuit voltage (Voc) of 168.8 mV and a short-circuit current density (Jsc) of 8.4 μA/cm2 under light illumination (AM 1.5 100 mW/cm2). The energy conversion efficiency and fill factor were found to be 3.4 × 10− 4% and 0.238 respectively. 相似文献