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排序方式: 共有643条查询结果,搜索用时 80 毫秒
1.
The 8-mol percentage Y2O3-stabilized Porous Zirconia was prepared using sol–gel method. Zirconium oxalate gel was prepared by the addition of appropriate
amount of oxalic acid solution into the 1 M aqueous solution of zirconium-oxy chloride. A cubic phase zirconia powder was
obtained by calcination and milling of the zirconium oxalate gel. Crystallization temperature was found about 450 °C from
the Differential thermal analysis. The phase analysis by X-ray diffraction shows the presence of cubic phase. Pellets sintered
at 1,350 °C were highly porous, and the electrical conductivity was found with lower value due to the porosity, and the hardness
was about 8.0 GPa.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006. 相似文献
2.
Chunlin Li Yilu Fu Guozhu Bian Tiandou Hu Yaning Xie Jing ZhanDepartment of Chemical Physics University of Science and Technology of China Hefei China Institute of High Energy Physics Chinese Academy of Sciences Beijing China 《天然气化学杂志》2003,12(3)
The Ni/CeO2-ZrO2-Al2O3 catalyst with different Al2O3 and NiO contents were prepared by hydrothermal synthesis method. The catalytic performance for CO2 reforming of CH4 reaction, the interaction among components and the relation between Ni content and catalyst surface basicity were investigated. Results show that the interaction between NiO and Al2O3 is stronger than that between NiO and CeO2-ZrO2.The addition of Al2O3 can prevent the formation of large metallic Ni ensembles, increase the dispersion of Ni, and improve catalytic activity, but excess Al2O3 causes the catalyst to deactivate easily. The interaction between NiO and CeO2 results in more facile reduction of surface CeO2. The existence of a small amount of metallic Ni can increase the number of basic sites. As metallic Ni may preferentially reside on the strong basic sites, increasing Ni content can weaken the catalyst basicity. 相似文献
3.
Kai Kamada Shintaro Udo Shuichi Yamashita Yuko Tsutsumi Yasumichi Matsumoto 《Solid State Ionics》2003,160(3-4):389-394
Quantitative analysis of metal cation doping by solid oxide electrochemical doping (SOED) has been performed under galvanostatic doping conditions. A M–β″-Al2O3 (M=Ag, Na) microelectrode (contact radius: about 10 μm) was used as cation source to attain a homogeneous solid–solid contact between the β″-Al2O3 and doping target. In Ag doping into alkali borate glass, the measured dopant amount closely matched the theoretical value. High Faraday efficiencies of above 90% were obtained. This suggests that the dopant amount can be precisely controlled on a micromole scale by the electric charge during electrolysis. On the other hand, current efficiencies of Na doping into Bi2Sr2CaCu2Oy (BSCCO) ceramics depended on the applied constant current. Efficiencies of above 80% were achieved at a constant current of 10 μA (1.6 A cm−2). The relatively low efficiencies were explained by the saturation of BSCCO grain boundaries with Na. By contrast, excess Na was detected on the anodic surface of ceramics at a constant current of 100 μA (16 A cm−2). In the present study, we demonstrate that SOED enables micromole-scale control over dopant amount. 相似文献
4.
A single phase solid solution of Ce-Zr-O can be made by using NH4HCO3 solution as precipitating agent. The influence of preparation conditions, such as pH, Zr4+/(CO3
2-+HCO3
-) and Ce3+/Zr4+ ratio on the formation of the solid solution were investigated. The results show that a single phase Ce-Zr-O solid solution
can be formed only under a narrow window of preparation conditions, indicating that some compounds are formed in the precipitating
process. The compound may contain Ce3+, Zr4+, CO3
2-, HCO3-, and OH-. The solid solution so prepared can be described as Ce0.37Zr0.63O2.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
室温下SO2 -4/ZrO2 催化剂 (SZ)上13 C标记的正丁烷异构化反应的原位13 CMASNMR谱研究结果表明 :其反应动力学符合Langmuir Hinshelwood一级可逆表面反应动力学公式 ,由该动力学公式计算得到的反应速率常数可以用于衡量固体催化剂的表面超强酸性 .这种新的表征方法显示采用一步 -醇热 -超临界干燥综合技术合成的SZ催化剂不仅比表面和硫酸根含量高 ,而且其超强酸性和异构化反应活性均明显优于常规法合成的催化剂 ,具有良好的应用前景 . 相似文献
6.
A study was carried out on the composition and nature of the stabilizing additive on the activity of nickel-containing composites
based on zirconia in the methane steam conversion. The methane conversions were 91–99% on Ni/ZrO2(Y, Sc, Ce) at 700–800 °C. 相似文献
7.
Hiromi Matsuhashi Masakazu Oikawa Hiromi Shibata Michiko Tanaka 《Reaction Kinetics and Catalysis Letters》1998,65(2):253-258
Reversible formation of F+-centers was observed over platinum promoted sulfated zirconia in the presence and absence of hydrogen. The intensity of ESR
signal of F+-centers was increased by treatment in He stream and it was decreased rapidly by supply of hydrogen in gas phase. This behavior
seems to be related to proton spillover. 相似文献
8.
Pt/钇稳定氧化锆固体电解质在高温下的电化学性质 总被引:1,自引:0,他引:1
用交流阻抗技术研究了二电极、三电极Pt/钇稳定氧化锆(简称YSZ)高温固体电化学体系.开路电位下,Pt/YSZ体系只有一个阻抗半圆,对应于电极体系的电化学活化控制过程,极化电阻随温度变化的表观活化能为171.5kJ/mol.Pt/YSZ界面的双电层电容约为300μF/cm2.阳极极化下,交流阻抗极化电阻显著减小;阴极极化下,极化电阻反而增大,并出现浓差控制现象. 相似文献
9.
New process to control hydrolysis step during sol-gel preparation of sulfated zirconia catalysts 总被引:2,自引:0,他引:2
Sulfated zirconia catalysts were prepared by sol-gel process using a new method allowing the control of the hydrolysis step
of zirconium alkoxides. Prepared samples were characterized by N2 adsorption (desorption) at 77 K, XRD, chemical analysis of total sulfur and XPS. Catalytic properties have been evaluated
in n-butane and n-hexane isomerization reactions. Obtained results show that time necessary for gelation is significant and
depends considerably on the nature of the zirconium precursor. Concerning the properties of the solids obtained by this method,
it has been noted that the use of the zirconium propoxide led to a better retention of the sulfate species, which improves
activity during isomerization reactions. It has been found also that an initial S/Zr molar ratio equal to 0.5 allowed to obtain
an optimal sulfur content and a high specific surface area. 相似文献
10.
C. Guizard C. Mouchet R. Vacassy A. Julbe A. Larbot 《Journal of Sol-Gel Science and Technology》1994,2(1-3):483-487
Basic principles involved in sol-gel processing of ceramic membranes are described. This process has been applied to ceramic ultrafiltration membranes and is now investigated to prepare ceramic nanofilters. In this paper special emphasis is put on new developments concerning microporous zirconia membranes obtained by the polymeric route. A zirconium alkoxide precursor modified with an acetylacetone ligand has been used in order to control particle growth in the sols and pore size distribution in the membranes. N2 adsorption and X-ray diffraction analysis have been performed on membrane materials showing the influence of process parameters (molar ratio r = acacH/Zr and sintering temperature T) on membrane structural evolution. 相似文献