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排序方式: 共有243条查询结果,搜索用时 31 毫秒
1.
H. H. Rehan 《Materialwissenschaft und Werkstofftechnik》2003,34(2):232-237
Water extracts from leaves of date palm, phoenix dactylifera, henna, Lawsonia inermis, and corn, Zea mays, were tested as corrosion inhibitors for steel, aluminum, copper and brass in acid chloride and sodium hydroxide solutions using weight loss, solution analysis and potential measurements. The inhibition action was found to critically depend on metal type and solution composition. Only, date palm and henna extracts were found highly effective in reducing corrosion rate of steel in acid chloride solutions and aluminum in sodium hydroxide solutions. The inhibition efficiency increased with increasing the concentration of the extract. The inhibition was interpreted in terms of chemisorption of some active ingredients in the leaves according to Temkin isotherm. 相似文献
2.
V. N. Parmon 《Catalysis Letters》1996,36(3-4):195-199
A series of vanadium-tin mixed oxide catalysts have been prepared by the solid-state reaction of V2O5 and SnO2 at 1250°C. The fresh and the used catalysts have been characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). High temperature oxygen chemisorption (HTOC) has been employed to titrate the coordinatively unsaturated vanadia sites. Ammoxidation of mesitylene has been carried out on these catalysts and an optimum composition of vanadium is arrived at. Better yields of tricyanobenzene (TCB) compared to literature values are obtained. A good correlation between the oxygen uptake and the TCB yield extends the applicability of HTOC to the fused oxide system.IICT Communication No. 3507. 相似文献
3.
Riccardo Carli Raymond Le Van Mao Claudia L. Blanchi Vittorio Ragaini 《Catalysis Letters》1993,21(3-4):265-274
Gallium species which were incorporated initially in the oxide form, were all in the (+3) oxidation state in the hybrid catalyst and exhibited two types of hydrogen chemisorption sites, shw and shs. The stronger sorption sites shs which predominated at higher gallium dispersion, corresponded probably to the most effective surface configuration for gallium in the aromatization ofn-butane. 相似文献
4.
Borgna A. Le Normand F. Garetto T. Apesteguia C. R. Moraweck B. 《Catalysis Letters》1992,13(3):175-188
The effect of an oxidative atmosphere (300 °C) is studied on fresh and sintered unchlorinated naphtha reforming catalysts containing 0.6–1% Pt. The TPR profiles show that only one species is formed using our experimental conditions, regardless of the mean crystallite size of the metal particles. The structural information supplied by EXAFS compared with cuboctahedral particle modeling, implies that such species is a surface platinum oxide, the structure of which is close to that of PtO2, but largely distorted. This is true whether the catalyst is sintered or not. 相似文献
5.
On Cu-ZSM-5 zeolite at room temperature, propane is physisorbed, while propene shows characteristics of chemisorption. The chemisorption mode has certain advantages for the catalytic control of automotive emissions. Alkane and alkene adsorption equilibria and kinetics are compared on Cu-ZSM-5 and on ZSM-5 free of alumina. The results are discussed in terms of the Langmuir adsorption isotherm. 相似文献
6.
Hua Song Lingzhi Zhang Rick B. Watson Drew Braden Umit S. Ozkan 《Catalysis Today》2007,129(3-4):346-354
The catalytic performance of cobalt catalysts supported on γ-Al2O3, TiO2, ZrO2 were studied for bio-ethanol steam reforming (BESR) reaction. The supported catalysts (10 wt%Co) were prepared by impregnation and characterized through Thermogravimetric analysis (TGA), H2 chemisorption, laser Raman Spectroscopy, Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), and temperature-programmed reaction (TPRxn). The metallic cobalt sites were found to correlate with the BESR reaction activity. The reaction and H2 chemisorption showed that ZrO2 supported catalyst showed the best dispersion and best catalytic activity. Over the 10% Co/ZrO2 catalyst, using a H2O:EtOH:inert molar ratio of 10:1:75 and a GHSV = 5000 h−1, 100% ethanol conversion and a yield of 5.5 mol H2/mol EtOH were obtained at 550 °C and atmospheric pressure. 相似文献
7.
We review our X-ray absorption spectroscopy studies of adsorbate geometries on the O-terminated (000
) and Zn-terminated (0001) basel faces, as well as the non-polar (10
0) prism face of ZnO. Studies employing near-edge X-ray absorption fine-structure (NEXAFS) and surface X-ray absorption fine-structure (SEXAFS) are included. 相似文献
8.
Nabel?A.?NegmEmail author Salwa?M.?I.?Morsy 《Journal of surfactants and detergents》2005,8(3):283-287
A weight loss technique was used to determine the corrosion inhibition efficiency of synthesized alkyl mono-and dibenzoate
triethanolammonium bromide derivatives (TEAMB, TEADB) in an acidic medium (2 N HCl) at different doses (50, 100, and 200 ppm).
The results showed that monoderivatives had a higher corrosion inhibition efficiency than diderivatives. The results were
correlated with several factors, including the alkyl chain length of the hydrophobic chains, interfacial tension (IT), critical
micelle concentration (CMC), and adsorption free energy of these inhibitors. Increasing the geometric length of the alkyl
chains in the synthesized inhibitors had an increasing effect on their corrosion inhibition efficiency, whereas decreasing
the CMC and IT had an increasing effect on their tendency toward corrosion inhibition. The number of hydrophobic chains attached
to the inhibitor molecules had a vital influence on their efficiency as corrosion inhibitors. 相似文献
9.
The effect of alumina pretreatment on the performance of alumina supported nickel catalysts was demonstrated in gas phase hydrogenation of toluene to methylcyclohexane. The state of the alumina was changed from pure to pure phase through various heat treatments in air. The catalysts were prepared from vapor phase by saturating the accessible binding sites on the pretreated alumina with the nickel precursor. The highest number of active sites for hydrogenation was observed for catalysts prepared on alumina having an incomplete phase transition and a / alumina phase ratio between 0.5 and 10. Results from temperature programmed desorption (TPD) studies revealed that a maximum in weakly chemisorbed hydrogen as well as in total amount of desorbed hydrogen was found for the same catalysts. By hydrogen chemisorption studies the total hydrogen uptake was found to correlate with the observed hydrogenation maximum. It is suggested that both the chemical and physical properties of the alumina influence the activity. An optimal metal-support interaction and structural defects on the alumina due to the phase transition can explain the observed maximum in the number of active sites and in hydrogen uptake. 相似文献
10.
杨珊珊;刘总堂;邢蓉;吴秀红;费正皓 《江苏石油化工学院学报》2013,(3):1-4
采用偏苯三甲酸酐、均苯四甲酸酐修饰氯甲基化的低交联大孔聚苯乙烯-二乙烯苯制备的超高交联吸附树脂(分别命名为ZT3和ZT4),通过比表面及孔径分析对其结构进行表征。以Amberlite XAD-4树脂作参照,通过等温吸附实验和吸附动力学实验探讨了修饰后的树脂对水溶液中BIT的吸附性能和机理。结果表明:ZT3、ZT4修饰的树脂比Amberlite XAD-4树脂对水溶液中BIT具有更好的吸附效果,这主要归因于树脂的微孔面积、高比表面积和树脂表面的羧基,Langmuir和Freundlich方程均能较好拟合修饰树脂对BIT的吸附等温线。BIT在ZT3和ZT4树脂上的吸附量都是随着溶液pH的增大而减小。 相似文献