DFT calculations have been performed to explore the ethanol adsorption on Pd (111) surfaces. Relative energies, equilibrium geometries, vibrational frequencies and electronic structures of monomer, dimer and one-dimensional (1D) chain of ethanol molecules adsorbed at the surface were investigated and analyzed. The calculations indicate that ethanol molecules prefer to adsorb at a top sites of the Pd (111) surface and the adsorption is exothermic. Adsorbed ethanol molecules are likely to form dimer and chain through the hydrogen bond interactions. The results also show that there are red shifts of ν(O-H) frequencies for ethanol molecules adsorbed over the Pd (111) surface.
Titanate modified bentonite could catalyze methane into synthesis carbon nanotubes at high temperature by thermal chemical vapor deposition. The element iron contained in bentonite acts as the catalytic metal of nanotubes. A conclusion was drawn that the quality and quantity of carbon nanotubes were best and largest respectively at 800 °C. If the temperature is higher than 900 °C,the quality of nanotubes would be bad. The catalytic capacity of modified bentonite would disappear below 700 °C. The catalyst is cheaper, and the treatment process of the catalyst is simpler than traditional metal catalyst , which may accelerate industrial synthesis of carbon nanotubes.
Yttrium Aluminium Garnet (YAG) has a extensive applications in many fields because of its excellent properties. In this study the products synthesized by co-precipitation method is regular, and the reaction is complete, the YAG ceramic obtained is white, its density is 2.42g/cm3 and shrinkage is 7.78%. The YAG ceramic tablets were investigated by Field emission scanning electron microscopy (FE-SEM), Electron probe microanalysis (EPMA) and X-ray diffractometer (XRD). The results show that the structure of YAG ceramic is loose with spherical grain size of 0.2-0.3μm. The main mineral phase of YAG ceramic is composed of polycrystalline Al5Y3O12 with good crystallinity, and containing very small amount of unreacted alumina and other impurities.
According to the conceptual model of high-level radioactive waste (HLW) geological disposal, first, HLW is carried out solidification treatment. Radioactive nuclide was simulated by Cerium (Ce), and Ce was solidified in the zirconite ceramic, solidified bodies of zircon ceramic with Ce were prepared by sol-gel method. In this paper, the basic principle and technological process of ceramic solidification is introduced. The samples were characterized and analyzed by XRD, SEM and EPMA, etc.. The results show that, the surface properties of ceramic tablet is better, and with high shrinkage after sintering, the lower compression force, the higher shrinkage of the ceramic tablet. Most of the diameter of Ceramic grains are in the range of 0.5-5 μm, existing some amorphous phase among the grains. Washing by ammonia, crystallization degree of sample is higher than without treatment, and can form crystals of (Zr,Ce) O2and (Zr, Ce) SiO4.
Bentonite has been regarded as buffer material for high-level radioactive waste (HLW) disposal all over the world, plenty of decay heat released from HLW is conducted through butter material, therefore, thermal conduction of compacted bentonite is very important. This study presents compacted GMZ Na-bentonite(with 8.9% water content, 1.8 g/cm3 compacting density) temperature and relative humidity change pattern with time and position variation taking intermittent warming method and using thermal conduction equipment, it is designed according to the conceptual model of HLW geological disposal repository. The results show that the temperature achieve a balance quickly, the temperature of compacted bentonite block which the distance is 2 cm to heat source reaches the first about 55°C balance stage after about 40 hours, radial temperature gradient (GT) increases with the temperature rising, average of GT during the first stage is 0.85°C/cm, average of GT during the second balance stage about 82°C is 1.57°C/cm; Affected by temperature, relative humidity increase rapidly at the beginning with the temperature rising, when the temperature reaches equilibrium, the relative humidity decreases slowly, the higher temperature of the compacted bentonite block is, the lower relative humidity is, the radial gradient of relative humidity (GHR) increase with heating time, average of GHR during the first stage about 55 °C is 1.32%/cm, average of GHR during the second stage about 82°C is 1.89 %/cm.
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