By taking advantage of silylanization, Al2O3 support was modified by organosilane and supported Pd-Cu-Clx/Al2O3 catalysts were prepared. The effects of hydrophobicity on catalyst stability during CO oxidation were inv...By taking advantage of silylanization, Al2O3 support was modified by organosilane and supported Pd-Cu-Clx/Al2O3 catalysts were prepared. The effects of hydrophobicity on catalyst stability during CO oxidation were investigated. The physicochemical properties and redox potential of the catalyst were characterized by N2 adsorption-desorption, XRD, H2-TPR, and XPS. In order to understand the relationship between the oxidation stability of CO and the presence of water, the CO oxidation mechanism was studied by in situ DRIFT. Support pretreatment markedly promoted catalyst stability during CO oxidation; CO conversion was 78% after 150 h at saturated humidity and freezing point. Modification led to an obvious decrease in chloride ion concentration and enhancement in hydrophobicity. The role of water in CO oxidation was complicated. The presence of water favored CO oxidation over active Pd~＋ species and Pd0 reoxidation by Cu^（2＋） species. Meanwhile, water also inhibited the formation of the active Pd~＋ species and helped to produce carbonate species. Compared with the form of the carbonate species, the inhibition of water to produce active Pd~＋ species played the main detrimental role in catalyst stability.展开更多
To better understand the process of precipitation and water cycle, the composition of stable isotope in precipitation and its influences by different vapor sources in the eastern of Qilian Mountains were conducted fro...To better understand the process of precipitation and water cycle, the composition of stable isotope in precipitation and its influences by different vapor sources in the eastern of Qilian Mountains were conducted from June 2013 to May 2014. The total of 100 precipitation samples were collected in Wushaoling national meteorological station located in the eastern of Qilian Mountains. The analysis indicates that the slope of Local Meteoric Water Line is lower than that of Global Meteoric Water Line. The average values of δ18 O and δD in precipitation are higher in summer but lower in winter. Except for negative correlation with relative humidity, the stable isotope values in precipitation are positive correlations with temperature, precipitation and water vapor pressure. Influenced by water vapor source, the values of d-excess are lower for the Westerly wind and the South Asia Monsoon onJuly and the Westerly wind and the East Asia Monsoon on August, but they are higher for the Westerly wind on other months, that they are also influenced by the weather conditions in rainfall process. The variation of stable isotope in precipitation exhibited significant temperature effect, and there is also some precipitation amount effect in spring and summer.展开更多
In this paper, turbulent data obtained from the Damxung site during the Secondary Tibetan Plateau Science Experiment (TIPEX) in 1998 are used to study the characteristics of the turbulent spectra, turbulence transport...In this paper, turbulent data obtained from the Damxung site during the Secondary Tibetan Plateau Science Experiment (TIPEX) in 1998 are used to study the characteristics of the turbulent spectra, turbulence transport, and the dissipation rates of turbulent kinetic energy, temperature variance, and humidity variance in the middle area of the Tibetan Plateau. The turbulent spectra of wind velocity, potential temperature, and humidity satisfy the-2/3 power law in the high frequency range. Horizontal transportation of heat and water vapor is negligible compared with vertical transportation under strong unstable conditions, and as the stability parameter z/L increases (where z is the observational height, and L is the Monin Obukhov length), horizontal transportation becomes dominant under near-neutral, neutral, and stable conditions. The non-dimensional temperature and humidity variances are 20% less than the temperature and humidity gradient variances. These deficits appear to increase as the absolute stability parameter increases. Moreover, the effects of turbulence transportation and pressure variance exist throughout the entire stability region.展开更多
This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. Th...This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. The study was carried out using three saturated salt solutions, which are Potassium Acetate 22.5%, Potassium Iodide 68.9% and Potassium Sulphate 97.3% to cover low, medium and high relative humidity. The study was carried out using different shapes and volumes half liter spherical, liter spherical and liter conical per each salt which was prepared. The apparatus which used in measurement system in the first time are the same which used after ten years. The results show that the change of relative humidity value after ten years ranged from 0.1% to 0.7%. This value is suitable within uncertainty ＋ 2%. The period of stability for each run for all cells was found to be more than five hours and this period enough for calibration. The measurements show that the cells are stable for more than ten years with accepted value.展开更多
基金supported by the National Key Research and Development Program of China(2016YFC0204300)National Natural Science Foundation of China(21207037,21333003,21571061)+1 种基金the "Shu Guang" Project of the Shanghai Municipal Education Commission(12SG29)the Commission of Science and Technology of Shanghai Municipality(15DZ1205305)~~
文摘By taking advantage of silylanization, Al2O3 support was modified by organosilane and supported Pd-Cu-Clx/Al2O3 catalysts were prepared. The effects of hydrophobicity on catalyst stability during CO oxidation were investigated. The physicochemical properties and redox potential of the catalyst were characterized by N2 adsorption-desorption, XRD, H2-TPR, and XPS. In order to understand the relationship between the oxidation stability of CO and the presence of water, the CO oxidation mechanism was studied by in situ DRIFT. Support pretreatment markedly promoted catalyst stability during CO oxidation; CO conversion was 78% after 150 h at saturated humidity and freezing point. Modification led to an obvious decrease in chloride ion concentration and enhancement in hydrophobicity. The role of water in CO oxidation was complicated. The presence of water favored CO oxidation over active Pd~＋ species and Pd0 reoxidation by Cu^（2＋） species. Meanwhile, water also inhibited the formation of the active Pd~＋ species and helped to produce carbonate species. Compared with the form of the carbonate species, the inhibition of water to produce active Pd~＋ species played the main detrimental role in catalyst stability.
基金funded by the Youth Innovation Promotion Association,CAS(2013274)National Nature Science Foundation of China(91547102 and 41661005)+2 种基金Gansu Province Science Fund for Distinguished Young Scholars(1506RJDA282)National Key R&D Program of China(2017YFC0404305)National Natural Science Foundation Innovation Research Group Science Foundation of China(41421061)
文摘To better understand the process of precipitation and water cycle, the composition of stable isotope in precipitation and its influences by different vapor sources in the eastern of Qilian Mountains were conducted from June 2013 to May 2014. The total of 100 precipitation samples were collected in Wushaoling national meteorological station located in the eastern of Qilian Mountains. The analysis indicates that the slope of Local Meteoric Water Line is lower than that of Global Meteoric Water Line. The average values of δ18 O and δD in precipitation are higher in summer but lower in winter. Except for negative correlation with relative humidity, the stable isotope values in precipitation are positive correlations with temperature, precipitation and water vapor pressure. Influenced by water vapor source, the values of d-excess are lower for the Westerly wind and the South Asia Monsoon onJuly and the Westerly wind and the East Asia Monsoon on August, but they are higher for the Westerly wind on other months, that they are also influenced by the weather conditions in rainfall process. The variation of stable isotope in precipitation exhibited significant temperature effect, and there is also some precipitation amount effect in spring and summer.
基金support of the National Natural Science Foundation of China(41075005)the Research Fund for the Doctoral Program of Higher Education(20110001130010)R&D Special Fund for Public Welfare Industry (Meteorology) by Ministry of Finance and Ministry of Science and Technology(GYHY201006014) in the present study
文摘In this paper, turbulent data obtained from the Damxung site during the Secondary Tibetan Plateau Science Experiment (TIPEX) in 1998 are used to study the characteristics of the turbulent spectra, turbulence transport, and the dissipation rates of turbulent kinetic energy, temperature variance, and humidity variance in the middle area of the Tibetan Plateau. The turbulent spectra of wind velocity, potential temperature, and humidity satisfy the-2/3 power law in the high frequency range. Horizontal transportation of heat and water vapor is negligible compared with vertical transportation under strong unstable conditions, and as the stability parameter z/L increases (where z is the observational height, and L is the Monin Obukhov length), horizontal transportation becomes dominant under near-neutral, neutral, and stable conditions. The non-dimensional temperature and humidity variances are 20% less than the temperature and humidity gradient variances. These deficits appear to increase as the absolute stability parameter increases. Moreover, the effects of turbulence transportation and pressure variance exist throughout the entire stability region.
文摘This paper study stability of saturated salt solutions cells at 25 ℃. These cells were prepared and measured at National Institute for Standard （NIS-Egypt） to study the stability of the saturated salt solutions. The study was carried out using three saturated salt solutions, which are Potassium Acetate 22.5%, Potassium Iodide 68.9% and Potassium Sulphate 97.3% to cover low, medium and high relative humidity. The study was carried out using different shapes and volumes half liter spherical, liter spherical and liter conical per each salt which was prepared. The apparatus which used in measurement system in the first time are the same which used after ten years. The results show that the change of relative humidity value after ten years ranged from 0.1% to 0.7%. This value is suitable within uncertainty ＋ 2%. The period of stability for each run for all cells was found to be more than five hours and this period enough for calibration. The measurements show that the cells are stable for more than ten years with accepted value.
