Controlled oxidation experiments were performed on Kovar alloy by changing oxidation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that sing...Controlled oxidation experiments were performed on Kovar alloy by changing oxidation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that single Fe3O4 and single FeO were respectively obtained when Kovar alloy was oxidized in N2-2.31%H2O-0.95%H2 at 500℃ and in N2-2.31%H2O-0.5%H2 at 1000℃, and all kinetic curves followed linear relation; mixed oxides of FeO and Fe3O4 formed when Kovar was oxidized in N2-2.31%H2O at 1000℃and parabolic kinetics were obeyed. Analysis of metallographic cross section of oxides indicated that oxygen diffusion inward through the oxide scale is responsible for intergranular oxide, which had formed beneath the oxide scales when the oxide products were mixed oxides of FeO and Fe3O4, and which did not occur when the oxide was single FeO or Fe3O4. The oxidation model was also established.展开更多
Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O...Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Zi0.3O2 were examined using a microreactor-gas chromatography （GC） NO＋CO reaction system and the methods of BET （Brun- auer-Emmett-Teller）, TG-DTA （themogravimetric and differential thermal analysis）, X-ray diffraction （XRD） and H2-temperature programmed reduction （TPR）. The results showed that NO conversions of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT （Brunauer, Deming, Deming and Teller） system and a typical mesoporous sample. There were two CuO diffraction peaks （2θ 35.5° and 38.7°）, and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks （α, β and γ） from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the y peak was the reduction of crystal phase copper oxide. In addition, a fourth peak （5） of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.展开更多
Expeditions during the summers of 2002 and 2003 implemented continuous monitoring of near-surface (2 m height) atmospheric CO2 and H2O concentrations at the 4500 m elevation on Muztagata. The resultant data sets revea...Expeditions during the summers of 2002 and 2003 implemented continuous monitoring of near-surface (2 m height) atmospheric CO2 and H2O concentrations at the 4500 m elevation on Muztagata. The resultant data sets reveal a slight decrease of CO2 concentrations (of about 5 μmol·mol?1) and changes in the diurnal variations from the end of June to the middle August. The daily maximum CO2 concentrations occur between 02:30―05:30 AM (local time) and the minimum levels occur between 12:00―15:30 PM. The atmospheric CO2 concentrations in the summer of 2002 were around 5 μmol·mol?1 lower than those during the same period of 2003, whereas the diurnal amplitude was higher. In contrast, we found that the daily mean atmospheric H2O content in 2003 was much lower than that in 2002 and there exists a striking negative correlation between CO2 and H2O con-centrations. We therefore suggest that the near-surface atmospheric CO2 concentration is affected not only by photosynthesis and respiration, but also by the air H2O content in the glaciated region around Muztagata.展开更多
Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene （2,6-DIPN） is a raw material for the production of ...Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene （2,6-DIPN） is a raw material for the production of advanced polyester materials such as PEN and liquid crystal polymers.In this study, the preparation of 2,6-DIPN through the isopropylation of industrial refined naphthalene with propylene was conducted in 0.5 L autoclave with steam dealuminated H-mordenite （SDHM） as the shape-selective catalyst instead of the conventional Friedel-Crafts catalysts and resulted in high selectivity and high yield of 2,6-DIPN.In order to slacken the deactivation of HM, the reaction was carried out in H2 atmosphere.The dehydrogenation of fused-ring polycyclics could be minimized and coke formation could be reduced.The preferred reaction conditions found were temperature of 275—300 ℃,hydrogen pressure of 0.4 MPa,reaction time of 7—8 h and 6%—7% of SDHM by mass,in which no side reactions were observed. From NH3-TPD profiles,it could be seen that the relative strength of strong acid sites of SDHM in hydrogen isopropylation was greater than that in nitrogen isopropylation after the same reaction period.Comparing with the results obtained in nitrogen atmosphere, the conversion of refined naphthalene and yield of 2,6-DIPN could be remarkably increased to an average value as high as 90 % and 35 % respectively.Hence the catalytic activity of SDHM could be maintained for a longer time in H2 atmosphere.展开更多
基金supported by the National Natural Science Foundation of China(No. 50671014).
文摘Controlled oxidation experiments were performed on Kovar alloy by changing oxidation atmosphere, temperature, and exposure time to produce films with different oxide type and thickness. The results indicated that single Fe3O4 and single FeO were respectively obtained when Kovar alloy was oxidized in N2-2.31%H2O-0.95%H2 at 500℃ and in N2-2.31%H2O-0.5%H2 at 1000℃, and all kinetic curves followed linear relation; mixed oxides of FeO and Fe3O4 formed when Kovar was oxidized in N2-2.31%H2O at 1000℃and parabolic kinetics were obeyed. Analysis of metallographic cross section of oxides indicated that oxygen diffusion inward through the oxide scale is responsible for intergranular oxide, which had formed beneath the oxide scales when the oxide products were mixed oxides of FeO and Fe3O4, and which did not occur when the oxide was single FeO or Fe3O4. The oxidation model was also established.
基金Project (No. Y504131) supported by the Natural Science Foundation of Zhejiang Province, China
文摘Using SnxTi1-xO2 as carriers, CuO/Sn0.9Zi0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide （CuO） were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Zi0.3O2 were examined using a microreactor-gas chromatography （GC） NO＋CO reaction system and the methods of BET （Brun- auer-Emmett-Teller）, TG-DTA （themogravimetric and differential thermal analysis）, X-ray diffraction （XRD） and H2-temperature programmed reduction （TPR）. The results showed that NO conversions of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Zi0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT （Brunauer, Deming, Deming and Teller） system and a typical mesoporous sample. There were two CuO diffraction peaks （2θ 35.5° and 38.7°）, and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks （α, β and γ） from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the y peak was the reduction of crystal phase copper oxide. In addition, a fourth peak （5） of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.
基金supported by the Chinese Academy of Sciences(Grant No.KZCX1-SW-01-10 and KZCX3-SW-339)the National Basic Research Program of China(Grant No.2005CB422004)the National Natural Science Foundation of China(Grant Nos.40471022 and 40121101).
文摘Expeditions during the summers of 2002 and 2003 implemented continuous monitoring of near-surface (2 m height) atmospheric CO2 and H2O concentrations at the 4500 m elevation on Muztagata. The resultant data sets reveal a slight decrease of CO2 concentrations (of about 5 μmol·mol?1) and changes in the diurnal variations from the end of June to the middle August. The daily maximum CO2 concentrations occur between 02:30―05:30 AM (local time) and the minimum levels occur between 12:00―15:30 PM. The atmospheric CO2 concentrations in the summer of 2002 were around 5 μmol·mol?1 lower than those during the same period of 2003, whereas the diurnal amplitude was higher. In contrast, we found that the daily mean atmospheric H2O content in 2003 was much lower than that in 2002 and there exists a striking negative correlation between CO2 and H2O con-centrations. We therefore suggest that the near-surface atmospheric CO2 concentration is affected not only by photosynthesis and respiration, but also by the air H2O content in the glaciated region around Muztagata.
文摘Isopropylation of naphthalene is a series reaction, which results in a variety of isomers having different alkylation levels.Among them, 2,6-diisopropylnaphthalene （2,6-DIPN） is a raw material for the production of advanced polyester materials such as PEN and liquid crystal polymers.In this study, the preparation of 2,6-DIPN through the isopropylation of industrial refined naphthalene with propylene was conducted in 0.5 L autoclave with steam dealuminated H-mordenite （SDHM） as the shape-selective catalyst instead of the conventional Friedel-Crafts catalysts and resulted in high selectivity and high yield of 2,6-DIPN.In order to slacken the deactivation of HM, the reaction was carried out in H2 atmosphere.The dehydrogenation of fused-ring polycyclics could be minimized and coke formation could be reduced.The preferred reaction conditions found were temperature of 275—300 ℃,hydrogen pressure of 0.4 MPa,reaction time of 7—8 h and 6%—7% of SDHM by mass,in which no side reactions were observed. From NH3-TPD profiles,it could be seen that the relative strength of strong acid sites of SDHM in hydrogen isopropylation was greater than that in nitrogen isopropylation after the same reaction period.Comparing with the results obtained in nitrogen atmosphere, the conversion of refined naphthalene and yield of 2,6-DIPN could be remarkably increased to an average value as high as 90 % and 35 % respectively.Hence the catalytic activity of SDHM could be maintained for a longer time in H2 atmosphere.
