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131.
Summary The capabilities of sulfur hexafluoride as a mobile phase for supercritical-fluid chromatography are investigated. An evaluation
of its overall utility on the basis of separations of standard aromatic hydrocarbon odel mixtures performed on a variety of
bonded-phase, packed columns with UV detection is presented. The dependence of separation performance upon operational parameters
is also examined. A comparative evaluation of the chroamtographic properties of supercitrical sulfur hexafluoride and those
of supercritical carbon dioxide is developed from these separations under corresponding supercritical state conditions. 相似文献
132.
133.
Cu/MoO3-TiO2/SiO2上光催化CO2和C3H8合成异丁烯醛的研究 总被引:2,自引:0,他引:2
采用表面改性法和等体积浸渍法制备了金属修饰的负载型复合半导体材料Cu/MoO3-TiO2/SiO2, 用X射线衍射、 比表面积测定、 红外光谱、 拉曼光谱和紫外-可见漫反射等技术对固体材料的结构、 吸光性能和化学吸附性能进行了表征, 研究了该材料对CO2和丙烷合成异丁烯醛的光促表面催化规律. 结果表明, 半导体活性组分MoO3和TiO2在所制备的催化剂Cu/MoO3-TiO2/SiO2表面形成化学键, 并存在多种活性吸附位; 金属Cu的修饰拓展了固体材料对光源的响应范围, 提高了反应体系的吸光能力; 固体材料对CO2和丙烷的有效吸附使其在较低温度下就能促进异丁烯醛的紫外光化学合成, 反应选择性达到85%左右. 根据实验结果对光促CO2和丙烷表面催化合成异丁烯醛的机理进行了讨论. 相似文献
134.
135.
Cu/TiO2-NiO上光促表面催化CO2和H2O合成CH3OH反应规律 总被引:8,自引:0,他引:8
采用溶胶-凝胶法制备了n(电子型)-p(空穴型) 复合半导体材料0.5%Cu/TiO2-2.0%NiO (w),利用X射线衍射(XRD)、透射电镜(TEM)、红外光谱(IR)、紫外-可见光漫反射(UV-Vis)、程序升温脱附(TPD)技术对材料结构、吸光性能、化学吸附性能进行了表征,研究了该材料对CO2和H2O合成CH3OH的光促表面催化反应(PSSR)规律.结果表明,所制备材料能够明显促进目的反应,室温条件下即有CH3OH生成.在200 ℃下,由于光-表面-热的协同效应,CO2转化率得以提高,且CH3OH的选择性达到87.5% .根据实验结果,得出CO2在材料表面的卧式吸附态为CH3OH的前驱物,并对PSSR机理进行了讨论. 相似文献
136.
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138.
This paper reports on studies on the reaction of InCl with SnCl2 to form ternary halides. The reaction route is investigated by x‐ray investigations at different temperatures. Depending on the modification of InCl as educt and on the temperature conditions the reaction follows different pathways which may include intermediate redox reactions of the type In+ + Sn2+ → In3+ + Sn0. 相似文献
139.
A procedure of analysis for small-angle X-ray scattering (SAXS) data has been established to obtain density fluctuation of supercritical fluids near the critical point. It is indispensable for the certain analysis to utilize both of high-quality SAXS data measured under stable thermodynamic condition and accurate P–ρ–T data in supercritical region. As a standard example, SAXS measurements have been performed for supercritical CO2, which is a suitable sample satisfying the condition for both experiment and analysis. The measurements were carried out along four isothermal conditions at reduced temperature of Tr = T/Tc = 1.020, 1.022, 1.043 and 1.064. Comparing the experimental density fluctuation with calculated one from the most reliable equation of state, the differences are within 8% at most. 相似文献
140.
The studies were devoted to determination of the effect of gas atmosphere and its pressure on the second step of decomposition
of hydrated titanium dioxide (HTD) promoted by sulfate groups.
It has been found that thermal decomposition of HTD at temperatures above 300°C consists of a number of processes such as
dehydroxylation, desulfuration, recrystallization and sintering of solid grains, photochemical processes (if the decomposition
proceeds in the presence of light) and adsorption of gas phase components (in the presence of air or SO2).
Kinetic parameters characterizing this step of decomposition have been determined for processes carried out in vacuum and
in argon or air atmospheres (at a pressure of 13.33hPa). The kinetic curves of decomposition carried out in the presence of
gases capable of being adsorbed on the surface of partly dehydrated HTD are featured by local extrema due to simultaneous
processes of decomposition and adsorption of gas components.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献