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Preparation, Characterization and Catalytic Properties of S2O8^2-/ZrO2 Supported by Tungsten Carbide
XUEHua-xin CHENJian-min 《高等学校化学研究》2004,20(1):68-72
A WC-supported S2O8^2-/ZrO2(PSZ) catalyst was prepared and characterized by means of XRD, BET, FTIR and XPS. The isomerization of n-pentane over the catalyst was investigated as well. The results show that the skeletal isomerization and the crack of n-pentane proceed simultaneously on WC-supported S2O8^2-/ZrO2 catalyst. The addition of tungsten carbide showed a significant enhancement in the activity and stability of the catalyst for n-pentane isomerization. The catalyst showed evidently a better activity than S2O8^2-/ZrO2 supported by Pt and WO3. The results can be interpreted by the existence of the tungsten oxycarbide compound(WCxOy) with carbidic, oxide and acidic sites. 相似文献
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S2O8^2—和SO4^2—促进ZrO2固体超强酸正戊烷反应性能差异的研究 总被引:5,自引:0,他引:5
考察了常温下S2O8^2-促进ZrO2(PSZ)固体超强酸催化剂上正戊烷的反应性能,并与SO4^2-促进ZrO2(SZ)反应相比较,观察到PSZ和SZ对正戊烷都具有异构化和裂解的双重作用,主要产物分别为异戊烷和异丁烷。正戊烷的异构化转化率和表观反应速率常数主要取决于样品的焙烧温度。但对于正戊烷异构化反应,PSZ的最佳焙烧温度为550℃,比SZ的低50℃。在各自的最佳焙烧温度下反应1h后,前者的异戊烷生成率为后者的1.3倍。通过S含量和比表面积测定以及用XRD和FTIR等手段分析了PSZ的物理化学特性。从原位FTIR谱图发现,PSZ(550℃)表面S-O键的红外吸收明显比SZ(600℃)的强;通过吡啶红外手段发现PSZ(550℃)吡啶离子吸收峰的红移大于SZ(600℃),表明前者的Lewis酸强于后者。 相似文献
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A new procedure, requiring expired sample volumes of approximately 2L, has been developed for the quantitative determination of n-pentane in human breath. The methodology capitalizes on the superior resolving power and separating efficiency of the open tubular capillary column and incorporates an effective prechromatographic cryofocusing technique. Molecular sieve is used to simultaneously remove moisture and carbon dioxide from breath samples which are “spiked” with an internal standard to optimize the validity of analysis. Reproducible data for both internal standard spiking (CV = 5.8%) and sample n-pentane level (CV = 3.2%) have been obtained, together with a mean recovery of 104%. Preliminary data show n-pentane levels in normal female subjects (n = 10) to range from 0.62 to 3.16 nmole/L (mean 1.76 nmole/L) and in males (n = 10) from 3.20 to 8.76 nmole/L (mean 5.66 nmole/L). 相似文献
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改性聚苯醚膜对有机混合液的渗透汽化分离 总被引:3,自引:0,他引:3
研究了溴代PPO地质膜以各种胺化学交联后对氯代烃如氯仿、氯代苯的水溶液的渗透汽化分离性能,以及对甲醇/正戊烷/乙醇/正戊烷等有机液的分离性能。通过和聚乙烯基吡咯烷酮物理共混,提高BPPO膜的极以改善对醇类/正戊烷混合的液的分离选择性。 相似文献
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A WC-supported S2O2-8/ZrO2(PSZ) catalyst was prepared and characterized by means of XRD, BET, FTIR and XPS. The isomerization of n-pentane over the catalyst was investigated as well. The results show that the skeletal isomerization and the crack of n-pentane proceed simultaneously on WC-supported S2O2-8/ZrO2 catalyst. The addition of tungsten carbide showed a significant enhancement in the activity and stability of the catalyst for n-pentane isomerization. The catalyst showed evidently a better activity than S2O2-8/ZrO2 supported by Pt and WO3. The results can be interpreted by the existence of the tungsten oxycarbide compound(WCxOy) with carbidic, oxide and acidic sites. 相似文献
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The wicking height of a heated, evaporating meniscus formed by surface-wetting liquid in a vertical capillary tube with dynamic flow has been investigated. Previous experimental results and analytical models for measuring/predicting wicking heights in capillaries are also reviewed. An analytical model is presented that accounts for both major and minor vapor pressure losses along the vertical capillary tube. It is shown that during thermo-mechanical instability, vapor/meniscus interaction can become more prevalent due to increased vapor generation/pressure near the meniscus free surface. A relatively simple procedure for estimating onset of meniscus instability is presented and, when used with the vapor Reynolds number, can estimate whether vapor pressure loss is significant. By comparing the current model with the available experimental data, it is shown that the wicking height of an unstable, evaporating meniscus of n-pentane in a vertical, glass capillary tube is better estimated by considering vapor flow pressure losses – providing a 40% improvement over previous models that neglect vapor flow. In addition to vapor flow pressure loss, the dynamic contact angle and thin film profile must also be calculated to ensure accurate prediction of wicking height. Although the proposed model shows improvement, it is prone to under-predicting the actual meniscus wicking height for stable, evaporating menisci at lower relative heat loads. The proposed model can be used for predicting wicking behavior of heated, vertically-aligned liquid columns in capillary structures – which is relevant to the design of miniature heat transfer equipment/media such as wicked heat pipes, micro-channels and sintered/porous surfaces. 相似文献
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研究了添加Al对SO42-/ZrO2超强酸样品的晶化、比表面、硫含量、超强酸性和正戊烷反应性能的影响,考察了活化温度、反应温度、Al含量和载Pt对催化剂活性和选择性的影响.SO42-/Al2O3ZrO2催化剂的酸强度与SO42-/ZrO2基本相当,但超强酸位比后者多,未载Pt时正戊烷反应活性和稳定性明显高于后者.负载Pt后,正戊烷异构化选择性和稳定性大大提高,但Pt/SO42-/Al2O3ZrO2催化剂的反应活性与Pt/SO42-/ZrO2相近,Al的促进作用不明显. 相似文献
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