超临界乙醇流体制备TiO2光催化剂(Ⅰ)合成与光催化性能

引　言自 1972年日本东京大学的藤 山鸟昭等和本多健一报道了在光电池中光辐射TiO2 可持续发生水的氧化还原反应产生H2 以来[1] ,纳米半导体多相光催化反应方面的研究得到了深入而广泛的开展 .光催化氧化法结构简单 ,操作条件容易控制 ,氧化能力强 ,无二次污染 ,加之TiO2 具有化学稳定性高、无毒、价廉、催化活性高等优点 ,因而具有广阔的应用前景[2 ] .TiO2 粒子形态 (包括粒径、晶型、表面性质等 )对光催化活性有较大影响[3～ 5] .目前大多数研究中主要采用商品TiO2 或将其改性后使用 ,难以在催化剂制备时优化与催化活性密切相关的粒…     

Electrocatalytic oxidation of ethanol on Pt–Mo bimetallic electrodes in acid medium

Pt–Mo alloy electrocatalysts were prepared by an arc-melting furnace process to investigate the origin of their enhanced activity toward ethanol oxidation. Two Mo contents were chosen in zones of the binary phase diagram where they are supposed to form either a pure alloy mixture or a solid solution. Pt–Mo alloy catalysts were more active than Pt-alone. Gradual Mo dissolution at the electrode surface was observed after voltammetric and chronoamperometric measurements. The dissolved Mo contributed to the catalytic effect of the electrode as underpotentially deposited (upd) adatoms. This dissolution probably also leads to an increase in the electrode surface roughness. Low molybdenum content in the electrode material enhances the activity toward ethanol oxidation when compared to Pt-alone. Ethanol oxidation was also investigated by in situ infrared reflectance spectroscopy in order to determine the presence of adsorbed intermediates like CO species. Acetaldehyde, acetic acid and CO₂ were also found by spectroscopic experiments.     

燃料电池氢源技术--中低温乙醇水蒸气重整制氢研究

采用浸渍-热分解法制备了一种纳米Ni/Y2O3催化剂,并应用X射线衍射、BET比表面测试分析手段对该催化剂的结构性能进行了表征,采用固定床反应器对催化剂的催化性能进行测试。结果表明:该催化剂对乙醇的水蒸气重整反应表现出较高的活性和稳定性,可作为燃料电池氢源技术中乙醇重整器的候选催化剂。     

Phase behavior of the base-catalyzed transesterification of soybean oil

Biodiesel is made by the transesterification of vegetable oils to form alkyl FA esters. High levels of conversion (>99%) are required to lower the total concentration of free and chemically bound glycerol to that allowed by the ASTM standard (0.240 wt%) for biodiesel. A polar dye was used to visualize the phase behaviors in methanolysis, ethanolysis, and butanolysis. The dye was more strongly colored in more polar phases. Methanolysis and ethanolysis reactions commenced as two phases (alcohol and oil), then formed emulsions, and ended as two phases as glycerol-rich phases separated. Ethanolysis was more easily initiated by mixing than was methanolysis. Ethanolysis also exhibited a much longer emulsion period and slower glycerol separation. The glycerol-rich phase was smaller in volume in ethanolysis than in methanolysis. Butanolysis remained one phase throughout, and no polar phase existed at any time. The results are consistent with the known phase compositions in these reactions. The concentrations of MG, DG, and TG in the products with time in stirred reactions were consistent with the observed phase behavior in the dye experiments.     

Anodic dissolution of spongy titanium in ethanol solution for preparation of nano-sized TiO2 powder

Nano-sized TiO₂ powder was prepared by electrochemical dissolution of spongy titanium in an ethanol solution following direct hydrolysis of the electrolyte solution. Characterization of the electrochemical product revealed that Ti(OEt)₄ was formed by anodic dissolution of spongy titanium in ethanol solution. X-ray diffraction and transmission electron microscope were, respectively, used to investigate the structure of TiO₂. This study showed that nano-sized TiO₂ prepared by this method has a structural and thermal stability with a narrow size distribution of 5-10 nm. The optimum electrochemical operating conditions established were a temperature of 333-343 K, current density of 400 A m⁻² and faradaic efficiency of 86%. Experiments showed that this process might be recommended as a promising technique for synthesis of nano-sized powder.     

HZSM-5型分子筛催化乙醇溶液脱水制备乙烯的工艺

以稀乙醇溶液为原料、自制分子筛HZSM-5为催化剂,催化脱水制备乙烯.考察了硅铝比、反应温度、质量空速及乙醇的质量浓度对该反应的影响,得到了较优化的反应工艺条件为:催化剂为HZSM-5(硅铝比30)分子筛,ρ(乙醇)为100~200 g/L,质量空速为2~6 h-1,反应温度为300℃.乙醇的转化率可达99%,乙烯的选择性达99%以上.     

乙醇和二甲醚微射流火焰燃烧特性研究

采用实验及数值计算研究了乙醇和二甲醚微圆管射流火焰燃烧特性。通过实验观察到不同燃料流速下乙醇和二甲醚火焰都具有四种典型的火焰形态；使用平面激光诱导荧光测试系统获得了微射流火焰的OH基元分布，实验结果表明在较高流速下稳定燃烧的乙醇火焰比二甲醚火焰直径小，且略高于二甲醚火焰；采用考虑详细化学反应机理的数值计算对乙醇和二甲醚火焰进行了数值模拟，计算结果与实验现象吻合较好；利用一维非预混对冲火焰计算进一步研究了这两种燃料的化学反应路径，分析结果表明乙醇和二甲醚火焰的中间产物有显著差异，两种燃料化学反应特性的差异导致了不同的微火焰结构。     

Study of operating variables in the transformation of aqueous ethanol into hydrocarbons on an HZSM‐5 zeolite

With the aim of determining the possibilities of directly upgrading the liquid obtained from carbohydrate fermentation, the effect of operating conditions (temperature, space time, water content in the feed) has been studied in the catalytic transformation of aqueous ethanol into hydrocarbons on an HZSM‐5 zeolite in an isothermal fixed bed reactor. Special attention has been paid to the effect of water content on the yield, product distribution and catalyst deactivation. Although deactivation by coke decreases as the water content is increased, this content must be limited at 450 °C and higher temperatures in order to avoid irreversible deactivation of the catalyst by dealumination. © 2002 Society of Chemical Industry     

Ethanol extraction of oil,gossypol and aflatoxin from cottonseed

Commercial processing of cottonseed requires hexane to extract and recover edible oil. Gossypol and aflatoxin are not removed from extracted meals. A bench-top extraction process with 95% (vol/vol) aqueous ethanol (EtOH) solvent has been developed that extracts all three of the above materials with a much less volatile solvent. In this process, cottonseed is pretreated and extracted with ambient 95% EtOH to remove gossypol and then extracted with hot 95% EtOH to extract oil and aflatoxin. Membranes and adsorption columns are used to purify the various extract streams, so that they can be recycled directly. A representative extracted meal contained a total gossypol content of 0.47% (a 70% reduction) and 3 ppb aflatoxin (a 95% reduction). Residual oil content was approximately 2%. Although the process is technically feasible, it is presently not economical unless a mill has a continual, serious aflatoxin contamination problem. However, if a plant cannot meet the hexane emission standards under the Clean Air Act of 1990, this process could provide a safer solvent that may expand the use and increase the value of cottonseed meal as a feed for nonruminants. Presented in part at the AOCS annual meeting, Toronto, Canada, May 1992.     

锂离子电池用磷腈类聚合物电解质的制备与性能

采用六氯环三磷腈高温开环聚合方法制备了聚二氯磷腈,然后采用醇钠法,取代聚二氯磷腈的氯,制备了聚二（二乙二醇单甲醚）磷腈（MEEP）,探索出了较佳的合成工艺,采用FT-IR、31P-NMR、13C-NMR、质谱对其进行了结构表征和分析。结果表明,所制备的磷腈聚合物确实为MEEP。采用自制的MEEP,与三氟甲基磺酸锂（LiCF3SO3）盐进行复配,制备了锂离子电池用聚合物固体电解质,对其热稳定性、导电性进行了测试,其开始分解温度在200℃以上,室温电导率达到了1.187×10-4S/cm（25℃）,具有较佳的导电性和热稳定性,可用于锂离子电池的电解质。