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.     

Synergistic Catalysis of Carbon Dioxide Hydrogenation into Methanol by Yttria-Doped Ceria/γ-Alumina-Supported Copper Oxide Catalysts: Effect of Support and Dopant

Methanol synthesis from carbon dioxide hydrogenation was studied over ceria/-alumina- and yttria-doped ceria (YDC)/-alumina-supported copper oxide catalysts to seek insight into the catalysis at metal–support interfaces. It was found that, in comparison with Cu/-Al₂O₃, the Cu/CeO₂/-Al₂O₃ and Cu/YDC/-Al₂O₃ catalysts exhibited substantial enhancement in activity and selectivity toward methanol formation. The extent of enhancement was augmented by increased ceria loading on -alumina and with increased yttria doping into ceria. The enhancement is inferred to result from the synergistic effect between copper oxide and surface oxygen vacancies of ceria.     

Antioxidant activity in leaves of some mediterranean plants

Hexane and methanol leaf extracts of sixteen Mediterranean plant species were obtained by percolation. Higher yields were observed for methanol (16.4–47.8%) than for hexane extracts (1.3–13%). Antioxidant activity of these extracts was determined by a rapid spectrophotometric method involving the combined oxidation of beta-carotene and linoleic acid. Leaf extracts were thus characterized by an Antioxidant Activity Coefficient (AAC) ranging from 0 to 1000. Hexane extracts gave much higher AAC values than the corresponding methanol extracts. In both cases, myrtle (Myrtus communis) showed the best antioxidant effectiveness.     

甲醇工业发展方向及应用分析

介绍了甲醇的几种重要的下游产品,如甲醛、甲酸甲酯、甲胺等,提出应大力生产和发展甲醇下游产品,并进一步拓宽甲醇的应用领域,加快甲醇应用新技术的开发工作。     

非晶有机锆聚合物的制备及光催化CO2合成甲醇

采用溶剂热法在增透的多孔玻璃表面制备负载非晶态有机锆聚合物。通过SEM，XRD，BET，FTIR，UV-Vis，ICP，有机元素分析，荧光光谱（PL）及紫外光电子能谱（UPS ）等手段对催化剂进行了测试分析。非晶态有机锆聚合物（2.64 eV）具有比NH2-UiO-66(Zr)（2.74 eV）更窄的禁带宽度，更稳定的光生电子。在光催化反应器中放入2片负载非晶态有机锆的玻璃（总面积50.4 cm2），在300 W的氙灯照射下催化还原CO2合成甲醇，反应4 h后甲醇的产量为443.0 μmol，转换频率（TOF）为8.9 h-1。当0.1 g NH2-UiO-66(Zr)为催化剂时，甲醇的产量为244.3 μmol，TOF仅为0.17 h-1。非晶有机锆聚合物的光催化性能明显优于NH2-UiO-66(Zr)粉末，且循环稳定性良好。     

新型车用清洁燃料——甲醇汽油

介绍了几种代用清洁燃料,着重介绍了甲醇燃料的特点、发展历史和使用现状,并且从其对环境的影响、着火爆炸的安全性以及毒性等方面论述了甲醇燃料的使用安全性能。     

4#甲醇合成系统技术改造

介绍4^#甲醇塔合成系统塔内件、分离器、循环机的技术改造，改变了运行方式，改造后生产能力提高，热稳定性好，操作裕度大，触煤使用寿命延长，经济效益显著。     

气相色谱法用于甲醇氧化转化率的研究

采用GDX 5 0 2为固定相 ,用GC色谱法对常温常压下甲醇氧化为甲醛的转化率进行监测。找出了分离测定甲醇、甲醛、水、甲酸、乙醇等物质的优惠色谱条件。该法灵敏度高 ,甲醇的最小检测量为 9 2 6× 10 - 7g。考察了氧化剂的种类、用量、介质的选择和氧化时间的长短、温度、溶剂等因素对甲醇氧化转化率的影响 ,得到了优惠反应条件。结果表明 :常温常压下 ,不采用任何催化甲醇氧化转化率可达 72 38% ,甲醛回收率为 92 0 8%。     

A glue method for fabricating membrane electrode assemblies for direct methanol fuel cells

We present a simple glue method for fabricating membrane electrode assemblies (MEA) for direct methanol fuel cells (DMFC). Rather than the conventional “dry” hot-pressing method that relies solely on hot-pressing at a high pressure and temperature to form a MEA, the “wet” method developed in this work introduces a binding agent, consisting of Nafion^® solution, between a polymer electrolyte membrane (PEM) and an anode/cathode. The introduced binding agent can provide a better adhesion and stronger binding force between a membrane and an electrode, thereby facilitating a better interfacial contact between the electrode and the Nafion^® membrane, which has been proved by scanning electron microscopy (SEM) analyses to the cross-sectional morphology of the MEA after long-term operation. The cell performance characterization showed the MEA fabricated by the glue method was more stable in cell performance than that fabricated by the conventional hot-pressing method. Cyclic voltammetry (CV) results also demonstrated the MEA fabricated by the glue method exhibited a higher electrochemical surface area (ESA) as a result of the improved interfacial contact between the Nafion^® membrane and the electrodes. Finally, the DMFC with the MEA fabricated by the glue method was characterized by the electrochemical impedance spectroscopy (EIS).     

Optimization of cathode catalyst layer for direct methanol fuel cells: Part I. Experimental investigation

The cathode catalyst layer (CL) in direct methanol fuel cells (DMFCs) has been optimized through a balance of ionomer and porosity distributions, both playing important roles in affecting proton conduction and oxygen transport through a thick CL of DMFC. The effects of fabrication procedure, ionomer content, and Pt distribution on the microstructure and performance of a cathode CL under low air flowrate are investigated. Electrochemical methods, including electrochemical impedance, cyclic votammetry and polarization curves, are used in conjunction with surface morphology characterization to correlate electrochemical characteristics with CL microstructure. CLs in the form of catalyst-coated membrane (CCM) have higher cell open circuit voltages (OCVs) and higher limiting current density; while catalyzed-diffusion-media (CDM) CLs display better performance in the moderate current density region. The CL with a composite structure, consisting both CCM and CDM, shows better performance in both kinetic and mass-transport limitation region, due to a suitable ionomer distribution across the CL. This composite cathode is further evaluated in a full DMFC and the cathode performance loss due to methanol crossover is discussed.