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It has been found that ethylene and propylene could be effectively hydrogenated by formic acid vapour over a Pd/carbon catalyst at low temperatures (<440 K). Surface hydrogen formation from formic acid is the rate-determining step for this hydrogenation reaction. Interaction of this hydrogen with the olefins is then fast. The conversion of formic acid in the presence of either of the olefins at any temperature is higher than in their absence. This has been explained by a much lower surface hydrogen concentration in the presence of the olefins. Direct experiments have confirmed that hydrogen inhibits the formic acid decomposition. Water vapour addition has a small positive effect on the decomposition of formic acid as well as on the hydrogenation of the olefins with formic acid. Catalysts consisting of gold supported on carbon or titania are both active in the production of hydrogen from formic acid. However, in contrast to the Pd/C catalyst, neither gives hydrogenation of the olefins with this acid. 相似文献
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The ac response of polyaniline thin films on platinum electrodes was measured at different dc potentials during the CO2 reduction in methanol/LiClO4 electrolyte with a small amount of 0.5 M H2SO4. The complex capacitance curves were simulated and the data obtained were used to calculate kinetic parameters, based on the assumption that the thermodynamic potential E0 is in the region of −0.2-−0.1 V versus saturated calomel electrode (SCE). With E0=−0.2 V versus SCE and β=0.6, a j0 value of ca. 10−4 A cm−2 was found for the electroreduction of CO2 on the polyaniline electrode. 相似文献
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Chemical studies of anthocyanins: A review 总被引:10,自引:0,他引:10
Araceli Castañeda-Ovando Ma. de Lourdes Pacheco-Hernández Ma. Elena Páez-Hernández José A. Rodríguez Carlos Andrés Galán-Vidal 《Food chemistry》2009
Anthocyanins are natural colorants which have raised a growing interest due to their extensive range of colours, innocuous and beneficial health effects. Despite the great potential of application that anthocyanins represent for food, pharmaceutical and cosmetic industries, their use has been limited because of their relative instability and low extraction percentages. Currently, most investigations on anthocyanins are focused on solving these problems, as well as their purification and identification. 相似文献
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将CO2转化为高附加值的化学品是实现碳循环, 缓解能源危机和环境问题的有效途径之一。金属与半导体复合电极, 利用光电耦合技术为CO2转化提供了一种新思路。本研究通过电沉积的方法在碱刻蚀处理后的Si片上制备了双金属Bi、Zn共修饰的Si基光电阴极(BiZnx/Si), 用于CO2的光电催化还原。研究表明, 引入金属Bi和Zn能够改善光的吸收性能, 降低电化学阻抗, 提高电化学活性比表面积(ECSA)。其中, BiZn2/Si最优的光电极电化学比表面积可达0.15 mF·cm-2。除此之外, 研究发现双金属共同作用有助于增强电极对中间体*OCHO的吸附作用, 在-0.8 V(vs. RHE)电势下, 最优的光电阴极BiZn2/Si生成HCOOH的法拉第效率高达96.1%。更重要的是, 光电阴极BiZn2/Si的光电流强度在10 h内维持-13 mA·cm-2, 表现出良好的性能稳定性。 相似文献