CO2 selective reduction to CO with H2 over a CeO2-supported nano-Au catalyst at atmospheric pres- sure was investigated. A high CO2 conversion, approaching the thermodynamic equilibrium value, and nearly 100% CO selec...CO2 selective reduction to CO with H2 over a CeO2-supported nano-Au catalyst at atmospheric pres- sure was investigated. A high CO2 conversion, approaching the thermodynamic equilibrium value, and nearly 100% CO selectivity were obtained. The surface formate intermediates generated during the reverse water-gas shift reaction at 400 ℃ were identified using in situ diffuse-reflectance infra- red Fourier-transform spectroscopy. The formate consumption to give CO and H20, determined using mass spectrometry, indicated that the reaction proceeded via an associative formate mecha- nism; this contributes to the high Au/CeO2 catalytic activity at low temperatures.展开更多
随着工业化进程高速发展,尤其受近期"雾霾"的影响,大气环境质量越来越受重视。空气中氧气补给是提高空气质量的关键方法之一。相对于传统制氧技术(如空气物理分离法、化学法以及水电解法等),空气源电化学连续分离制纯氧技术...随着工业化进程高速发展,尤其受近期"雾霾"的影响,大气环境质量越来越受重视。空气中氧气补给是提高空气质量的关键方法之一。相对于传统制氧技术(如空气物理分离法、化学法以及水电解法等),空气源电化学连续分离制纯氧技术具有空气源分离制纯氧、能量效率高、连续运行、环境友好、安静、易规模放大等特点,可实现室内外场合应用。该技术的关键部件是质子交换膜燃料电池和固体聚合物电解质电解池(简称燃料电池和电解池)。分别考察了其单池操作条件对性能的影响,如燃料电池的操作温度、相对湿度、气体利用率和压强,以及电解池的供水方式、循环水流速、操作温度等。测试了燃料电池单池极化曲线、电化学交流阻抗谱,并计算了膜电导率和活化能。对极化曲线进行拟合得出塔菲尔(Tafel)斜率、氧还原反应交换电流密度i0以及传质影响参数m、n等基本动力学参数。结果表明,氢空燃料电池单池最优化条件为:常压条件下,操作温度为60℃,峰值功率密度可达0.42 W·cm^(-2),膜面电阻为77 m?·cm^2,膜电导率为41.4 m S·cm^(-1)。Tafel斜率受温度影响较小,在120 m V·dec^(-1)左右,但受相对湿度影响较大。相对湿度对单池性能影响显著。电解池单池最优化操作条件为:操作温度对性能影响较大且最佳为65℃,膜面电阻为1.08?·cm^2,膜电导率为11.7 m S·cm^(-1)。循环水流速对性能影响较小。供水方式的优劣次序为两极供水≈阳极供水>阴极供水。在上述实验条件下,燃料电池中Nafion®211膜和电解池中Nafion®115膜的活化能计算值分别为3.75和4.61 k J·mol^(-1)。基于燃料电池和电解池的单池电化学性能优化,研究结果可为后续的制氧机系统中电池堆的实施提供实验依据。展开更多
基金supported by the National Natural Science Foundation of China (11475041, 11175036, 21373037)the Fundamental Research Funds for the Central Universities (DUT16QY49)~~
文摘CO2 selective reduction to CO with H2 over a CeO2-supported nano-Au catalyst at atmospheric pres- sure was investigated. A high CO2 conversion, approaching the thermodynamic equilibrium value, and nearly 100% CO selectivity were obtained. The surface formate intermediates generated during the reverse water-gas shift reaction at 400 ℃ were identified using in situ diffuse-reflectance infra- red Fourier-transform spectroscopy. The formate consumption to give CO and H20, determined using mass spectrometry, indicated that the reaction proceeded via an associative formate mecha- nism; this contributes to the high Au/CeO2 catalytic activity at low temperatures.
文摘随着工业化进程高速发展,尤其受近期"雾霾"的影响,大气环境质量越来越受重视。空气中氧气补给是提高空气质量的关键方法之一。相对于传统制氧技术(如空气物理分离法、化学法以及水电解法等),空气源电化学连续分离制纯氧技术具有空气源分离制纯氧、能量效率高、连续运行、环境友好、安静、易规模放大等特点,可实现室内外场合应用。该技术的关键部件是质子交换膜燃料电池和固体聚合物电解质电解池(简称燃料电池和电解池)。分别考察了其单池操作条件对性能的影响,如燃料电池的操作温度、相对湿度、气体利用率和压强,以及电解池的供水方式、循环水流速、操作温度等。测试了燃料电池单池极化曲线、电化学交流阻抗谱,并计算了膜电导率和活化能。对极化曲线进行拟合得出塔菲尔(Tafel)斜率、氧还原反应交换电流密度i0以及传质影响参数m、n等基本动力学参数。结果表明,氢空燃料电池单池最优化条件为:常压条件下,操作温度为60℃,峰值功率密度可达0.42 W·cm^(-2),膜面电阻为77 m?·cm^2,膜电导率为41.4 m S·cm^(-1)。Tafel斜率受温度影响较小,在120 m V·dec^(-1)左右,但受相对湿度影响较大。相对湿度对单池性能影响显著。电解池单池最优化操作条件为:操作温度对性能影响较大且最佳为65℃,膜面电阻为1.08?·cm^2,膜电导率为11.7 m S·cm^(-1)。循环水流速对性能影响较小。供水方式的优劣次序为两极供水≈阳极供水>阴极供水。在上述实验条件下,燃料电池中Nafion®211膜和电解池中Nafion®115膜的活化能计算值分别为3.75和4.61 k J·mol^(-1)。基于燃料电池和电解池的单池电化学性能优化,研究结果可为后续的制氧机系统中电池堆的实施提供实验依据。
