新型镧基质子导体及其在氢分离中的应用

A hydrogen separation membrane using perovskite-type proton conductors has following advantages: hydrogen can be extracted not only from hydrogen molecules but also from hydrogen compounds; hydrogen can be extracted up from low concentration gas to high concentration gas; the rate of hydrogen extration can be controlled by electric current; pressurization of supplied gas is not required; high-temperature operation is possible on the site of the reactor; and the ceramics are strong against irradiation, etc. However, the poor chemical stability and low conductivity hinders their practical use seriously. In this project, novel La-based proton conductors including doped La2Mo2O9 and doped LaNbO4 will be systematically studied by doping or co-doping, or by making into composites in order to obtain mateirals with high conductivity and better stability. The synthesis and sintering technique will be optimized for the high density and the thin film will be prepared. The effects of electrode materials and their preparation methods on the catalytic activity are investigated. Finally, tubular hydrogen sepeartion membrane are prepared and used for hydrogen seperation test. And the factors which influence the hydrogen permeability are discussed. In addition, the control mechanism and the electrochemical reaction model for hydrogen seperation will be found. Through the project, is expected to obtain novel proton conductors with better comprehensive properties, enrich the electrode material and its preparation technique, and provide new ideas for high performance hydrogen separation membrane using proton conductors.

基于钙钛矿型质子导体的氢分离膜可以提取氢分子及含氢化合物中的氢；对气体的浓度没有限制；可以通过电流控制氢采集率；无需加压；还可以用在反应堆高温侧在线提氢及其同位素，并且耐辐照；然而化学稳定性差和电导率低等问题严重限制了其实际应用。本项目提出研究新型镧基质子导体包括La2Mo2O9基和LaNbO4基两种体系的质子导电性，通过离子掺杂或共掺杂、复合获得稳定性好、电导率高的材料，通过优化制备工艺提高材料的致密度，实现其薄膜化制备，并研究电极材料及其制备工艺对催化活性的影响，最终制备管式氢分离膜进行氢分离试验，系统研究影响氢渗透率的因素，探讨氢分离的控制机制和电化学反应模型，实现高的氢渗透率。通过本项目的实施，有望获得综合性能优良的质子导体新体系，丰富电极材料及其制备技术，为高性能质子导体氢分离膜提供新的思路。

基于质子导体的氢分离膜可以提取氢分子及含氢化合物中的氢，本项目围绕新型镧基质子导体包括La2Mo2O9基、LaNbO4基以及La28-yW4+yO54+δ基材料，系统研究了双掺杂、工艺优化以及复合等方法对材料性能的影响，获得稳定性好、电导率高的新材料，其中1%CaF2/LaNbO4复相陶瓷和(La0.98K0.02)27.08W4.92O55.38-θ陶瓷在湿H2气氛800℃的电导率分别为6.37×10-3S/cm、3.14×10-3S/cm。在此基础上，优化了等静压法和浸渍提拉法制备管式电解质膜的工艺参数，并创新性地采用旋转烧结技术，以及通过控制旋转的速度，制得圆整度较高、致密性较好的管式电解质陶瓷膜，致密度、氦漏率等结果表明，等静压法制备的管式电解质陶瓷膜优于浸渍提拉法。随后通过对电极材料和电极制备工艺的优化，改善了电极的性能及其与管式电解质膜的结合强度，结果表明低温下Ni电极相较于Pt电极的催化活性较低，而随着温度升高到600℃以上的工作温度时Ni电极与Pt电极的催化活性差距缩小。结合优化的电解质膜和电极制备工艺，制备了带有电极的高温质子导体型氢分离器件，并进行了氢分离测试实验，采用一侧通100%H2，一侧通8%H2-92%Ar的条件进行氢泵的测试，800℃测得的开路电压为105mV，热循环9次的氢分离曲线非常接近，1.4V的氢分离能力达到约5mAcm-2。最后通过Autolab电化学工作站和气相色谱探讨了氢分离的机理和控制因素。