聚合物/储氢合金复合材料用于氢气回收的基础问题研究

The hydrogen storage alloys are used to recycle hydrogen from hydrogen-rich exhaust for their unprecedented advantages such as the higher hydrogen storage capacity, environment-friendly characteristic and good reusability, but the drawbacks of easy to be poisoned by other impurity gases among the hydrogen-rich exhaust and excessive pulverization of the alloy hamper their development and application. It is confirmed by our previous work that the composite of alloy LaNi4.7Al0.3 coated with Polymethyl Methacrylate possesses better anti-poisoning and anti-pulverization ability while its preparation and chemical mechanism are not clear at present. In this project, we intend to prepare a polymer/hydrogen alloy composite with multiple function of coating-separating-purifying by melt blending, make a investigation about the influence of composite's preparation technology together these affected factors on its microstructure and characterization, explore the relationship between the gas selective property as well as the dehydrogenation-hydrogenation reaction of the polymer and its microstructure, observe the effect and law of the impurity gases, temperature, and pressure on poisoning polymer/hydrogen storage alloy and its pulverization, establish the relationships between the composite/ purity hydrogen storage material and its composition, melt blending process, the coated structure and the dehydrogenation-hydrogenation property, and the efficiency of hydrogen recovery, respectively and reveal the anti-poisoning and anti-pulverization mechanism of the polymer/hydrogen storage alloy in the process of effectively recycling hydrogen , which provides a reliable experimental basis for enhancing the composite's anti-poisoning and anti-pulverization ability. The study result makes an important theoretical significance and practical value in solving the issue of recycling hydrogen by means of metal hydride.

用储氢合金从富氢尾气中回收氢气具有储氢量大、环境友好、循环利用等特点，但富氢尾气中的杂质气体导致合金易毒化以及合金自身过度粉化，从而阻碍其应用。前期研究证实，聚甲基丙烯酸甲酯包覆AB5型合金具有较好的抗毒性和抗粉化能力，但其制备与机理有待探索。项目拟采用熔融共混法制备具有包覆-分离-净化功能的聚合物/储氢合金复合体系，研究其制备技术及其影响因素对其微观结构的影响及表征；探究聚合物的气体选择性、脱加氢反应性能与其微观组织结构之间的关系；考察杂质气体、温度与压力对聚合物/储氢合金的中毒、粉化的作用规律；建立复合储氢材料成分、熔融共混工艺、包覆结构与脱加氢性能、氢回收效率与纯度之间的关系，揭示聚合物/储氢合金复合体系具有良好回收氢气效果的抗毒化和抗粉化机理，为改善聚合物/储氢合金的抗毒化和抗粉化能力提供了可靠的实验基础。研究对解决金属氢化物回收氢气的难题具有重要的理理论意义和实用价值。

工业废气中含有大量副产H2，如果能加以回收利用，可获得大量低成本的氢。AB5系储氢合金具有在室温及中等压力下能快速吸氢及可逆放氢并且储氢容量较大的优点，被认为是最具应用潜力的储氢合金体系之一。但工业废气中的CO等杂质气体可导致储氢合金中毒，即使储氢合金的吸氢（或放氢）速率变慢和吸氢容量下降。本项目以LaNi5合金为研究对象，探索了CO对AB5系储氢合金储氢性能的影响规律及毒化机理，主要研究内容如下：（1）用真空感应熔炼制备了LaNi4.7M0.3(M=Ni, Al, Co, Mn)系储氢合金，研究了元素取代后AB5系合金在H2+300 ppm CO混合气体中的吸放氢规律，探讨了CO的毒化机理；（2）研究了温度对LaNi4.7M0.3(M=Ni, Al, Co, Mn)合金在混合气体中吸放氢性能的影响，对吸放氢规律给予了解释；（3）研究了用聚甲基丙烯酸甲酯（PMMA）包覆对LaNi4.7Al0.3合金抗CO毒化性能的影响，考察了不同包覆比例对合金在混合气体中的吸放氢性能的影响规律。本项目主要采用了压力-成分-温度（PCT）、差热量热法（DTA）、差示扫描量热法（DSC）、热重分析（TG）、X射线衍射（XRD）、扫描电子显微镜（SEM）、X射线光电子能谱（XPS）等性能检测和分析测试方法对实验进行了分析，结果表明：.CO气体的存在导致LaNi4.7M0.3(M=Ni, Al, Co, Mn)储氢合金吸放氢性能不同程度的下降。元素取代后，吸氢规律为Al>Co>Ni>Mn；放氢规律为Ni>Co> Al>Mn；.提高合金体系的吸放氢循环温度可显著提高吸放氢性能。毒化后样品的热分解温度排序为Al>Co>Ni>Mn；80℃时，在混合气体中吸氢时，吸氢曲线上会出现两个不同的吸氢阶段；.用PMMA包覆后，样品的抗毒化性能有所提高，且包覆比例较高时性能较好，但对吸氢速率影响也较大。包覆对样品放氢速率的影响较复杂，刚开始，2:1的样品放氢较慢，但随着循环次数的增加，1:1的样品放氢较慢；实验结果表明，纯的PMMA对H2具有选择透过性，且不吸收H2和CO气体。