钙钛矿型氧化物在化学链中应用的实验研究

发布时间：2018-06-23 23:54

  本文选题：太阳能热化学 + 天然气基化学链燃烧　； 参考：《中国科学院大学(中国科学院工程热物理研究所)》2017年硕士论文

【摘要】：太阳能与天然气互补的热化学燃料转化及发电系统与不同热力循环相结合,可以实现太阳能的高效利用,减少化石能源消耗量和CO2排放量。但是,目前天然气基化学链燃烧还原反应需要较高的驱动温度,中低聚光比的槽式聚光集热系统不能满足还原反应温度的需求;采用高聚光比的太阳能聚光集热形式,如塔式太阳能聚光集热系统驱动化学链还原反应的发生,存在太阳热能与反应所需热品位差过大,使得太阳热能的品位提升潜力较小,且塔式聚光集热系统存在结构复杂、材料要求高及成本较高等不足,一定程度上限制了太阳能与天然气互补的热化学燃料转化及发电系统的应用。基于钙钛矿型氧化物独特的结构特点和优异的性能,本文提出用钙钛矿型氧化物替代常规氧化物作为化学链燃烧的氧载体,重点在钙钛矿型氧化物的A、B位元素选择上开展了研究,通过改变A、B位的元素,掺杂和改变材料的制备方法等途径,进行一系列实验验证工作,以寻找适用于中低温太阳能的最佳氧载体材料。本文研究了天然气基的化学链燃烧,采用溶胶-凝胶法制备了 A位分别是La、Sr、Ba的钙钛矿型氧化物,通过对材料的物化表征和反应性能的研究,初步判断La是一种较为合适的A位元素。采用燃烧法和溶胶-凝胶法制备了相应的材料,通过对比两种制备方法所得材料的微观形貌、制备周期、反应活性等参数,初步确定燃烧法是一种较为理想的材料制备方法。采用燃烧法制备了 La系的Ni基钙钛矿型氧化物,用XRD、SEM、BET等分析手段对材料进行物化表征,并在热重中研究了材料的反应性能,初步确定钙钛矿型氧化物LaNiO3是一种有潜力的适用于中低温太阳能的氧载体。为了进一步降低还原反应温度、提高低温下的释氧量等,通过对氧化物LaNi03的B位进行掺杂以改善材料的性能。结果表明,氧化物LaCu0.1Ni0.9O3可以在350℃的温度下与CH4发生还原反应,反应速率较快,lmol氧载体在还原反应过程中可以释放0.42mol氧气,具有较强的低温释氧能力,且具有良好的循环再生性和稳定性,在30次循环氧化还原反应中始终保持较高的反应性,30次循环反应之后氧载体表面烧结现象不明显,仍保持良好的孔隙结构,表明LaCu0.1Ni0.9O3是一种可用于中温太阳能驱动的天然气基化学链燃烧的氧载体。本论文基于钙钛矿型氧化物优异的特性,探索中温太阳能驱动的天然气基钙钛矿化学链燃烧新方法,寻找出了一种可以和低聚光比的槽式聚光系统的集热温度相匹配的天然气基化学链燃烧系统的新材料。
[Abstract]:Solar energy and natural gas complementary thermochemical fuel conversion and power generation system combined with different thermal cycles can achieve the efficient use of solar energy and reduce fossil energy consumption and CO2 emissions. However, at present, the reduction reaction of natural gas based chemical chain combustion needs higher driving temperature, and the trough condensing heat collecting system with low and low concentration ratio can not meet the demand of reduction reaction temperature, and the solar energy concentrator with high concentration ratio can not meet the demand of reduction reaction temperature. For example, if the reduction reaction of chemical chain driven by tower solar energy collector system occurs, the difference between solar thermal energy and the heat grade required for the reaction is too large, which makes the potential of improving solar thermal energy small, and the structure of tower solar energy collector system is complex. The shortage of high material requirement and high cost limits the application of thermochemical fuel conversion and power generation system which is complementary to solar energy and natural gas to some extent. Based on the unique structure and excellent properties of perovskite-type oxides, this paper proposes to use perovskite-type oxides instead of conventional oxides as oxygen carriers for chemical chain combustion. The emphasis is on the selection of elements at the Agna B site of perovskite oxides. A series of experimental verification work has been carried out by changing the elements of the AZB site, doping and changing the preparation methods of the materials, etc. In order to find the best oxygen carrier material suitable for medium and low temperature solar energy. In this paper, the chemical chain combustion of natural gas was studied. Perovskite oxides at position A were prepared by sol-gel method. It is preliminarily judged that La is a more suitable element at position A. The corresponding materials were prepared by combustion method and sol-gel method. By comparing the microstructure, preparation period, reaction activity and other parameters of the two preparation methods, it was preliminarily determined that the combustion method is an ideal method for the preparation of materials. Ni-based perovskite oxides of La system were prepared by combustion method. The physical and chemical properties of the materials were characterized by XRDX SEMT-BET, and the reaction properties of the materials were studied by thermogravimetry. It is preliminarily confirmed that perovskite oxide La NiO3 is a potential oxygen carrier suitable for medium and low temperature solar energy. In order to further reduce the temperature of the reduction reaction and increase the oxygen release at low temperature, the B site of the oxide Lani03 was doped to improve the properties of the material. The results show that the oxide LaCu0.1Ni0.9O3 can be reduced to Ch _ 4 at 350 鈩，

本文编号：2059013