镍基钙钛矿低温催化氨分解性能的研究
发布时间：2018-10-22 15:26
【摘要】：质子交换膜燃料电池(PEMFC)以氢气作为燃料，质量轻、无污染、效率高，在电动汽车及各种可移动设备的动力电源方面具有潜在的应用前景。近年来，由于NH3具有储氢密度高、运输和生产等技术较完备、价格低廉、分解后无COx生成等优点，被作为燃料电池的原位供氢法而备受关注。但氨是一种非常稳定的分子，它的分解过程是可逆和吸热的反应，需要很高的温度才能完全分解。因此，利用氨分解制氢作为移动氢源，低温氨分解催化剂的设计是关键问题。 钙钛矿具有热稳定性、强氧化还原能力、品种多样性、高净化废气能力、成本低廉等优点，本文将其用于氨分解制氢反应研究，以期获得利于氨分解反应的新型催化剂。 首先，本文制备了一系列钙钛矿型LaBO3（B=Ni，Co，Fe，Cr）催化剂，，采用氨分解活性评价测试、TPR、XRD表征手段分析了决定钙钛矿催化氨分解的主要因素，确定了B位最佳元素为Ni，氨在LaNiO3上，10000h-1、640℃条件下可达到100%的转化率。同时，将Ni系钙钛矿与普通Ni氧化物进行对比，发现钙钛矿的结构有利于提高催化剂的氨分解活性。在此基础上还探讨了La1-xMxNiO3(M=Sr、Y、Ce，x=0.2，0.4，0.6，0.8)的氨分解活性，得出M最佳元素是Ce，当Ce的掺杂量x=0.4时活性最好，低温和高温的活性均明显提高。 其次，本文将LaNiO3负载于不同的载体（MgO、SiO2、γ-Al2O3）上，考察载体对镍系钙钛矿催化氨分解性能的影响，研究结果表明，以SiO2为载体的负载型催化剂的氨分解活性较好，且NiO的负载量对氨分解活性有很大的影响，w(NiO)=20%时，在640℃可获得100%的氨转化率，与非负载LaNiO3活性相当，在保持相同活性的基础上，减少了活性组分的用量，从而降低了生产成本。 另外，本文探讨了载体MCM-41介孔分子筛对LaNiO3催化氨分解活性的影响，研究发现，介孔分子筛MCM-41大的比表面和规整的介孔结构，更有利于活性组分的分散，增加了有效活性位，提高了活性组分的反应能力，表现出很好的氨分解催化活性。最后，在上述研究的基础上制备了一种新型催化剂，以NiO计，负载量为20%wt的La0.6Ce0.4NiO3/MCM-41，并对其进行氨分解活性测试，结果表明其具有很好的催化活性，在536℃时氨即可完全分解。
[Abstract]:Proton exchange membrane fuel cell (PEMFC), which uses hydrogen as fuel, is light, pollution-free and efficient, and has potential applications in power supply for electric vehicles and various mobile devices. In recent years, because of the advantages of high density of hydrogen storage, complete technology of transportation and production, low price and no formation of COx after decomposition, NH3 has attracted much attention as an in-situ hydrogen supply method for fuel cells. However, ammonia is a very stable molecule, its decomposition process is reversible and endothermic reaction, which requires a high temperature to completely decompose. Therefore, the design of low temperature ammonia decomposition catalyst is a key problem. Perovskite has the advantages of thermal stability, strong redox ability, variety diversity, high purification capacity and low cost. In this paper, perovskite has been used in the study of ammonia decomposition to produce hydrogen, in order to obtain a new catalyst for ammonia decomposition. Firstly, a series of perovskite-type LaBO3 catalysts were prepared. The main factors determining the ammonia decomposition of perovskite catalysts were analyzed by means of ammonia decomposition activity evaluation and TPR,XRD characterization. The best element at position B is Ni, ammonia on LaNiO3, and the conversion rate can reach 100% at 10000h-1640 鈩
本文编号：2287541
[Abstract]:Proton exchange membrane fuel cell (PEMFC), which uses hydrogen as fuel, is light, pollution-free and efficient, and has potential applications in power supply for electric vehicles and various mobile devices. In recent years, because of the advantages of high density of hydrogen storage, complete technology of transportation and production, low price and no formation of COx after decomposition, NH3 has attracted much attention as an in-situ hydrogen supply method for fuel cells. However, ammonia is a very stable molecule, its decomposition process is reversible and endothermic reaction, which requires a high temperature to completely decompose. Therefore, the design of low temperature ammonia decomposition catalyst is a key problem. Perovskite has the advantages of thermal stability, strong redox ability, variety diversity, high purification capacity and low cost. In this paper, perovskite has been used in the study of ammonia decomposition to produce hydrogen, in order to obtain a new catalyst for ammonia decomposition. Firstly, a series of perovskite-type LaBO3 catalysts were prepared. The main factors determining the ammonia decomposition of perovskite catalysts were analyzed by means of ammonia decomposition activity evaluation and TPR,XRD characterization. The best element at position B is Ni, ammonia on LaNiO3, and the conversion rate can reach 100% at 10000h-1640 鈩
本文编号：2287541
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