添加碱金属化合物对Li-N-H体系储氢材料动力学性能的增强

发布时间：2018-07-14 09:18

【摘要】：随着人们对能源的需求日益增加,寻找绿色、环保、可再生的新型能源替代当前的-次化石能源已经迫在眉睫。氢能凭借其清洁环保、储藏量大、能量密度高的优点,被科学家们作为未来理想能源载体的候选者之一。在氢能的发展过程中,至关重要的技术难题是解决氢气的储存问题。在诸多不同种类的储氢材料中,“金属-氮-氢”基储氢材料,由于具有储氢量大、运行温度低、动力学性能优良的特点,成为近些年来储氢材料学者们研究的热点。自从陈萍等人在2002年首次提出Li-N-H的储氢体系后,该体系在世界范围内受到广泛关注。该文章提出Li3N能够通过以下两个连续的反应可逆地储存超过10 wt%的氢气。之后不久,LiNH2-LiH体系也作为一个经典的储氢体系被广泛研究,因为它可以通过下述反应更容易的吸/放6.5 wt%的氢气。近几年,有研究表明碱金属钾化合物包括氢化钾、氨基钾、氢氧化钾以及钾的卤化物在改善Li-Mg-N-H储氢体系的动力学性能方面有良好的催化效果。本文在此基础之上,研究并讨论了碱金属氢氧化物、碱金属氢化物、碱金属氨基化物的添加,对Li-N-H体系储氢性能的影响,并讨论其反应机理。1.碱金属氢氧化物加入对LiNH2-LiH体系储氢材料脱氢性能的增强我们研究并讨论了LiOH, NaOH, KOH三种氢氧化物添加对LiNH2-LiH体系脱氢性能的影响,并确定了三种碱金属氢氧化物对于LiNH2-LiH体系脱氢性能都有明显的增强效果。在这三种氢氧化物之中,以KOH效果最为显著。相对于LiNH2-LiH样品较宽的脱氢曲线而言,加入5mol% KOH之后其峰型变得尖锐,并且放氢起点温度降低了36℃,峰值温度降低了42℃。进一步结构表征显示,在球磨过程中碱金属氢氧化物可以与LiH发生反应生成对应的氢化物,而这一现象是碱金属氢氧化物添加的LiNH2-LiH体系动力学性能增强的主要原因。2.碱金属氢化物加入对LiNH2-LiH体系储氢材料脱氢性能的增强我们研究并讨论了加入三种碱金属氢化物(LiH, NaH, KH)的LiNH2-LiH体系脱氢性能。研究结果表明,三种碱金属氢化物对LiNH2-LiH体系脱氢性能都有着明显的增强效果,其中以KH加入的LiNH2-LiH体系效果最为显著。相对于LiNH2-LiH样品较宽的脱氢曲线而言,加入5 mol%KH之后其峰型变得尖锐,并且放氢起点温度降低了20℃,峰值温度降低了30℃。通过机理讨论我们得出,KH添加LiNH2-LiH体系动力学性能之所以得到增强,是因为KH与NH3反应产生催化效果,加速了脱氢反应的进行。在后续循环性能测试中,相对于未添加的LiNH2-LiH样品而言,5 mol%KH加入的LiNH2-LiH样品表现出理想的循环性能。3.碱金属氨基化物添加对LiNH2-LiH体系储氢材料脱氢性能的增强这一部分我们讨论了加入三种碱金属氨基化物(LiNH2, NaNH2, KNH2)的LiNH2-LiH体系脱氢性能。研究结果表明,三种碱金属氨基化物中只有KNH2对LiNH2-LiH体系脱氢性能都有着明显的增强效果。相对于LiNH2-LiH样品较宽的脱氢曲线而言,加入5 mol%KNH2之后其峰型变得尖锐,并且放氢起点温度降低了40℃,峰值温度降低了34℃。进一步结构研究表明,KNH2在球磨过程中与LiH反应生成KH,是加入5mol% KNH2的LiNH2-LiH脱氢动力学性能提升的主要原因。最后,在循环性能测试中,相对于未添加的LiNH2-LiH样品,5 mol% KNH2加入的LiNH2-LiH样品表现出理想的循环性能。
[Abstract]:With the increasing demand for energy, it is imminent to find green, environmental and renewable energy instead of the current secondary fossil energy. Hydrogen energy is one of the candidates for the future ideal energy carrier by virtue of its clean environment, large storage and high energy density. The important technical problem is to solve the problem of hydrogen storage. In many different kinds of hydrogen storage materials, "metal nitrogen hydrogen" based hydrogen storage material has become a hot spot for the researchers of hydrogen storage materials in recent years because of its high hydrogen storage capacity, low operating temperature and good dynamic performance. Since Chen Ping and others first proposed L in 2002. After the hydrogen storage system of i-N-H, the system is widely concerned around the world. This article suggests that Li3N can store more than 10 wt% of hydrogen by two consecutive reactions. After that, the LiNH2-LiH system is also widely studied as a classic hydrogen storage system, because it can easily absorb / release 6. through the following reaction. 5 wt% hydrogen. In recent years, some studies have shown that alkali metal potassium compounds, including potassium hydroxide, potassium amino acid, potassium hydroxide, and potassium halide have good catalytic effect in improving the dynamic properties of Li-Mg-N-H hydrogen storage system. Based on this, the alkali metal hydroxide, alkali metal hydride, alkali metal amino group are discussed and discussed. The effect of addition of chemicals on the hydrogen storage properties of Li-N-H system, and the reaction mechanism of the reaction mechanism,.1. alkali metal hydroxide added to the dehydrogenation of hydrogen storage materials in the LiNH2-LiH system, we studied and discussed the effects of the addition of three kinds of hydroxides of LiOH, NaOH, KOH on the dehydrogenation performance of the LiNH2-LiH system, and the determination of three kinds of alkali metal hydrogen oxidation. Among the three kinds of hydroxides, KOH has the most remarkable effect on the dehydrogenation performance of the LiNH2-LiH system. Compared with the wider dehydrogenation curve of the LiNH2-LiH sample, the peak shape becomes sharp after the addition of 5mol% KOH, and the starting temperature of the hydrogen release is reduced by 36, and the peak temperature is reduced by 42. The sign shows that the alkali metal hydroxide can react with LiH to produce the corresponding hydride during the ball milling process, and this phenomenon is the main reason for the enhancement of the dynamic properties of the LiNH2-LiH system added by the alkali metal hydroxide. The addition of.2. alkali metal hydride to the dehydrogenation performance of the hydrogen storage material in the LiNH2-LiH system has been studied and discussed. The dehydrogenation performance of the LiNH2-LiH system with three kinds of alkali metal hydride (LiH, NaH, KH) was added. The results showed that the dehydrogenation performance of the three kinds of alkali metal hydrides had obvious enhancement effect on the dehydrogenation performance of the LiNH2-LiH system, and the LiNH2-LiH system with KH added was the most significant. Compared with the wider dehydrogenation curve of the LiNH2-LiH sample, the addition of 5 mol%KH was added. Then the peak shape becomes sharp, and the starting temperature of the hydrogen release is reduced by 20, and the peak temperature is reduced by 30. Through the mechanism, we conclude that the dynamic performance of the KH adding LiNH2-LiH system is enhanced because the reaction between KH and NH3 has a catalytic effect and accelerates the dehydrogenation reaction. As for the non added LiNH2-LiH samples, the LiNH2-LiH samples added by 5 mol%KH showed the ideal cyclic properties of the.3. base metal aminoides to enhance the dehydrogenation performance of the LiNH2-LiH system hydrogen storage materials. We discussed the dehydrogenation properties of the LiNH2-LiH system of adding three kinds of alkali metal aminoides (LiNH2, NaNH2, KNH2). The results show that only KNH2 in the three alkali metal amino groups has obvious enhancement effect on dehydrogenation performance of LiNH2-LiH system. Compared with the wider dehydrogenation curve of LiNH2-LiH sample, the peak shape becomes sharp after adding 5 mol%KNH2, and the starting temperature of the hydrogen release is reduced by 40, and the peak temperature is reduced by 34. In the ball milling process, KNH2 reacts with LiH to produce KH, which is the main reason for the improvement of LiNH2-LiH dehydrogenation kinetics for adding 5mol% KNH2. Finally, in the cycle performance test, the LiNH2-LiH samples with 5 mol% KNH2, compared to the non added LiNH2-LiH samples, show the ideal cycle performance.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

【相似文献】