镍掺杂稀土氧化物纳米颗粒的制备及其分解水合肼产氢性能的研究

发布时间：2018-06-05 23:34

  本文选题：稀土氧化物 + 水合肼　； 参考：《天津工业大学》2017年硕士论文

【摘要】：目前,环境和能源问题日益严重,氢能作为一种清洁高效的新能源而备受关注。水合肼(N_2H_4·H_2O)是一种含氢量高,且便于存储运输的液体储氢材料,研究发现,水合肼在催化剂的作用下可以选择性分解产生N2和H_2,有利于氢能的应用和开发。本文采用液相共还原的方法制备了用于催化分解水合肼产氢的镧、钕、镨等元素氧化物掺杂镍的纳米催化剂。该方法以镍和稀土元素的盐为前驱物,硼氢化钠为还原剂,在室温下共还原得到Ni1-x-(REO)x催化剂(REO为稀土氧化物),并对制得的催化剂进行水合肼催化分解试验。(1)室温条件下通过液相共还原方法制备出不同配比的Ni-Nd_2O_3纳米颗粒,采用X射线衍射(XRD)、透射电镜(TEM)、能谱分析(EDS)、X射线光电子能谱分析(XPS)对Ni-Nd_2O_3颗粒的形貌和组成进行表征,考察了纳米颗粒对水合肼的催化分解性能。结果表明,Nd_2O_3会对镍的晶体结构和形貌产生影响,提高催化剂的分散程度;在70℃的条件下,Ni0.94-(Nd_2O_3)0.06纳米催化剂具有很好的水合肼的分解性能,氢气选择性为99%,转化频率TOF值为52.17h~(-1),重复试验中催化剂的催化性能基本保持不变,具有很好的稳定性;(2)室温条件下通过液相共还原方法制备出不同配比的Ni-La2O3纳米颗粒,采用XRD、TEM、EDS、XPS对Ni-La203颗粒的形貌和组成进行表征,并考察了纳米颗粒对水合肼的催化分解性能。研究发现,La2O3会对镍的晶体结构和形貌产生影响,可以有效减小纳米颗粒的颗粒粒径;在70℃的条件下,Ni_(0.8)-(La_2O_3)_(0.2)纳米催化剂具有最佳的水合肼分解性能,氢气选择性为95%,转化频率TOF值为61.76h~(-1) 7次重复催化试验的结果表明该催化剂具有较高的稳定性;(3)碱性环境可以提高水合肼分解反应的选择性。对反应体系中NaOH的浓度进行考察,研究发现,在反应体系中加入NaOH溶液可以提高水合肼分解反应的H_2选择性,且随着NaOH浓度的增加,催化反应的H_2选择性逐渐升高,当NaOH浓度增大到一定程度时,催化反应的H_2选择性不再随之改变,在单独加入NaOH进行水合肼分解测试时,水合肼不能被分解,说明NaOH溶液在水合肼分解反应中起到促进剂的作用。
[Abstract]:At present, environmental and energy problems are becoming more and more serious. Hydrogen energy as a clean and efficient new energy has attracted much attention. It is found that hydrazine hydrate can selectively decompose to produce N _ 2 and H _ 2s _ 2 under the action of catalyst, which is beneficial to the application and development of hydrogen energy. In this paper, nanocrystalline catalysts doped with oxides of lanthanum, neodymium and praseodymium were prepared by liquid phase co-reduction for the catalytic decomposition of hydrogen from hydrazine hydrate. In this method, nickel and rare earth salt are used as precursors, sodium borohydride is used as reductant, The Ni1-x-(REO)x catalyst was prepared by co-reduction at room temperature. The prepared catalyst was prepared by hydrazine hydrate catalytic decomposition test. At room temperature, different proportions of Ni-Nd_2O_3 nanoparticles were prepared by liquid phase co-reduction. The morphology and composition of Ni-Nd_2O_3 particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The catalytic decomposition of hydrazine hydrate was investigated. The results showed that the effect of Sid _ 2O _ 3 on the crystal structure and morphology of nickel and the dispersion of the catalyst were improved, and the nanometer catalyst Ni0.94-Nd2O30.06 had good decomposition performance of hydrazine hydrate at 70 鈩，

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