钼增强铜基纳米材料的合成及其催化性能研究

发布时间：2018-05-01 20:33

本文选题：Cu + 纳米粒子　；参考：《江西师范大学》2017年硕士论文

【摘要】：在过去的几十年里,氢气被认为是一种极具前景的能源载体。然而,寻找安全、高效的方法来储存和运输氢气,以转型到氢能社会,依旧面临巨大的挑战。氨硼烷由于无毒,拥有高的储氢质量分数(19.6 wt%)和稳定性,被认为是一种很有前景的化学储氢材料。1摩尔氨硼烷在合适的催化剂存在下可以水解产生3摩尔的氢气。贵金属催化剂由于具有较高的催化活性,被广泛用于氨硼烷水解产氢反应中,但其价格昂贵,储量有限,限制了其广泛的应用。因此,寻找低成本、高活性的非贵金属催化剂成为了研究热点。本文围绕Cu基非贵金属催化剂的制备、表征以及催化性能开展研究。主要内容如下:采用简单的方法快速合成了无表面活性剂和载体修饰的非贵金属Mo、W、Cr增强Cu催化剂。与Cu纳米粒子(15.6 nm)相比,掺杂Mo、W、Cr可以显著降低纳米粒子的颗粒尺寸(5-7 nm)和提高催化剂的分散度。此外,研究结果表明,掺杂Mo、W、Cr可以降低Cu纳米粒子的结晶度,这些可能导致催化剂拥有较高的催化活性。单独的Cu催化剂的催化活性很低,210分钟才使得氨硼烷水解产生2.6摩尔比的氢气,单独的Mo、W和Cr对氨硼烷水解产氢反应没有催化活性,而少量Mo、W、Cr掺杂Cu催化剂后(Cu0.9Mo0.1、Cu0.9W0.1和Cu0.95Cr0.05),催化活性得到显著提高,其中Cu0.9Mo0.1催化剂表现出最优的催化性能,可以在3.4分钟内使得氨硼烷完全水解产氢,氢气转化频率(TOF)达到14.9 mol(H2)·mol(metal)-1·min-1,在所有已报道的Cu催化剂中处于一个相对高的值。在室温下通过简单的共还原法合成了非贵金属Mo增强CuCo催化剂。与相应的单金属和双金属催化剂相比,Cu0.72Co0.18Mo0.1催化剂表现出更高的催化活性,催化氨硼烷水解产氢反应的转化频率为46 mol(H2)·mol(metal)-1·min-1。研究结果表明,Mo的引入不仅可以减小纳米粒子的颗粒尺寸,还可以改变催化剂表面的电子结构。此外,发现碱的加入会显著促进氨硼烷水解产氢,而氨硼烷可以稳定的存在于碱溶液中,说明碱在氨硼烷水解产氢反应中只是起到助催化剂的作用。Cu0.72Co0.18Mo0.1催化剂在加入NaOH(1 M)的情况下,催化氨硼烷完全水解产氢只需约0.6分钟,氢气转化频率达到119 mol(H2)·mol(metal)-1·min-1,不仅高于所有已报道的非贵金属催化剂,而且还高于商业化的Pt/C催化剂。因此,碱促进Cu0.72Co0.18Mo0.1催化剂可以代替贵金属催化剂用于氨硼烷水解产氢反应,有望促进氨硼烷作为储氢材料走向实际应用。
[Abstract]:In the past few decades, hydrogen has been regarded as a promising energy carrier. However, the challenge of finding safe and efficient ways to store and transport hydrogen to a hydrogen society remains enormous. Because of its nontoxicity, high hydrogen storage mass fraction (19.6 wtt) and stability, aminoborane is considered as a promising chemical hydrogen storage material, which can hydrolyze to produce 3 moles of hydrogen in the presence of suitable catalyst. Due to its high catalytic activity, noble metal catalysts are widely used in the hydrolysis of ammonioborane to produce hydrogen. However, their high price and limited reserves limit their wide application. Therefore, the search for low-cost, high-activity non-precious metal catalysts has become a research hotspot. The preparation, characterization and catalytic properties of Cu-based non-noble metal catalysts were studied in this paper. The main contents are as follows: a simple method was used to rapidly synthesize non-surfactant and carrier modified non-noble metal Mohln / Cr reinforced Cu catalyst. Compared with Cu nanoparticles (15.6 nm), the doping of Mo-WN Cr can significantly reduce the particle size of the nanoparticles and increase the dispersion of the catalyst. In addition, the results show that the crystallinity of Cu nanoparticles can be reduced by doping Mo-WN Cr, which may lead to higher catalytic activity of the catalysts. The catalytic activity of the single Cu catalyst was very low for 210 minutes, which resulted in the hydrolysis of aminoborane to produce 2.6 molar ratio of hydrogen, while the single MohlW and Cr had no catalytic activity for the hydrolysis of ammonioborane to produce hydrogen. However, the catalytic activity of Cu _ (0.9) Mo _ (0.1) Cu _ (0.9) W _ (0.1) and Cu _ (0.95Cr) _ (0.05) C _ (2) was significantly increased after a small amount of Mo _ (Mo) W ~ (+) Cr was doped with Cu catalyst. Among them, the Cu0.9Mo0.1 catalyst showed the best catalytic activity, which could make the ammonia borane completely hydrolyze to produce hydrogen within 3.4 minutes. The conversion frequency of hydrogen is 14.9 mol / h _ 2) mol(metal)-1 min-1, which is a relatively high value in all reported Cu catalysts. The non noble metal Mo reinforced CuCo catalyst was synthesized by a simple co reduction method at room temperature. Compared with the corresponding monometallic and bimetallic catalysts, Cu0.72Co0.18Mo0.1 catalyst showed higher catalytic activity, and the conversion frequency of the hydrogen-producing reaction of ammonioborane hydrolysis was 46 mol / h _ 2) mol(metal)-1 min-1. The results show that the introduction of Mo can not only reduce the particle size of the nanoparticles, but also change the electronic structure of the catalyst surface. In addition, it was found that the addition of alkaloids could significantly promote the hydrolysis of aminoborane to produce hydrogen, and that ammonioborane could exist stably in alkali solution. The results show that alkali can only act as a catalyst in the hydrolysis of ammonioborane to produce hydrogen. Cu0.72Co0.18Mo0.1 catalyst can only be used as catalyst for the complete hydrolysis of ammonioborane to produce hydrogen by adding NaOH(1 M, and it only takes about 0.6 minutes for the complete hydrolysis of aminoborane to produce hydrogen. The hydrogen conversion frequency reached 119mol / h _ 2) mol(metal)-1 min-1, which was higher than that of all reported non-noble metal catalysts, but also higher than commercial Pt/C catalysts. Therefore, the alkali-promoted Cu0.72Co0.18Mo0.1 catalyst can be used in the hydrolysis of ammonioborane to produce hydrogen instead of the noble metal catalyst, which is expected to promote the practical application of aminoborane as a hydrogen storage material.
【学位授予单位】：江西师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TB383.1

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