铝基水解过程超声波活化制氢研究

发布时间：2018-05-01 16:32

本文选题：铝颗粒 + 超声波空化　；参考：《沈阳航空航天大学》2015年硕士论文

【摘要】：氢气作为一种清洁能源载体,较好解决了能源短缺和环境污染两大问题。目前,传统的制氢方法存在制氢成本昂贵、氢气纯度不高等弊端。金属铝水解制氢具有价格低廉、储氢密度高、制氢纯度优良等优点具有较大的发展潜力。但通常情况下,铝水反应过程中生成的氢氧化铝饱和凝胶层包裹新鲜的铝颗粒,阻止其继续反应。因此如何破除氧化膜及原位再生的惰性膜成为制氢的关键。本文利用超声波活化的方法破除铝表面氧化膜及再生的惰性膜,以期达到金属铝与水高效反应的目的。重点研究了超声波功率和反应温度对金属铝水解过程和产氢特性的影响,采用XRD和SEM分析残渣成分及微观结构,氮吸附比表面分析不同阶段的铝颗粒孔径及比表面积变化。结果表明,超声波功率和水浴温度与铝水反应诱导时间成反比,与产氢速率成正比。随着水浴温度增加,最高产氢速率分别为4.8m L/min?g、6.8m L/min?g、8.3m L/min?g及10mL/min?g。在较高的温度下,加快了Al(OH)3难容物的生成,从而覆盖在金属铝表面阻碍后续的反应,导致二次反应峰的形成。超声波提高了铝基水解的最高反应速率和氢气产量,但超声波功率达到225W时出现超声空化衰竭,致使氢气转化率不再提升。添加CaO的铝基材料具有较高的反应速率和较短的反应诱导期。在超声场的作用下,铝基材料两个反应阶段产氢速率明显升高,且慢速阶段出现延迟,延迟时间长短与超声波功率成正比。铝基材料水解快速反应阶段非常剧烈,且有效产氢时间较短,为便于工业应用,通过制备Ca基、Na基成型材料,以期达到高效稳定持续产氢的目的。重点研究了CaO、NaOH、NaCl的配比对成型材料产氢特性的影响。结果表明,CaO/NaOH质量比为2:3时可实现100min稳定产氢;添加CaO、NaCl的铝基粉产氢速率与CaO/NaCl质量比成正比关系,且稳定产氢时间持续至600min。CaO/NaCl质量比决定了氢气转化率及反应速率。
[Abstract]:As a clean energy carrier, hydrogen can solve the problems of energy shortage and environmental pollution. At present, the traditional method of hydrogen production has the disadvantages of high cost and low purity of hydrogen. Hydrogen production by aluminum hydrolysis has the advantages of low price, high density of hydrogen storage and excellent purity of hydrogen production. However, in general, the aluminum hydroxide saturated gel layer formed during the reaction of aluminum and water encapsulates the fresh aluminum particles and prevents them from continuing to react. Therefore, how to break down the oxide film and in situ regenerate inert film becomes the key to hydrogen production. In this paper, the oxidation film and regenerated inert film on aluminum surface are broken by ultrasonic activation method, in order to achieve the purpose of high efficiency reaction between aluminum and water. The effects of ultrasonic power and reaction temperature on the hydrolysis process and hydrogen production characteristics of aluminum were studied. The residual composition and microstructure were analyzed by XRD and SEM, and the changes of pore size and specific surface area of aluminum particles at different stages were analyzed by nitrogen adsorption ratio. The results show that the ultrasonic power and water bath temperature are inversely proportional to the induction time of the reaction and are directly proportional to the rate of hydrogen production. With the increase of water bath temperature, the highest hydrogen production rate is 4.8 mL / min, 6.8 mL / min ~ (-1) L/min?g and 10 mL / min ~ (-1) 路min ~ (-1) 路min ~ (-1) 路min ~ (-1) 路min ~ (-1) 路min ~ (-1), respectively. At a higher temperature, the formation of Al(OH)3 is accelerated, which hinders the subsequent reaction on the surface of aluminum, resulting in the formation of the secondary reaction peak. Ultrasonic enhanced the highest reaction rate and hydrogen production of aluminum-base hydrolysis, but ultrasonic cavitation failure occurred when ultrasonic power reached 225 W, resulting in no increase of hydrogen conversion. The Al base material with CaO has higher reaction rate and shorter reaction induction period. Under the action of ultrasonic field, the hydrogen production rate of aluminum based materials increased obviously in two reaction stages, and the delay occurred in slow phase, and the delay time was proportional to the ultrasonic power. The rapid reaction stage of hydrolysis of aluminum based materials is very intense and the effective hydrogen production time is relatively short. In order to facilitate industrial application, Ca base and Na based molding materials are prepared in order to achieve the purpose of high efficiency, stability and continuous hydrogen production. The effect of the ratio of CaOO and NaOHHN NaCl on the hydrogen production characteristics of the molded materials was studied. The results show that the hydrogen production rate of 100min can be stabilized when the mass ratio of Cao / NaOH is 2:3, and the hydrogen production rate of aluminum base powder added with CaOO / NaOH is proportional to the mass ratio of CaO/NaCl, and the hydrogen conversion and reaction rate are determined by the time of stable hydrogen production to the mass ratio of 600min.CaO/NaCl.
【学位授予单位】：沈阳航空航天大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ116.2

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