Ultrasonic irradiation on hydrolysis of magnesium hydride to enhance hydrogen generation

Abstract

Abstract:This paper describes the ultrasonic irradiation on the hydrolysis of magnesium hydride to enhance hydrogen generation; the effects of the ultrasonic frequency and the sample size on the hydrogen generation were mainly examined. In the experiments, three MgH 2 particle and nanofiber samples were soaked in distilled water and ultrasonically irradiated at frequencies of 28, 45, and 100 kHz. Then, the amount of hydrogen generated was measured. We found that the low frequency of ultrasonic irradiation and the relatively small sample size accelerated the hydrolysis reaction MgH 2 + 2H 2 O = Mg(OH) 2 + 2H 2 + 277 kJ. In particular, the MgH 2 nanofibers exhibited the maximum hydrogen storage capacity of 14.4 mass% at room temperature at a frequency of 28 kHz (ultrasound irradiation). The results also experimentally validated that a combination of ultrasonic irradiation and MgH 2 hydrolysis is considerably effective for efficiently generating hydrogen without heating and adding any agent.

Effect of carbons (G and CFs), TM (Ni, Fe and Al) and oxides (Nb 2 O 5 and V 2 O 5 ) on hydrogen generation from ball milled Mg-based hydrolysis reaction for fuel cell

“…Kushch et al have demonstrated that hydrogen generation is improved via the interaction of magnesium with organic acids [12]. Ultrasonic irradiation was also considerably effective in improving the hydrolysis of MgH 2 [13]. Grosjean et al [14e16] showed that ball milling of pure mag nesium has no effect on the Mg reactivity for hydrolysis in pure water.…”

Chemical equilibrium analysis for hydrolysis of magnesium hydride to generate hydrogen

“…The need for compact, safe, and inexpensive hydrogen sources is a key issue for the development of fuel cells. One of the most attractive metal hydrides for hydrogen generation is magnesium hydride, (MgH 2 ) [7][8][9][10][11][12][13][14][15][16][17]. It is an especially promising material owing to its quite high hydrogen capacity of 7.6 mass% and relatively low production cost.…”

Unconventional Approaches to Hydrogen Sorption Reactions: Non‐Thermal and Non‐Straightforward Thermally Driven Methods

“…Ultrasonic irradiation has also been used to facilitate the generation of hydrogen from MgH 2 during hydrolysis, i. e. MgH 2 +H 2 O→Mg(OH) 2 +2H 2 . The fast generation of fresh surfaces due to particles’ collisions increased the reaction rate by 15 folds as compared to a non‐sonicated MgH 2 powder. In this case ∼ 5.2 wt % H 2 was released in just two hours.…”