scholarly journals Hydrogen generation by hydrolysis reaction using magnesium alloys with long period stacking ordered structure

2021 ◽  
Author(s):  
M. Legrée ◽  
V. Charbonnier ◽  
S. Al Bacha ◽  
K. Asano ◽  
K. Sakaki ◽  
...  
Keyword(s):  
Magnesium Alloys ◽  
Hydrogen Generation ◽  
Hydrolysis Reaction ◽  
Ordered Structure ◽  
Long Period

Hydrolysis of MgH2 in MgCl2 solutions as an effective way for hydrogen generation

2021 ◽  
pp. 38-52
Author(s):  
V. Berezovets ◽  
◽  
A. Kytsya ◽  
Yu. Verbovytskyy ◽  
I. Zavaliy ◽  
...  
Keyword(s):  
Hydrogen Generation ◽  
Strong Acid ◽  
Magnesium Hydride ◽  
Hydrolysis Reaction ◽  
Hydrolysis Rate ◽  
Reaction Yield ◽  
Buffer Solution ◽  
Passivation Film ◽  
Products Of Reaction ◽  
Hydrolysis Of

Magnesium hydride (MgH2) has a high hydrogen storage capacity (7.6 wt%) and the Mg element is abundant on the earth. Due to its strong reduction ability, even at room temperature it can provide the hydrogen yield reaching 15.2 wt% H (1703 mL/g) when interacting with water, which makes it very attractive for the application in supplying hydrogen for autonomous H energy systems. However, the hydrolysis reaction is rapidly inhibited by the Mg(OH)2 passivation layer formed on the surface of MgH2. In order to remove the passivation film and improve the efficiency of the MgH2 hydrolysis process, several methods including alloying, ball milling, changing the aqueous solution, have been successfully utilized. In this paper the process of hydrolysis of magnesium hydride in aqueous solutions of MgCl2 used as a promotor of the interaction has been studied in detail. It was found that the initial hydrolysis rate, pH of the reaction mixture, and overall reaction yield are all linearly dependent of the logarithm of MgCl2 concentration. It has been shown that pH of the reaction mixture in the presence of MgCl2 is well described by considering a system “weak base and its salt with strong acid” type buffer solution. Reference data for this hydrolysis reaction were also carefully analyzed. The mechanism and the kinetic model of the process of MgH2 hydrolysis in water solutions involved passivation of the MgH2 surface by the formed Mg(OH)2 precipitate followed by its repassivation have been proposed. The obtained after the hydrolysis reactions precipitates were studied using XRD and EDS. It was found also that the final products of reaction consist of Mg(OH)2 (brucsite type) and remaining MgH2. This fact shows that the formation of solid species such as MgCl2 xMgO yH2O at the studied conditions is unlikely and decreasing of pH the reaction mixture has a different nature.

Mg-based composites as effective materials for storage and generation of hydrogen for FC applications

2021 ◽  
pp. 53-80
Author(s):  
D. Korablev ◽  
◽  
A. Bezdorozhev ◽  
V. Yartys ◽  
J. Solonin ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Hydrogen Generation ◽  
High Energy ◽  
High Energy Density ◽  
Hydrolysis Reaction ◽  
Preparation Technique ◽  
Power Sources ◽  
Safety Issues ◽  
Renewable Power ◽  
Physical And Chemical

Today, hydrogen is considered as an ideal choice for storing and carrying energy produced by renewable power sources since it is renewable, eco-friendly and has a high energy density. However, due to the low hydrogen storage capacity, high cost and safety issues of the conventional storage methods, several challenges need to be resolved to effectively use hydrogen in mobile applications. Solid-state hydrogen storage in atomic form in hydrides is a promising method of storage for this purpose, particularly because a double amount of hydrogen can be produced via hydrolysis reaction of chemically active hydrides. Among the metal hydrides, magnesium hydride (MgH2) is considered to be one of the most attractive candidates. However, the hydrolysis reaction is rapidly hindered by the passivation layer formed on the surface of MgH2. In order to improve MgH2 hydrolysis efficiency various approaches have been applied. This paper reviews recent progress on the modifications of MgH2-based materials by adding different type of additives, including metals, oxides, hydroxides, halides and surfactants. The introduced additives possess different catalytic properties due to their intrinsic physical and chemical characteristics, and therefore can strongly influence the hydrolysis reaction of MgH2. The most promising results were obtained for various salt additives showing that the reaction rate depends mostly on the additive type rather than on concentration. The effect of preparation technique on the hydrolysis of MgH2 – MgCl2 composites was studied in detail. The obtained results indicate that efficient hydrolysis performance can be achieved by ball milling of the freshly synthesized MgH2 with 5 wt.% MgCl2 and 1 wt.% TiC–2TiB2 additives. The combination of the applied approaches exhibited a notable synergistic effect on the hydrogen generation.

Hydrogen Generation From Acetic Acid Catalyzed Magnesium Hydride Using an On-Demand Hydrogen Reactor

2016 ◽  
Author(s):  
Tien-Chien Jen ◽  
Joshua Adeniran ◽  
Esther Akinlabi ◽  
Chung-Hsing Chao ◽  
Yen-Hsi Ho ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Organic Acid ◽  
Hydrogen Generation ◽  
Magnesium Hydride ◽  
Hydrolysis Reaction ◽  
Hydrogen Yield ◽  
Acetic Acid Concentration ◽  
External Temperature ◽  
On Demand ◽  
Acid Catalyzed

This study reports an acetic acid catalyzed hydrolysis reaction for hydrogen generation from magnesium hydride (MgH2) using an on-demand hydrogen reactor. Acetic acid, a weak and benign organic acid, has been reported as a single catalyst in hydrolysis reaction for hydrogen generation using other substrates, but this is the first study where acetic acid has been employed as a catalyst in a magnesium hydride hydrolysis reaction for hydrogen generation. In this study, the effects of MgH2 weight, acetic acid concentration and external temperature on hydrogen generation from MgH2 were examined. The results of the hydrolysis reaction indicated that the weight of MgH2 was the major factor influencing hydrogen generation, followed by the concentration of acetic acid while the effect of external temperature was insignificant. Similarly, hydrogen yield was proportional to the weight of MgH2 with a reported maximum hydrogen yield at each weight been: 0.4g (∼ 0.07 L); 0.8 g (∼ 0.125 L) and 1.2 g (∼1.285 L). The successful use of acetic acid in the study reinforced the versatility of the on-demand hydrogen reactor and as a scalable technology for hydrogen generation.

Improvement of corrosion resistance of magnesium alloys for biomedical applications

2015 ◽  
Vol 33 (3-4) ◽  
pp. 101-117 ◽  
Author(s):  
Kai Chen ◽  
Jianwei Dai ◽  
Xiaobo Zhang
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Biomedical Applications ◽  
Mg Alloys ◽  
Localized Corrosion ◽  
Biodegradable Implants ◽  
Ordered Structure ◽  
Corrosion Rates ◽  
Long Period ◽  
Treatment Techniques

AbstractIn recent years, magnesium (Mg) alloys have attracted great attention due to superior biocompatibility, biodegradability, and other characteristics important for use in biodegradable implants. However, the development of Mg alloys for clinical application continues to be hindered by high corrosion rates and localized corrosion modes, both of which are detrimental to the mechanical integrity of a load-bearing temporary implant. To overcome these challenges, technologies have been developed to improve the corrosion resistance of Mg alloys, among which surface treatment is the most common way to enhance not only the corrosion resistance, but also the bioactivity of biodegradable Mg alloys. Nevertheless, surface treatments are unable to fundamentally solve the problems of fast corrosion rate and localized corrosion. Therefore, it is of great importance to alter and improve the intrinsic corrosion behavior of Mg alloys for biomedical applications. To show the significance of the intrinsic corrosion resistance of biodegradable Mg alloys and attract much attention on this issue, this article presents a review of the improvements made to enhance intrinsic corrosion resistance of Mg alloys in recent years through the design and preparation of the Mg alloys, including purifying, alloying, grain refinement, and heat treatment techniques. The influence of long-period stacking-ordered structure on corrosion behavior of the biodegradable Mg alloys is also discussed.

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