Explore chapters and articles related to this topic
Burner Technology for Hydrogen Fuel
Published in Debi Prasad Mishra, Advances in Combustion Technology, 2023
Debi Prasad Mishra, Swarup Y. Jejurkar
Among the metal hydrides, compounds with elemental metals include magnesium hydride (MgH2) and aluminum hydride (AlH3). MgH2 requires high temperatures above 573 K for activation to overcome the thermodynamic and kinetic restrictions [4]. While storage could be as high as 7%, this is still a developing field. AlH3 bonds hydrogen rather weakly and could enable densities as high as 10% at 373 K. However, manufacture (also called regeneration) of AlH3 is very difficult [4]. Intermetallic hydrides and their processing are expensive [4]. Alanates are complex metal hydrides in which hydrogen is part of a complex (AlH4–) anion bonded with a cation (e.g. Na+). Due to the presence of light elements in alanates, gravimetric hydrogen capacities increase, although high temperatures are required for their activation [4].
Magnesium: A Potential Hydrogen Storage Medium
Published in Hussein K. Abdel-Aal, Magnesium, 2019
For a magnesium-hydride system, the potential as a reversible storage medium for hydrogen has led to significant improvements. This basically deals with the hydrogenation and dehydrogenation reaction kinetics. This can be partially achieved by reducing the particle size of the hydrides using ball milling.
Dependence of NiTi hydride stability by co-substitution by (Zr,Mg) onto Ti and (Cr,Cu) onto Ni: first-principles study
Published in Philosophical Magazine, 2020
S. Sebaihi, Y. Khelfaoui, M. Bououdina, I. Belabbas, Y. Bouhadda
Along other elements, Magnesium (Mg) stands as the most used for substitution/doping of NiTi compound. Owing to its high storage capacity of about 7.6 wt.%, low density and low cost, magnesium hydride (MgH2) has attracted much interest as potential and promising hydrogen storage medium [15–19]. However, its high hydrogen desorption temperature and high activation energy seriously limited its use in wide range of practical applications [1]. Therefore, Ni-Ti-Mg based hydrogen storage alloys have been largely investigated [1, 20, 21]. NiTi doped MgH2 materials displayed significant improvement in dehydrogenation and hydrogenation processes due to the addition of intermetallic Ti alloys as catalysts [10, 19].
A critical review for hydrogen application in agriculture: Recent advances and perspectives
Published in Critical Reviews in Environmental Science and Technology, 2023
Renyuan Wang, Xijia Yang, Xunfeng Chen, Xia Zhang, Yaowei Chi, Dan Zhang, Shaohua Chu, Pei Zhou
The saturation of hydrogen in water is about 1.6 ppm, which is difficult to reach saturation. To solve the problem of fast escape speed, researchers have provided several different supply methods (Figure 2). HRW, hydrogen rich nano bubble water (HNW) (Longna et al., 2021), magnesium hydride (MgH2) (Li, Liu, et al., 2020), NH3⋅BH3 (Zhao et al., 2021), and nano materials (Wang et al., 2021) are used to increase the release time of hydrogen, improve the residence time of hydrogen, and achieve the biological effect of hydrogen. At present, the most common method of supplying hydrogen is to use HRW, and the preparation of HRW is generally relatively simple. Hydrogen is introduced into water to produce hydrogen saturated solution with a concentration of (1.6 ppm, 0.8 mM) in water. Because the equipment for producing HRW is different, the concentration of HRW is also different. In addition, the methods of detecting hydrogen concentration are different, so it is difficult to determine the exact concentration of HRW in each study. In order to improve the retention time and biological effectiveness of hydrogen in water, HNW was developed (Longna et al., 2021). HRW was produced by a nano hydrogen bubble water generator. The diameter of nano bubbles is less than 500 nm, with high internal pressure and a large surface area. They also have a negatively charged surface. In conclusion, the characteristics of these bubbles are considered to contribute to the better dissolution of H2, which means that the H2 treatment time can be prolonged (Fan et al., 2020; Hancock et al., 2021). Similarly, nanomaterials also have a larger specific surface area, which some researchers utilize to store hydrogen and improve its supply time and efficiency. It has been reported to construct hollow mesoporous silica nanoparticles loaded with aminoborane (AB@hMSN) as a hydrogen releasing nanomaterial that can continuously supply hydrogen in plants for a long time. AB@hMSN shows high hydrogen carrying capacity and more lasting hydrogen release behavior in slightly acidic environments (Wang et al., 2021). Magnesium hydride in special formulations or coatings can release longer and more lasting H2 into the solution (Li, Li, et al., 2021). Use of MgH2 as a hydrogen donor, would leave magnesium, plus the chemical coating used to passivate the reaction as by-product which could lead to excessive intake of magnesium by plants and could cause adverse reactions. Furthermore, the hydrolysis of magnesium hydride will produce hydroxides which could improve the pH value in the system and have a negative impact on agriculture. There are also suggestions to use some organic acids to solve the problem of pH (Li, Liu, et al., 2020). However, applications of MgH2 need more evaluation and balance. The hydrogen donors currently used can make the storage and transportation of H2 safer. More evidence is needed to determine the safety and economic feasibility of using hydrogen in agricultural production.