Hydrogen production from hydrolysis of magnesium wastes reprocessed by mechanical milling under air (original) (raw)
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Journal of Cleaner Production, 2021
Autonomous low-pressure hydrogen on demand system was found promising to supply fuel cell technology for light or short distance mobility applications. Among the various hydrogen production technologies, the hydrolysis reaction method of magnesium-based materials is one of the most suitable. Magnesium (Mg) powder ball milled with the simultaneous addition of graphite and nickel under Ar was used as the hydrolysis reagent for hydrogen production. The effects of the solution composition (i.e. NaCl, NH 4 Cl and HCl) and the temperature (i.e. from 0 C to 60 C) of the solution on the hydrolysis performances were discussed. The hydrolysis reaction was complete (i.e. yield ¼ 100%) in less than 5 minutes, except that performed at 0 C, regardless the hydrolysis solution. The activation energy of the reaction decreases with lowering the pH of the hydrolysis solution. Semi-quantitative analysis was performed to evaluate the variation of CH 4 , CO, CO 2 and moisture contents in the hydrogen produced by the hydrolysis. The exothermicity of the reaction and the composition of the hydrolysis solution showed a major impact on the purity of hydrogen. Under standard pressure and ambient temperature conditions, the hydrolysis of magnesium-based materials is considered as a clean hydrogen production technique. Our results should be taken as the starting point to evaluate the purity of the hydrogen produced by the hydrolysis of Mg-based materials according to the ISO standard 14687:2019.
Materials
A method for magnesium scrap transformation into highly efficient hydroreactive material was elaborated. Tested samples were manufactured of magnesium scrap with no additives, or 5 and 10 wt.% Devarda’s alloy, by ball milling for 0.5, 1, 2, and 4 h. Their microstructural evolution and reaction kinetics in 3.5 wt.% NaCl solution were investigated. For the samples with additives and of scrap only, microstructural evolution included the formation of large plane-shaped pieces (0.5 and 1 h) with their further transformation into small compacted solid-shaped objects (2 and 4 h), along with accumulation of crystal lattice imperfections favoring pitting corrosion, and magnesium oxidation with residual oxygen under prolonged (4 h) ball milling, resulting in the lowest reactions rates. Modification with Devarda’s alloy accelerated microstructural evolution (during 0.5–1 h) and the creation of ‘microgalvanic cells’, enhancing magnesium galvanic corrosion with hydrogen evolution. The 1 h milled...
Waste to Hydrogen: Elaboration of Hydroreactive Materials from Magnesium-Aluminum Scrap
Sustainability
Ball-milled hydroreactive powders of Mg-Al scrap with 20 wt.% additive (Wood’s alloy, KCl, and their mixture) and with no additives were manufactured. Their hydrogen yields and reaction rates in a 3.5 wt.% NaCl aqueous solution at 15–35 °С were compared. In the beginning of the reaction, samples with KCl (20 wt.%) and Wood’s alloy (10 wt.%) with KCl (10 wt.%) provided the highest and second-highest reaction rates, respectively. However, their hydrogen yields after 4 h were correspondingly the lowest and second-lowest percentages—(45.6 ± 4.4)% and (56.0 ± 1.2)% at 35 °С. At the same temperature, samples with 20 wt.% Wood’s alloy and with no additives demonstrated the highest hydrogen yields of (73.5 ± 10.0)% and (70.6 ± 2.5)%, correspondingly, while their respective maximum reaction rates were the lowest and second-lowest. The variations in reaction kinetics for the powders can be explained by the difference in their particle sizes (apparently affecting specific surface area), the cr...
2020 IEEE 11th International Conference on Mechanical and Intelligent Manufacturing Technologies (ICMIMT), 2020
Low-grade magnesium (Mg) waste from post-consumer products and production waste cannot be recycled efficiently and economically. This work addresses this challenge by converting this waste into hydrogen. Hydrogen (H2) offers a wide range of benefits and the greatest of them all is its ability and flexibility to be used as a green energy carrier. In this work Mg waste is re-melted, loaded on one side of a stainless steel and allowed to solidify at room temperature to form a galvanic Mg stainless steel couple. Mg reacts slowly with water and releases hydrogen at room temperature and this is followed by the formation of magnesium hydroxide on its surface. Stainless steel net is considered as a metallic catalyst and two acids as accelerators reacting with the couples separately. A set of couples were used to generate hydrogen in 3.5% by weight acetic acid (CH3COOH). The experimental results show that a mean accumulated H2 volume of 3.17-3.21 litres was produced in 3600 seconds. Another set of couples produced H2 in 1.5 wt. % of iron chloride (FeCl3). The results confirmed FeCl3 as an excellent hydrolysis reaction accelerator with stainless steel as an effective catalyst. On average, the reaction yielded 2700mL of H2 over 3600 seconds which appear to be substantially higher than the litres achieve when CH3COOH was considered as an accelerator.
Hydrogen reaction kinetics of Mg-based alloys synthesized by mechanical milling
Journal of Alloys and Compounds, 2006
The influence of mechanical milling of Mg-based mixtures on the structure and hydrogen sorption properties was investigated by measuring the rate of hydrogen absorption, nuclear magnetic resonance and X-ray diffraction. In order to separate different factors responsible for hydrogenation kinetics, we compare the results of milling of both pure Mg and the mixture of Mg with different metallic and oxide additives in argon at 77 K and in hydrogen atmosphere at room temperature, with the milling tools made of steel and brass. It was established that the role of grain size and different catalytic additives is considerable only for an initial formation of MgH 2 phase during mechanical activation in hydrogen. The most important effect of mechanical activation at the late stages of milling consists of the formation of a special structural state of the hydrogen-containing phase, independently on the type of the catalyst. The observed enhancement of the proton spin-lattice relaxation rate in the samples prepared by ball milling in hydrogen is attributed to the effect of paramagnetic centers which are an intrinsic feature of such a structural state.
Solid-State Conversion of Magnesium Waste to Advanced Hydrogen-Storage Nanopowder Particles
Nanomaterials, 2020
Recycling of metallic solid-waste (SW) components has recently become one of the most attractive topics for scientific research and applications on a global scale. A considerable number of applications are proposed for utilizing metallic SW products in different applications. Utilization of SW magnesium (Mg) metal for tailoring high-hydrogen storage capacity nanoparticles has never been reported as yet. The present study demonstrates the ability to produce pure Mg ingots through a melting and casting approach from Mg-machining chips. The ingots were used as a feedstock material to produce high-quality Mg-ribbons, using a melting/casting and spinning approaches. The ribbons were then subjected to severe plastic deformation through the cold rolling technique. The as-cold roll Mg strips were then snipped into small shots before charging them into reactive ball milling. The milling process was undertaken under high-pressure of pure hydrogen gas (H2), where titanium balls were used as mi...
Solid State Phenomena, 2012
Magnesium is light, abundant and it can store up to 7.6 wt. % of hydrogen forming MgH2 and accordingly it is a promising material for hydrogen storage. Processing of Mg-based mixtures by high-energy ball milling (HEBM) can produce materials with high level H-sorption properties. In the present report, we display and compare the effects of different nanocrystalline additives (MgF2, Fe, NbH0,89, FeF3, VF3) on the formation of MgH2 by reactive milling. The H-desorption behavior of the as-prepared nanocomposites is also evaluated. A combined catalytic effect is observed due to the synergic action of MgF2 and Fe (or NbH0,89) on the hydrogenation rate during processing. The transition metal fluorides promote as well the MgH2 synthesis. By using more energy-intensive milling conditions and adequate additives in given proportions (e.g. 5 mol. % FeF3), is shown to be very effective for a full and fast synthesis (4 h) of MgH2 by reactive milling.
Waste Mg-Al based alloys for hydrogen storage
International Journal of Hydrogen Energy, 2018
Magnesium has been studied as a potential hydrogen storage material for several decades because of its relatively high hydrogen storage capacity, fast sorption kinetics (when doped with transition metal based additives), and abundance. This research aims to study the possibility to use waste magnesium alloys to produce good quality MgH2. The production costs of hydrogen storage materials is still one of the major barriers disabling scale up for mobile or stationary application. The recycling of magnesium-based waste to produce magnesium hydride will significantly contribute to the cost reduction of this material. This study focuses on the effect of different parameters such as the addition of graphite and/or Nb2O5 as well as the effect of milling time on the material hydrogenation/de-hydrogenation performances. In addition, morphology and microstructural features are also evaluated for all the investigated materials.
Hydrogen Generation by the Hydrolysis of MgH2
Materials Science, 2020
UDC 546.3-19′11 Magnesium hydride (MgH 2) is a hydrogen-rich compound generating significant amounts of hydrogen in the process of hydrolysis, i.e., in the course of its chemical interaction with water or with aqueous solutions. This process is of great interest for the on-site hydrogen generation aimed at application of H 2 as a fuel for PEM fuel cells. We propose a review of recent reference publications in the field and also present the results of our own research. The increase of the rates of H 2 release and the completeness of transformation of MgH 2 are two important goals, which can be attained by optimizing the size of the powders of MgH 2 by ball milling, by using catalysts added to MgH 2 and to aqueous solutions, and by increasing the interaction temperature. The effect of these parameters on the degree of conversion and the rates of hydrogen evolution are analyzed in detail and the best systems to reach the efficient hydrolysis performance are identified. The mechanism of catalytic hydrolysis is proposed, while further improvements of the process of hydrolysis are required and additional studies of this important topic are needed.