Al-water Reaction Research Articles

Development of Cost-Effective Sn-Free Al-Bi-Fe Alloys for Efficient Onboard Hydrogen Production through Al–Water Reaction

Leveraging the liquid-phase immiscibility effect and phase diagram calculations, a sequence of alloy powders with varying Fe content was designed and fabricated utilizing the gas atomization method. Microstructural characterizations, employing SEM, EDS, and XRD analyses, revealed the successful formation of an incomplete shell on the surfaces of Al-Bi-Fe powders, obviating the need for Sn doping. This study systematically investigated the microstructure, hydrolysis performance, and hydrolysis process of these alloys in deionized water. Notably, Al-10Bi-7Fe exhibited the highest hydrogen production, reaching 961.0 NmL/g, while Al-10Bi-10Fe demonstrated the peak conversion rate at 92.99%. The hydrolysis activation energy of each Al-Bi-Fe alloy powder was calculated using the Arrhenius equation, indicating that a reduction in activation energy was achieved through Fe doping.

The Effects of the Secondary-Phase Distribution on the Dissolution Rate and Mechanical Properties of Soluble Al-Mg-Ga-In-Sn Alloys

The relationships between microstructure, dissolution, and mechanical properties of a soluble Al-Mg-Ga-In-Sn alloy are investigated in the present study. The findings demonstrate that the influence of low-melting-point elements on the dissolution of aluminum alloys can be attributed to the formation of secondary phases composed of Mg2Sn and In3Sn at grain boundaries and their participation in the Al–water reaction. After annealing, the secondary phases at grain boundaries transform from point-like and block-like discontinuous particles to strip-like continuous intergranular phases which envelop the Al matrix, resulting in a 29.8% reduction in the volume. These transformations increase the total contact area of the Al–water interface, amplifying the corrosion current of the annealed alloy to more than 30 times that of the as-cast alloy, thereby accelerating the dissolution rate. Unlike magnesium–lithium alloys, the soluble Al-Mg-Ga-In-Sn alloy exhibits a balanced strength, ductility, and dissolution rate, which presents it as a cost-effective, lightweight, structurally and functionally integrated material for the realm of petroleum exploration.

Hydrogen production from aluminum-water reactions at low Temperatures: based on an in-situ two powders of different particle sizes

To investigate the granule reaction of two-micron aluminum powders with water at low temperatures, differential scanning calorimetry was used to analyze the initial exothermic temperature. Additionally, adiabatic accelerated calorimetry was employed to study the exothermic reaction under adiabatic conditions. The hydrogen production and particle size variation were investigated in order to gain insights into the Al-water reaction in a reactor with no induction time. Through focused beam reflectance measurement analysis, it was observed that during the reaction process of Al-water, particle sizes initially increased and then decreased. Specifically, the particle size of 3 µm aluminum powder experienced a 189% increase after the reaction while 25 µm aluminum powder decreased by 29%. Ultimately, both types of particles reached similar final sizes around 13.89 µm. The process of Al-water reaction was explained and hydrogen production was analyzed, and the kinetic model was obtained.

Al-water reaction generates metastable aluminum cluster ions and their use in advanced oxidation processes

Our previous work indicated that hydroxyl radicals (HO•) exist in the filtrate of Al + acid + H2O2 system. In this work, the behind mechanism was investigated in detail and a new catalyst for advanced oxidation processes (AOPs) was found for the first time. It was revealed that metastable hexacoordinated aluminum cluster ions ([Al(H2O)63+]*), which are produced by Al-water reaction, can be as direct catalyst and decompose H2O2 into HO• in a full pH range (2.5–12.0), and efficiently degrade and mineralize organic pollutants without precipitates. Of course, their catalytic activity in acidic aqueous solution is higher than that in neutral and alkaline solutions. Furthermore, [Al(H2O)63+]* cluster ions have an excellent recyclability and their catalytic efficiency for generating HO• and degrading phenol and bisphenol A (BPA) did not decrease significantly even the cycling number was up to ten. Meanwhile, [Al(H2O)63+]* cluster ions have a long lifetime and can keep their catalytic activity for more than three months under ambient condition. The present finding shows that Al3+ ions can be also as a cost-efficient catalyst for AOP technology.

Novel porous Al-based composites for improved Al–water reaction performances by spark plasma sintering

A series of novel porous hydrogen-generation materials with the formulae Al–(BiO)2CO3, Al–4BiNO3(OH)2·BiO(OH), and Al–Bi2(SO4)3 were synthesized by ball milling and spark plasma sintering (SPS).

An overview of hydrogen production from Al-based materials

Abstract A profound overview of the recent development for on-time, on-demand hydrogen production from light metal-based hydrolysis is presented. Hydrogen energy is one of the clean and renewable energy sources which has been recognized as an alternative to fossil fuels. In addition, aluminum is the most suitable light activity metal for hydrolysis materials attributed to its safety, environmental friendliness, high-energy density, inexpensive, and low density with high strength ratio. In general, dense oxide films formed act as a barrier on aluminum surfaces. Accordingly, effective removal of the oxide film is a key measure in solving the Al–water reaction. In this review, recent advances in addressing the main drawbacks including high-purity aluminum with acid–alkali solutions, nano-powders of aluminum or composite with acid–base solutions, ball-milled nano-powders, alloying blocks, and gas atomization powders are summarized. The characteristics of these three technologies and the current research progress are summarized in depth. Moreover, it is essential to promote low-cost aluminum-based materials based on effective hydrogen production efficiency and explore ways for practical large-scale applications.

3D printing Al porous metamaterials with triply periodic minimal surfaces (TPMS) for hydrogen generation from Al-water reaction

Porous metamaterials with three-dimensional periodic minimal surfaces provide new inspirations to develop catalytic hydrogen generation materials owing to their excellent mass transfer. Herein, ten kinds of Al porous metamaterials with triply periodic minimal surfaces (TPMS) were prepared by selective laser melting (SLM) for hydrogen generation from Al–H2O reaction. The structures of TPMS type Al materials significantly affect their hydrogen generation performance, and the increased reaction area and liquid flow rate of TPMS structure can effectively improve the galvanical replacement reaction and rapidly form a Ni/Al battery, thus accelerating the hydrogen generation. Compared to conventional aluminum powder, the obtained Diamond type Al porous metamaterial exhibit short induction period, high hydrogen generation yield (81.4 % after 2 h reaction) and high hydrogen generation rate (468 mL-H2·min−1·gAl−1), easy activation of surface passivation film, good structural stability and convenience to recycle the materials after use. This work highlights a simple, low-cost and optional porous structure design strategy that can be applied in the field of safe and efficient catalytic hydrogen generation.

Modelling and assessment of hydrogen combined cycle power plant using aluminum-water reaction as renewable fuel

Owing to contamination of air and environmental hazards, the demand for sustainable fuels in power plants and other heat engines has climbed undeniably. Aluminum metal is classified among high energy density and low carbon content, which can be reacted with water and repeatedly released a large amount of heat and hydrogen. Since hydrogen is one of the zero-carbon and clean fuels, aluminum can be exploited as a promising energy-carrying and renewable source of energy. This paper is dedicated to the customization of two novel schemes of the combined cycle of power generation systems. The main components of the proposed integrated installations include a hydrogen turbine, gas turbine, multi pressure steam turbines, condenser, heat recovery steam generator and aluminum-water reactor, in which pressurized water absorbs produced heat of the reactor then superheated steam expands in steam turbines. Direct supplied hydrogen, which is generated from the Al-water reaction, expands in the hydrogen turbine and subsequently burns in the combustion chamber of the gas turbine. Hydrogen properties, consumed heat of reactor, generated powers, effects of streams pressure, energetic and exergetic productivity variation of both schemes were evaluated comparatively to ensure the best system performance along with the high net efficiency. According to the numerical analysis of the thermodynamic characteristics in steady state regime using EES software, the energy and energy efficiencies of scheme A were calculated to be 40.72% and 38.36%, besides in scheme B were 39.6% and 37.3%, respectively.

A hydrometallurgical perspective of aluminium dross recycling

To meet the objective of recovering aluminium from aluminium dross, it is essential to recycle it and save natural resources for posterity. Aluminium dross, a waste generated in an enormous quantity, is formed over the top surface of the molten bath when the surrounding oxygen comes into contact and forms a thick semi-solid layer of oxide. Pure metallic aluminium, which is entrapped within the oxides, is extracted using three different routes i.e., Pyrometallurgy, hydrometallurgy and hydrothermal. Metallic aluminium is recovered using the pyrometallurgical route by melting dross in a rotating furnace. In hydrometallurgy, chemical treatments of dross ensures the synthesis of a wide range of products. Newly developed technique like hydrothermal is used to produce zeolites, molecular sieves, and many other useful products. Apart from the solid products, gases like H2, NH3 and CH4 are produced by recycling dross when the Al-water reaction takes place in the presence of acids or alkalis. The present study comprises major aspects of dross recycling via the hydrometallurgical route.

Heat treatment enhancing the hydraulic fracturing performances of Al-Cu-Ga-In-Sn alloys

For improving the mechanical properties of Al-Ga-In-Sn alloys used to make dissolvable hydraulic fracturing tools, the effects of Cu and heat treatment on the microstructures and the Al-water reactivities of Alloys with Cu addition were investigated. The XRD and SEM were employed to investigate their microstructures. When the Cu content of alloys is above 1 wt%, Cu can dissolve in Al grains and form CuAl2 phases at Al grain boundaries, which can strengthen Al-Cu-Ga-In-Sn alloys. Cu will not form intermetallic compounds with Ga, In, and Sn, so liquid GIS phases are still observed at Al grain boundaries. The Cu and Ga atoms can diffuse from CuAl2 and GIS phases to Al grains during solution treatment. The CuAl2 phases can precipitate in Al grains during the artificial aging treatment of alloys. The increment of Cu, and Ga contents of Al grains, and the formed CuAl2 precipitates in Al grains will further strengthen the heat treatment alloys. Al-water reactivities of as-cast and heat treatment alloys were performed in different water temperatures. The solute Cu in Al grains and CuAl2 phases at Al grain boundaries will occupy the contacting sites for Al reacting with water, leading to H2 generation rates and H2 yield of reactivity of Cu-bearing alloys with water decreasing. After heat treatment, the increment of Cu content and CuAl2 precipitates in Al grains will occupy more contacting sites for Al reacting with water, resulting in a lower H2 yield of Al-water reaction of heat treatment alloys than that of as-cast alloys.

The effect of cracks and alloy phase conditions on the hydrolysis characteristics of Al-10Bi alloy powder (composites)

The Al-water reaction has attracted many attentions as it's a convenient method for on-demand hydrogen generation. Although a variety of additives have been demonstrated to promote the activity of Al, the most likely mechanism is simply the inference made from surface conditions and reaction characteristics. In this study, the activation of two kinds of active Al-10Bi alloys powders was prepared by both melting alloy and mechanical alloy methods. The activity of the as obtained powders was analyzed through various methods including XRD, SEM. 3D characterization of active Al powders was conducted using synchrotron X-ray tomography to reveal the inner structure of ball milled active Al alloy powders. Results show that ball milling could effectively introduce a large number of cracks both on the surface and the inner of powders. The number of cracks increased further after adding salt during ball milling. The relation between the inner structure of the Al alloys and their hydrolysis reaction products was also discussed. The specific surface area, the number and distribution of cracks alloy phase are all important factors that influence the hydrolysis reaction of the active alloy powder.

Insight of external ultrasound on energy-production acceleration from renewable Al-water reaction in Al-based metallic materials

Harnessing renewable metal fuels to supplement conventional bio-mass energy supply in certain areas is steadily demanded under the current global energy policy of CO2 emission reduction. The Al-to-power of a semi-cycle phase in the renewable conception by hydrolysis in aluminum-based metallic materials is viewed promising, yet surficial oxidation of aluminum matrices and the reaction by-products always deactivate the materials. Ultrasound induction in the hydrolysis process is proposed as an effective route to maintain a high-hydrolysis activity, but the trials on metallic materials are still blank. This article addresses the ultrasound accelerated hydrolysis of a representative aluminum-based metallic material, and the process was in-situ explored by high-speed photography to unravel the mechanism along with numerical modelling. The result shows that ultrasound fractures the particle material and exfoliates the reaction by-product layer to instantly expose more fresh aluminum, resulting in accelerated hydrogen generation. Using these discoveries, the employment of ultrasound in exploiting the hydrolysis of Al-based materials to meet the renewable metal-fuel demand is anticipated.

Enhanced hydrogen generation performances and mechanism of Al-water reaction catalyzed by flower-like BiOCl@CNTs

Al-based composites for hydrogen generation possess many advantages like relatively high H2 capacity and low cost, but their application is hindered by the easy formation of alumina membrane on the Al surface. In this work, a novel flower-like BiOCl@CNTs composite has been fabricated firstly, and then introduced into Al powders by ball milling (Al–BiOCl@CNTspowder) or ball milling combining spark plasma sintering (SPS) (Al–BiOCl@CNTsblock). It is found that the flower-like BiOCl@CNTs can significantly promote the H2 generation from Al-water reactions. Moreover, the performance of Al–BiOCl@CNTspowder for H2 generation can be further improved by SPS treatment. The Al-7 wt% BiOCl@CNTsblock exhibits excellent H2 release performance at room temperature with a H2 yield of 1172.9 mL·g−1 and a conversion yield of 92.7% compared with Al-7 wt% BiOCl@CNTspowder (864.9 mL·g−1 and 68.4%). Furthermore, the Al–BiOCl@CNTsblock demonstrates a favorable oxidation resistance, such as a H2 yield of 912.5 mL·g−1 even after being exposed to air for 35 days. The X-ray diffraction (XRD) analysis illustrates the formation of Bi, Bi2O3 and AlCl3in situ can enhance the Al-water reaction. Density functional theory calculation reveals doped Bi or Bi2O3 can promote charges transfer from Al to Bi or Bi2O3. And the doped Bi can enhance the adsorption of H2O on the Al surface to improve H2 generation of the Al–BiOCl@CNTs.

Soaked Al powder for efficient reduction of hexavalent chromium in neutral solution

Zero-valent Al (ZVAl) is a good electron donor, however its surface passive film impedes the electron release from inside to outside. In this work, a soaking procedure was adopted to activate ZVAl powder, which was used to remove hexavalent chromium (Cr(VI)) in neutral solution. The results indicated that the soaking process can greatly enhance Cr(VI) reduction due to a layer of loose and fine flocculent Al(OH)3 grains covering on Al particles, which adsorb Cr(VI) ions and speed up the electron release from inner Al. There is an optimal soaking time, which can promote ZVAl to reduce Cr(VI) to Cr(III) in neutral solution up to 90% within 2 min. Mechanism analyses revealed that adsorption of Cr(VI) ions on soaked Al surfaces are beneficial for them to receive more electrons from inner Al, leading to reduction of Cr(VI) ions favorable in competition with Al-water reaction, because these two processes consume electrons simultaneously. It was also found that the soaked Al powder has a good reusability and Cr(VI) removal is >70% when it was recycled for 5 times. This study provides an effective way for activating Al to reduce heavy metal ions in water.

A Facile Temperature-Controlled "Green" Method to Prepare Multi-kinds of High-Quality Alumina Hydrates via a Ga-In-Sn-Alloyed Aluminum-Water Interface Reaction.

The Al sheets alloyed by Ga-In-Sn are generally utilized to react with water for H2 production, while the valuable byproducts, i.e., alumina hydrates, have not been fully studied. In this work, through controlling the reaction temperature, three types of alumina hydrates, bayerite (40 °C), pseudo-boehmite (PB) (70–120 °C), and boehmite (130–160 °C), were successfully prepared based on a series of interface reactions and structural transformations. These alumina hydrates and their calcined products (alumina) possess high purity with a total impurity element content of <450 ppm, especially an extremely low sodium content (<21 ppm) and iron content (<52 ppm). Significantly, the obtained pseudo-boehmite displays excellent surface properties (specific surface area: 332.7 m2 g–1, pore volume: 0.3 cm3 g–1, and pore diameter: 3.6 nm), competitive to the current commercial SB powder by Sasol. This work not only deepens the understanding of the byproducts in a Ga-In-Sn-alloyed Al–water reaction but also establishes a facile “green” method oriented to industrial applications, which is promising for the linkage benefits of the hydrogen production industry.

Gas-liquid dual phase inhibition method for explosion accident of wet Al dust collection system based on KH2PO4

Metal dust has explosion risk in wet dust removal system. In this study, a gas–liquid dual phase explosion hydrogen inhibition method (EHIM) is proposed. The inhibitory effect of KH2PO4 on Al dust explosion in a dust removal pipe (gas phase) and Al dust hydrogen generation in a wet dust collector (liquid) is discussed separately and collectively. Adding 70% KH2PO4 totally inhibits the formation of Al dust explosion flames while inhibiting Al–water reaction in the wet dust collector at the same time. Inside the dust removal pipe, KH2PO4 acts in the initial stage of Al dust combustion and works as a pyrolysis endothermic coolant under 220℃–380℃; inside the aqueous solution of the dust collector, it generates AlPO4 with water and creates a film over the surface of the Al particles, which isolates water from Al, thus blocking Al–water reaction. Our new method offers a novel way of protecting the safety of wet dust removal systems.

Enhanced hydrogen production properties of a novel aluminum-based composite for instant on-site hydrogen supply at low temperature

Al-water reaction for hydrogen production faces the problems of long induction time and low conversion efficiency at low temperature (below 273.15 K), which has seriously limited its applications. To realize the instant hydrogen production of Al composites at low temperature, low melting point metals (Ga, In, Sn) and additives (NaCl, g-C3N4, LiH) were selected to prepare Al composites with high reactivity. Compared with the other Al composites, Al alloy/NaCl/LiH/g-C3N4 composites exhibit the enhanced low temperature hydrogen production performance in 23 wt% NaCl aqueous solution at 253.15 K. For all Al alloy/NaCl/LiH/g-C3N4 composites, the induction time of Al-water reaction at 253.15 K has completely eliminated. The highest hydrogen generation volume of 1095 mL·gAl−1 and the maximum hydrogen generation rate of 120 mL·gAl−1·s−1 were obtained for Al alloy/NaCl/1.5%LiH/g-C3N4 composite. It is proposed that LiH can induce Al-water reaction instantly starting at 253.15 K. The released heat and micro alkaline environment further promote the Al-water reaction and enhance the hydrogen conversion efficiency. In particular, g-C3N4 additive can improve the antioxidant properties of Al composites. This study provides a novel way for the development and application of Al composites in real-time hydrogen production at low temperature.

Enhanced Hydrogen Generation Performances and Mechanism of Al-Water Reaction Catalyzed by Flower-Like Biocl@Cnts

Enhanced Hydrogen Generation Performances and Mechanism of Al-Water Reaction Catalyzed by Flower-Like Biocl@Cnts

Preparation of high active Al-Ga-In-Sn alloy by alloying & ball milling method and its hydrogen production via water splitting

The Al-water reaction has attracted the attention for it’s a convenient method for producing hydrogen for fuel cell. In this study, High active Al alloy was prepared using a melting-mechanical crushing-mechanical ball milling method. The microstructure and phase compositions of Al alloy and reaction products were investigated via X-ray diffraction and scanning electron microscopy with energy dispersed X-ray. The different low-melting-point phases at the Al grain boundaries are related to the activation of the Al alloy. This work The H2 generation performance of the alloy prepared by this method can be significantly improved. The highest H2 generation rate and H2 conversion efficiency can reach 613mL.min-1 and 76.27% at room temperature.

Kinetics study of hydration reaction between aluminum powder and water based on an improved multi-stage shrinking core model

Hydrogen evolution and hydration kinetics of aluminum-particle-water reaction are investigated by a series of isothermal experiments. Morphology development of the Al particle during the hydration reaction process is characterized by SEM and XRD. An improved multi-stage analytical model has been developed and validated with the experimental data. The pre-exponential factor and activation energy for the alumina hydrolysis, Al-water reaction, and diffusion in the product layer are estimated based on the proposed model. The effects of growing particle size, formation and breakage of initial porous boehmite (AlOOH) layer, multi-stage reaction kinetics on the overall reaction rate are incorporated in the model. The study results show that the overall reaction rate is jointly controlled by simultaneous action of individual driving force, including mass transfer, chemical reaction and diffusion. The improved model enables the predictions of induction period and the evolution rate of hydrogen as a function of time, temperature and particle size.