Absorption Of Hydrogen Gas Research Articles

Estimation of the Heat Generation of the Metal Composite Powder Absorbing the Pulsed Flow of Hydrogen Gas

Anomalous heat generation during the exposure of nickel or palladium powder to hydrogen or deuterium gas injected with pulse flow is reported here. In our previous report in ICCF23, a temperature rise of about 10 K was observed after the absorption of 0.5 MPa hydrogen gas by Pd-Ni-Zr composite powder at 244. In these tests hydrogen gas was injected slowly. In this research, we added a solenoid valve to our reaction system with a small chamber, and we conducted a hydrogen gas absorption experiment with pulsed flow generated by a solenoid valve, up to 295 and 5 MPa. As a result, a temperature rise of over 100 K was observed. We also estimated the energy generated in the experiments. As a result, the heat release rate estimated is about 30 W, for a very small reaction chamber with only 3 g of Pd-Ni-Zr composite powder, even though we have done experiments during a very short period of fewer than ten minutes for absorption. The result indicates that the pulsed flow of hydrogen gas increases the amount of heat generation.

Temperature and Pressure Dependence of Anomalous Heat Generation Occurring in Hydrogen Gas Absorption by Metal Powder

As reported in previous papers, anomalous heat generation occurs when nickel or palladium powder is exposed to hydrogen or deuterium gas, while there is also a chemical effect that occurs when hydrogen (or deuterium) gas is absorbed by mixed oxides of Pd and Zr. Many experiments were previously conducted while increasing either initial temperature or pressure in the reaction chamber. In this report, we conducted fundamental experiments of hydrogen gas absorption by metal powder, while increasing both temperature and pressure simultaneously. The experiments were conducted in conditions up to 244°C and 0.5 MPa, using a small constant-volume reaction system developed by us. As a result, about 4 K of temperature rise was observed in the experiment using nickel powder, and about 10 K was observed in the experiment using Pd-Ni-Zr composite powder. In these experimental results, there are positive correlations between the temperature rise and both the initial temperature and loaded gas pressure. This result may show that the temperature rise is assisted by not only preheating but also gas absorption under higher pressure.

Performance analysis of LaNi5 added with expanded natural graphite for hydrogen storage system

This paper presents a comparative study of two cases of metal hydride hydrogen storage units working on (i) LaNi5 (ii) Compacts of LaNi5 incorporated with expanded natural graphite (ENG). It has been observed from the previous studies that the hydriding/dehydriding reactions eventually causes large strain changes, due to which the hydride forming metal alloys disintegrate and form a powder bed. Such reactor beds usually have a low thermal conductivity which minimizes the heat transfer phenomenon occurring during the absorption of hydrogen gas. Therefore, there is a need to implement heat augmentation methods to significantly enhance the thermal conductivity. The objective of this research is to present a 2-D numerical model using Finite Volume Method (FVM) and estimate the hydrogen storage performance of a cylindrical metal hydride bed for both the cases, i.e. powdered metal hydride bed and ENG compacts-based reactor bed at different values of inlet pressure and heat transfer fluid temperature. In this study, a detailed investigation on the absorption process reveals that reactor beds with compacted disks of LaNi5 and ENG demonstrate an enhanced effective thermal conductivity and efficient mass transfer. The simulation results show that a remarkable improvement in the heat transfer and hydrogen storage capacity with reduced absorption time can be achieved by using LaNi5 and ENG compacts. It was observed that the average reactor bed temperature dropped from 345.13 K to 337.37 K when the ENG based compacted disks was introduced into the reactor bed. Moreover, for supply pressure of 24 bar and fluid temperature of 293 K, the time taken to absorb hydrogen into the rector to achieve stabilized hydrogen storage capacity was estimated to be 446s and 232 s for the case of metal hydride and ENG compacts-based bed, respectively.

Iron oxide-Palladium core-shell nanospheres for ferromagnetic resonance-based hydrogen gas sensing

Interfaces of ferromagnetic transition metals such as Iron, Cobalt, and Nickel with non-magnetic palladium are of interest due to their unique magnetic and spintronic properties. These interfaces enable ferromagnetic resonance (FMR) based sensing of hydrogen gas. In the present work, we synthesized Fe3O4–Pd core-shell nanospheres via a one-pot synthesis method using the thermal decomposition of Fe3+ acetylacetonate in the presence of a reducing agent to produce the Fe3O4 core, followed by the reduction of a Pd2+ precursor to form the pure Pd shell. We found that our in-situ synthesized core-shell nanostructure is magnetically active and shows excellent H2 gas sensing properties. The effect of reversible hydrogen gas absorption on the magnetism of Fe3O4–Pd core-shell nanospheres was investigated. The hydrogen-induced ferromagnetic-resonance (FMR) peak shift amounted to 30% of the peak linewidth for the virgin state of the sample. In addition, in the presence of hydrogen gas, we observed a fully reversible decrease in the FMR peak linewidth by about two times. This was accompanied by a nearly doubling of the FMR peak height. Response and recovery times of about 2 and 50 s, respectively, were extracted from the measurements. All the data was collected using a mix of just 3% hydrogen in a nitrogen carrier gas.

Development and evaluation of nanostructured palladium thin film prepared by dealloying using dilute citric acid for hydrogen gas sensing application

The safe application of H2 gas requires a high-performance H2 gas sensing system. An attractive H2 gas sensor for industrial application which has H2 gas selectivity, high sensitivity, high response, high durability, small size, and low cost has not been developed yet. Durability is one of the most important problems in H2 gas sensors using Pd. This study focused on electric resistivity changes in metallic Pd with hydrogen gas absorption. Nanostructured palladium (NSPd) films for a hydrogen gas sensing material were fabricated by a dealloying method using dilute citric acid. Fabricated NSPd films exhibited a nanoscaled network structure or aggregated particle structure, a linear electric resistance change with hydrogen gas concentration, and high sensitivity compared to flat pure Pd films. Therefore, NSPd film is useful for hydrogen gas sensing applications and has both high sensitivity and low usage of the noble metal. Furthermore, we also revealed a degradation mechanism of pure Pd film due to repeated H2 gas exposure, and this phenomenon did not appear in the NSPd film. NSPd also showed a higher durability with repeated H2 gas exposure compared to pure Pd film. We concluded that NSPd is suitable for use as a practical H2 gas sensor due to its cost effectiveness and high sensing ability.

Numerical investigation of heat and mass transfer during hydrogen sorption in a mixture of AB2 – AB5 metal hydride for hydrogen storage

Abstract This paper presents the investigation of a two dimensional coupled model of heat and mass transfer in a mixture of AB2 – AB5 metal hydride (MH) systems of a cylindrical configuration during hydrogen sorption using COMSOL 5.3a commercial software. The parametric study on the sorption process has been studied with variation of heat transfer coefficient (HTC), and activation energy (AE) to understand the effects they have on the reaction kinetics of the sorption process. The simulation results demonstrate the importance of mutual dependence between the temperature propagation in the body of metal hydride, the absorbed concentration of the hydrogen gas, and the gas pressure for the absorption of hydrogen gas in metal hydrides. The decrease in the activation energy is found to have significant effect on the dynamic performances of hydrogen absorption in the MH reactors with an increased amount of hydrogen conversion, whilst the variation of heat transfer coefficient displayed insignificant change in hydrogen conversion. The simulated results show good agreement with the experimental results obtained from HYSA Systems and were implemented for use in the STILL RX60-30L electric forklift fuel cell applications designed by HYSA Systems in the University of the Western Cape.

Manipulation of the inverse spin Hall effect in palladium by absorption of hydrogen gas

The spintronic properties of a palladium thin film have been investigated in the presence of hydrogen gas in cobalt/palladium bilayers. Measurements of the inverse spin Hall Effect (ISHE) using cavity ferromagnetic resonance allow estimations of the spin Hall conductivity and spin diffusion length in both nitrogen and hydrogen gas atmospheres. Unwanted spin rectification effects are removed using a simple method of inverting the spin current direction with respect to the measurement setup. Absorption of hydrogen gas in the Pd layer at just 3% concentration results in a reduced ISHE voltage amplitude and bilayer resistance. Fitting the ISHE voltage against the Pd layer thickness demonstrates that the spin diffusion length decreases by 23% in the presence of a hydrogen gas. On the other hand, the results indicate that there is no significant change in the spin Hall conductivity of Pd due to hydrogen absorption.

Study on the gaseous and electrochemical hydrogen storage properties of as-milled Ce[sbnd]Mg[sbnd]Ni-based alloys

For gaining further insight into the involvement of the gaseous and electrochemical hydrogen storage properties of CeMg12-type alloys, partial substitution and ball milling were both used to synthesize the nanocrystalline and amorphous CeMg11Ni + x wt.% Ni (x = 100, 200) samples. This research aims at elucidating the functional roles of Ni content and milling time on samples' structure and hydrogen storage performance. X-Ray diffraction and high-resolution transmission electron microscope were used to reveal the micro constructions of alloys. To determine the gaseous hydrogen storage property, Sievert's apparatus and a thermal gravity analysis bonded with a H2 probe were adopted. The dehydrogenation activation energy was computed in the Kissinger method. The electrochemical performances of the as-milled samples were measured through a constant current system. Further researches showed that the electrochemical performance of as-milled samples had been dramatically improved by increasing Ni content. With milling duration lengthens, the gaseous hydrogen absorption capacity, gaseous hydriding rate and high rate discharge capability of samples reached the maximal values, but electrochemical discharge capacity and gaseous dehydriding rate always increased. The dehydrogenation activation energy decrease resulted by improving Ni percent and milling duration was deemed as the cause of the excellent gaseous kinetics of samples.

Highly ameliorated gaseous and electrochemical hydrogen storage kinetics of nanocrystalline and amorphous CeMg12-type alloys by mechanical milling

An attempt that effectively advances the quantity of hydrogen storage for CeMg12-type alloys was adopting a method of partial substitution of Mg in alloy by Ni. It is also employing mechanical ball-milling technology to prepare the nanocrystalline and amorphous CeMg11Ni + x wt.% Ni (x = 100, 200) alloys. And these two factors, Ni content after replacement as well as ball grinding time, affecting the structures and hydrogen storage dynamics belonging experimental alloys were studied systematically. Thereinto, characterization analysis on structures was using XRD, SEM and HRTEM. Then, the test of gaseous hydrogen storage performance was carried out through Sievert device as well as differential scanning calorimeter (DSC) that connected with H2 detector. Besides, Arrhenius and Kissinger equations were served as a convenient method for calculating the hydrogen desorption activation energy of alloys. Finally, it can adopt the automatic galvanostatic system to measure the electrochemical hydrogen storage performance. It is shown that, for experimental alloys, the more Ni content shows beneficial on the formation of glass, meanwhile, it also strikingly ameliorates both gaseous and electrochemical hydrogen storage dynamics properties. In addition, milling time varying brings a very large impact upon hydrogen storage properties of alloys. When the ball-grinding time is constantly changing, the gaseous hydrogen absorption capacity, gaseous hydriding rate as well as high-rate discharge ability (HRD) of alloys are able to appear the maximum values respectively. However, following the prolongation of milling time, both electrochemical discharge capacity and gaseous dehydrogenating rate raise all the time. The increase in Ni content and the prolongation of milling time can both enhance the gaseous hydrogen storage dynamics of alloys, inferring that their essence all can be attributed to the reduction of the activation energy of hydrogen desorption.

Numerical Study of Solid State Hydrogen Storage System with Finned Tube Heat Exchanger

Absorption of hydrogen gas inside the metal hydride (MH)-based hydrogen storage system generates significant amount of heat. This heat must be removed rapidly to improve the performance of the system which can be accomplished by embedding a heat exchanger inside the MH bed. In this article, a tubular shape MH system, equipped with a heat exchanger consisting of copper tube and pin fin is presented. A detailed 3D mathematical model is developed using COMSOL Multiphysics 4.3b for the numerical study of absorption and desorption processes inside the storage system. Impact of various operating and geometric parameters on the charging time of the storage system has been examined. It is observed that these geometric and operating parameters influence the charging time of the storage system. In the last, the impact of heat exchanger material on the performance of the storage system is explored. It is found that aluminum made heat exchanger is the best for the storage systems. The absorption process is accomplished in 1152 s at the operating parameters of 15 bar, 298 K, and 6.75 lit/min. This numerical work suggests that the efficient design of storage system is very important for rapid absorption and desorption of hydrogen.

Structure and hydrogen storage performances of La–Mg–Ni–Cu alloys prepared by melt spinning

The (Mg24Ni10Cu2)100-xLax(x = 0, 5, 10, 15, 20) alloys were prepared adopting the method of melt spinning technology. Adding La brings on the formation of secondary phases of La2Mg17 and LaMg3, while it does not change the major phase of Mg2Ni. Originally, there already have nanocrystals and amorphous structures in the experimental alloys, and the addition of La is more conducive to the formation of glass. With adding La in as-spun alloys, the gaseous hydrogen absorption capacity was significantly reduced, but it markedly improved their hydriding rates. Adding La and melt spinning considerably enhanced the dehydriding rate, the reason for which is the decrease of activation energy incurred by adding La and melt spinning. In addition, the discharge capacity of the alloys were able to reach a maximum value during La content varying, and it obviously increased with spinning rate rising.

Effect of half substitution of R (R = Nd, Gd and Er) for Ca on crystal structure and hydrogen storage properties of CaMgNi4

The effect of half substitution of R (R = Nd, Gd and Er) for Ca in CaMgNi4 compound on crystal structure and hydrogen storage properties was investigated. It was found that R0.5Ca0.5MgNi4 compounds have the C15b-type MgCu4Sn structure. The half substitution leads to the improvement of gaseous hydrogen absorption−desorption thermodynamics. Furthermore, each R0.5Ca0.5MgNi4 alloy electrode shows better cycle stability and high-rate discharge performance than CaMgNi4, especially in the case of half substitution of Nd.

Impact of Hydrogen Gas on the Inverse Spin Hall Effect in Palladium/Cobalt Bilayer Films

The influence of hydrogen gas absorption on the inverse spin Hall effect (iSHE) is measured in palladium/cobalt bilayer films. The iSHE is driven by ferromagnetic resonance in the Co layer and manifests as a dc voltage across the Pd layer. In the presence of hydrogen gas, the iSHE peak shifts downward in applied field together with the ferromagnetic resonance absorption peak for the material. In parallel, an increase in the iSHE peak height and width is measured.

Kinetics of Hydrogen Absorption and Desorption in Titanium

Titanium is reactive toward hydrogen forming metal hydride which has a potential application in energy storage and conversion. Titanium hydride has been widely studied for hydrogen storage, thermal storage, and battery electrodes applications. A special interest is using titanium for hydrogen production in a hydrogen sorption-enhanced steam reforming of natural gas. In the present work, non-isothermal dehydrogenation kinetics of titanium hydride and kinetics of hydrogenation in gaseous flow at isothermal conditions were investigated. The hydrogen desorption was studied using temperature desorption spectroscopy (TDS) while the hydrogen absorption and desorption in gaseous flow were studied by temperature programmed desorption (TPD). The present work showed that the path of dehydrogenation of the TiH2 is d®b®a hydride phase with possible overlapping steps occurred. The fast hydrogen desorption rate observed at the TDS main peak temperature were correlated with the fast transformation of the d-TiH1.41 to b-TiH0.59. In the gaseous flow, hydrogen absorption and desorption were related to the transformation of b-TiH0.59 Û d-TiH1.41 with 2 wt.% hydrogen reversible content.

Hydrogen storage behavior of nanocrystalline and amorphous La–Mg–Ni-based LaMg12-type alloys synthesized by mechanical milling

Nanocrystalline and amorphous LaMg11Ni+x% Ni (x=100, 200, mass fraction) alloys were synthesized by mechanical milling. The electrochemical hydrogen storage properties of the as-milled alloys were tested by an automatic galvanostatic system. The gaseous hydrogen absorption and desorption properties were investigated by Sievert's apparatus and differential scanning calorimeter (DSC) connected with a H2 detector. The results indicated that increasing Ni content significantly improves the gaseous and electrochemical hydrogen storage performances of the as-milled alloys. The gaseous hydrogen absorption capacities and absorption rates of the as-milled alloys have the maximum values with the variation of the milling time. But the hydrogen desorption kinetics of the alloys always increases with the extending of milling time. In addition, the electrochemical discharge capacity and high rate discharge (HRD) ability of the as-milled alloys both increase first and then decrease with milling time prolonging.

Highly improved hydrogen storage capacity and kinetics of the nanocrystalline and amorphous PrMg12-type alloys by mechanical milling

Nanocrystalline and amorphous PrMg11Ni + x wt.% Ni (x = 100, 200) alloys were synthesized by mechanical milling. Effects of Ni content and milling duration on the structures, hydrogen storage capacity and kinetics of the as-milled alloys were investigated systematically. The structures were characterized by XRD and HRTEM. The hydrogen desorption activation energy was calculated by using Kissinger method. The results show that increasing Ni content dramatically improves the electrochemical discharge capacity of the as-milled alloys. Furthermore, the variation of milling time has a significant impact on the kinetics of the alloys. As the milling time increased, the high-rate discharge ability (HRD), gaseous hydrogen absorption capacity and hydrogenation rate increased at first but decreased finally, while the dehydrogenation rate always increased.

Hydrogen Storage Properties of as-Cast La1-xSmxMgNi3.6 -Co0.4 (x = 0∼0.4) Alloys

La 1- x Sm x MgNi 3.6 Co 0.4 ( x = 0∼0.4) alloys were prepared by a vacuum intermediate frequency induction furnace with a high purity helium gas as the protective atmosphere. The effects of partially substituting Sm for La on the phase structure, morphology and hydrogen storage properties of the alloys were investigated. The detections of XRD and SEM reveal that the as-cast alloys contain two phases, LaMgNi 4 and LaNi 5 . The hydrogen storage capacity (wt%) of the alloys decreases with increasing Sm content, namely 1.859, 1.707, 1.585, 1.578 and 1.471, corresponding the variation of x from 0 to 0.4. The P-C-T curves of the alloys show flat plateaus corresponding to the absorption/desorption pressure plateaus of the LaMgNi 4 hydride. Meanwhile, the enthalpy change (Δ H ) and entropy change (Δ S ) of the LaMgNi 4 hydrides for hydriding decrease from −40.37 kJ/mol ( x =0) to −26.99 kJ/mol ( x =0.4) and from −101.9 J·(mol/K) −1 ( x =0) to −77.56 J·(mol/K) −1 ( x = 0.4), respectively. The electrochemical measurement displays that the maximum discharge capacity of the alloy electrodes declines from 347 mAh/g to 270.5 mAh/g, which is similar to the trend of the gaseous hydrogen absorption capacity. On the contrary, the cycle stability of the as-cast alloys obviously improves with the Sm content increasing, which can be attributed to the facilitated corrosion resistance by Sm substituting.

Hydrogen Storage Thermodynamics and Dynamics of Nd–Mg–Ni-Based NdMg12-Type Alloys Synthesized by Mechanical Milling

Nanocrystalline and amorphous NdMg12-type NdMg11Ni + x wt% Ni (x = 100, 200) hydrogen storage alloys were synthesized by mechanical milling. The effects of Ni content and milling time on hydrogen storage thermodynamics and dynamics of the alloys were systematically investigated. The gaseous hydrogen absorption and desorption properties were investigated by Sieverts apparatus and differential scanning calorimeter connected with a H2 detector. Results show that increasing Ni content significantly improves hydrogen absorption and desorption kinetics of the alloys. Furthermore, varying milling time has an obvious effect on the hydrogen storage properties of the alloys. Hydrogen absorption saturation ratio (\(R_{ 1 0}^{\text{a}}\); a ratio of the hydrogen absorption capacity in 10 min to the saturated hydrogen absorption capacity) of the alloys obtains the maximum value with varying milling time. Hydrogen desorption ratio (\(R_{ 2 0}^{\text{d}}\), a ratio of the hydrogen desorption capacity in 20 min to the saturated hydrogen absorption capacity) of the alloys always increases with extending milling time. The improved hydrogen desorption kinetics of the alloys are considered to be ascribed to the decreased hydrogen desorption activation energy caused by increasing Ni content and milling time.

Effect of nanostructure and partial substitution on gas absorption and electrochemical properties in Mg2Ni-based alloys

Mg2Ni-based alloys have been intensively investigated as gaseous hydrogen absorption materials and negative electrode materials for Nickel-Metal Hydride (Ni–MH) battery. In this work, three Mg2Ni-based samples (micrometer Mg2Ni, nanometer Mg2Ni and nanometer Mg2Ni0.75Cu0.25) were synthesized from Mg, Ni and Cu nanoparticles and commercially available micrometer Ni particles. The metal nanoparticles were fabricated by hydrogen plasma metal reaction technique. The structure and morphology of these three Mg2Ni-based samples were studied. Gaseous hydrogen absorption and electrochemical properties of these samples were investigated and compared. Amongst these three samples, the nanometer Mg2Ni shows best gas absorption kinetics of 3.0 wt.% in 1 min under 4 MPa hydrogen at 623 K; the nanometer Mg2Ni0.75Cu0.25 sample shows a highest first cycle electrochemical capacity of 346 mAh/g. The effect of nanostructure and partial substitution on gas absorption and electrochemical performance was clarified.

Effect of elemental substitution on the structure and hydrogen storage properties of LaMgNi4 alloy

Intermetallic compounds with the nominal formula LaMgNi3.6M0.4 (M=Ni, Co, Mn, Cu, Al) were prepared through induction melting, and the structure and hydrogen storage properties of the resultant alloys were extensively investigated. Results showed that the alloys exhibit sizable hydrogen absorption capacity and that elemental substitution significantly influences their microstructure and hydrogen storage properties. The discharge capacities of the alloy electrodes decrease in the order Co>Ni>Al>Cu>Mn. Moreover, the electrochemical kinetics of the alloys depend on their microstructures and phase compositions. Smaller grain size is helpful to improve the electrochemical kinetics. The gaseous hydrogen absorption capacities of the alloys are approximately 1.7wt.% in the first hydrogenation process. Cracking caused by hydrogenation and dehydrogenation also significantly improves the hydrogen absorption kinetics of the alloy particles. The hydrogen storage capacities of the alloys rapidly decrease with increasing cycle number. This result is attributed to amorphisation of the LaMgNi4 phase during hydrogen absorption–desorption cycling (H2-induced amorphisation). Our findings provide new insights into the capacity degradation mechanism of La–Mg–Ni system hydrogen storage alloys that may improve their cycling stability.