Hydrogen Saturation Research Articles

Effect of carbon-supported rare earth oxide catalysts on the microstructure, hydrogen storage kinetics, and thermodynamics of Mg-La-Ni alloys

In this study, using an improved chemical vapor deposition carbonization method, Eu2O3@C, PrO1.83@C, and La2O3@C composite catalysts were successfully synthesized and incorporated into Mg96La3Ni alloys via ball milling. These catalysts significantly enhanced the hydrogen storage properties of the alloys, particularly in terms of hydrogenation kinetics. Among the catalysts, PrO1.83@C demonstrated the most significant improvement. At 360 °C, the Mg96La3Ni alloy containing 3 wt% PrO1.83@C achieved a 75.1 % hydrogenation saturation ratio within 2 min and released 3 wt% H2 in 3.1 min. While the catalysts did not significantly alter the alloy's thermodynamics, they substantially reduced the dehydrogenation activation energy. The addition of 3 wt% Eu2O3@C, PrO1.83@C, and La2O3@C lowered the activation energy barriers to 116.6, 101.4, and 114.8 kJ/mol H2, respectively, compared to 121.67 kJ/mol H2 for the pristine Mg96La3Ni alloy. This enhancement is attributed to the synergistic effects of the "hydrogen pump" mechanism of rare earth hydrides and the abundant active sites provided by the carbon component, which collectively promote faster hydrogen diffusion and nucleation reactions.

NiMo-MMO catalyst derived from LDHs precursors toward the deep hydrogenation of pyrene

A series of Ni-based catalysts were prepared via structural topological transformation from the Ni@Al2O3 layered double hydroxides (LDHs) precursors, and applied for the deep catalytic hydrogenation saturation of pyrene in a high-pressure reactor. The pore structures, active species dispersion, surface morphology, amount and type of acid of the prepared catalysts were characterized by BET, XRD, SEM, TEM, XPS, SEM, NH3-TPD and Py-IR. We studied the influence of physicochemical properties of Ni-based catalysts on the regularity and mechanism of deep hydrogenation of pyrene. Meanwhile, the synergy between Ni and Mo, and the interaction between active metals and support were discussed to further reveal the constitutive relationship during the hydrogenation reaction of pyrene. The results of the evaluation of the catalytic hydrogenation of pyrene show that the as-prepared NiMo mixed metal oxide (MMO) catalyst showed excellent catalytic activity: ∼95% pyrene conversion, 90.12% for the selectivity of deep hydrogenation products (hexahydropyrene, decahydropyrene and hexadecahydropyrene). It was expected that the successfully preparation and utilization of NiMo-MMO catalyst could provide a theoretical basis for the design of this kind of catalysts for deep catalytic hydrogenation of polycyclic aromatic hydrocarbons (PAHs).

Investigation of hydrogen storage properties on the Mg-La-Ni alloy compounded with C@Pr2O3 composite catalyst

To explore the effect of C@Pr2O3 on the hydrogen storage performance of Mg-La-Ni alloy. In experiment, a nanostructured composite catalyst C@Pr2O3 was prepared using chemical blowing carbonization. The microstructures of the catalyst and alloy powder were characterized using techniques such as transmission electron microscope, high-resolution transmission electron microscopy, scanning electron microscope, and selective region electron diffraction. Hydrogen storage properties of the alloy were evaluated using Pressure-composition-temperature equipment, and it was observed that the addition of the catalyst significantly enhanced the hydrogen kinetics of the alloys. At 320 ℃, the two-minute hydrogen saturation ratio of Mg96NiLa3 +5 wt% C@Pr2O3 was 80.65 %, Mg96NiLa3 +7 wt% C@Pr2O3 releases 3 wt% H2 at 340 °C for 6 min. This can be attributed to the addition of nanoscale C and catalyst Pr2O3, which improved the hydrogen kinetics of the alloys. The dehydrogenation activation of Mg96NiLa3 +5 wt%C@Pr2O3 is 85.2 kJ/mol, enhancing the rate of hydrogen release while simultaneously reducing the activation energy required for dehydrogenation of the alloy. The enthalpy of hydrogen absorption of Mg96NiLa3 +5 wt% C@Pr2O3 was 72 KJ/mol. However, the thermodynamic properties of the alloy were still not satisfied with the requirements of practical application.

Molecular transformation of heavy oil during slurry phase hydrocracking process: influences of operational conditions

The influences of reaction temperature, duration, pressure, and catalyst concentration on the molecular transformation of residual slurry phase hydrocracking process were investigated. The molecular composition of the heteroatom compounds in the residue feedstock and its upgrading products were characterized using high-resolution Orbitrap mass spectrometry coupled with multiple ionization methods. The simultaneous promotion of cracking and hydrogenation reactions was observed with increasing of the reaction temperature and time. Specifically, there was a significant increase in the cracking degree of alkyl side chain, while the removal of low-condensation sulfur compounds such as sulfides and benzothiophenes was enhanced. In particular, the cracking reactions were more significantly facilitated by high temperatures, while an appropriately extended reaction time can result in the complete elimination of the aforementioned sulfur compounds with a lower degree of condensation. Under conditions of low hydrogen pressure and catalyst concentration, the products still exhibit a high relative abundance of easily convertible compounds such as sulfoxides, indicating a significant deficiency in the effectiveness of hydrogenation. The hydrogen pressure exhibits an optimal value, beyond which further increments have no effect on the composition and performance of the liquid product but can increase the yield of the liquid product. At significantly high catalyst concentration, the effect of desulfurization and deoxidation slightly diminishes, while the aromatic saturation of highly condensed compounds was notably enhanced. This hydrogenation saturation effect cannot be attained through manipulation of other operational parameters, thereby potentially benefiting subsequent product processing and utilization. This present study demonstrates a profound comprehension of the molecular-level residue slurry phase hydrocracking process, offering not only specific guide for process design and optimization but also valuable fundamental data for constructing reaction models at the molecular level.

Study on the mechanical properties of X80 pipeline steel under pre-charged high-pressure gaseous hydrogen

Hydrogen embrittlement (HE) is a significant challenge to the safe operation of hydrogen-blended natural gas pipelines. The mechanical properties of X80 steel were studied after H2 pre-charging followed by mechanical properties tests and fracture morphologies observation. Results indicated that the hydrogen saturation time of X80 steel was roughly 48 h. H2 pre-charging induced a decline in strength, plasticity, and fatigue properties, while hydrogen-assisted fatigue crack growth occurred during the early stage of fatigue crack growth rate tests. Additionally, the fracture morphologies transited from primary microvoid coalescence to a mixed mode characterized by ductile dimples and quasi-cleavage planes with increasing hydrogen. The HE susceptibility increased with increasing hydrogen partial pressure and decreasing loading frequency, but there existed a critical value (6 × 10−7 s−1) for the strain rate effect on the HE susceptibility. Under H2 pre-charging conditions, the predominant HE mechanism was the hydrogen-enhanced local plasticity (HELP) mediated hydrogen-enhanced decohesion (HEDE) mechanism.

Experimental study and correlation analysis for the effect of hydrogen pressure on biomass fluidized hydropyrolysis under N2-H2 mixed atmosphere

The utilization of fluidized bed reactors for the biomass hydropyrolysis vapor upgrading is essential in the conversion of biomass into liquid fuels. Conducting pyrolysis experiments in fluidized bed reactors with a N2-H2 mixed atmosphere is advantageous for system operation as it allows for lower minimum operating velocities, enhances pyrolysis efficiency, and reduces heat loss. This research examines the impact of hydrogen pressure in a bubbling fluidized bed reactor using a N2-H2 mixed carrier gas, with poplar wood as the feedstock and Ni-Moγ/Al2O3 as the catalyst. Through experimental and correlation analyses, significant relationships are observed between hydrogen pressure and the production of liquid and gas-phase products, with varying effects attributed to changes in hydrogen ratio and reaction pressure. Elevated hydrogen ratios facilitate secondary reactions such as the CO2 hydrogenation, resulting in a decline in CO2 production and an elevation in the yields of light hydrocarbons and aqueous phase products. Augmenting the reaction pressure to enhance hydrogen pressure aids in promoting hydrogen saturation and cracking, and amplifying the hydrogen pressure through an increase in the reaction pressure at a specific hydrogen ratio proves more efficacious in enhancing both the quantity and quality of bio-oil produced. In the context of poplar hydropyrolysis vapor upgrading utilizing a Ni-Moγ/Al2O3 catalyst, a hydrogen ratio of 50 % at a reaction pressure of 1.5 MPa emerged as the preferred option for achieving a 12 % bio-oil yield with a moderate average bio-oil carbon number and satisfactory hydrogenation levels. This comprehensive investigation examines the influence of hydrogen pressure on biomass hydropyrolysis, highlighting variations in the impacts of changes in hydrogen ratio and reaction pressure on pyrolysis results. These results offer a theoretical framework for discerning distinctions between hydropyrolysis investigations carried out in pure hydrogen atmospheres versus mixed N2-H2 atmospheres.

Phenomenal study of microbial impact on hydrogen storage in aquifers: A coupled multiphysics modelling

Underground hydrogen storage (UHS) has been considered as an integral part of energy transition from fossil fuels to renewable sources. Porous aquifers can serve as typical sites for this purpose due to their worldwide distribution and huge storage capacity. However, the diverse microbial species that inhabit the aquifers are known to be able to catalyze in-situ biochemical reactions within the hosting rock. These reactions can normally lead to microbial consumption of hydrogen, microbial clogging of pore space and thus affect hydrogen injection and withdrawal rates as reported in the literature. So far, these phenomena have been widely reported but rarely quantified. In this study, we build a coupled hydrological-mechanical-chemical-biological (HMCB) multiphysics model to simulate these microbe-related processes during UHS in aquifers. The model consists of a complete set of partial differential equations to describe: (1) rock deformation; (2) water-hydrogen two-phase flow; (3) microbes and dissolved hydrogen transport; (4) mineral dissolution/precipitation; and (5) microbial activities involving adsorption/desorption and growth/decay. All these processes are linked together through the porosity/permeability models which consider the joint impacts of microbial clogging, mineral dissolution/precipitation and effective stress. This multiphysics model is verified against laboratory biochemical reaction data and microbial transport data. Then, the verified model is used to investigate the impacts of iron-reduction bacteria (IRB) activities on UHS in aquifers. Based on the simulation results, it can be concluded that (1) hydrogen saturation at the top surface of the aquifer is the greatest while microbial activities surrounding the injection well is stimulated the most; (2) microbial activities influence the initial few cycles of hydrogen injection and withdrawal but the impacts gradually diminish with the dissolution of Fe2O3; (3) hydrogen recovery efficiency is degraded due to the combined effects of hydrogen consumption, water production and microbial clogging with the microbial clogging impact being the most significant; and (4) effective stress impacts aquifer permeability throughout UHS operations while microbial clogging influences it in the initial few cycles. For mineral dissolution/precipitation, the impact can be neglected.

In Situ and Continuous Decoding Hydrogen Generation in Solar Water-Splitting Cells.

Photoelectrochemical (PEC) water splitting is gaining recognition as an effective method for producing green hydrogen. However, the absence of in situ, continuous decoding hydrogen generation tools hampers a detailed understanding of the physics and chemistry involved in hydrogen generation within PEC systems. In this article, we present a quantitative, spatiotemporally resolved optical sensor employing a fiber Bragg grating (FBG) to probe hydrogen formation and temperature characteristics in the PEC system. Demonstrating this principle, we observed hydrogen formation and temperature changes in a novel cappuccino cell using a BiVO4/TiO2 photoanode and a Cu2O/CuO/TiO2 photocathode. Our findings demonstrate that FBG sensors can probe dynamic hydrogen formation at 0.5 s temporal resolution; these sensors are capable of detecting hydrogen concentrations as low as 0.6 mM. We conducted in situ and continuous monitoring of hydrogen and temperature to ascertain various parameters: the rate of hydrogen production at the photocathode surface, the time to reach hydrogen saturation, the distribution of hydrogen and temperature, and the rate of hydrogen transfer in the electrolyte under both external bias and unbiased voltage conditions. These results contribute valuable insights into the design and optimization of PEC water-splitting devices, advancing the in situ comprehensive monitoring of PEC water-splitting processes.

Rational design of semi-interpenetrating network based on hyperbranched polyglycerol grafted MXene/polyurethane–epoxy for compressed hydrogen storage

Hydrogen (H2) energy has emerged as a promising alternative in the automotive sector to replace fossil fuel; however, its storage with volumetric efficiency remains a challenge. The latest type IV storage vessel featuring a polymeric liner with composite overwrap incurs hydrogen saturation, which eventually causes failure. To prevent the H2 dissolution in the liner, we have developed a barrier coating comprised of polyurethane/epoxy semi-interpenetrating network (S-IPN) combined with hyperbranched polyglycerol grafted MXene (h-MXene). The hyperbranched structure facilitated the dispersion of MXene in the coating solution by enhancing the exfoliation and improved the polymer filler interaction by forming covalent and H-bonding through end-terminal hydroxyl groups. Leveraging the dense network of S-IPN combined with the dispersed layer structured h-MXene significantly increased the tortuosity of the spray-coated barrier film applied to the nylon 6 liner. The coating exhibited a 90 % reduction in the H2 gas permeability at only 2 wt% h-MXene concentration, which further improved to above 98 % at 10 wt% loading. Additionally, the h-MXene considerably improved the adhesion with the liner even in a highly stretched condition, signifying the durability of the coating under cyclic pressurization and depressurization of the storage vessel.

Unveiling the Ni2+ coordination sites effect of Ni-Al spinel catalysts for phenanthrene hydrogenation saturation

Nickel–aluminum (Ni–Al) spinel catalysts with distinct Ni/Al molar ratios were synthesized to construct Ni2+ coordination sites. Owing to the favorable distribution of Ni2+ coordination sites and the presence of suitable concentration of Ni2+ in octahedral sites, Ni/Al-0.725 catalyst achieved an 86.1 % average yield of perhydrophenanthrene, which was higher than that obtained with Ni/Al-0.25 (6.3 %). Characterization results indicated that Ni2+ of the Ni/Al-0.725 catalyst was present in octahedral sites and ∼ 40.4 % Ni2+ was reduced to Ni, whereas the active Ni metal of Ni/Al-0.25 catalyst mainly comprised Ni2+ occupying tetrahedral sites as precursors. Furthermore, the Ni/Al-0.725 catalyst exhibited the smallest Ni particle size (2.82 nm) and the largest Ni available surface (19.62 m2/gsample), which helped alleviate competitive adsorption among aromatic hydrocarbons. The Ni reduced by the spinel catalysts was in an electron-deficient state, which enhanced the adsorption of polycyclic aromatic hydrocarbons.

Ramsay 1 and Ramsay 2, learnings from the first natural hydrogen exploration wells in Australia

In October and November 2023, Gold Hydrogen, an ASX listed natural hydrogen explorer, drilled Ramsay 1 and Ramsay 2, the first natural hydrogen exploration wells in Australia. Twinning an historic well, the Ramsay Oil Bore 1 well in PEL687 in South Australia, the objective of the Ramsay 1 and Ramsay 2 wells was to find movable naturally generated hydrogen in the subsurface and establish the presence of a commercially attractive natural hydrogen resource base. This paper highlights some of the learnings from the process of designing and executing these natural hydrogen exploration wells and how the initial hurdles of demonstrating the presence of a hydrogen resource were overcome during the drilling phase. Using modified standard drilling technology and dedicated hydrogen detection tools (calibrated real time mud gas analysis), Gold Hydrogen has shown that exploration for natural hydrogen resources can be done safely and cost effectively. The main learnings included the application of a calibrated hydrogen detection methodology to derive a pseudo hydrogen saturation log and the successful selection of drilling mud and casing compliant with long term hydrogen exposure. As global drilling for natural hydrogen is still in its infancy, these modifications to the exploration well design and execution could have a significant impact on future drilling for this highly attractive carbon free energy source. With a program of seismic data acquisition and follow-up wells planned for 2024, Gold Hydrogen is leading a group of Australian natural hydrogen explorers, who are trying to unlock commercial natural hydrogen resources in the world.

Impact of gas type on microfluidic drainage experiments and pore network modeling relevant for underground hydrogen storage

Underground hydrogen storage (UHS) in geological reservoirs is proposed as a technically feasible solution to balance mismatch between supply and demand in emerging markets. However, unique hydrogen properties and coupled flow mechanisms require new investigations to fully understand transport and storage of hydrogen in porous media across scales. Here we use microfluidics to investigate the effect of gas type and injection rate on flow patterns, saturation and connectivity of the gas phase. We visually observe that gas flow is characterized by capillary fingering, further confirmed by fractal dimension analysis. At lower injection rates, the gas saturation after drainage appears to increase with gas viscosity, with lower hydrogen saturation compared to methane and nitrogen. The maximum gas saturations (39–46 %) were achieved at higher injection rates, showing no clear correlation to gas type. However, the high-rate injections lead to undesired outcomes in terms of formation of disconnected gas ganglia, mostly pronounced for nitrogen. We identify an optimal injection rate to achieve maximum gas saturation with the least amount of disconnected gas. The experimental results are supported with pore network modeling to derive relative permeability and capillary pressure functions.

An experimental study of hydrogen implantation to minerals: Role of the solar wind as a source of water in terrestrial bodies

The solar wind is a possible source for hydrogen and other volatiles on planetary bodies. To better understand the role of the solar wind during the volatile acquisition of planetary materials, we conducted hydrogen implantation experiments on olivine, orthopyroxene, quartz single crystals. Depth profiles of hydrogen concentration after implantation are determined by the Nuclear Resonance Reaction Analysis. We find that energetic hydrogen particles penetrate into the sample and accumulate at a certain depth. The hydrogen concentration increases with the hydrogen fluence until a “saturation level” is attained. Hydrogen saturation level (e.g., ∼10–20 at.% in olivine, equivalent to 0.5–1.2 wt%) far exceeds the equilibrium solubility in the bulk crystal at a similar thermodynamic condition (∼10−22 wt%). The results of olivine show that the hydrogen penetration depth increases whereas the saturation level decreases (weakly) with the beam energy. Hydrogen saturation level also depends on the mineral species in the order: olivine > orthopyroxene > quartz. The experimental results can be applied to explain some observations on the high surface water content of some planetary bodies including Itokawa asteroid and the Moon. We also explore the possibility of hydrogenated dusts by the solar wind implantation as a source for water on terrestrial planets. We conclude that if all dusts were exposed to the solar wind and all implanted hydrogen were converted to water, then >10 ocean masses would have been acquired for Earth by ∼100 years. However, the main part of the proto-planetary disk was not exposed to the solar wind and dusts could have been hydrogenated only when they were far from the equatorial plane of the disk. We discuss a possible mechanism to transport the hydrogenated dusts to the disk interior via turbulent mixing. Also, our experimental results and the mass dependence of the particle energies in the solar wind suggest that the D/H ratio of the dusts exposed to the solar wind will be higher than the solar wind value.

Modelling of hydrogen diffusion leading to embrittlement in austenitic stainless steels

The paper presents the 3-D model of the hydrogen diffusion in austenitic stainless steel. In order to model the material behaviour, a real microstructure taking into account the grain boundaries, the dislocations density, the vacancies number and the precipitates state was analysed in order to the implemented in the employed software (ANSYS). The effect of each single hydrogen trap was physically determined. The simulations were carried out by modelling the material microstructure with a high number of elements and nodes in order to improve the affordability of the obtained results. The model allowed to identify the hydrogen diffusion mode in different conditions by evaluating the weight that each single trap has on the overall process. The developed model allowed also to define the hydrogen saturation of the microstructure in different conditions of temperature.

Bottom-up and top-down controls on Alteromonas macleodii lead to different dissolved organic matter compositions.

The effects of both bottom-up (e.g. substrate) and top-down (e.g. viral lysis) controls on the molecular composition of dissolved organic matter have not been investigated. In this study, we investigated the dissolved organic matter composition of the model bacterium Alteromonas macleodii ATCC 27126 growing on different substrates (glucose, laminarin, extracts from a Synechococcus culture, oligotrophic seawater, and eutrophic seawater), and infected with a lytic phage. The ultra-high resolution mass spectrometry analysis showed that when growing on different substrates Alteromonas macleodii preferred to use reduced, saturated nitrogen-containing molecules (i.e. O4 formula species) and released or preserved oxidized, unsaturated sulfur-containing molecules (i.e. O7 formula species). However, when infected with the lytic phage, Alteromonas macleodii produced organic molecules with higher hydrogen saturation, and more nitrogen- or sulfur-containing molecules. Our results demonstrate that bottom-up (i.e. varying substrates) and top-down (i.e. viral lysis) controls leave different molecular fingerprints in the produced dissolved organic matter.

Enrichment of nitrogen compounds in heavy oils by complexation with ZrCl4 and detailed characterization using FT-ICR MS and ion mobility spectrometry

Nitrogen compounds in heavy oils have significant deleterious impacts on the petroleum products and processes. It is of great significance to characterize the structures of nitrogen compounds during hydrodenitrogenation (HDN) in heavy oils, but the low content of nitrogen compounds after HDN is not conducive to structural analysis. Zirconium tetrachloride (ZrCl4) was found as an efficient complexing agent to enrich both basic and non-basic nitrogen compounds in heavy oils. The molecular weight ranges of the basic and non-basic nitrogen compounds were similar before and after ZrCl4 enrichment. The distribution of carbon number and double bond equivalent (DBE) of basic N1 species in the enriched feedstock was very close to that of the original feedstock, while the basic N1 species in the enriched product behaved a higher DBE distribution. The non-basic nitrogen compounds with higher DBE in the feedstock and product were also more likely to be enriched. Moreover, multi-heteroatomic non-basic nitrogen compounds were more inclined to be enriched than the non-basic N1 species due to the possible synergism of multi-heteroatoms. The numbers of detected multi-heteroatomic non-basic N2, N1O1, and N1O2 compounds obtained by high resolution mass spectrometry increased by 40 to nearly 70 times. The double bond equivalent (DBE) of these refractory multi-heteroatomic non-basic nitrogen compounds in the deep HDN product was much lower than those in the feedstock, due to the hydrogenation saturation reaction during HDN. The representative core structures of refractory basic nitrogen compounds were deduced by ESI+ FT-ICR MS coupled with collision-induced dissociation (CID), and the side chains were proposed by ion mobility spectrometry (IMS). Two typical kinds of refractory basic N1 compounds were suggested in the HDN product. One was a compact structure with multiple naphthenic rings and short side chains. The other had a large molecular size with aromatic rings and long side chains. ZrCl4 as a complexing agent can effectively enrich nitrogen compounds in heavy oil, especially for the hydrotreated heavy oils. This enrichment method facilitates the structural characterization of refractory nitrogen compounds in heavy oil HDN process by FT-ICR MS and IMS. These results provide valuable information for the improvement of HDN processes and catalysts.

General impurity gas blanket effect mechanism and elimination strategies for hydrogen storage materials

Hydrogen energy has attracted considerable attention as the promising alternative to fossil energy. However, pollutants in H2 inevitably affect the hydrogenation kinetics of hydrogen storage materials (HSMs). In this work, the general physical blanket effect mechanism of impurity gases (He/Ar/CH4/N2/CO2/NO2) on the hydrogenation kinetics is extracted and confirmed to be a single physical process unrelated to HSMs for the first time. Specifically, the selective absorption of H2 by HSMs induces the local enrichment of impurity gases and impede H2 diffusion physically. For example, ZrCo can achieve its theoretical capacity (2.0 wt% H2) in 1.2 bar pure H2 within 40 s, while only 0.46 wt% H2 could be absorbed in 1.2 bar 3 mol% CH4 + 97 mol% H2 mixed gas even after 0.4 h. Such blanket effect may interlace with chemical surface poisoning effect and bring variability on hydrogenation kinetics. Notably, among the investigated impurity gases, He/Ar/N2/CH4 are absolute inactive gases which cannot impede hydrogenation, thus excluding the chemical surface poisoning effect originated from active gases. This allows the precise extraction of intrinsic physical blanket effect quantitatively, instructing comprehensive strategies to promote the fast hydrogenation saturation for HSMs. In summary, optimizing engineering parameters including dynamical hydrogenation operation provides an effective approach to remarkably promote hydrogen absorption kinetics of HSMs.

Thermodynamic Stability and Electronic Properties of Graphene Nanoflakes

We conducted a large set of ab initio density functional theory computations to model a variety of hammer-terminated graphene nanoflakes—finite counterparts of armchair graphene nanoribbons. We focused on the relationships among the length and width of the nanoflakes, the stoichiometry and the conformation of the hydrogen saturation of the caps, and the resulting electronic structure. The energetics and the thermodynamic stability of the nanoflakes were investigated as well. Based on this study, we provide a recipe for determining the most stable saturation of the dangling bonds at the caps, which is generally disregarded in theoretical studies, and we prove that this step is crucial for a reliable description of the electronic structure of these systems. Data analysis proved that flakes far from the most stable C–H pattern exhibited electronic properties that were typical of an unsaturated bonding structure. Based on thermodynamics, we also proved that, for any given flake, there was a well-defined hydrogen content and a conformation of H atoms at the caps, which were favored across a wide range of environmental conditions.

ПЕРСПЕКТИВИ РОЗВИТКУ ВОДНЕВОЇ ЕНЕРГЕТИКИ З МОЖЛИВІСТЮ ВІДНОВЛЕННЯ МЕМБРАН ДЛЯ ПАЛИВНИХ ЕЛЕМЕНТІВ ПІСЛЯ КОНТАКТУ З ВОДНЕМ

The prospects for the development of hydrogen energy and the influence of temperature on the change in the shape of the membrane for fuel cells in contact with hydrogen have been studied. It has been confirmed that the change in the shape of the plate from the α-PdHn gradient alloy develops in two stages. The experimental regularities of the change in the shape of the palladium membrane during operation in a hydrogen environment were investigated. It was determined that upon contact with hydrogen, a temporary gradient material "metal-hydrogen" is formed in the membrane, which causes the development of hydrogen concentration stresses, and the maximum change in the shape of the membrane, which occurs at a constant temperature, depends on the diffusion coefficient and the equilibrium solubility of hydrogen in palladium. However, when the temperature changes, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladium also change, which affects the temperature dependence of the final shape change of the membrane. This fact makes it possible to effectively plan and determine the time of hydrogen penetration into the membrane, control the change of shape and adjust the operating modes of the fuel cell. It is the equilibrium solubility of hydrogen in palladium and its diffusion coefficient when the temperature changes in the main that determine the maximum and final change in the shape of the membrane, and the temperature determines the fluctuation of the change in the shape of the membrane when the temperature of the hydrogen flow entering the chamber changes. Thus, the complete return of the membrane to its initial state at increased temperature clearly indicates the implementation of a coherent membrane bending mechanism. Upon completion of hydrogen saturation by the coherent mechanism under the conditions of reaching equilibrium with the gas phase, the original palladium membrane turns out to be transformed into a membrane of the equilibrium alloy α-PdHnо, which inherits the initial state of a pure palladium membrane. Therefore, to model the hydrogen penetration process in the fuel cell, it is necessary to know the gas flow rate, membrane permeability and gas temperature, as well as the diagram of the fuel cell where these processes take place. At the same time, scientists still hope for the future development of hydrogen energy, despite the existing difficulties. This requires additional research and development of new technologies to remove obstacles to the transition to hydrogen as a primary energy source

In-situ influence of TiF3 catalyst on the hydrogen storage behavior of Mg-Ni-Y based alloy

Solid-state magnesium-based hydrogen storage encounters challenges associated with sluggish hydrogen absorption and desorption kinetics. The incorporation of catalysts is considered a promising means to improve the hydrogen absorption and desorption kinetics of these alloys. In this experiment, we prepared the Mg80Ni15Y5 alloy via vacuum melting and incorporated TiF3 in varying weight percentages of 1, 3, 5, and 7 wt% through ball milling. The phase composition and microstructure of the samples were analyzed and measured using X-ray diffraction meter (XRD), Transmission Electron Microscope (TEM), Selected Area Electron Diffraction (SAED), and Scanning Electron Microscope (SEM) techniques. The results revealed that the TiF3 introduced two catalytically phases, MgF and TiF2. And TiF2 transforms into TiH2 after hydrogen absorption, which covers the surface of MgH2 and prolongs the nucleation time of MgH2.Furthermore, the addition of TiF3 made the surface of alloy markedly coarser and more irregular and few cracks, providing channels for hydrogen diffusion. This behavior optimized the kinetic performance of the alloy. It was observed that the samples containing 7 wt%TiF3 achieved 99.2 % hydrogen saturation even in low-temperature. It's worth mentioning that the addition of 7 wt% TiF3 to the Mg80Ni15Y5 alloy significantly reduced the dehydrogenation activation energy to 58.5 kJ/mol, as opposed to pure magnesium with an activation energy of 158.2 kJ/mol. This substantial reduction has effectively accelerated the hydrogen absorption and desorption rates of the alloy. However, it had only a negligible impact on the thermodynamic properties of the sample with 7 wt%TiF3.