Hydride Method Research Articles

Current state and development trends of hydrogen technologies

The article analyzes the current state of research and development in the field of production, storage and use of hydrogen fuel. It was revealed that the most environmentally friendly method is the hydrogen production by electrolysis based on nuclear power. At the same time, in Russia, the development of hydrogen energy is a priority in the energy sector in general and nuclear energy in particular. Specific investment in electrolyzers with a solid polymer membrane is about 3100-2050 $/kW. By 2030, the cost is predicted to be $950/kW and $740/kW for electrolysis with proton-exchange and alkaline electrolyte, respectively. To store hydrogen, research is being carried out mainly on the metal hydride method, as well as gaseous compressed in special high-strength composite tanks under pressure up to 100 MPa and in large-volume underground tanks. The use of hydrogen fuel for power generation is planned mainly on the basis of fuel cells and micro gas turbines. The average cost of a power plant based on solid oxide fuel cells in 2020 amounted to 1720-1430 $/kW. By 2035 and 2050, $960/kW and $770/kW respectively are predicted. A promising area of development in the field of fuel cells is reversible fuel cells.

Visualization of Hydrogen Bubbles in Porous Transport Layer in Toluene Direct Electro-Hydrogenation Electrolyzer Using X-Ray CT System

Introduction Currently, the use of renewable energy is being promoted as an approach to decarbonization. However, renewable energy requires stable energy storage and supply because the amount of electricity is affected by time and climate. One of the solutions is use of hydrogen as an energy source. As the demand for hydrogen increases in the future, a large amount of hydrogen will be needed, and the storage and transportation of large amounts of hydrogen will also be necessary. However, the methods for storing and transporting large amounts of hydrogen have not yet been established, and this is one of the challenges in the current hydrogen utilization. One of the methods for storing and transporting large amounts of hydrogen is the organic hydride method. The organic hydride method is a method of storing and transporting hydrogen using hydrogenation and dehydrogenation of organic compounds. Among these, the use of toluene and methylcyclohexane (MCH) has attracted attention. The advantages of using toluene and MCH include the following: because toluene and MCH are liquids at normal temperature and pressure, they can be transported at about 1/500th the volume of direct hydrogen gas transport; toluene and MCH can be reused; hydrogenation and dehydrogenation are the only reactions, so no byproducts are generated; and they can be transported in the same way as petroleum. Hydrogen can be transported in the same way as petroleum. Therefore, it is expected to be used as a storage and transport medium for hydrogen.A toluene direct electro hydrogenation electrolyzer is available as a means of hydrogenating toluene. In the toluene direct electro hydrogenation electrolyzer, hydrogen and toluene are supplied to the electrolyzer, and electricity is applied to protonate the hydrogen and supply it to toluene to produce MCH. The advantages are that cost and time losses can be reduced because water electrolysis and toluene hydrogenation can be performed simultaneously, there is no heat loss in the reaction, and the theoretical decomposition voltage can be reduced compared to electrolysis of water and hydrogenation of toluene separately. However, during hydrogenation of toluene, a part of the water being electrolyzed is transferred to the toluene reaction surface, reducing the reaction efficiency to MCH. In addition, part of the protonated hydrogen becomes hydrogen bubbles, which inhibit the fuel supply and reduce the reaction area. Furthermore, the phenomena of water movement and hydrogen bubbles in toluene hydrogenation have not yet been studied.In this study , we aim to understand the generation of hydrogen bubbles by visualizing the phenomena in toluene hydrogenation using a toluene direct electro hydrogenation electrolyzer with an X-ray CT system, and to provide a guideline for future research on the suppression of hydrogen bubble generation and water movement. Fig. 1 shows a schematic diagram of the toluene direct electro- hydrogenation electrolyzer used in this experiment. The electrolyzer consists of a catalyst layer, a gas diffusion layer (GDL), and a separator, in that order. The electrolyzer is operated by supplying toluene to the anode side and hydrogen to the cathode side, and electricity is supplied. Visualization of the interface between the GDL and catalyst layer on the cathode side of the electrolyzer during operation using an X-ray CT system allows the phenomena on the reaction surface to be visualized. Figure 2 Visualization of the inside of the electrolyzer during operation. Fig. 2 (a) shows the electrolyzer filled with MCH and (b) shows the electrolyzer filled with toluene. The toluene electrolyzer generates fewer hydrogen bubbles, which confirms that the reaction is normal, and the correlation between the current density and the generation of hydrogen bubbles is examined. Figure 1

Ternary antimonide NaCd4Sb3: hydride synthesis, crystal structure and transport properties

AbstractA new compound NaCd4Sb3 (R m, a=4.7013(1) Å, c=35.325(1), Å, Z=3, T=100 K) featuring the RbCd4As3 structure type has been discovered in the Na−Cd−Sb system, in addition to the previously reported NaCdSb phase. NaCd4Sb3 and NaCdSb were herein synthesized using sodium hydride as the source of sodium. The hydride method allows for targeted sample composition, improved precursor mixing, and an overall quicker synthesis time when compared to traditional methods using Na metal as a precursor. The NaCd4Sb3 structure was determined from single‐crystal X‐ray diffraction and contained the splitting of a Cd site not seen in previous isostructural phases. NaCd4Sb3 decomposes into NaCdSb plus melt at 766 K, as determined via in‐situ high‐temperature PXRD. The electronic structure calculations predict the NaCd4Sb3 phase to be semi‐metallic, which compliments the measured thermoelectric property data, indicative of a p‐type semi‐metallic material. The crystal structure, elemental analysis, thermal properties, and electronic structure are herein discussed in further detail.

Preparation of Single-Crystal Isotopically Enriched 70Ge by a Hydride Method

Preparation of Single-Crystal Isotopically Enriched 70Ge by a Hydride Method

Determining the minimum ignition energy of toluene vapor containing hydrogen towards a risk assessment for liquid organic hydride storage in hydrogen refueling stations

Hydrogen refueling stations associated with on-site hydrogen production systems based on the organic chemical hydride method (HRS-OCH) will process both hydrogen (H2) and toluene generated by the dehydrogenation of methylcyclohexane. In such systems, toluene containing varying levels of dissolved H2 will be stored in on-site tanks, such that H2 could be released into the tank headspace to form flammable toluene/H2/air mixtures. As a means of examining the associated safety hazards, the present work experimentally determined the minimum ignition energy (MIE) values for toluene/H2/air mixtures with varying proportions, using a cylindrical explosion vessel. The MIE for toluene containing 1 vol% H2 was found to be 0.319 mJ (the ignition probability is greater than 3.3 %), and thus similar to the values for pure toluene/air mixtures. H2 proportions above 2 vol% decreased the MIE by an order of magnitude, such that the value approached that for pure H2/air mixtures (0.021 mJ). This low MIE would allow these mixtures to be readily ignited by a static electrical discharge from toluene after accumulating a charge through flow processes. To reduce the ignition risk to an acceptable level, the concentration of H2 in the gas phase of HRS-OCH storage tanks should therefore be less than 1 vol%. Consequently, safe operation of HRS-OCH facilities requires the installation of H2 stripping processes, such as the use of membrane separation units.

Regularities of hydrogen accumulation and distribution in titanium coatings formed on a steel substrate by the cathode-arc method

The main direction in the field of the use of hydrocarbon resources is the creation of a metal hydride hydrogen battery. Hydrides are solid non-volatile substances that are formed when certain metals are combined with hydrogen. The principle of using hydrides as a medium for storing hydrogen is simple: under pressure, the metal captures hydrogen, which dissolves in the metal, forming a new chemical, and when the hydride is heated, the gas is given back. The metal hydride method of hydrogen storage is based on the ability of a number of intermetallic compounds, metals, alloys and composite materials to reversibly and selectively absorb hydrogen. The object of the study is titanium coatings formed on samples of 12X18H10T stainless steel by the cathode-arc method. In the course of the study, ion-plasma deposition of coatings was carried out. Scanning electron microscopy was also performed. The phase composition and structure of the titanium coating in the initial and submerged state were evaluated. Gas-phase hydrogenation was carried out, followed by an assessment of the effect of hydrogen on the alloy structure. Titanium was deposited by the cathode-arc method. Deposition of titanium coatings was carried out on the Raduga-Spektr installation, microstructure analysis was carried out on SEM using a Hitachi TM–2800 gas-phase hydrogen saturation microscope using an automated Gas Reaction Controller complex, a Shimadzu XRD-7000S diffractometer, and an inert gas melting method using a LECO RHEN 602 hydrogen analyzer.

Prospective metal hydride hydrogen storage and purification technologies

To develop metal hydride reactors for storage and purification hydrogen of various types. Integrate metal hydride hydrogen storage and purification devices with a fuel cell (FC) and an electrolyzer with a solid polymer electrolyte. METHODS. For the melting of samples of intermetallic compounds (IMC), the method of melting in an electric arc furnace with a non-consumable tungsten electrode on a water-cooled copper crystallizer in an argon atmosphere is used. The study of the integral characteristics of metal hydride devices and the study of the processes during the extraction of hydrogen from a mixture of gases is carried out using thermal mass flow meters and a thermoconductometric gas analyzer. RESULTS. The results of the development and creation of metal hydride reactors for the storage and purification of hydrogen of various types are presented. The results of experimental studies of the system integration of metal hydride reactors, fuel cells, and an electrolyzer are presented. CONCLUSION. The accumulation of energy in hydrogen makes it possible to use the lowest possible gas pressure in the reactor, thereby obtaining the maximum safety during operation of the device, as well as avoiding mandatory safety certification and training of personal personnel on working with high-pressure cylinders. The use of the metal hydride method of flow purification shows high rates of hydrogen extraction for subsequent accumulation and use in the fuel cell at high volume hydrogen contents in the mixture (≥10% vol.), while the method of periodic evacuation of accumulated impurities is most effective at low hydrogen contents in the mixture (<10% vol.). Experimental power plants H>2Bio and H2Smart with an electric power of 200 W and 1 kW are developed, the results of the main operating modes of power plants are presented.

Assessment of the Health Risks Associated with the Ingestion of Heavy Metals (As, Cd, Cr, Pb, Ni, Zn, Hg) in Vegetable Crops in the City of Daloa (Ivory Coast)

In order to assess the health risks associated with the ingestion of heavy metals or trace metal elements (TME) contained in foodstuffs from market garden crops, we sampled the tomato, cabbage, onion and leaves of 'onions and lettuce grown in the lowlands of the town of Daloa. The concentrations of ETM contained in these market garden products were determined by an Atomic Absorption Spectrophotometer (AAS) using three methods such as the flame method (Zn), the oven method (Pb, Cd, As, Cr, Ni) and the hydride (Hg) method. The results obtained showed that the heavy metals studied are present in fruits and vegetables with the most important Zn, Cr and Ni contents. However, metals such as arsenic, mercury and zinc present a concentration higher than that of the standard in force for the foodstuffs studied. Thus, the consumption of market garden products from cultivated soils in the areas studied could present dangers for the exposed population. Indeed, the study of the health risks associated with the ingestion of these vegetables has shown that for arsenic and zinc the determined Danger Quotient are all greater than 1. Which means that these vegetable crops present risks. related to the ingestion of zinc and arsenic. this means that the exposed population is theoretically out of danger. The values obtained from the Health Impact (SI) are all less than 1 for the population surveyed. On the other hand, for the estimated population of the city of Daloa we observe an IS> 1.

ANALYSIS OF EXISTING METHODS FOR URANIUM-PLUTONIUM MIXED NITRIDE FUEL FAB-RICATION IN RUSSIA AND ABROAD

This paper presents a review and a brief analysis of existing methods for producing mixed uranium nitride and plutonium, developed by both Russian and foreign scientists. The main parameters of the processes are considered, and their advantages and disadvantages are studied. Currently, the main areas of nitride fuel production are the metal hydride method and carbothermic reduction from the starting oxides. The methods are traditional ceramic technology. The starting products for the manufacture of nitride fuel powder can be either oxides (uranium dioxide and plutonium dioxide) or metals (uranium, plutonium and their alloys). To date, the technology for the manufacture of nitride fuel powder has not been finally selected. When considering existing methods, significant emphasis was placed on industrial applications and the simplicity of the hardware design processes. The laboratory methods are reflected in the work, which make it possible to simplify the process and reduce the costs of obtaining powders of mixed uranium and plutonium nitrides. However, they have significant difficulties in the technological implementation and low productivity of the processes. Of special interest among laboratory methods for producing mixed uranium and plutonium nitrides is the method of high-voltage electric pulse consolidation. This method allows sintering of tablets at the stage of powder pressing from mixed uranium and plutonium nitrides by passing a short high-voltage discharge with a power of several kW directly through the powder.

Preliminary study on hydrogen storage for fuel of fuel cell using Fe3Al metal hydride system

Fe3Âl alloy for hydrogen storage was successfully synthesized from Fe (70 wt%) and Al (30 wt%) through ball-mill method in 5 hours milling and Ball to Powder Ratio (BPR) 10:1 to produced mechanical alloy. The results was confirmed by XRD diffraction pattern at 2¸ = 44.791° (10) which is characteristic peak of Fe3Al. The material was applied on hydrogen storage to form metal hydride in which at various temperature and pressure. The Fe3Al alloy performance for hydrogen storage for fuel cell application was indicated from the capacity of hydrogen adsorption and the ability to supply hydrogen for fuel cell. Characterization by using SEM-EDX on adsorption used alloy showed that Fe3Al Alloy has homogeneous surface and no cracks revealed. XRD pattern of alloy after being used to adsorb hydrogen showed a typical pattern at 2¸ = 44.667° (11). Based on the results it can be concluded that hydrogen storage capacity increases with increasing temperature and pressure, and the average adsorption capacity were 58%. Hydrogen storage by the metal hydride method has met the storage criteria established by the US Department of Energy (DOE) as clean and efficient urban energy for the future.

Features of β-Phase Decay in Ti–22Nb–6Zr Alloy

Abstract—A compact powder Ti–22Nb–6Zr alloy was obtained by powder metallurgy methods. The initial alloy powder was synthesized by the calcium hydride method. It was shown that, after consolidation during vacuum sintering and subsequent hot isostatic pressing, the residual porosity of the consolidated material did not exceed 1%. The physicomechanical properties and structural features of the powder alloy obtained were investigated. It was established that, after hot isostatic pressing, there was no release of brittle ω phase in the structure of β-Ti alloy. In the range of heating temperatures of 550–700 K, the β phase was prone to decay with the formation of the α phase of a lamellar morphology and a small amount of the ω phase. The appearance of decay products was accompanied by dilatometric effects and an increase in Young’s modulus. It was shown that, regardless of the method of powder consolidation, the resulting alloy exhibited elinvarity (a small change in Young’s modulus with increasing temperature) in the temperature range of 200–500 K. It was determined that, at room temperature, samples with ~8% pores had Young’s modulus of about 64 GPa; when the porosity level was reduced to <1%, Young’s modulus increased to 73.5 GPa.

Features of the Initial Stage of the Heteroepitaxy of Silicon Layers on Germanium When Grown from Silicon Hydrides

Data on the dependence of the growth rate of Si layers deposited onto Ge(111) by the hydride method on their thickness at the initial heteroepitaxy stage are reported. The effect of a Ge substrate within ten grown silicon single layers on the Si-film growth rate is demonstrated. Based on the data obtained, the kinetic coefficients responsible for the rate of the main physicochemical processes related to the interaction of hydride molecular beams with the growth surface are calculated. An analysis of the capture probability and rates of pyrolysis of the adsorbed Si(Ge) hydride molecules on the pure Ge(Si) surfaces reveals the dependence of their behavior on the growing-layer thickness. Comparison of the results obtained during Si-layer growth on Ge shows that the pure germanium surface has higher adsorption and catalytic abilities with respect to silane molecules than the pure Si surface. The unstrained pure Si surface has higher adsorption and catalytic characteristics with respect to Ge-hydride molecules.

Особенности начальной стадии гетероэпитаксии слоев кремния на германии при их выращивании из гидридов кремния

AbstractData on the dependence of the growth rate of Si layers deposited onto Ge(111) by the hydride method on their thickness at the initial heteroepitaxy stage are reported. The effect of a Ge substrate within ten grown silicon single layers on the Si-film growth rate is demonstrated. Based on the data obtained, the kinetic coefficients responsible for the rate of the main physicochemical processes related to the interaction of hydride molecular beams with the growth surface are calculated. An analysis of the capture probability and rates of pyrolysis of the adsorbed Si(Ge) hydride molecules on the pure Ge(Si) surfaces reveals the dependence of their behavior on the growing-layer thickness. Comparison of the results obtained during Si-layer growth on Ge shows that the pure germanium surface has higher adsorption and catalytic abilities with respect to silane molecules than the pure Si surface. The unstrained pure Si surface has higher adsorption and catalytic characteristics with respect to Ge-hydride molecules.

A fully renewable and efficient backup power system with a hydrogen-biodiesel-fueled IC engine

Renewable energy is free, abundant, clean and could contribute towards a significant reduction of the global warming emissions. It is massively introduced as a source of electricity production across the globe and is expected to become the primary source of energy within the following decades. However, despite the naturally replenished energy, the supply is not always available. For this reason, it is necessary at times of excess energy, any surplus quantity to be sufficiently captured, stored and later used when a deficit occurs. In this paper, an overview of a backup power system operating with a hydrogen-biodiesel dual-fuel internal combustion engine is provided. The system is utilizing the organic chemical hydride method for safe hydrogen storage and transportation. The high energy content of hydrogen stored in the form of an organic hydride under ambient conditions makes it an ideal energy backup medium for large-scale and long-term applications. The research work focusses on the operation and emissions output of the dual-fuel internal combustion engine running on fully renewable fuels and the results are compared with the conventional petroleum-derived diesel engine. Biodiesel-hydrogen operation shows significant benefits in the reduction of carbon and soot emissions but deteriorates the NOx formation compared to the conventional diesel-powered engines. The operation of the engine at high loads can provide high exhaust thermal energy while alternative combustion strategies are necessary to be implemented at low load conditions for the optimum operation of the backup power system.

Innovative System for Hydrogen Storage and Transportation by Organic Chemical Hydride Method

Innovative System for Hydrogen Storage and Transportation by Organic Chemical Hydride Method

Sources of Carbon Impurities in the Preparation of High-Purity Monoisotopic 28Si by a Hydride Method

This paper examines sources of carbon impurities in polycrystalline monoisotopic 28Si prepared by a hydride method. Analytical data on the concentrations of carbon-containing impurities in volatile silicon compounds (28SiH4 and 28SiH4), process gases (Ar and H2), and polycrystalline 28Si are used to identify the major sources of carbon in the polycrystalline 28Si prepared by the hydride method. These are the starting 28SiH4 and calcium hydride used in 28SiH4 conversion into 28SiH4. The rate of carbon intake into polycrystalline silicon from the apparatus material during the monosilane pyrolysis process does not exceed 9 × 1011 cm–2 h–1. Polycrystalline silicon has been precipitated from monosilane with different concentrations of hydrocarbon impurities. At hydrocarbon concentrations in the range 10–4 to 10–3 mol %, the carbon concentration in the monosilane correlates with that in the silicon obtained from it. High-purity monosilane has been used to prepare polycrystalline 28Si samples with concentrations of carbon impurities in the range (0.8–2.3) × 1015 cm–3. Based on calculations of the carbon impurity distribution along the length of a zone-refined ingot, we examine the effect of the initial carbon concentration in the starting polycrystal on the yield of single-crystal monoisotopic 28Si. Requirements are formulated for the carbon concentration in polycrystalline 28Si which ensure a high yield of single crystals with parameters suitable for metrological applications.

Hydrogen-diesel dual-fuel engine optimization for CHP systems

Combined heat and power (CHP) systems utilizing an internal combustion engine benefit from improved energy efficiency, by capturing heat that is usually wasted, and reduced energy costs. The cogeneration systems can be used domestically and in remote areas for enhancing the energy security and reducing the national energy requirements.In this paper, the study focuses on the combustion optimization of the compression-ignition engine of a CHP system using the organic chemical hydride (OCH) method for the dehydrogenation of a hydrogen energy carrier. An experimental investigation was performed on a single-cylinder hydrogen-diesel dual-fuel engine for optimizing its combustion performance and reducing the harmful emissions. The engine operated at a constant speed of 1,500 rpm and 7 bar IMEP under three different hydrogen rates representing low-, medium- and high-hydrogen energy share ratios.The analysis showed that hydrogen fuel with high EGR rates and single diesel injection could provide a simultaneous reduction of carbon emissions up to 80% combined with a reduction in NOx of over 50% and an enhanced thermal efficiency. Total hydrocarbons were the only emissions deteriorated compared to the conventional diesel operation. Engine operation with 55% and 75% hydrogen energy ratios passing the Tier 4 Nonroad Compression Ignition emission standards was achieved.

Evaluation of the impact of anthropogenic activities on arsenic, cadmium, chromium, mercury, lead, and polycyclic aromatic hydrocarbon levels in seafood from the Gulf of Naples, Italy

ABSTRACTThe principal aim of this study was to monitor the occurrence of some metals and polycyclic aromatic hydrocarbons (PAHs) in fish and mussels from the Gulf of Naples. A comparison with previous researches of the same area was carried out, and the intakes of these compounds through the diet and their effect on the tolerable intake values (when available) were assessed. Cadmium (Cd), chromium (Cr), and lead (Pb) were detected by flameless atomic absorption spectroscopy (Cd, Cr, and Pb); arsenic (As) and mercury (Hg) were detected by applying the hydride method. PAHs were detected by high-performance liquid chromatography. Widespread contamination was found. Among the metals, Hg showed the highest maximum levels of 284.94 ng/g wet weight (ww) in fish and 480.00 ng/g ww in mussels. Chrysene, phenanthrene, fluoranthene, anthracene, and benzo[k]fluoranthene were the most common PAHs in fish, whereas benzo[a]anthracene, pyrene, phenanthrene, acenaphthylene, and acenaphthene were the most frequently occurring compounds in mussels. The concentrations of As, Cr, Hg, Pb, and PAHs in fish were found to decrease over a period of 30 years, whereas the Cd levels remained constant. The Hg, Pb, and PAH levels in mussels increased over the period 2010 to 2016. Finally, the average consumption of mussels led to the highest effect on the Tolerable Daily Intake of Hg, which was exceeded by 19%.

Production of germanium stable isotopes single crystals

It is reported on production of germanium stable isotopes 72Ge, 73Ge,74Ge,76Ge single crystals with high isotopic and chemical purity by hydride method. Separation of isotopes was carried out by centrifugal method using monogermane as the initial volatile substance. Samples of monoisotopic monogermanes 72GeH4, 73GeH4,74GeH4, 76GeH4 were purified by the method of low‐temperature rectification. Elementary polycrystalline germanium was extracted by pyrolysis from respective monogermane and purified from impurities by the method of zone melting. Single crystals of germanium isotopes were grown by Czochralski method. The content of the main isotope in the produced single crystals 72Ge, 73Ge,74Ge,76Ge was 99.98; 99.90; 99.93 and 87.5 at. %, respectively, and the content of the impurities of stable elements was less than 10−5 –10−6 mass %.

OER Activity of Ir-Ta-Zr Composite Anode as a Counter Electrode for Electrohydrogenation of Toluene

The organic chemical hydride method using the toluene (TL)/methylcyclohexane (MCH) system is one of the prospective energy carrier technologies for hydrogen storage and transportation. The direct electrohydrogenation of toluene with water decomposition using electric power is a highly efficient energy conversion process for the MCH synthesis. In this process, an IrO2-based directionally stable electrode® (DSE®) for the oxygen evolution reaction (OER) is used as the anode because of its good electrocatalytic activity and durability. However, further improvement in the activity is needed for practical applications. In this study, the effect of Zr addition substituted for Ta in IrO2-Ta2O5/Ti, which is a typical OER anode, on the electrocatalytic activity has been investigated in sulfuric acid with TL contamination. The activity of both the IrO2-Ta2O5/Ti and the IrO2-Ta2O5-ZrO2/Ti was higher and less affected by TL contamination than the IrO2/Ti. The activity of the IrO2-Ta2O5-ZrO2/Ti increased with the Zr content. The Zr addition increased the real surface area along with the increase in the double layer capacitance; on the other hand, the increase in activity was more than that of the surface area. Therefore, the Zr additive would affect not only the real surface area increase, but also the electrocatalytic activity.