Certain Amount Of Hydrogen Research Articles

Fracture failure analysis of high-strength bolts in power plant steel structures

The high-strength bolts of a power plant steel structure fractured and failed in many places. To find the cause of the failure, this paper analyzed the failure reasons of fractured bolts through macroscopic inspection, chemical composition analysis, mechanical performance test, metallographic inspection, and fracture microscopic analysis. The results show that the main cause of bolt fracture is that improper heat treatment leads to a carburized layer on the surface of the bolt, which makes the surface of the bolt sensitive to hydrogen. At the same time, there is a certain amount of hydrogen in the material matrix, which leads to hydrogen accumulation and cracks in the bolt at the stress concentration. Eventually, the cracks propagate and lead to fracture failure.

Visualization and simulation study of ammonia blending with hydrogen as combustion application in lean-burn condition

Ammonia (NH3), as one of the two zero-carbon fuels, has attracted lots of attention. However, its poor properties, including slow laminar burning velocity (LBV), high ignition energy, and low flammability, make it unfavorable for use in engines. On the other hand, hydrogen (H2), another zero-carbon fuel, has a much higher LBV and flammability. Adding a certain amount of hydrogen to ammonia mixture has the potential to improve the combustion process and extend the lean-burn limit of ammonia. This paper investigates the combustion and emission improvements of ammonia blended with a small amount of hydrogen under lean-burn conditions, both experimentally and numerically. A new NH3/H2 chemical reaction mechanism was developed to accurately predict ignition delay time (IDT), LBV and NO generation under a wide range of initial conditions. The flame propagation schlieren and NO chemiluminescence measurements with a homogenous NH3/H2 mixture ignited by a spark plug in constant volume combustion chamber (CVCC) were conducted. The 3D numerical simulations in CVCC, coupled with the new mechanism, were validated with the experimental results. The hydrogen energy fraction up to 30 % (X30) and ER down to 0.4 (ER0.4) were studied in experiments and simulations. The results showed that, in comparison to pure ammonia (X0) at ER1.0, lean-burn conditions can be extended to ER0.6 and ER0.4 for X10 and X30, respectively, while still achieving a shorter combustion duration. NO is initially increased and then decreased with decreasing ER, regardless of hydrogen addition. Comparatively, X30ER0.4 can achieve relatively low NOx emissions, and maintaining an equivalent combustion rate with a low combustion temperature.

CO2 Electroreduction to Fuels Using Solid Oxide Electrodes: Beyond Ni-YSZ

Ni-YSZ electrodes form the benchmark in Carbon Dioxide electroreduction to CO. Ni-YSZ due its popular use in Solid Oxide Fuel Cells forms the basis of various process steps. Unfortunately, this material remains active only if a certain amount of hydrogen is supplied along side CO2 to the inlet of the reaction. Consequently, the Ni-YSZ results in CO production via reverse water gas shift (RWGS) reaction when H2 is supplied at the inlet. The currents for the electrode originate from electrolysis of H2O which is formed as a result of reverse water has shift. We have quantified the amount of CO produced from RWGS vs direct CO2 electrolysis in such a system using online mass spectrometry (MS). Electrochemical impedance spectroscopy measurements where analysed using distribution of relaxation times analysis. Under low concentration of H2 the overall impedance is dominated by H2 mass transfer. Effects of concentration of various reactants were measured using online MS. The process of pretreatment of the electrodes and catalyst surface development during reaction were tracked using in situ Raman Spectroscopy and optical spectrocopy. Electrodes were structurally characterised using SEM, TEM, XPS and ICP-OES measurememts. Various new combination of mixed metal oxide electrodes Ni(M)-YSZ were tested and compared with the performance of pure Ni-YSZ. Ni-YSZ electrode when used under pure CO2 results in catastrophic failure of the electrode performance. We have investigated this failure using in situ Raman and Mass spectrometry. The mechanism of CO2 production in pure CO2 stream was found to be drastically different from when a small amount of H2 is used. Figure 1

Optimum Hydrogen Injection in Phosphorus-Doped Polysilicon Passivating Contacts.

It has previously been shown that ex situ phosphorus-doped polycrystalline silicon on silicon oxide (poly-Si/SiOx) passivating contacts can suffer a pronounced surface passivation degradation when subjected to a firing treatment at 800 °C or above. The degradation behavior depends strongly on the processing conditions, such as the dielectric coating layers and the firing temperature. The current work further studies the firing stability of poly-Si contacts and proposes a mechanism for the observed behavior based on the role of hydrogen. Secondary ion mass spectrometry is applied to measure the hydrogen concentration in the poly-Si/SiOx structures after firing at different temperatures and after removing hydrogen by an anneal in nitrogen. While it is known that a certain amount of hydrogen around the interfacial SiOx can be beneficial for passivation, surprisingly, we found that the excess amount of hydrogen can deteriorate the poly-Si passivation and increase the recombination current density parameter J0. The presence of excess hydrogen is evident in selected poly-Si samples fired with silicon nitride (SiNx), where the injection of additional hydrogen to the SiOx interlayer leads to further degradation in the J0, while removing hydrogen fully recovers the surface passivation. In addition, the proposed model explains the dependence of firing stability on the crystallite properties and the doping profile, which determine the effective diffusivity of hydrogen upon firing and hence the amount of hydrogen around the interfacial SiOx after firing.

Copper Rich Composite Materials Based on Carboxylic Cation Exchangers and Their Thermal Transformation.

The effect of a cupric deposit (Cu2+, CuO) on the thermal decomposition of carboxylic cation exchangers (CCEs) is not known, and such studies may have practical significance. CCEs have a very high ion exchange capacity, so an exceptionally large amount of CuO (which is a catalyst) can be precipitated inside them. Two CCEs, macroreticular (Amberlite IRC50) and gel-like (Amberlite IRC86), served as a polymeric support to obtain copper-rich hybrid ion exchangers. Composites with CuO particles inside a polyacrylic matrix (up to 35.0 wt% Cu) were obtained. Thermal analyses under air and under N2 were performed for CCEs in the H+ and Cu2+ form with and without a CuO deposit. The results of sixteen experiments are discussed based on the TG/DTG curves and XRD patterns of the solid residues. Under air, the cupric deposit shifted the particular transformations and the ultimate polymeric matter decomposition (combustion) toward lower temperatures (even about 100–150 °C). Under N2, the reduction of the cupric deposit to metallic copper took place. Unique composite materials enriched in carbonaceous matter were obtained, as the products of polymeric matrix decomposition (free radicals and hydrogen) created an additional amount of carbon char due to the utilization of a certain amount of hydrogen to reduce Cu (II) to Cu0.

Experimental Study of a System for Hydrogen Permeation from Gas Phase to Liquid Sodium

In the framework of sodium fast reactors, the management of tritium contamination in the sodium secondary circuit and the control of its release into the atmosphere is fundamental. In order to capture and recover tritium by coprecipitation worth hydrogen in cold traps, it is necessary to maintain a certain amount of hydrogen dissolved in the liquid sodium stream. Hydrogen injection by permeation through nickel membranes has been proposed to provide a continuous hydrogen intake to a liquid sodium stream, allowing the desired hydrogen concentration to be reached. A permeator prototype and the related process have been designed. Permeation tests have been carried out in an experimental facility set up at CEA Cadarache at sodium temperatures from 375°C to 450°C and hydrogen partial pressures from 5 × 103 to 3 × 104 Pa in order to quantify their influence on hydrogen permeation flux. Measurements on both the gas and sodium sides provide a complete hydrogen content observability over the system. Experimental results show a good agreement with the theoretical permeation laws for hydrogen pressures below 2 × 104 Pa and provide an estimation of the temperature dependency of the permeability coefficient, which will be useful for the industrial scale-up of the process.

Effects of temperature and atmosphere on the formation of oligomers during the pyrolysis of lignin

Here the effects of pyrolysis temperatures and atmospheres on content and characteristics of the oligomer-rich fractions obtained after sequential extraction of alkali lignin (AL)-derived pyrolysis oil (PO) were investigated to obtain effective regulation pathways for the reduction of the oligomers content in PO. The results showed that the content of oligomers and main monophenols produced by AL under a pyrolysis temperature of 600 °C was relatively low and high, respectively. Additionally, the functional group strength of oligomer-rich fractions was affected to a lesser extent by pyrolysis temperature. By contrast, the nitrogen and argon atmosphere exerted a slightly different effect on the composition and characteristics of oligomer-rich fractions. However, in comparison with argon, the presence of a certain amount of hydrogen (H2/Ar = 1:9, v/v) promoted the preferential hydrogenation of unsaturated bonds during AL pyrolysis, and was beneficial to reduce the content of oligomers and enhance the yield of monophenols by inhibiting the occurrence of secondary reactions. In view of these findings, an effective regulation pathway featuring a pyrolysis temperature of 600 °C and the presence of a certain amount of hydrogen is recommended for reducing the content of oligomers and enhancing the content of monophenols.

Z-scheme heterojunction through interface engineering for broad spectrum photocatalytic water splitting

In this paper, we have designed the composite material of black phosphorus/tungsten nitride (BP/WN) with near-infrared light (NIR light) response as a noble-metal free photocatalyst for the first time. Modification of bulk BP by ball milling can control the band gap of the composite material to achieve efficient photocatalytic hydrogen evolution in the near-infrared region. At wider than 420 nm, and with illumination wider than 700 nm, a certain amount of hydrogen can be produced without any hole quencher. The rate of photocatalytic hydrogen evolution from pure water reaches 10.77 μmolg−1 h−1 under NIR light without any cocatalyst. The presence of a Z-type heterojunction effectively separates photogenerated carriers and prolongs the lifetime of photogenerated carriers, thereby enhancing the photocatalytic performance. The results indicate that BP/WN photocatalysts can provide a new approach to artificial photosynthesis and renewable energy conversion.

Design of plasmonic CuCo bimetal as a nonsemiconductor photocatalyst for synchronized hydrogen evolution and storage

Solar-driven hydrogen evolution with sustainable energy sources, which require earth-abundant, robust and efficient photocatalysts for fuel production, is highly desirable. Here, we propose an alternative promising configuration of a dendrite-like plasmonic CuCo bimetal as a nonsemiconductor photocatalyst, which exhibits exceptional photocatalytic activities for H2 evolution (77.1 μmol g−1 h−1) under sunlight irradiation without a sacrificial agent. Notably, a certain amount of hydrogen evolved by photocatalytic water splitting was conserved by the photocatalyst at room temperature, demonstrating that the integration of hydrogen evolution and storage was realized in this device. Electrons were produced by the surface plasmon resonance (SPR) effect of the Cu component in CuCo bimetal, and Co nanosheets were grown in situ on the surface of Cu, which can facilitate the transfer of photoinduced charge as a cocatalyst. Specifically, the photocatalyst shows excellent chemical stability with X-ray photoelectron spectroscopy and X-ray diffraction characterization after four consecutive cycles over a total of 20 h. This work provides insights into a plasmonic nonsemiconductor photocatalytic system in the hydrogen energy field.

Atomistic State of Absorbed Hydrogen in Electrodeposited Platinum Films

Hydrogen absorption into electrodeposited metal films is largely influenced by the depositing conditions. We have been investigating the hydrogen absorption into electrodeposited platinum (Pt) films that depends on a change in hydrogen adsorption state with applied potential.1 The microstructure of electrodeposited Pt films was affected by the absorbed hydrogen.2 In this study, we investigate an atomistic state of absorbed hydrogen in electrodeposited Pt films. Pt films were potentiostatically deposited on a gold foil from a solution containing 0.024 mol dm-3 K2PtCl4 at pH of 0.8. A Ag/AgCl electrode was used as the reference electrode and a Pt plate was used as the counter electrode. The amount of hydrogen in samples was measured by thermal desorption spectroscopy (TDS) in a temperature range between 300 and 1100 K. The amount of hydrogen in deposited Pt films was calculated by subtracting the total amount of desorbed hydrogen of the gold foil substrates from that of the samples. The amount of hydrogen in potentiostatically deposited Pt films (+0.1 ~ -0.3 V vs. Ag/AgCl) as a function of film thickness is summarized in Fig. 1. The amount of hydrogen was nearly 0 for Pt films deposited at +0.1 V (Fig. 1 ●). It was 1 ~ 2×10-7 mol cm-2 and independent of the film thickness at 0 V (Fig. 1 ◇). For the Pt films deposited at -0.1 and -0.2 V, a positive correlation was observed between the amount of hydrogen and the film thickness (Fig. 1 ○ and △), respectively. The positive correlation of ca. 1.7×10-7 mol cm-2 µm-1 indicates that hydrogen was uniformly contained at atomic ratio ([H]/[Pt]) of 0.015 in the Pt films. For the Pt films deposited at -0.3 V, the positive slope, that is, content of uniformly absorbed hydrogen was much larger than that for the films deposited at -0.1 and -0.2 V (Fig. 1 □). Positive vertical intercepts of 2 ~ 6×10-7 mol cm-2 for -0.1 ~ -0.3 V indicate that a certain amount of hydrogen was contained even in the initial deposits. Pt deposition at +0.1 V onto the Pt film deposited at 0 V reduced the amount of hydrogen to nearly 0. The Pt deposition at 0 V onto the Pt film deposited at +0.1 V increased the amount of the hydrogen to ca. 1×10-7 mol cm-2. These results suggest the possibility that the certain amount of hydrogen indicated by the vertical intercepts of Fig. 1 exists near film surface. Acknowledgements The present work was partly supported by JSPS KAKENHI (JP26289276 and JP17K06864). References A. Yokoyama, S. Karatsu, M. Sumikawa, N. Fukumuro, and S. Yae, ECS Trans., 75(52) 55 (2017).N. Hisanaga, N. Fukumuro, S. Yae, and H. Matsuda, ECS Trans., 50(48), 77 (2013). Figure 1

Evaluation of hydrogen permeation rate through zirconium pipe

To launch a fusion reactor stably, it is necessary to prepare sufficient amount of tritium by an external tritium source. Tritium production using nuclear reactions by neutron and Li in a high temperature gas-cooled reactor (HTGR) is an attractive method. An important issue is tritium confinement in high temperature conditions of HTGR. Covering Li compound by Al2O3 is a promising method because hydrogen permeability in Al2O3 is quite low. Furthermore, it is expected that inserting Zr between Li compound and Al2O3 suppresses tritium permeation because Zr has a large hydrogen absorption capacity. For example, a cylindrical multilayer structure consisted of Zr – Li compound – Zr – Al2O3 is a candidate structure to confine generated tritium. To evaluate hydrogen permeation rate through cylindrical Zr material, in this work, hydrogen permeation experiments were carried out for two samples of one-side sealed Zr pipe. Hydrogen permeation rate in one sample was proportional to as the square root of hydrogen pressure but that in another sample, which had retained a certain amount of hydrogen before the experiment, did not indicate an obvious pressure dependence regardless of almost the same experimental procedure except hydrogen permeation direction. Since observed hydrogen permeation rate in Zr was faster than that in Al2O3, under the multi confinement structure by Zr – Li compound – Zr – Al2O3, the generated tritium in Li compound diffuses promptly in whole Zr inside Al2O3 layer and it is expected tritium is stored stably in the structure.

Understanding Volumetric and Gravimetric Hydrogen Adsorption Trade-off in Metal-Organic Frameworks.

Metal-organic frameworks (MOFs) are porous crystalline materials that are promising for adsorption-based, on-board storage of hydrogen in fuel-cell vehicles. Volumetric and gravimetric hydrogen capacities are the key factors that determine the size and weight of the MOF-filled tank required to store a certain amount of hydrogen for reasonable driving range. Therefore, they must be optimized so the tank is neither too large nor too heavy. Because the goals of maximizing MOF volumetric and gravimetric hydrogen adsorption loadings individually are incompatible, an in-depth understanding of the trade-off between MOF volumetric and gravimetric loadings is necessary to achieve the best compromise between these properties. Here we study, both experimentally and computationally, the trade-off between volumetric and gravimetric cryo-adsorbed hydrogen deliverable capacity by taking an isoreticular series of highly stable zirconium MOFs, NU-1101, NU-1102, and NU-1103 as a case study. These MOFs were studied under recently proposed operating conditions: 77 K/100 bar →160 K/5 bar. We found the difference between highest and lowest measured deliverable capacity in the MOF series to be ca. 40% gravimetrically, but only ca. 10% volumetrically. From our molecular simulation results, we found hydrogen "monolayer" adsorption to be proportional to the surface area, whereas hydrogen "pore filling" adsorption is proportional to the pore volume. Thus, we found that the higher variability in gravimetric deliverable capacity in contrast to the volumetric capacity, occurs due to the proportional relation between gravimetric surface area and pore volume in the NU-110x series in contrast to the inverse relation between volumetric surface area and void fraction. Additionally, we find better correlations with geometric surface areas than with BET areas. NU-1101 presents the highest measured volumetric performance with 46.6 g/L (9.1 wt %), whereas NU-1103 presents the highest gravimetric one with 12.6 wt % (43.2 g/L).

Quantitative NEXAFS and solid-state NMR studies of sp3/(sp2 + sp3) ratio in the hydrogenated DLC films

The classification of diamond-like carbon (DLC) films is imperative in guiding large-scale industrial productions. However, it is not easy to classify this issue based on the structural composition and obtained properties, especially, when the film contains a certain amount of hydrogen. In the present study, two types of hydrogenated DLC films were prepared by electron-cyclotron-resonance chemical-vapor-deposition method with pure C2H2 and Ar gasses with applied negative bias voltages of 0 and 0.5kV. The structural and surface analyses of these films have shown significant changes of physical and mechanical properties with high reproducibility and low oxygen contents. The comparison of H/C atomic ratio extracted from the combination of Rutherford backscattering and elastic recoil detection analysis and the solid-state nuclear magnetic resonance (NMR) illustrated that the NMR analysis of the present work provides a significant contribution. Therefore, we compared quantitatively the sp3/(sp2+sp3) ratios in the hydrogenated DLC films using the near-edge X-ray absorption fine-structure (NEXAFS) and solid-state NMR methods. The signals of hydrocarbon sp3 (CH, CH2 and CH3) and a network of sp3 hybridized carbon (C-sp3) can be separated by the solid-state 13C NMR measurement, from which it is concluded that the former do not enable a detailed interpretation for the internal structural changes of the hydrogenated DLC films with the increase of applied bias voltage.

Coke suppression of kerosene by wall catalytic steam reforming

A new method is developed to decrease coke formation during the thermal cracking of kerosene with applications in air-breathing jet engines. Endothermic catalytic steam reforming of kerosene is tested to investigate the potential for consuming excess heat and decreasing coke deposition rates. A plate reactor is used to simulate an engine-cooling channel and to compare the coke deposition with and without use of a reforming catalyst. The reactor temperature and the blending proportions of water fed to the reactor are varied across experiments. Spraying catalyst on the channel's inner surface prevents the production of filamentous coke, the production of which is catalyzed by the metal surface. The generation of a certain amount of hydrogen from the catalytic steam reforming of kerosene favors the reverse direction of the Diels–Alder and polymerization reactions, consuming the aromatic coke precursors and decreasing the coke formation rate. The effects of varying water content and reactor temperature on coke formation have been investigated during the thermal cracking of kerosene with catalysis. The coking rate decreases with an increase in water content. However, the suppression of coking become weaker as the fuel temperature is increased.

Hydrogen Plasma Treatments of Amorphous/Crystalline Silicon Heterojunctions

Hydrogen plasma post-deposition treatments of amorphous/crystalline silicon heterojunctions, which are known to enable superior passivation, are further investigated. The influence of certain plasma process parameters, including substrate temperature, gas pressure, plasma power density, excitation frequency and distance between electrode and substrate, is examined. The passivation quality after a hydrogen plasma step is depending on the density of atomic hydrogen in the plasma and on sufficient hydrogen diffusion to the interface. A variation of the electrode to substrate distance reveals that the indiffusion of hydrogen is accompanied by dry etching of the amorphous layer. To reach sound passivation quality it is necessary to introduce a certain amount of hydrogen, while at the same time limit the damage due to etching of the amorphous silicon and maintain the right amorphous silicon film thickness for solar cell application.

Continuous spin detonation of a coal-air mixture in a flow-type plane-radial combustor

Regimes of continuous spin detonation of coal particles in an air flow in a flow-type plane-radial combustor 500 mm in diameter are studied. The tested substance is fine-grained cannel coal from Kuzbass having a particle size of 1–7 µm and containing 24.7% of volatiles, 14.2% of ashes, and 5.1% of moisture. A certain amount of hydrogen is added for coal transportation into the combustor and promotion of the chemical reaction on the surface of solid particles. To reduce air pressure losses in channels connecting the manifold and the combustor, their cross section is increased to limiting values (25 cm2), whereas the combustor exit diameter is reduced. The angle of the air flow direction and the combustor geometry are also varied. The minimum pressure difference in the air injection channels (16%) is reached with stability of continuous spin detonation in the combustor being retained. The domain of continuous spin detonation regimes in the coordinates of the fuel flow rate and specific flow rate of the mixture is constructed. The results of studying detonation burning of solid fuels can find applications in power engineering, chemical industry, and environmental science, in particular, contamination by combustion products.

Hydrogen Sensing with Ni-Doped TiO2 Nanotubes

Doping with other elements is one of the efficient ways to modify the physical and chemical properties of TiO2 nanomaterials. In the present work, Ni-doped TiO2 nanotubes were fabricated through anodic oxidation of NiTi alloy and further annealing treatment. The hydrogen sensing properties of the nanotube sensor were investigated. It was found that the Ni-doped TiO2 nanotubes were sensitive to an atmosphere of 1,000 ppm hydrogen, showing a good response at both room temperature and elevated temperatures. A First-Principle simulation revealed that, in comparison with pure anatase TiO2 oxide, Ni doping in the TiO2 oxide could result in a decreased bandgap. When the oxide sensor adsorbed a certain amount of hydrogen the bandgap increased and the acceptor impurity levels was generated, which resulted in a change of the sensor resistance.

Influence of pressure and temperature on the fatigue strength of Type-3 compressed-hydrogen tanks

Abstract The pressure of compressed hydrogen changes with temperature when mass and volume are constant. Therefore, when a compressed-hydrogen tank is filled with a certain amount of hydrogen it is necessary to adjust the filling pressure according to the gas temperature. In this study, we conducted hydraulic pressure-cycle tests to investigate the fatigue life of Type-3 compressed-hydrogen tanks when environmental temperature and filling pressure are changed. The results indicated that the fatigue life at low temperatures (−40 °C, 28 MPa) and room temperature (15 °C, 35 MPa) was almost equal. However, the fatigue life at high temperatures (85 °C, 44 MPa) was shorter than that under other conditions, suggesting that stress changes caused by thermal stress affect the fatigue life of the Type-3 tank.

Production of enriched methane by a molten-salt concentrated solar power plant coupled with a steam reforming process: An LCA study

Enriched Methane is a gas mixture consisting of methane and a certain amount of hydrogen (10–30%vol) that finds out several applications such as fuel of Internal Combustion Engines (ICEs). To produce EM, a steam reforming reactor whose heat duty is supplied by a molten-salt stream heated up by a concentrating solar power (CSP) plant can be used, in order to generate the hydrogen steam by solar energy. In fact, molten salts at temperatures up to 550°C can allow to reach the necessary thermal level inside the reactor to promote steam reforming reaction.The combination of technologies such as EM steam reformer, concentrating solar power (CSP) systems and molten-salt heat carriers, allows a partial decarbonation of the fossil fuel, thanks to the production of hydrogen, together with the possibility to carry solar energy in the current natural gas grid.The aim of this work is to present a Life Cycle Assessment of a novel hybrid plant for the production of EM from a solar steam reforming reactor. The performance, of this innovative architecture have been evaluated from an environmental point of view by the use of a LCA software (SimaPro7) and compared with the ones of traditional plants (reformer and cracker for the hydrogen production). The results highlight the lower environmental footprint of this innovative plant compared to the environmental impact of the two traditional plant considered in this work. The fossil energy duty of the MS-CSP-SR plant is about 50% less than that required from the conventional cracker and reformer production plants. The conventional plants are also characterized by a Global Warming Potential of about 75% higher than that of the MS-CSP-SR plant.

Detonation combustion of coal

Results of an experimental study of continuous spin detonation of a coal-air mixture with addition of a certain amount of hydrogen in a plane-radial vortex chamber 500 mm in diameter are presented. The tested substance is fine-grained cannel coal from Kuzbass, which has a particle size of 1–7 µm and contains 24.7% of volatiles, 14.2% of ashes, and 5.1% of moisture. Stable regimes of continuous spin detonation with transverse detonation waves having velocities of 1.86–1.1 km/s with respect to the cylindrical wall of the combustor are obtained for the first time. The mass fraction of hydrogen is 1.5–0.88% of the air flow rate and 50–3.4% of the coal consumption rate. The maximum specific coal consumption rate of 106 kg/(s · m2) is obtained.