High Hydrogen Content Research Articles

Woody biomass waste derivatives in decarbonised blast furnace ironmaking process

Modern ironmaking process relies significantly on fossil-related fuels, which ultimately results in the enormous CO2 emitted into the atmosphere. Biomass of plant origin, as a carbon-neutral energy source, has been considered as an alternative to fossil-based reducing agents such as coke. This study aims to investigate the potential of three woody biomass waste derivatives produced from biomass waste pyrolysis and gasification, namely charcoal, bio-oil, and bio-syngas, as the reducing agents in blast furnace. A model based on heat and mass balance and Gibbs free energy minimisation is proposed to simulate an ironmaking process with assistance of these derivatives. The effects of specific composition of biomass waste derivatives on process operation, CO2 emissions, and coke replacement are explored. Also the effects of H2-rich gas produced from biomass waste gasification on the blast furnace operation are estimated. Results indicate that reactions of woody biomass waste derivatives in blast furnace are complex and greatly dependent on composition. When charcoal has a higher carbon content, lower CO2 concentration is found from the top gas. The higher content of hydrogen in bio-oil will inhibit further reduction in CO2 emissions. Bio-syngas with H2/CO ratio of 1.3 proves to have a remarkable potential to reduce CO2 emissions. From the aspects of available biomass waste resources across the world, woody biomass waste derivatives as reducing agents are more suitable for countries with the limited pig iron production. This study provides a reference on the future of moving forward the decarbonised ironmaking by using woody biomass waste derivatives.

Comparative analysis of ammonia and hydrogen fuel blends in diesel engines on performance, emission, vibration, and acoustic profiles

In the current study two kinds of gaseous fuels, ammonia and hydrogen tested along with the neat diesel. A series of test conducted in the diesel engine for the samples such as diesel, S1, S2, S3 and S4. The samples were varied based on the two different flow rates 5 LPM and 10 LPM. The parameters such as brake thermal efficiency (BTE), brake specific energy consumption (BSEC), combustion parameters, emissions, and noise levels were determined. The research suggests that the typical properties of ammonia and hydrogen blends contribute to engine performance and efficiency. The S4 blend, 10 LPM of NH3 and 10 LPM of H2, with a higher hydrogen content, was found to significantly enhance BTE across all engine brake powers compared to conventional diesel fuel. A notable increase in BTE with a climb on the brake power was observed, suggesting superior fuel energy utilization due to the blend's high-energy content. An inverse relationship was established between BTE and BSEC, where diesel demonstrated higher BSEC, indicative of greater thermal loss and inefficiency. Combustion analysis revealed a reduction in heat release rate for ammonia blends, this eventually compensated by hydrogen addition by optimizing autoignition and accelerating combustion. Emission studies highlighted a uniform increase in nitrogen oxides for all blends; however, the combination of hydrogen with ammonia was shown to mitigate NOx formation by lowering flame temperatures. Additionally, vibrational analysis demonstrated that ammonia and hydrogen blends reduce engine vibration, especially at higher loads, and contribute to decreased combustion and exhaust noise.

Effect of long reaction distance on gas composition from organic-rich shale pyrolysis under high-temperature steam environment

When high-temperature steam is used as a medium to pyrolyze organic-rich shale, water steam not only acts as heat transfer but also participates in the chemical reaction of organic matter pyrolysis, thus affecting the generation law and release characteristics of gas products. In this study, based on a long-distance reaction system of organic-rich shale pyrolysis via steam injection, the effects of steam temperature and reaction distance on gas product composition are analyzed in depth and compared with other pyrolysis processes. The advantages of organic-rich shale pyrolysis via steam injection are then evaluated. The volume concentration of hydrogen in the gas product obtained via the steam injection pyrolysis of organic-rich shale is the highest, which is more than 60%. The hydrogen content increases as the reaction distance is extended; however, the rate of increase changes gradually. Increasing the reaction distance from 800 to 4000 mm increases the hydrogen content from 34.91% to 69.68% and from 63.13% to 78.61% when the steam temperature is 500 °C and 555 °C, respectively. However, the higher the heat injection temperature, the smaller the reaction distance required to form a high concentration hydrogen pyrolysis environment (hydrogen concentration > 60%). When the steam pyrolysis temperature is increased from 500 °C to 555 °C, the reaction distance required to form a high concentration of hydrogen is reduced from 3800 to 800 mm. Compared with the direct retorting process, the volume concentration of hydrogen obtained from high-temperature steam pyrolysis of organic-rich shale is 8.82 and 10.72 times that of the commonly used Fushun and Kivite furnaces, respectively. The pyrolysis of organic-rich shale via steam injection is a pyrolysis process in a hydrogen-rich environment.

Thermal creep in a pre-hydrided Zr1 % Nb nuclear fuel cladding tube

The effect of hydrogen on the thermal creep behaviour of Zr1 %Nb alloy fuel cladding tubes for use in light water-cooled nuclear reactors was investigated. The tubes were hydrogen charged using an alternative method with a hydrogen content in the range 371–656 wppm H. Comparative constant-stress creep tests were carried out at 350 °C, under stress ranging from 150 to 225 MPa, on both non-hydrided and hydrided tubes. These creep tests were followed by a microstructural analysis of the specimens exposed to creep using SEM and TEM. It was found that these creep tests were conducted in the transition zone between the power-law and power-law breakdown creep regions. Hydrogen, either in solid solution (atomic hydrogen) or as precipitated zirconium hydrides, altered the creep behaviour of the hydrided tubes, and the impact of hydrogen depended on the hydrogen content CH. It was observed that under the creep loading conditions considered here with a hydrogen content CH < 450 wppm H, the presence of hydrogen resulted in an increase in the creep rate; however, a higher concentration of hydrogen caused a decrease in the creep rate. The difference in the effects of hydrogen on the creep rate was explained by the different roles of hydrogen in solid solution and in the form of zirconium hydride precipitates.

Experimental study on the explosion behavior of nonuniform hydrogen/methane/air mixtures in a duct

An experimental study is performed on the explosion behavior of a nonuniform hydrogen/methane/air mixture with varying hydrogen volume fractions (α(H2)) in the fuel used and different mixing levels of the fuel/air mixture (characterized by the diffusion time (td) of the hydrogen/methane mixture). Results show that both α(H2) and td considerably impact the explosion behavior of the nonuniform hydrogen/methane/air mixture. Increasing α(H2) and td can increase the uniformity of the hydrogen/methane/air mixture. A triple flame is observed in highly nonuniform mixtures instead of the finger- and tulip-shaped flames seen in more uniform mixtures. The shape of the flame front varies with the degree of fuel/air mixing. As α(H2) and td increase, the propagating flame gradually transitions from a triple flame to a tulip-shaped flame. The flame tip velocity and overpressure increase with α(H2) and td. For a fixed td, the flame tip velocity and overpressure increase slightly as the α(H2) rises from 0 to 40% and rapidly for a large α(H2). These findings suggest that improving the uniformity of hydrogen/methane/air mixtures could increase the severity of explosions for fuels with high hydrogen contents.

Experimental investigation of the characteristics of combustion in the full hydrogen blending range of methane-hydrogen mixtures in a MILD model combustor

MILD combustion technology is expected to enable safe and stable low-emission combustion of hydrogen-doped fuels, or pure hydrogen fuels, in gas turbines designed for zero-carbon emissions. To improve combustion stability at high hydrogen content while maintaining low NOx emissions, a MILD model combustor was modified, specifically the upstream fuel/air distribution and mixing method. And the combustion stability of the modified MILD combustor was significantly extended. Here, the combustion characteristics of the modified MILD combustor are experimentally investigated at 0–100% hydrogen contents. The investigation results demonstrate that unlike the combustion stability region at low hydrogen concentrations, a narrow thermoacoustic instability region occurs at 60% hydrogen content. As the hydrogen content increases, the instability region becomes narrower while shifting towards lower equivalence ratios. The change in hydrogen content is accompanied by a significant peak energy migration of the dynamic pressure. The OH* chemiluminescence images showed that the heat release zone became more concentrated with increasing hydrogen content. And the dominance of high-frequency peak energy correlates to lateral motion, whereas the dominance of low-frequency peak energy corresponds to axial motion. This transition in flame dynamics occurs not only for different hydrogen contents but also for different equivalence ratios of pure hydrogen combustion. In contrast, NOx emissions are not sensitive to hydrogen content. At the same time, the MILD model combustor produces low emissions, with NOx emissions of less than 10 ppm@15%O2 at adiabatic flame temperatures ranging from 1200 K to 2100 K. These results show that the MILD model combustor has favorable fuel suitability.

Structural, hydrogen storage capacity, electronic and optical properties of Li-N-H hydrogen storage materials from first-principles investigation

Although Li-N-H systems are promising hydrogen storage materials, the structural feature, phonon dynamical, electronic and optical properties of Li-N-H systems are unclear. To solve these problems, we apply the first-principles method to study the structural stability, hydrogen storage capacity, dehydrogenation energy, electronic and optical properties of three Li-N-H systems (Li4NH, Li2NH and LiNH2). The calculated results show that Li4NH and LiNH2 are thermodynamic and dynamical stabilities. Although Li2NH is a dynamical instability, it is a thermodynamic stability at the ground state. Importantly, the calculated gravimetric hydrogen storage capacity is 1.19 wt% for Li4NH, 3.35 wt% for Li2NH and 8.02 wt% for LiNH2, respectively. Essentially, the high hydrogen storage capacity of LiNH2 is related to the formation of [NH2] group due to the strong electronic interaction between N and H. Furthermore, Li2NH shows metallic behavior. However, the calculated band gap is 1.958 eV for Li4NH and 3.016 eV for LiNH2. The change of band gap of Li-N-H hydrides is demonstrated by the dielectric functional. In addition, this LiNH2 with high concentration of hydrogen has better storage optical properties compared to Li4NH and Li2NH.

Monte Carlo simulation and optimization of neutron ray shielding performance of related materials

Polymers have become widely used substrate materials for shielding neutron rays because of their high hydrogen content and easy processing procedures. Rare-earth materials are also being gradually adopted as neutron absorbers because of their considerable thermal neutron absorption cross-sections. This paper utilizes the FLUKA Monte Carlo simulation program to compare the shielding effects of various polymers and rare-earth oxides on neutron rays across different energy ranges. The study investigates the superior shielding materials for neutron radiation in each energy range. Subsequently, a series of materials are simulated by combining the preferred shielding materials for neutron rays in each energy range, exploring the influence of material composition and composite structure on the effectiveness of neutron ray shielding. It is revealed that the preferred material for shielding neutron rays changes for different energy ranges. For low-energy neutron rays, rare-earth oxides such as Sm2O3 and Gd2O3 demonstrate the most effective shielding, whereas for high-energy neutron rays, polyethylene (PE) provides the best shielding performance. Materials with different compositions show varying preferred structures when dealing with a 252Cf neutron source. However, in mitigating the secondary gamma rays generated during the neutron shielding process, stacked-type materials exhibit the most effective shielding performance.

Innovation in the synthesis of hydrazine borane by mechanochemical method and hydrolysis of hydrazine borane with Pd/TiO2 catalyst

With its high hydrogen content (15.4 wt%), hydrazine borane (HB, N2H4BH3) is a promising hydrogen storage material. It is easy to prepare and does not create harmful substances during the release of hydrogen, making it suitable for research. In this study, hydrazine borane was synthesized using two methods, one was solution phase synthesis method (literature method), and the other solid state synthesis method (mechanochemical). For the first time, we report a mechanochemical synthesis of HB from the hydrazine hemisulfate salt, sodium borohydride. HB was characterized by B NMR, FTIR, and XRD. Furthermore,the use of nanostructured titanium dioxide (TiO2) supported Pd metallic catalyst in HB hydrolysis was investigated to production hydrogen.

Highly active and stable Ni@SiO2 catalyst for ammonia decomposition

Ammonia is considered as a potential hydrogen carrier as its high hydrogen content. Hydrogen release still presents challenges due to the lack of efficient catalyst. In this work, we report a Ni@SiO2 catalyst prepared through a sol–gel method, which displays satisfied catalytic activity and remarkable long-term stability. The origination of activity and stability has been investigated carefully by various characterizations. The strong interaction between nickel species and silica species is responsible for the excellent performance via generating small nickel particle and hindering the sintering of nickel during the high temperature reaction condition. This study offers novel insights into the design and preparation of highly efficient catalysts for ammonia decomposition to produce hydrogen.

Effect of electrochemical charging on the hydrogen embrittlement susceptibility of a low-alloyed tempered martensitic steel submitted to high internal pressure

The influence of hydrogen on the mechanical behavior of a quenched and tempered 42CrMo4 steel has been evaluated by means of high internal pressure fracture tests carried out on hydrogen precharged notched cylindrical specimens. The notched cylindrical specimens were precharged for 3 h time with 1.2 mA/cm2 in two different aqueous media: 1 M H2SO4 added with 0.25 g/l As2O3 and 3.5% of NaCl solution. Hydraulic fracture tests were performed at different ramps of pressure: 7000, 220, 80, 60 and 30 MPa/h, respectively. Hydrogen damage was more marked when the acid aqueous medium (1 M H2SO4 + 0.25 g/l As2O3) was employed. In this case, a higher hydrogen concentration was introduced, leading to hydrogen decohesion micromechanisms (HEDE) near the notched region, especially when tests were performed at 60 MPa/h. Hydrogen embrittlement susceptibility is discussed in terms of the microstructural singularities and the operative fracture micromechanisms observed in each case.

Additively Manufactured Silicone Polymer Composite with High Hydrogen Getter Content and Hydrogen Absorption Capacity.

Hydrogen getters consisting of 1,4-bis[phenylethynyl] benzene (DEB) and a carbon-supported palladium catalyst (Pd/C) have been used to mitigate the accumulation of unwanted hydrogen gas in a sealed system. Here, we report the formulation of a composite resin consisting of silicone polymer plus DEB-Pd/C as an active getter material and the additive manufacturing of silicone getter composites with a high getter content (up to 50 wt %). NMR and DSC studies suggest no reaction between the silicone polymer resin and DEB even at elevated curing temperatures (75 °C). Getter composites with varying amounts of getter and filler were formulated, and their rheological properties were studied. The two composite resins with good printability parameters and different getter contents were chosen to make 3D-printed samples. The hydrogen absorption capacity of these samples was studied at a low hydrogen pressure of 750 mTorr of pure hydrogen. The getter composite with 50 wt% of getter showed normalized DEB conversion of 83%, with the hydrogen adsorption capacity of 100.2 mL of H2 per gram of polymer getter composite.

Numerical investigation on knock intensity, combustion, and emissions of a heavy-duty natural gas engine with different hydrogen mixing strategies

With the continuous development of hydrogen energy technology, mixing hydrogen has become a potential method to enhance the performance of natural gas engines and reduce emissions. Aiming to offer guidance for optimizing strategies for mixing hydrogen from the perspectives of knock control and thermal efficiency enhancement, a three-dimensional model of a commercial heavy-duty natural gas engine is constructed based on the actual boundary conditions from a high load bench test. In this study, simulations were conducted under conditions where the hydrogen volume fraction ranged from 0% to 40%. The study explored the effects of two injection strategies, port fuel injection of hydrogen-enriched natural gas (PFI) and port fuel injection of natural gas combined with direct injection of hydrogen into the cylinder (PFI + DI), on engine knocking, performance, and emissions. Results indicate that for various injection strategies, there is an increasing trend in knock intensity (KI) with the higher hydrogen mixing ratio. When the hydrogen volume fraction exceeds 20%, the timing of direct hydrogen injection significantly affects KI. This effect is mainly caused by the distribution of unburned hydrogen at the knock onset crank angle (KOCA). Compared to other injection strategies, the PFI + DI strategy when the direct hydrogen injection time at 120°CA BTDC results in a high concentration of hydrogen near the spark plug at the ignition moment, combined with good mixture uniformity in the cylinder. This leads to the shortest CA0-10 and CA10-90, and achieves a maximum indicated thermal efficiency (ITE) of 44.68% under 20% hydrogen volume fraction. Compared to the original natural gas engine, the ITE increased by 2.9% and the NOx emissions increased by 166%, while the HC and CO emissions decreased by 88% and 53%.

Exploring Deactivation Reasons of Biomass-Based Phosphorus-Doped Carbon as a Metal-Free Catalyst in the Catalytic Dehydroaromatization of n-Heptane.

Catalytic dehydroaromatization of n-alkanes into high-value aromatics has garnered extensive interest from both academia and industry. Our group has previously reported that phosphorus-doped carbon materials exhibit high selectivity for C-H bond activation in the dehydroaromatization of n-hexane. In this study, using n-heptane as a probe, we synthesized biomass-based phosphorus-doped carbon catalysts to investigate the impact of hydrogen heat treatment and carbon deposition on catalyst structure. Despite achieving an initial conversion of n-heptane at approximately 99.6%, with a toluene selectivity of 87.9%, the catalyst activity fell quickly. Moreover, longer hydrogen treatment time and higher hydrogen concentrations were found to accelerate catalyst deactivation. Thermogravimetric analysis (TGA) and N2 adsorption measurements (BET) indicated that a small amount of coke deposition was not the primary cause of catalyst deactivation. Temperature-programmed desorption of ammonia gas (NH3-TPD) revealed a significant decrease in acid-active functional groups. X-ray photoelectron spectroscopy (XPS) and solid-state 31P NMR spectroscopy confirmed the reduction of active central phosphorus species. These results suggest that catalyst deactivation primarily arises from the decrease in acidity and the partial reduction of phosphorus-containing groups, leading to a substantial loss of active sites. This work contributes new perspectives to understanding the properties and design improvements of metal-free carbon catalysts.

Deciphering the Pivotal Reaction Conditions for Hydrogen Production from Tar Catalytic Cracking by Perovskite

The catalytic cracking of pyrolysis gasification tar into H2 has garnered significant attention due to its exceptional conversion efficiency. In this study, the effects of pollutant concentration, residence time, weight hourly space velocity (WHSV), and reaction temperature on the hydrogen performance of LaFe0.5Ni0.5O3 perovskite were comprehensively investigated. Results revealed that moderate pollutant concentration (0.3 g/L), low-medium residence time (250 SCCM), and low WHSV (0.24 gtoluene/(gcat·h)) facilitated efficient interaction between LaFe0.5Ni0.5O3 and toluene, thus achieving high hydrogen production. An increase in reaction temperature had minimal effect on the hourly hydrogen production above 700 °C but caused a significant increase in methane production. Additionally, the effects of oxygen evolution reactions, methane reactions, and methane catalytic cracking reactions of perovskite induced by different reaction conditions on tar cracking products were discussed in detail. Compared to previous reports, the biggest advantages of this system were that the hydrogen production per gram of tar was as high as 1.002 L/g, and the highest hydrogen content in gas-phase products reached 93.5%, which can maintain for approximately 6 h. Finally, LaFe0.5Ni0.5O3 showed good thermal stability, long-term stability, and catalyst reactivation potential.

Stress corrosion cracking behavior and mechanism of 2205 duplex stainless steel under applied polarization potentials

In this work, a non-steady electrochemical model for assessing stress corrosion cracking (SCC) of 2205 duplex stainless steel (DSS) under applied polarization potentials was proposed, and the SCC mechanism was revealed. With the negative shift of potentials, hydrogen enhances SCC susceptibility by deteriorating passive film, inhibiting repassivation and causing serious damage. In particular, at −850 mV (vs. SCE), the synergetic effect of anodic dissolution (AD) and hydrogen embrittlement (HE) causes severe pitting and SCC. The negative shift of applied potentials changes the preferential pit/SCC initiation site due to high hydrogen concentration in austenite.

Reliability of Domestic Gas Flow Sensors with Hydrogen Admixtures.

Static flow sensors (e.g., thermal gas micro electro-mechanical sensors-MEMS-and ultrasonic time of flight) are becoming the prevailing technology for domestic gas metering and billing since they show advantages in respect to the traditional volumetric ones. However, they are expected to be influenced in-service by changes in gas composition, which in the future could be more frequent due to the spread of hydrogen admixtures in gas networks. In this paper, the authors present the results of an experimental campaign aimed at analyzing the in-service reliability of both static and volumetric gas meters with different hydrogen admixtures. The results show that the accuracy of volumetric and ultrasonic meters is always within the admitted limits for subsequent verification and even within those narrower of the initial verification. On the other hand, the accuracy of the first generation of thermal mass gas flow sensors is within the limits of the verification only when the hydrogen admixture is below 2%vol. At higher hydrogen content, in fact, the absolute weighted mean error ranges between 3.5% (with 5%vol of hydrogen) and 15.8% (with 10%vol of hydrogen).

Multiscale evaluation of hydrogen-assisted mechanical degradation in grade 2 titanium

The mechanism of hydrogen embrittlement in grade 2 titanium was studied by a combined micro and nanoscale approach. Insights into the hydrogen related deformation and degradation mechanisms were acquired via a unique characterisation procedure, correlating the topological observations on the fracture surface after tensile testing to the dislocation arrangement underneath. Focused ion beam lift-out was employed to extract a subsurface slice perpendicular to the fracture surface. High resolution characterisation provided information about the dislocation configuration and active hydrogen-assisted degradation mechanism. A high hydrogen content forms a brittle titanium hydride phase, failing via hydride cleavage. At a moderate hydrogen quantity, hydrogen in solid solution is responsible for a ductility decrease via the hydrogen-enhanced localised plasticity mechanism.

Comparison of Thermochemical and Physical Properties of Some Indonesian Agricultural Wastes

Indonesia is one of the largest agricultural countries in the world. Two main agricultural sub-sectors in Indonesia are food crops and estate crops. Agricultural waste is one of the biomass energy sources that has the potential to replace fossil energy sources. The weakness of energy sources from different types of agricultural waste is their heterogeneous thermochemical and physical properties. The objective of the experimental study is to compare the thermochemical and physical properties of fourteen selected agricultural wastes in Indonesia. The thermochemical properties that were compared are high heating value (HHV), percentage of lignocellulosic components, and ultimate analysis, while that of physical properties are the grindability, hydrophilicity, and proximate analysis. A material with high fixed carbon, low moisture, and low ash contents is preferred as a solid fuel source. Based on the experimental results of proximate analysis, coffee husk has the highest fixed carbon content (20.85%). Empty fruit bunch has the lowest moisture content (7.04%). Palm kernel shell has the lowest ash content (1.82%). Based on the results of the ultimate analysis, the palm kernel shell is the sample with the highest carbon content (49.42%), while the empty fruit bunch has the highest hydrogen content (6.69%). The coconut shell was identified as containing the lowest nitrogen (0.14%) and sulfur 0.052%). Peanut shell is the easiest to grind, while empty fruit bunch is the hardest to grind materials. The hydrophilicity of sugarcane trash is lower than other samples (9.34%). Coconut shell has the highest percentage of cellulose (47.21%). Several pairs of agricultural waste have similar properties that can be used as considerations for handling management and co-utilization.

Superlubricity of Silicon-Based Ceramics Sliding against Hydrogenated Amorphous Carbon in Ultrahigh Vacuum: Mechanisms of Transfer Film Formation.

Tribological interfaces between silicon-based ceramics, such as Si3N4 or SiC, are characterized by high friction and wear in unlubricated conditions. A solution to this problem is to use them in combination with a hydrogenated amorphous carbon (a-C:H) countersurface from which a passivating carbon film is transferred onto the ceramic surface. However, the mechanisms underlying a stable film transfer process and the conditions that favor it remain elusive. Here, we present friction experiments in ultrahigh vacuum in which friction coefficients lower than 0.01 are achieved by sliding Si3N4 against a-C:H with 36 at. % hydrogen but not against a-C:H with 20 at. % hydrogen. Chemical surface analyses confirm that the superlubric interface forms via the transfer of a hydrocarbon nanofilm onto the Si3N4 surface. Quantum-mechanical simulations reveal that a stable passivating a-C:H film can only be transferred if, after initial cold welding of the tribological interface, the plastic shear deformation is localized within the a-C:H coating. This occurs if the yield shear stress for plastic flow of a-C:H is lower than that of the ceramic and of the shear strength of the a-C:H-ceramic interface, i.e., if the a-C:H hydrogen content ranges between ∼30 and ∼50 at. %. While the importance of a relatively high hydrogen content to achieve an efficient passivation of a-C:H surfaces in a vacuum is well-documented, this work reveals how the hydrogen content is also crucial for obtaining a stable a-C:H transfer film. These results can be extended to glass, SiC, and steel, supporting the generality of the proposed mechanism.