Safe Hydrogen Research Articles

Total- and semi-bare noble metal nanoparticles@silica core@shell catalysts for hydrogen generation by formic acid decomposition

Catalysts are involved in a number of established and emerging chemical processes as well as in environmental remediation and energy conversion. Nanoparticles (NPs) can offer several advantages over some conventional catalysts, such as higher efficiency and selectivity. Nowadays, versatile and scalable nanocatalysts that combine activity and stability are still lacking. Here, we report a comprehensive investigation on the production and characterization of hybrid nano-architectures bringing a partial or total bare surface together with their catalytic efficiency evaluation on, as a proof-of-concept, the formic acid decomposition reaction. In this regard, formic acid (FA) is a convenient and safe hydrogen carrier with appealing features for mobile applications, fuel cells technologies, petrochemical processes and energetic applications. Thus, the design of robust catalysts for FA dehydrogenation is strongly demanded. Due to this, we produced and evaluated nano-architectures with various equilibrium between the size-increase of the active part and the barer catalytic surface. Overall, this work paves the way for the development of new approaches for green energy storage and safe delivery.

The experiment study to assess the impact of hydrogen blended natural gas on the tensile properties and damage mechanism of X80 pipeline steel

Environmental hydrogen embrittlement has become a non-negligible problem in the hydrogen blended natural gas transportation. To qualitatively study the degradation mechanism of X80 steel used in the natural gas pipelines, the slow strain tensile experiments are carried out in this work. The nitrogen and hydrogen are adopted to simulate the hydrogen blended natural gas to explore the tensile properties of X80 steel. According to the volume proportion of hydrogen, the test atmospheres are divided into the reference atmosphere and the hydrogen-contained atmospheres of 1%, 2.2% and 5%. The tensile experiments of the smooth and notched specimens are conducted in the above gas atmospheres. Mechanical properties and fracture morphologies after stretching are further analyzed. The results show that the hydrogen blended natural gas has little effect on the tensile and yield strengths. Distinguished from the hydrogen volume proportion of 1% and 2.2%, with the increase of hydrogen proportion, the effect of hydrogen on mechanical properties of specimens increases significantly. Moreover, the deteriorated mechanical properties of notched specimens are more seriously than those of smooth specimens. This work provides the basis for safe hydrogen proportion for X80 pipeline steel when transporting hydrogen blended natural gas.

Recent Progress in Hydrogen Flammability Prediction for the Safe Energy Systems

Many countries consider hydrogen as a promising energy source to resolve the energy challenges over the global climate change. However, the potential of hydrogen explosions remains a technical issue to embrace hydrogen as an alternate solution since the Hindenburg disaster occurred in 1937. To ascertain safe hydrogen energy systems including production, storage, and transportation, securing the knowledge concerning hydrogen flammability is essential. In this paper, we addressed a comprehensive review of the studies related to predicting hydrogen flammability by dividing them into three types: experimental, numerical, and analytical. While the earlier experimental studies had focused only on measuring limit concentration, recent studies clarified the extinction mechanism of a hydrogen flame. In numerical studies, the continued advances in computer performance enabled even multi-dimensional stretched flame analysis following one-dimensional planar flame analysis. The different extinction mechanisms depending on the Lewis number of each fuel type could be observed by these advanced simulations. Finally, historical attempts to predict the limit concentration by analytical modeling of flammability characteristics were discussed. Developing an accurate model to predict the flammability limit of various hydrogen mixtures is our remaining issue.

An innovative and comprehensive approach for the consequence analysis of liquid hydrogen vessel explosions

Hydrogen is one of the most suitable solutions to replace hydrocarbons in the future. Hydrogen consumption is expected to grow in the next years. Hydrogen liquefaction is one of the processes that allows for increase of hydrogen density and it is suggested when a large amount of substance must be stored or transported. Despite being a clean fuel, its chemical and physical properties often arise concerns about the safety of the hydrogen technologies. A potentially critical scenario for the liquid hydrogen (LH2) tanks is the catastrophic rupture causing a consequent boiling liquid expanding vapour explosion (BLEVE), with consequent overpressure, fragments projection and eventually a fireball. In this work, all the BLEVE consequence typologies are evaluated through theoretical and analytical models. These models are validated with the experimental results provided by the BMW care manufacturer safety tests conducted during the 1990's. After the validation, the most suitable methods are selected to perform a blind prediction study of the forthcoming LH2 BLEVE experiments of the Safe Hydrogen fuel handling and Use for Efficient Implementation (SH2IFT) project. The models drawbacks together with the uncertainties and the knowledge gap in LH2 physical explosions are highlighted. Finally, future works on the modelling activity of the LH2 BLEVE are suggested.

Activation of bulk aluminum and its application in a hydrogen generator

Aluminum is a highly energy dense material that can enable simple and safe hydrogen generation when reacted with water. We present a method for activating cold-worked non-recrystallized bulk aluminum objects (aluminum bbs) by surface treatment with a heated gallium-indium (Ga-In) eutectic melt. Afterwards, the activated aluminum can be reacted with water to generate hydrogen gas, heat and aluminum oxihydroxide. The elevated temperature of the eutectic melt during treatment allows the Ga-In to efficiently penetrate the aluminums’ plastically strained grain boundaries, causing liquid metal embrittlement and activation of the aluminum. This unique method of activation produces a highly reactive aluminum fuel using only 3–4 wt% Ga-In eutectic which can then be reacted with water in a controllable manner.The surface treatment time, temperature of the melt, and composition of the melt were varied and the effects on hydrogen yields were compared. It was found that the addition of temperature, sufficient time in the melt, and gallium/indium ratio were key to activation efficiency. The activated aluminum was then tested in a small-scale hydrogen generator, which steadily and controllably produced nearly 94% of expected hydrogen yield using less than 4% gallium-indium eutectic for activation.

ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ ТЕХНОЛОГІЇ ОТРИМАННЯ ВОДНЮ ШЛЯХОМ ВИКОРИСТАННЯ РЕГЕНЕРАЦІЙНОГО КОНТУРУ З РОТОРНО-ПОРШНЕВОЮ РОЗШИРЮВАЛЬНОЮ МАШИНОЮ

The article discusses a promising technology for the production and safe accumulation of hydrogen from the Black Sea hydrogen sulfide, which includes the following processes: production of hydrogen sulfide from the depths of the Black Sea; separation of hydrogen sulfide and seawater; destruction of hydrogen sulfide to produce a hydrogen-containing gas; separation of hydrogen from a hydrogen-containing gas; safe hydrogen storage; safe transportation of hydrogen. It is proposed to use the regeneration circuit to increase the efficiency of this technology, which includes: an expansion machine for high-pressure hydrogen sulfide, a seawater hydraulic turbine, and a heat pump installation. It is proposed to evaluate the efficiency of the application of the technology for the production and safe accumulation of hydrogen from the Black Sea hydrogen sulfide by effective capacity, which includes: thermal power of hydrogen, power of the regeneration circuit; the power needed to carry out hydrogen production processes. It is proposed to use the 20RPD-4.4/1.75 rotary piston engine as a hydrogen sulfide expansion machine that will satisfy all the requirements. Rational operating modes and limiting values of the efficiency of using the technology for obtaining and safe accumulation of hydrogen from the Black Sea hydrogen sulfide for daily hydrogen production of 200 kg/day were determined depending on the degree of hydrogen sulfide conversion during destruction, the gas content of hydrogen sulfide in seawater and the depth of immersion of the lifting pipeline using the regeneration circuit. The minimum permissible degrees of conversion at which the efficiency of using the technology for obtaining and safe accumulation of hydrogen from the Black Sea hydrogen sulfide for a gas content of hydrogen sulfide of 2.5 m3/m3 at a depth of immersion of the lifting pipeline of 250...1000 m is 0.427 ... 0.413, for 5 m3/m3 – 0.375...0.363, for 7.5 m3/m3 – 0.363...0.350, for 10 m3/m3 – 0.356...0.343. The use of the regeneration circuit allowed us to reduce the minimum permissible degrees of conversion for the gas content of hydrogen sulfide of 2.5...10 m3/m3 at a depth of immersion of the lifting pipeline of 250...1000 m by 0.136 ... 0.069.

Features of gas breakdown in narrow discharge gaps at high pressures

Plasma treatment of porous polymeric materials is a critical technology for creating new polymer materials that can be used in various applications. Porous polymers can be used in new approaches for creation of safe and compact hydrogen storage systems that can dramatically change existing hydrogen energy utilization. There are other potential applications for the development of new types of biocompatible and biodegradable polymeric materials for general use and for creation of new types of implants and dressing materials in medicine. Clarification of breakdown conditions of narrow discharge gaps in the micrometer region and optimization of the treatment process for different gap dimensions is the goal of this paper. The article is devoted to the experimental study of the breakdown process in the discharge gap by pulsed barrier discharge at different pressures and gaps in the region of the minimum of the Paschen curve. New approximation of the Paschen curve with the variable γ as a function of Pd, which is in good correlation with experimental results, has been proposed. A new approach is proposed for treating the inner surface of dielectric material pores with a barrier discharge, optimizing the pressure inside the pores; treating pores of a micron size requires a pressure significantly higher than atmospheric. The first results were obtained, which demonstrated the possibility of modifying the thickness of the polymer material by treatment with the barrier discharge at the time of gas pressure relief in the discharge chamber.

Spatially decoupled hydrogen evolution in alkaline conditions with a redox targeting-based flow battery

Conventional water electrolyzer simultaneously generates H2 and O2 in neighboring electrode compartments which raises various issues by gas mixing. Thus, decoupled water electrolysis is desired to avoid the problems. Motivated by the above, spatially decoupled hydrogen evolution reaction (HER) is demonstrated in this work, leveraging a redox targeting-based flow battery employing iron triethanolamine (Fe(III)TEA)-K2MnO4 redox couple. This system spatially separates HER from the electrode compartment. Sustained hydrogen is achieved by reaction between regenerated Fe(II)TEA and water in the negative electrolyte storage tank. The Faradaic efficiency of the decoupled HER is 70% and keeps stable upon prolonged operation. The onset overpotential of HER is 24 mV which is lower than previous studies. We anticipate the approach presented in this work would offer an alternative solution to water electrolysis for scalable and safe hydrogen production with improved gas purity.

Rh2S3/N‐Doped Carbon Hybrids as pH‐Universal Bifunctional Electrocatalysts for Energy‐Saving Hydrogen Evolution

AbstractUsing hydrazine oxidation reaction (HzOR) to replace the oxygen evolution reaction is an effective way to decrease the overpotential of the anodic reaction in overall water splitting (OWS), facilitating cost‐effective and safe hydrogen production. Herein, Rh2S3/N‐doped carbon hybrids (Rh2S3/NC) are first reported as novel and efficient bifunctional electrocatalysts for hydrazine‐assisted hydrogen generation over a wide pH range. Specifically, Rh2S3/NC exhibits low overpotentials for the hydrogen evolution reaction (HER) in alkaline (38 mV), neutral (46 mV), and acidic (21 mV) electrolytes, to reach the current density of 10 mA cm−2, and maintains the activities over 70 h. Meanwhile, Rh2S3/NC also displays competitive HzOR performance at all‐pH electrolytes. Thus, serving as a bifunctional electrocatalyst for both HER and HzOR, Rh2S3/NC shows overwhelming‐Pt/C performance in three electrolytes, and can save over 93.3%, 85.2%, and 78.3% energy consumption compared to the corresponding OWS system. Moreover, theoretical calculations confirm that Rh2S3/NC owns low free‐energy changes of the H adsorption and the dehydrogenation of adsorbed NHNH both of which are beneficial to enhance catalytic activity. This work develops a novel bifunctional electrocatalyst with free pH‐dependent condition for the hydrazine‐assisted electrolysis system to furtherly reduce the cost of massive industrial H2 production.

Effect of Toluene on PEMFC Performance

AbstractLiquid organic hydrogen carriers (LOHCs) are promising means for hydrogen transportation. They are compatible with existing liquid fuel transport infrastructure and enable for efficient and safe hydrogen storage and transfer over long distances. Toluene and dibenzyltoluene are considered the two most promising LOHCs. Toluene is probably a contaminant found in hydrogen released from these LOHC liquids.The impact of hydrocarbon contaminants on automotive type fuel cells has been analyzed to a limited extent, and a few species only have specific limits (CO, CO2, HCOOH, HCHO, CH4). Currently, hydrocarbons are limited to a total of 2 ppm (methane basis) in the automotive hydrogen fuel standard, ISO 14687:2019. This may lead to strict impurity levels for species from LOHC, and therefore higher costs of hydrogen purification and quality assurance.This work presents contamination studies with toluene. The measurements were conducted using a PEMFC short stack with anode recirculation and with high fuel utilization (98%). The results show no effect or only a small contamination effect with up to 20 ppm toluene, and clear contamination with 50 ppm toluene. This supports the need for more studies so that a separate limit can be defined for toluene in future versions of the ISO 14687.

Fabrication of Pd/ Ni Alloy Nanotubes Via Electrospinning for High Performance Hydrogen Detection

Hydrogen is one of the most important “next generation energy sources”, which is free for environment pollution, with water as the only emission. Due to the danger of hydrogen explosion when mixed with air, as well as the low specific heat capacity of hydrogen, the temperature required for combustion can be reached immediately even a little heat absorbed. Therefore, it’s necessary to search an effective way to monitor hydrogen leakage at room temperature.In this study, the Pd based hydrogen sensor was investigated. During the transduction process, volumetric expansion occurred due to the hydrogen absorption at room temperature to achieve safe hydrogen detection. Previous research indicated that Pd/Ni alloy films/ nanofibers can achieve higher catalytic activity, stability and sensitivity than pure Pd films/nanofibers due to the synergistic effect between Pd and Ni 1 ,2,3 . But both the films and nanofibers structures have limited specific surface area and therefore limited exposed hydrogen adsorption sites. To overcome these problems, we fabricated the porous Pd nanotubes alloyed with Ni by using Polyvinylpyrrolidone (PVP) and SiO2 templates electrospinning route, then the PVP and SiO2 templates were selectively removed by calcination and etching 4 , respectively. The sensing performance was measured by monitoring the resistance curves of sensing platform at various hydrogen concentrations. Compared to Pd/Ni nanofibers structures, tubular structures achieved lower LOD and higher sensitivity which are attributed to the high surface area and abundant hydrogen adsorption active sites. High performance Pd/Ni nanotubes can be successfully fabricated in an effective and facile approach for hydrogen detection at room temperature. At last, the effects of the concentration of Ni in Pd on the sensing performance was also investigated.

Determining Plasmonic Hot Electrons and Photothermal Effects during H2 Evolution with TiN–Pt Nanohybrids

Hydrogen storage in chemical compounds is a promising strategy to enable lightweight, high-density, and safe hydrogen technologies. However, the hydrogen release rate from these chemicals is limite...

A "philosophical molecule," hydrogen may overcome senescence and intractable diseases.

It has been revealed that the cause of senescence and diseases is associated with the reactive oxygen species “hydroxyl radicals” (·OH). Senescence and diseases may be overcome as long as we can scavenge •OH mostly produced in mitochondria. It is one and only one “molecular hydrogen” (H2) that can both penetrate into the mitochondria and scavenge the •OH. The H2 in the body can function in disease prevention and recovery. H2 gas is explosive so that a safe hydrogen inhaler has to be developed for home use. We would like to advocate the great use of H2.

Black TiO2 nanoparticles with efficient photocatalytic activity under visible light at low temperature: regioselective C–N bond cleavage toward the synthesis of thioureas, sulfonamides, and propargylamines

Several different colored forms of TiO2 were prepared through the easy treatment of white TiO2 and NaBH4 as a safe hydrogen source. Then, tertiary amines were harnessed toward the regioselective synthesis of three prominent scaffolds.

A facile and highly efficient transfer hydrogenation of ketones and aldehydes catalyzed by palladium nanoparticles supported on mesoporous graphitic carbon nitride

A novel transfer hydrogenation methodology for the reduction of ketones (14 examples) and benzaldehyde derivatives (12 examples) to the corresponding alcohols using Pd nanoparticles supported on mesoporous graphitic carbon nitride (mpg-C3N4/Pd) as a reusable catalyst and ammonia borane as a safe hydrogen source in an aqueous solution MeOH/H2O (v/v = 1/1) is described. The catalytic hydrogenation reactions were conducted in a commercially available high-pressure glass tube at room temperature, and the corresponding alcohols were obtained in high yields in 2–5 min. Moreover, the presented transfer hydrogenation protocol shows partial halogen selectivity with bromo-, fluoro-, and chloro-substituted carbonyl analogs. In addition, the present catalyst can be reused up to five times without losing its efficiency, and scaling-up the reaction enables α-methylbenzyl alcohol to be produced in 90% isolated yield.

A MOF-templated approach for designing ruthenium–cesium catalysts for hydrogen generation from ammonia

Ammonia is regarded as a safe hydrogen energy carrier due to its high hydrogen content and narrow flammable range. Herein, we report a novel metal-organic framework (MOF) templated approach to synthesize highly active catalysts for the hydrogen production from ammonia. Calcination of ruthenium-impregnated UiO-66(Zr)-NH2 leads to formation of small ruthenium nanoparticles (<3 nm) with a strong interaction with the resulting mesoporous zirconia support. These catalysts present a turnover frequency considerably higher than Ru/CNTs catalysts, defying the established believe of 3–5 nm as optimum Ru size for this reaction. Moreover, cesium promoter acts as an electronic modifier of Ru and also as a molecular spacer enhancing the stability under reaction conditions. Despite the exciting potential of this approach, the collapse of MOF framework structures during the calcination process limits the accessibility with an estimated ~16% of the ruthenium accessible, underestimating the actual turnover frequency (TOF) values.

Formation of the Structure and Properties upon Thermohydrogen Treatment of the Alloy Based on Titanium Aluminide Ti2AlNb

Abstract—Changes in the structure, phase composition, microhardness, and modulus of elasticity upon thermohydrogen treatment of the VTI4 alloy based on the orthorhombic titanium aluminide Ti2AlNb alloyed with hydrogen to 12.5 at % have been studied using electron microscopy, X-ray diffraction analysis, and microindentation. It has been shown that the alloying of this alloy with hydrogen leads to a decrease in peak stresses and to an increase in the degree of deformation to the formation of cracks in the course of upsetting at 900°C. The kinetics of dehydrogenation at the temperatures of 600 and 700°C for 4 h in an argon flow and in vacuum has been studied. The thermohydrogen treatment of the VTI4 alloy makes it possible to obtain a thermostable state with a safe hydrogen content with a predominance of the O phase in the structure and high physical and mechanical properties (the Vickers hardness up to 5300 MPa, the contact modulus of elasticity to 114 GPa) after the final dehydrogenating annealing in the vacuum at 600°C for 4 h.

First-Principles Study on Hydrogen Storage Performance of Transition Metal-Doped Zeolite Template Carbon

The hydrogen adsorption characteristics and mechanism of transition metal-doped zeolite template carbon (ZTC) as a novel porous material are studied by theoretical calculations employing first-principle all-electron atomic orbital method based on density functional theory. The stability of transition metal atoms (Sc, Ti, and V) decorated on zeolite template carbon is investigated by calculating the absorption binding energy. The adsorption configurations of the doped metal atom and adsorbed hydrogen are obtained from the energy functional minimization of first-principles calculations. The underlying mechanism for improving hydrogen storage performance of ZTC by doping transition metal atoms are explored through analyzing charge/spin populations of metal atoms in combination with the calculated results of hydrogen adsorption quantity and binding energy. To improve the hydrogen storage capability, the Sc, Ti, and V are individually introduced into the ZTC model according to the triplex axisymmetry. The hydrogen storage properties of ZTC decorated with different metal atoms are characterized by the adsorption energy and structure of several hydrogen atoms. The more energetically stable complex system with higher binding energy and adsorbing distance of hydrogen than lithium-doped ZTC can be achieved by doping Sc, Ti, V atoms in ZTC, which is expected to fulfill the substantial safe hydrogen storage by increasing hydrogen capacity with multi-sites doping of transition metal atoms. The present investigation provides a theoretical basis and predictions for the following experimental research and design of porous materials for hydrogen storage.

CFD Design of Hydrogenation Reactor for Transformation of Levulinic Acid to γ-Valerolactone (GVL) by using High Boiling Point Organic Fluids

Levulinic acid (LA) has been ranked as one of the “Top 10” building blocks for future bio-refineries as proposed by the US Department of Energy. It is considered one of the most important platform molecules for the production of fine chemicals and fuels based on its compatibility with existing processes, market economics, and industrial ability to serve as a platform for the synthesis of important derivatives. Hydrogenation of LA to produce γ-valerolactone (GVL) is an active area of research due to the potential of GVL to be used as a biofuel in its own right and for its subsequent transformation into hydrocarbon fuels. This paper contains a new design for a simple, cost effective, and safe hydrogenation reactor for the transformation of levulinic acid to γ-valerolactone (GVL) by utilizing high boiling point organic fluid. The hydrogenation reactor is composed of a heating source—organic fluid (called “DOWTHERM A” or “thermex”) and the catalytic reactor. The advantages of high boiling temperature fluids, along with advances in hydrocracking and reforming technologies driven by the oil and gas industries, make the organic concept more suitable and safer (water coming in contact with liquid metal is well understood in the metallurgical industry to be a steam explosion hazard) for heating the hydrogenation reactor. COMSOL multi-physics software version 4.3b was applied in this work and simultaneously solves the continuity, Navier-Stokes (fluid flow), energy (heat transfer), and diffusion with chemical reaction kinetics equations. It was shown that the heat flux supplied by the DOWTHERM A organic fluid could provide the necessary heat flux required for maintaining the hydrogenation process. It was found that the mass fractions of hydrogen and levulinic acid decreased along the reactor axis. The GVL mass fraction increased along the reactor axis.

Hydrogen[sbnd]oxygen steam generator for a closed hydrogen combustion cycle

The paper deals with the problems of hydrogen combustion in an oxygen environment to produce high-temperature steam to be used in electricity generation at various power stations including nuclear power plants (NPP). For example, the use of H2/O2 steam generator within a hydrogen energy complex may allow increasing the NPP power and efficiency under operating conditions due to hydrogen steam superheating of the main working fluid in a steam-turbine unit. In addition, the use of the hydrogen energy complex may allow adapting NPP to variable electric load schedules with the increasing share of such power stations as well as developing environmentally friendly technologies for electricity generation. In the paper, a new solution to the problem of the effective and safe use of hydrogen energy at NPP with a hydrogen energy complex has been proposed.Technical solutions to hydrogen combustion in an oxygen environment using direct injection of cooling water or water steam into combustion products may have a significant weakness, namely the “quenching” phenomenon occurring during water/water steam injection resulting in the recombination efficiency decrease during the cooling of combustion products which is reflected in the increased proportion of non-condensable gases. In this case, the supply of such mixture to the steam-power cycle may be unsafe, as it could result in the increased concentration of unburned hydrogen in the steam turbine flow path. In the paper, a closed hydrogen cycle along with the hydrogen steam superheating system on its basis has been proposed to solve this problem. The closed-circuit system of hydrogen combustion preventing hydrogen permeation into the working fluid of a steam cycle completely as well as ensuring its full oxidation due to some excess of circulating oxygen has been investigated by the authors.Two types of H2/O2 combustion chambers for the system of safe hydrogen steam superheating in NPP cycle by using the closed-circuit system of hydrogen combustion in an oxygen environment have been considered in the study. The required parameters of H2/O2 steam generator with regard to operating temperature conditions as well as the power range of H2/O2 steam generators with the proposed combustion chamber construction design have been determined by mathematical modeling of the combustion and heat-mass-exchange processes.