Low Hydrogen Solubility Research Articles

Hydrogen Solubility of Shale Oil Containing Polar Phenolic Compounds

Many refineries use hydrogen to upgrade heavy fuel feedstocks, and therefore, hydrogen solubility is an important parameter. Shale oil is a fuel for which hydrotreatment is of interest, but no data about its hydrogen solubility can be found in the literature. This Article presents experimental data for the hydrogen solubility of two shale oil samples measured at high temperatures and pressures (423–527 K and 40–140 bar). Experiments were performed using a continuous flow apparatus. Results show that the shale oil had a lower hydrogen solubility than most other fuels, probably due to the high content of polar phenolic compounds in the oil. Removing about 80% of the phenolic compounds increased the hydrogen solubility by approximately 0.1 mol H2/kg oil (which is about 15 to 45%, depending on the solubility). Analysis also showed that current prediction methods used for petroleum and coal liquids cannot reliably be used for predicting the hydrogen solubility of this shale oil and other similar fuels.

Solute hydrogen and hydride phase implications on the plasticity of zirconium and titanium alloys: a review and some recent advances.

In this contribution, we propose a review of the possible implications of hydrogen on mechanical behaviour of Zr and Ti alloys with emphasis on the mechanisms of plasticity and strain hardening. Recent advances on the impact of oxygen and hydrogen on the activation volume show that oxygen content hinders creep but hydrogen partially screens this effect. Both aspects are discussed in terms of a locking-unlocking model of the screw dislocation mobility in prismatic slip. Additionally, possible extension of this behaviour is suggested for the [Formula: see text] pyramidal slip. The low hydrogen solubility in both Zr and Ti leads in many cases to hydride precipitation. The nature of these phases depends on the hydrogen content and can show crystallographic orientation relationships with the hexagonal compact structure of the alloys. Some advances on the thermal stability of these phases are illustrated and discussed in relation with the deepening of the misfit dislocations. Under tensile loading, we showed that hydrides enhance the hardening process in relation with internal stress due to strain incompatibilities between the Zr and Ti matrix and hydride phases. Different plastic yielding processes of hydrides were identified, which progressively reduce these strain incompatibilities.This article is part of the themed issue 'The challenges of hydrogen and metals'.

Dispersion and dissolution of a buoyancy driven gas plume in a layered permeable rock

AbstractUsing a series of simplified models, we explore the controls on the migration, dispersion and eventual dissolution of a plume of hydrogen gas which may, in principle, rise under buoyancy through a layered permeable rock if released from a Geological Disposal Facility (GDF). We show that the presence of low permeability shale barriers causes the gas to spread laterally as it rises. Averaging over the length scale of the barriers, we use expressions for the Darcy velocity of the gas to describe the dispersion of a tracer and illustrate the effect with a new experiment using a baffled Hele‐Shaw cell. While the plume is flowing, a large volume of gas may build up beneath the barriers. If the gas flux subsequently wanes, much of the gas will drain upward through the formation and spread on the upper impermeable boundary of the formation. However, a significant capillary‐trapped wake of gas may develop beneath each barrier. Owing to the low solubility of hydrogen in water and assuming relatively slow groundwater flow rates, this trapped hydrogen may require a period of tens to hundreds of thousands of years to dissolve and form a cloud of hydrogen rich water. Although simplified, these models provide a framework to assess the possible travel times and pathways of such a gas plume.

Hydrogen diffusion in bulk MgB2

The diffusion of hydrogen in MgB2 is crucial to the kinetics of rehydrogenation of Mg(BH4)2. We report a comprehensive combination of first-principles calculations and Kinetic Monte Carlo Simulations to examine the energetics of diffusion of hydrogen atoms through bulk MgB2. From these calculations we find that diffusion is fast for the neutral interstitial hydrogen defect and that the overall migration barrier for hydrogen diffusion in MgB2 is 0.22eV, showing that rapid diffusion of hydrogen is possible even at moderate temperatures. The interstitial hydrogen defect formation energy is around 0.8eV at 0K, indicating a low hydrogen solubility at moderate temperatures.

Thermodynamic Evaluation of Potential Organic Hydrogen Carriers

Thermodynamic Evaluation of Potential Organic Hydrogen Carriers

Pressure-Induced Formation of Noble Metal Hydrides

Noble metals (Ru, Rh, Pd, Ag, Os, Ir, Pt, and Au) do not form hydrides with hydrogen under ambient conditions originated from the extremely low solubility of hydrogen in them. Because of such limitation, finding these hydrides under ambient conditions is scarce. Here we use a combination of particle swarm optimization technique on crystal structure prediction and first-principles calculations based on density functional theory to explore the reactivity of hydrogen with noble metals under high pressure. We demonstrated that except for Au, other noble metals can commonly form monohydrides under high pressure even at zero temperature. We find universal high pressure structure features of these monohydrides–the structures either are stable or eventually transform into closed packed fcc or hcp with hydrogen occupying the octahedral interstitial sites of the metal sublattices. Of particular interest by the introduction of hydrogen are the high pressure structural changes of these noble metals, which, however, remain remarkably stable for pure elements. Our research highlights the key role of pressure played in the formation of these noble metal hydrides.

Uptake and Distribution of Tritium in Copper

The uptake of tritium on the surface and in the bulk of copper upon exposure to a 50 % T/H mixture at 300 or 473 K was investigated using a chemical etching technique. Concentrations of tritium approaching saturation are achieved fairly rapidly in Cu even at low temperatures because of comparatively high diffusivity and low solubility of hydrogen in this material. The results were interpreted by a diffusion model. Most notorious are the very high concentrations of tritium on the topmost surface and subsurface. They were quantified by etching and confirmed by BIXS. In addition, there is evidence for tritium trapping in the subsurface region.Tritium-loaded copper specimens release tritium chronically at ambient temperature. The egress of tritium manifests in the gas phase almost exclusively as tritiated water.

Determination of hydrogen diffusivity and permeability in W near room temperature applying a tritium tracer technique

Tungsten is a primary candidate of plasma facing material in ITER and beyond, owing to its good thermal property and low erosion. But hydrogen solubility and diffusivity near ITER operation temperatures (below 500K) have scarcely studied. Mainly because its low hydrogen solubility and diffusivity at lower temperatures make the detection of hydrogen quite difficult. We have tried to observe hydrogen plasma driven permeation (PDP) through nickel and tungsten near room temperatures applying a tritium tracer technique, which is extremely sensible to detect tritium diluted in hydrogen.The apparent diffusion coefficients for PDP were determined by permeation lag times at first time, and those for nickel and tungsten were similar or a few times larger than those for gas driven permeation (GDP). The permeation rates for PDP in nickel and tungsten were larger than those for GDP normalized to the same gas pressure about 20 and 5 times larger, respectively.

A continuum-scale model of hydrogen precipitate growth in tungsten plasma-facing materials

The low solubility of hydrogen in tungsten leads to the growth of near-surface hydrogen precipitates during high-flux plasma exposure, strongly affecting migration and trapping in the material. We have developed a continuum-scale model of precipitate growth that leverages existing techniques for simulating the evolution of 3He gas bubbles in metal tritides. The present approach focuses on bubble growth by dislocation loop punching, assuming a diffusing flux to nucleation sites that arises from ion implantation. The bubble size is dictated by internal hydrogen pressure, the mechanical properties of the material, as well as local stresses. In this article, we investigate the conditions required for bubble growth. Recent focused ion beam (FIB) profiling studies that reveal the sub-surface damage structure provide an experimental database for comparison with the modeling results.

Characterization of hydrogen-induced crack initiation in metastable austenitic stainless steels during deformation

Hydrogen-induced crack initiation in hydrogen-charged metastable austenitic stainless steels during deformation at 295 K is characterized by performing a combined tensile and hydrogen release experiment and scanning probe microscopy. Strain-induced martensite (α′) not only provides a path for rapid hydrogen diffusion in austenite (γ) but also promotes crack initiation. Hydrogen rapidly diffuses from α′ and accumulates at the boundary between the α′-rich and γ-rich zones during deformation due to the high hydrogen diffusivity and low hydrogen solubility in α′, resulting in crack initiation at the boundary between the α′-rich and γ-rich zones. The hydrogen-induced crack initially grows along the boundary between the α′-rich and γ-rich zones and then propagates in the α′-rich zone.

Electrochemically elaborated palladium nanofilms on Pt(1 1 1): Characterization and hydrogen insertion study

Ultrathin palladium films, from 1 to 60 monolayers (ML) thick, have been obtained on Pt(1 1 1) by electrodeposition of Pd II from chloride-containing electrolytes. The first ML was obtained by palladium underpotential deposition (UPD). The role of chloride concentration on the growth mode is discussed. Film roughness obtained with 3 × 10 −3 M HCl solutions slowly increases by ca. 25% from 5 to 60 ML. Large terraces remain present on deposits up to 20 ML. For larger thicknesses, their width gradually decreases and new hydrogen adsorption sites appear. The behaviour of these Pd nanofilms with regard to hydrogen insertion was studied in H 2SO 4 0.1 M. Absorption branches of the electrochemical isotherms were measured for 10 ML and 16 ML deposits. Compared to bulk Pd, enlarged solid solution domains and lower hydrogen solubility are observed. The role of the Pt(1 1 1) substrate is evidenced by comparing the shape of the isotherms with those measured using unsupported Pd nanoparticles.

Hydrogen Permeation of Thin Pd-25Ag Membranes Prepared by Cold Rolling and Microsystem Technology

Hydrogen permeation of thin Pd-25Ag membranes with the thickness down to 1.2 mm was investigated by conventional gas permeation method within the temperature range of 473–673 K. The thin Pd-25Ag membranes with the thickness down to 51 mm were prepared by cold rolling method. The 1.2 mm-thick Pd-25Ag membrane was prepared by microsystem technology. The hydrogen permeation of the prepared Pd25Ag membranes was independent of the membrane thickness until down to 51 mm. The 51 mm-thick Pd-25Ag membrane had the hydrogen permeability lower by 60% than that of the bulk Pd-25Ag metal. It mainly resulted from slow surface reaction and lower hydrogen solubility near the surface of the 51 mm-thick Pd-25Ag membrane. The hydrogen permeability of the 1.2 mm-thick Pd-25Ag membrane was one order lower than that of bulk Pd-25Ag metal because the hydrogen permeation was mainly limited by surface reaction. However, literature review indicated that the microfabricated 1.2 mm-thick Pd-25Ag membrane had the hydrogen permeability superior to those conventional Pd-25Ag membranes supported by porous materials, suggesting attractive advantages of the microsystem technology in hydrogen-separation membrane applications. [doi:10.2320/matertrans.MRA2007260]

Amorphous Fe-based metal foam

A foam synthesis method that takes advantage of the viscous high-temperature liquid state of Fe-based bulk glass-forming alloys to produce amorphous steel foam is introduced. Zirconium hydride is utilized as a foaming agent taking advantage of the low hydrogen solubility of these glass-forming alloys. Amorphous foams with porosities up to 65% were produced having homogenous cellular morphologies that exhibit cell-size uniformity. Even though intracellular solid regions as thin as a few micrometers are detected, on a global scale the cellular structure is determined to be incapable of alleviating the foam from the brittle nature of the monolithic glass.

Sevoflurane Breakdown Produces Flammable Concentrations of Hydrogen

Fires, explosions, and extreme heat production may occur when sevoflurane reacts with desiccated barium hydroxide lime. The identity of the flammable gas has not previously been published, although carbon monoxide, methanol, formaldehyde, and methyl formate have been identified in low quantities. The authors reacted sevoflurane with excess desiccated barium hydroxide lime or soda lime at 55 degrees, 100 degrees, 200 degrees, 300 degrees, and 400 degrees C. Formaldehyde, methanol, sodium formate, and hexafluoroisopropanol were reacted with barium hydroxide lime at 300 degrees or 400 degrees C. The authors measured hydrogen production by gas chromatography with a thermal conductivity detector and calculated the molar yield of hydrogen produced. Up to 3 moles of hydrogen were produced per mole of sevoflurane degraded. Each mole of formaldehyde produced up to 2 moles of hydrogen at 400 degrees C. Formate and hexafluoroisopropanol produced up to 1 mole of hydrogen each at 400 degrees C. More than 2 moles of hydrogen were produced by methanol at 400 degrees C. Soda lime and barium hydroxide lime produced similar amounts of hydrogen from sevoflurane above 200 degrees C, but barium hydroxide lime produced more than soda lime at lower temperatures. The temperature above which large amounts of hydrogen were produced seemed to be 300 degrees C. Up to 3 moles of hydrogen are produced by the chemical reaction of sevoflurane with heated, desiccated absorbent. The high yield, ease of ignition, and low tissue solubility of hydrogen make it the most likely fuel in anesthesia machine fires due to the reaction of sevoflurane with desiccated absorbent.

Supercritical hydrogenolysis of fatty acid methyl esters: Phase equilibrium measurements on selected binary and ternary systems

Fatty alcohols (FOH) are industrially obtained by heterogeneous catalytic hydrogenolysis of fatty acid methyl esters (FAME). Reaction rates are strongly dependent on hydrogen concentration at the catalyst surface, which is limited by the low solubility of hydrogen and high mass-transport resistance of the liquid substrate. The addition of a supercritical solvent can bring the reactive mixture into a single phase, increasing the reaction rate by several orders of magnitude. Propane has shown to be an adequate supercritical medium for these reactions. To find the homogeneous region and to determine the most favorable process conditions, it is a prerequisite to know the phase equilibrium boundaries of the reactive mixture as the reaction proceeds. This paper reports experimental phase equilibrium data on binary and ternary mixtures of propane with the reactants and reaction products of the hydrogenolysis of methyl palmitate: methyl palmitate, hydrogen, hexadecanol and methanol. A temperature region between 300 and 450 K, and pressures up to 15 MPa were covered. A liquid–liquid–vapor region was found in the system hexadecanol + hydrogen + propane, showing retrograde behavior of the lighter liquid phase.

Kinetics of catalytic hydrogenation of [formula omitted]-ionone and application of a presaturated one-liquid flow reactor for the production of fine chemicals

Fine chemicals are commonly produced in batch or semibatch reactors, which are frequently operated on a rather limited basis with respect to the knowledge of the kinetics. A typical example is the hydrogenation of the flavor-substance β -ionone. The previously unknown kinetics were studied under industrially relevant conditions (180–230 ° C, 5–90 bar, Raney-Ni). The conversion of the triple-unsaturated β -ionone up to complete hydrogenation proceeds via a network of three parallel and four consecutive reactions. The kinetic parameters were determined, including the influence of external and particularly internal diffusion. Furthermore, the applicability of the presaturated one-liquid flow (POLF) reactor was studied. In this steady-state system, the liquid is externally presaturated with hydrogen, and then fed into a fixed-bed reactor. This leads to a simple – e.g. with respect to scale-up – two-phase system (liquid and solid catalyst) compared to common three-phase batch reactors (and also to “steady-state alternatives” like a trickle bed). For the given reaction, a liquid recycle is installed to compensate the low hydrogen-solubility. Results of experiments and modelling show the good applicability of the POLF-reactor with respect to temperature control, required reactor size, and the inherent advantages of a steady-state process.

Phase equilibrium behavior for hydrogenolysis components: three-phase equilibria LLV and retrograde behavior

Fatty alcohols (FOH) are mostly used in lubricant and surfactant industry. The traditional process to obtain FOH is by heterogeneous catalytic hydrogenolysis, at high pressure, of the corresponding fatty acids methyl esters (FAME). The low solubility of hydrogen into the liquid phase leads to low concentration at the catalyst surface and very low reaction rates. Using a supercritical solvent it is possible to bring the whole reaction mixture into a homogeneous single phase. In this way the concentration of the reactants and the operation variables can be independently controlled, the solubility and mass transfer limitations are removed, giving a drastic increase of the reaction rate. Knowledge of the phase equilibria of the reaction mixture, and the boundaries of the homogeneous phase region are required in order to determine the most favorable operating conditions for supercritical hydrogenolysis. In the present work, the phase behavior of binary and ternary mixtures with methyl palmitate, hexadecanol, hydrogen and propane is analyzed. The range of temperatures covered was between 300 K and 450 K and of pressures up to 16 MPa. Three-phase liquid–liquid–vapor equilibria were found for the system hydrogen + propane + hexadecanol, with retrograde behavior of the lighter liquid.

Effect of solidification mode and morphology of microstructure on the hydrogen content of duplex stainless steel weld metal

The evolution rate of hydrogen from a duplex weld depends on sample geometry, temperature and microstructure. These factors have important consequences for the determination of hydrogen in duplex stainless steel welds. Because of the low hydrogen diffusibility and high hydrogen solubility in austenite, a standard method (BS 6693: 1988) which existed to determine the hydrogen content of ferritic steel welds as a means of assessing welding consumables, is not suitable for duplex welds. As a result of extensive research, a modified test method has been used involving encapsulation of the weld sample in Pyrex, evolution at 400 °C for 24 h, and followed by hydrogen analysis in an Oerlikon/Yanaco gas chromatograph. In this present work, the effect of solidification mode and microstructure on weld hydrogen content, and the evolution of hydrogen from such welds has been investigated by using experimental electrodes which are designed to give varying ferrite/austenite ratio in the welds. It was found that the measured weld hydrogen contents were almost constant since they arose from the flux/binder combinations which were the same for each type of experimental electrodes. Thus, the potential hydrogen from each type was the same and similar amounts became trapped during the rapid solidification of the weld pool, irrespective of final ferrite content.

Hydrogen permeation barrier performance characterization of vapor deposited amorphous aluminum oxide films using coloration of tungsten oxide

Low hydrogen diffusivity and solubility of aluminum oxide make a vapor deposited aluminum oxide (Al 2O 3) film an anticipated hydrogen permeation barrier coating. In this paper, amorphous Al 2O 3 film was deposited using filtered vacuum arc method. As a substrate, vapor deposited amorphous tungsten oxide (WO 3) film was used in order to characterize hydrogen permeation barrier performance of the Al 2O 3 film utilizing coloration of WO 3 when it forms H x WO 3. The samples were exposed to the flux and angular quantified atomic hydrogen beam, and the degree of coloration was characterized by visible to near infrared range transmission spectroscopy. Using this method, a half-micron thick amorphous Al 2O 3 film reducing atomic hydrogen reaching the underlying WO 3 film to 3×10 −4 was measured. Furthermore, Al 2O 3 film as thin as 20 nm showed atomic hydrogen reduction of 4×10 −3. The results indicate effectiveness of thin vapor deposited Al 2O 3 film as a permeation barrier against atomic hydrogen.

Solvent‐based fatty alcohol synthesis using supercritical butane: Flowsheet analysis and process design

AbstractThe liquid‐phase hydrogenolysis of fatty esters to fatty alcohols is an important step in the industrial manufacture of surfactants and detergents. High operating pressures are necessary, due to the low solubility of hydrogen in fatty esters feeds. In principle, these high operating pressures might be overcome by use of a suitable solvent, but only at the expense of large solvent recycle and cumbersome product‐solvent separation. The employ of supercritical solvents may resolve these drawbacks, as an elegant solvent‐product separation is possible by reverting to the subcritical regime. In the present work the hydrogenolysis of methyl palmitate in supercritical butane is investigated by simulation. Operating conditions are analyzed on the basis of vapor liquid equilibrium data and chemical equilibrium considerations. Separation and recycle problems are evaluated and discussed on the basis of a flowsheet analysis. It is demonstrated that an efficient hydrogenolysis process may be developed by using supercritical butane as solvent. A moderate operating pressure (9 MPa) and temperature (470 K) lead to high conversion levels and high product purity. A hydrogen to ester molar ratio of 4∶1 in the feed is achievable, which compares favorably to existing liquid‐and gas‐phase processes, and allows recycle streams to be reduced.