Solubility Of Hydrogen In Palladium Research Articles

ПЕРСПЕКТИВИ РОЗВИТКУ ВОДНЕВОЇ ЕНЕРГЕТИКИ З МОЖЛИВІСТЮ ВІДНОВЛЕННЯ МЕМБРАН ДЛЯ ПАЛИВНИХ ЕЛЕМЕНТІВ ПІСЛЯ КОНТАКТУ З ВОДНЕМ

The prospects for the development of hydrogen energy and the influence of temperature on the change in the shape of the membrane for fuel cells in contact with hydrogen have been studied. It has been confirmed that the change in the shape of the plate from the α-PdHn gradient alloy develops in two stages. The experimental regularities of the change in the shape of the palladium membrane during operation in a hydrogen environment were investigated. It was determined that upon contact with hydrogen, a temporary gradient material "metal-hydrogen" is formed in the membrane, which causes the development of hydrogen concentration stresses, and the maximum change in the shape of the membrane, which occurs at a constant temperature, depends on the diffusion coefficient and the equilibrium solubility of hydrogen in palladium. However, when the temperature changes, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladium also change, which affects the temperature dependence of the final shape change of the membrane. This fact makes it possible to effectively plan and determine the time of hydrogen penetration into the membrane, control the change of shape and adjust the operating modes of the fuel cell. It is the equilibrium solubility of hydrogen in palladium and its diffusion coefficient when the temperature changes in the main that determine the maximum and final change in the shape of the membrane, and the temperature determines the fluctuation of the change in the shape of the membrane when the temperature of the hydrogen flow entering the chamber changes. Thus, the complete return of the membrane to its initial state at increased temperature clearly indicates the implementation of a coherent membrane bending mechanism. Upon completion of hydrogen saturation by the coherent mechanism under the conditions of reaching equilibrium with the gas phase, the original palladium membrane turns out to be transformed into a membrane of the equilibrium alloy α-PdHnо, which inherits the initial state of a pure palladium membrane. Therefore, to model the hydrogen penetration process in the fuel cell, it is necessary to know the gas flow rate, membrane permeability and gas temperature, as well as the diagram of the fuel cell where these processes take place. At the same time, scientists still hope for the future development of hydrogen energy, despite the existing difficulties. This requires additional research and development of new technologies to remove obstacles to the transition to hydrogen as a primary energy source

ВИКОРИСТАННЯ ВОДНЯ В ЕНЕРГЕТИЦІ

As a result of the conducted literature research the experimentally fixed positions about features of the hydrogen-induced deformation of a palladium plate are described. It is determined that when hydrogen saturation in the metal, a temporary gradient material "metal-hydrogen" is formed and hydrogen stress concentrations always occur. This in turn provides effective planning and determination of the time of penetration of hydrogen into the metal. The obtained experimental facts allow to control the change of shape and regulate the modes of operation of the fuel cell during the operation of the products. It is described that the maximum bending of the plate occurs at a constant temperature, and is determined by two fundamental properties of the palladium system - hydrogen, namely, the diffusion coefficient and equilibrium solubility of hydrogen in palladium. However, when the temperature changes, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladium changes, which determines the temperature dependence of the final bending of the plate and its change) when interacting with hydrogen. The scientific novelty is the use of the known material palladium, which in contact with hydrogen becomes a temporary gradient alloy with variable physical properties. It is established that the heat exchange in the plate and the energy balance around the plate depends on the rate of interaction of hydrogen and material, as well as the rate of heat flux that occurs during chemical reactions in fuel cells and heat loss in the fuel cell. The practical significance of the work lies in the possibility of using certain physical bases in practice in the manufacture of specific devices that work as a fuel cell with hydrogen. You can also model this process in MaCad and improve the operating conditions of fuel cells and hydrogen sensors, because at low temperatures there is a relatively small residual bending of the main components, and accordingly there are changes in the shape of these components.

ЕНЕРГОЗБЕРІГАЮЧІ ПАЛИВНІ ЕЛЕМЕНТИ З ВИКОРИСТАННЯМ ВОДНЯ

Performed research work to determine the effect on the fuel cells of the temperature and change the shape of the elements (plates) in contact with hydrogen. It has been confirmed that the plate change takes two stages. In the first short time step, the maximum form of plate change is achieved. The temperature-dependence of the maximum bending of the plate obeys the extreme law. In the second, substantially longer phase, the plate is straightened. At low temperatures, the residual stationary bending of the plate is 20-30% of the maximum bending value. With increasing temperature, the bending rate of the plate increases and at 320-350oS the phenomenon becomes completely reversible. The mechanism of changing fuel cell form is discussed. As a result of the study, the experimental regularities of the hydrogen-induced form of change of the palladium plate are established, it is determined that a temporary "metal-hydrogen" gradient material is formed at hydrogen saturation and hydrogen concentration stresses always arise. This, in turn, provides for efficient planning and determination of the time of penetration of hydrogen into the metal, controlling the shape change, and allowing the fuel cell to operate. It is determined that the maximum bending of the plate with increasing temperature changes according to the extreme law and in the temperature range 220-260oS the bending reaches the maximum value. It is shown that the maximum bending of the plate is determined by two fundamental properties of the Pd-H system, namely, the diffusion coefficient and the equilibrium solubility of hydrogen in palladium. The scientific novelty is the use of the known material palladium, which in contact with hydrogen becomes a temporary gradient alloy with variable physical properties. It is established that the heat exchange in the plate and the energy equilibrium around the plate are based on the velocity on the heat flux that occurs during reactions in the fuel cells and the heat losses that occur in the fuel cell. The practical importance of the work lies in the possibility of using the developed algorithm in practice in the manufacture of specific devices operating on the basis of a fuel cell - hydrogen, with the possibility of modeling this process in Matlab. But improving the working conditions of fuel cells and hydrogen sensors, because at low temperatures there is a relatively small residual bending of the plate, and accordingly the shape of the fuel cell.

Investigation of hydride formation and decomposition in palladium using the electrochemical permeation technique

In addition to providing hydrogen transport data, the electrochemical permeation technique can be used to determine the terminal solid solubility of hydrogen in palladium, and to assess in situ the dislocation density resulting from stresses associated with the formation and decomposition of palladium hydride. It is suggested that this method may prove useful in the evaluation of solid-state hydrogen storage materials.

Features of the action of low-energy gamma radiation on the hydrogen permeability of certain materials

This paper determines the diffusion coefficients, the constants of permeability, and solubility of hydrogen in palladium, nickel, and Armco iron under the action of low-energy gamma radiation. It was established that without radiation all of the kinetic diffusion curves of hydrogen in palladium and nickel straighten well in a functional scale. In armco iron, some deviations are observed.

Improvement of electrochemical methods for studying the diffusion and solubility of hydrogen in metals

It is shown that electrochemical methods yield reliable data for the solubility and diffusion of hydrogen in metals provided that care is taken with the measurements and their interpretation with regard to the electrochemical problems. The applicability of this method to investigations of the diffusion and solubility of hydrogen in palladium is demonstrated. Results for Sieverts' constant, the hydrogen diffusion coefficients and the activation energy of hydrogen diffusion in well-annealed palladium are presented. The influence of deformation on the diffusion and solubility behaviour is discussed as suggested by Kirchheim.

The influence of high methane concentrations on the stability of catalytic flammable-gas sensing elements

The influence of the form of the palladium catalyst used in catalytic flammable-gas sensing elements on their stability following exposure to high methane concentrations has been investigated. Carbon deposition was found to have an adverse effect on the response of some types of element. However, improvement in stability to coking effects can be achieved either by depositing palladium on a high surface-area support or by using a coprecipitation of palladium and thoria. For a series of Pd + ThO 2 elements having different Pd:ThO 2 ratios, the apparent hydrogen solubility was determined by a temperature-programmed technique. The solubility of hydrogen in palladium is known to increase with decreasing dispersion. Good correlation was obtained between the dispersion inferred from the solubility data and the rate of coking. Thus the role of thoria as a coke prevention agent is to decrease the palladium particle size, resulting in a lower rate of methane decomposition.

Effects of V Admixtures on the Mobility and Solubility of Hydrogen in Palladium Investigated with SX-APS

Effects of V Admixtures on the Mobility and Solubility of Hydrogen in Palladium Investigated with SX-APS

The effect of the α- β phase change on the α phase solubility of hydrogen in palladium

Following the α- β phase change in palladium, there is an enhanced solubility of hydrogen at a given equilibrium pressure within the low hydrogen content α phase. There are marked similarities between the absorption isotherms for hydrogen following the phase change and those exhibited by heavily cold-worked palladium. Partial thermodynamic parameters for hydrogen absorption are reported for palladium plastically deformed by the phase change.

Solubility of hydrogen in small particles of palladium

The solubility of hydrogen in palladium, m, defined as the number of dissolved hydrogen atoms divided by the total number of metal atoms has been measured between 273 and 343 K from 13.3 to 53.3 kPa. At a given temperature and pressure, m was found to decrease linearly as the percentage dispersion D of the metal increased, m being zero at D = 100%. Measurements of m were carried out under conditions such that the surface of the metal particles was covered with almost a monolayer of hydrogen. This chemisorbed hydrogen seems to affect solubility of hydrogen in bulk palladium in a way similar to that of silver in palladium-silver alloys. Values of m are potentially helpful in the characterization of used palladium catalysts.

Diffusion and solubility of hydrogen in palladium and palladium--silver alloys

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiffusion and solubility of hydrogen in palladium and palladium--silver alloysGerhard L. HolleckCite this: J. Phys. Chem. 1970, 74, 3, 503–511Publication Date (Print):February 1, 1970Publication History Published online1 May 2002Published inissue 1 February 1970https://doi.org/10.1021/j100698a005RIGHTS & PERMISSIONSArticle Views3001Altmetric-Citations272LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (936 KB) Get e-Alerts

Theoretical aspects of the absorption of hydrogen by palladium and its alloys. Part 2.—Possible effects of lattice expansion on the solubility of hydrogen in palladium

A model is developed which takes account of possible changes in strain energy as a function of hydrogen content when hydrogen is absorbed by palladium. Using independent data the attractive interaction between absorbed atoms is calculated and is found to be in good agreement with the value obtained from isothermal data. The model predicts a limiting solubility at H/Pd < 1.0 and a minimum heat of solution of hydrogen at H/Pd ≈ 0.6, in agreement with experiment. The possible extension of the model to some other metal-hydrogen systems is discussed.

Cooperative Phenomena in Pd-H System I

Some modifictions are made in Lacher's theory of the solubility of hydrogen in palladium by considering the change in energy of protons with the volume of the metal. Existence of two phases with different lattice constants and unsymmetrical form of the absorption isotherm are explained.

VI. Note on the solubility of hydrogen in palladium

VI. Note on the solubility of hydrogen in palladium

The Statistics of the Hydrogen-Palladium System

In a recent paper, the solubility of hydrogen in palladium was discussed. The statistical theory employed was essentially the same as that given by Fowler† for critical adsorption, the only modification necessary being to take into account the dissociation of the hydrogen molecules on absorption. In the present paper Peierls' theory‡ is applied to the same problem in order to enable a comparison to be made between the theories. According to both theories we must postulate that the absorbed (adsorbed) particles go into a definite number of potential energy holes and that the heat of absorption increases as the number of holes filled increases. Fowler uses the Bragg and Williams type of approximation to determine the energy of the particles in the holes; while Peierls supposes that there is an interaction energy V for each pair of neighbouring adsorbed particles and that all those arrangements of the particles in the holes having the same number of nearest neighbours have the same energy. The calculation of the dependence of the energy on the arrangements is approximated to by a method due to Bethe.

A theoretical formula for the solubility of hydrogen in palladium

It is known that the amount of hydrogen dissolved by Pt, Mo, Cu, Co, Fe, and Ni is directly proportional to the square root of the hydrogen pressurep. Furthermore, these metals take up hydrogen without changing their lattice structure. It has been shown by Fowler and Smithells (1937) that one can get a theoretical interpretation of the observed solubility, if one assumes that the hydrogen dissolves as protons which are free to move throughout practically the whole volume of the metal. The theory has been extended, using slightly different assumptions, to include the metals V, Ta, Ti, and Zr. In these cases definite metallic hydrides are formed having lattice structures differing from that of the pure metal, and at higher pressures the amount of absorbed hydrogen saturates, being no longer proportional to √p. In the present paper we shall give a statistical interpretation of the solubility of hydrogen in palladium. Palladium seems to offer an advan­tageous starting-point for an attempt at a more profound extension of the theory outside the region where the √plaw is valid. It has been thoroughly investigated experimentally and is capable of taking up large volumes of hydrogen without changing its lattice structure (Linde and Borelius 1927; Krüger and Gehm 1933)