Металлогидридная технология активации водорода
Рассмотрен эффект активации водорода металлогидридами. Установлено, что активированный водород существует в различных формах: в виде возбужденных молекул, возбужденных атомов и положительных ионов. Для изучения активации водорода использованы различные методы - масс-спектрометрии. Обсуждаются причин...
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Інстиут проблем машинобудування ім. А.М. Підгорного НАН України
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nasplib_isofts_kiev_ua-123456789-1418972025-02-09T17:30:44Z Металлогидридная технология активации водорода Металогідридна технологія активації водню Metal Hydride Technology of Hydrogen Activation Соловей, В.В. Авраменко, А.Н. Левтеров, А.М. Умеренкова, К.Р. Нетрадиційні енерготехнології Рассмотрен эффект активации водорода металлогидридами. Установлено, что активированный водород существует в различных формах: в виде возбужденных молекул, возбужденных атомов и положительных ионов. Для изучения активации водорода использованы различные методы - масс-спектрометрии. Обсуждаются причины формирования активированного водорода при взаимодействии с гидридообразующими материалами. Для гидридообразующих материалов один из возможных факторов, приводящих к активации водорода с последующей десорбцией в газовую фазу, является изобарный гистерезис. Гистерезис в системах металл-водород имеет место, когда давление образования гидрида выше, чем давление его разложения. Использование явления металлогидридной активации может улучшить энергетические характеристики практически всех типов энергопреобразующих устройств, использующих водород в качестве рабочего тела. Этот эффект может быть использован в реакциях гетерогенного катализа, в частности, при воспламенении водород-кислородных смесей, в устройствах, использующих водород в качестве рабочего тела, как экологически чистый энергоноситель в двигателях или в энергетических и электрофизических установках. Показано экспериментально и теоретически, что использование атомов и возбужденных молекул водорода в качестве активационной добавки к традиционным топливам приводит не только к экономии последнего, но и к уменьшению содержания токсичных продуктов в отработанных газах. Небольшая – 0,5 %-я примесь атомарного водорода в зону горения является столь же эффективной, как и добавка 10 – 12 % обычного молекулярного водорода. Использование энергии возбуждения неравновесных состояний водорода представляется одним из весьма перспективных путей решения проблемы повышения эффективности энергетического оборудования и совершенствования его экологических характеристик. Розглянуто ефект активації водню металогідридами. Встановлено, що активований водень існує в різних формах: у вигляді збуджених молекул, збуджених атомів і позитивних іонів. Для вивчення активації водню використано різні методи мас-спектрометрії. Обговорюються причини формування активованого водню при взаємодії з гідридотвірними матеріалами. Цей ефект може бути використаний в реакціях гетерогенного каталізу, зокрема, під час займання воднево-кисневих сумішей, в пристроях, що використовують водень як робоче тіло, як екологічно чистий енергоносій в двигунах або в енергетичних і електрофізичних установках. The effect of hydrogen activation by metal hydrides is considered. It is established that activated hydrogen exists in different forms: in the form of excited H2 molecules, excited hydrogen atoms and positive ions. To study the activation of hydrogen, various methods of mass spectrometry were used. The reasons for the formation of activated hydrogen in interaction with hydride-forming materials are discussed. For hydride-forming materials, one of the possible factors leading to the activation of hydrogen followed by desorption into the gas phase is isobaric hysteresis. Hysteresis in metal-hydrogen systems occurs when the pressure of hydride formation is higher than the pressure of its decomposition. The use of the phenomenon of metal hydride activation can improve the energy characteristics of virtually all types of energy-converting devices using hydrogen as a working fluid. This effect can be used in reactions of heterogeneous catalysis, in particular, in the ignition of hydrogen-oxygen mixtures, in devices using hydrogen as a working medium, as an environmentally friendly energy carrier in engines or in power and electro-physical facilities. It is shown both experimentally and theoretically that the use of atoms and excited hydrogen molecules as an activation ionic additive to traditional fuels leads not only to saving the latter but also to reducing the content of toxic products in the exhaust gases. A small (0.5 %) admixture of atomic hydrogen in the combustion zone is just as effective as the addition of 10 – 12 % of ordinary molecular hydrogen. The use of excitation energy for nonequilibrium states of hydrogen appears to be one of the most promising ways to solve the problem of increasing the efficiency of energy equipment and improving its environmental characteristics. 2018 Article Металлогидридная технология активации водорода / В.В. Соловей, А.Н. Авраменко, А.М. Левтеров, К.Р. Умеренкова // Проблеми машинобудування. — 2018. — Т. 21, № 1. — С. 49-54. — Бібліогр.: 13 назв. — рос., англ. 0131-2928 https://nasplib.isofts.kiev.ua/handle/123456789/141897 662.769.21; 544-971; 54-19 ru Проблеми машинобудування application/pdf application/pdf Інстиут проблем машинобудування ім. А.М. Підгорного НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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Russian |
| topic |
Нетрадиційні енерготехнології Нетрадиційні енерготехнології |
| spellingShingle |
Нетрадиційні енерготехнології Нетрадиційні енерготехнології Соловей, В.В. Авраменко, А.Н. Левтеров, А.М. Умеренкова, К.Р. Металлогидридная технология активации водорода Проблеми машинобудування |
| description |
Рассмотрен эффект активации водорода металлогидридами. Установлено, что активированный водород существует в различных формах: в виде возбужденных молекул, возбужденных атомов и положительных ионов. Для изучения активации водорода использованы различные методы - масс-спектрометрии. Обсуждаются причины формирования активированного водорода при взаимодействии с гидридообразующими материалами. Для гидридообразующих материалов один из возможных факторов, приводящих к активации водорода с последующей десорбцией в газовую фазу, является изобарный гистерезис. Гистерезис в системах металл-водород имеет место, когда давление образования гидрида выше, чем давление его разложения. Использование явления металлогидридной активации может улучшить энергетические характеристики практически всех типов энергопреобразующих устройств, использующих водород в качестве рабочего тела. Этот эффект может быть использован в реакциях гетерогенного катализа, в частности, при воспламенении водород-кислородных смесей, в устройствах, использующих водород в качестве рабочего тела, как экологически чистый энергоноситель в двигателях или в энергетических и электрофизических установках. Показано экспериментально и теоретически, что использование атомов и возбужденных молекул водорода в качестве активационной добавки к традиционным топливам приводит не только к экономии последнего, но и к уменьшению содержания токсичных продуктов в отработанных газах. Небольшая – 0,5 %-я примесь атомарного водорода в зону горения является столь же эффективной, как и добавка 10 – 12 % обычного молекулярного водорода. Использование энергии возбуждения неравновесных состояний водорода представляется одним из весьма перспективных путей решения проблемы повышения эффективности энергетического оборудования и совершенствования его экологических характеристик. |
| format |
Article |
| author |
Соловей, В.В. Авраменко, А.Н. Левтеров, А.М. Умеренкова, К.Р. |
| author_facet |
Соловей, В.В. Авраменко, А.Н. Левтеров, А.М. Умеренкова, К.Р. |
| author_sort |
Соловей, В.В. |
| title |
Металлогидридная технология активации водорода |
| title_short |
Металлогидридная технология активации водорода |
| title_full |
Металлогидридная технология активации водорода |
| title_fullStr |
Металлогидридная технология активации водорода |
| title_full_unstemmed |
Металлогидридная технология активации водорода |
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металлогидридная технология активации водорода |
| publisher |
Інстиут проблем машинобудування ім. А.М. Підгорного НАН України |
| publishDate |
2018 |
| topic_facet |
Нетрадиційні енерготехнології |
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https://nasplib.isofts.kiev.ua/handle/123456789/141897 |
| citation_txt |
Металлогидридная технология активации водорода / В.В. Соловей, А.Н. Авраменко, А.М. Левтеров, К.Р. Умеренкова // Проблеми машинобудування. — 2018. — Т. 21, № 1. — С. 49-54. — Бібліогр.: 13 назв. — рос., англ. |
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Проблеми машинобудування |
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НЕТРАДИЦІЙНІ ЕНЕРГОТЕХНОЛОГІЇ
ISSN 0131–2928. Проблеми машинобудування, 2018, Т. 21, № 1 49
V. V. Solovei, Doctor of Technical
Sciences
A. N. Avramenko, Candidate of Technical
Sciences
A. M. Lievtierov, Candidate of Technical
Sciences
K. R. Umerenkova, Candidate of Technical
Sciences
A. Podgorny Institute of Mechanical
Engineering Problems of NASU,
Kharkiv, Ukraine,
е-maіl: solovey@ipmach.kharkov.ua
UDC 662.769.21; 544-971; 54-19
METAL HYDRIDE TECHNOLOGY OF
HYDROGEN ACTIVATION
Розглянуто ефект активації водню металогідридами.
Встановлено, що активований водень існує в різних
формах: у вигляді збуджених молекул водню, збуджених
атомів водню і позитивних іонів. Для вивчення активації
водню використано різні методи мас-спектрометрії.
Обговорюються причини формування активованого водню
при взаємодії з гідридотвірними матеріалами. Цей ефект
може бути використаний в реакціях гетерогенного
каталізу, зокрема, під час займання водень-кисневих
сумішей, в пристроях, що використовують водень як
робоче тіло, як екологічно чистий енергоносій в двигунах
або в енергетичних і електрофізичних установках.
Ключові слова: водень, металогідрид,
активація, мас-спектрометрія, газовий розряд.
Introduction
One of the features of the reversible interaction between hydride-forming metals and alloys with hy-
drogen gas is the effect of its sorption activation. This effect is confirmed by both direct and indirect results
of numerous experiments and consists in the fact that the processes of formation and decomposition of me-
tallic hydrides are accompanied by significant deviations of the state of the near-surface region of the gas
phase from the thermodynamic equilibrium. At the same time, the emission of hydrogen atoms, atomic and
molecular ions, as well as excited molecules is observed from the surface of a metallic hydride in the gas
phase.
This feature allows us to expand the areas of practical application of hydrogen in the processes of
heterogeneous catalysis, in the case of ignition of hydrogen-oxygen mixtures, in devices that use hydrogen as
a working fluid when supplying energy from an external source, as well as in electro-physical devices. Thus,
it is shown both experimentally and theoretically that the use of atoms and excited hydrogen molecules as an
activating supplement to traditional fuels leads not only to the economy of the latter but also to the reduction
of the content of toxic products in the exhaust gases. A small (0.5 %) admixture of atomic hydrogen in the
combustion zone is as effective as the addition of 10 – 12 % of conventional molecular hydrogen. The use of
the excitation energy for nonequilibrium hydrogen states appears to be one of the most promising ways of
solving the problem of increasing the efficiency of energy equipment and improving its environmental char-
acteristics.
Hydrogen metal-hydride activation
The formation of thermodynamically nonequilibrium states of gas particles interacting with the sur-
face of a solid is a consequence of heterogeneous physicochemical processes in a gas-solid system and oc-
curs both in the case of the particle flux on the surface from the gas phase and in the case of desorption of
solid-absorbed particles diffusing from volume to surface. If hydride-forming materials (metals and alloys)
act as solids and hydrogen is a gas, then the case in point is metal-hydride activation. The ability to create
nonequilibrium concentrations of excited molecules, atoms or hydrogen ions near the surface, i.e., to hydro-
gen activation, is one of the specific features of hydride-forming materials. Hydrogen metal-hydride activa-
tion is due to physicochemical processes both on the interface between the gas phase and the surface of the
metal, and when hydrogen interacts with the crystal lattice. Such activation can occur as a result of the disso-
ciative chemisorption of the H2 molecule on transition metal clusters or when vacant surface adsorption cen-
ters are successively replaced with hydrogen atoms coming from the volume of metal [1]. In these cases, a
layer of reactive hydrogen atoms is formed on the surface of a metal hydride, which can take part in catalytic
reactions, both directly on this surface and after the transition to the surfaces of the intermediate hydrogen-
inert carriers of Al2O3, SiO2, HxWO3, HxMoO3, NH4CI, i.e. by means of the spillover effect [2].
V. V. Solovei, A. N. Avramenko, A. M. Lievtierov, K. R. Umerenkova, 2018
mailto:solovey@ipmach.kharkov.ua
НЕТРАДИЦІЙНІ ЕНЕРГОТЕХНОЛОГІЇ
ISSN 0131–2928. Проблеми машинобудування, 2018, Т. 21, № 1 50
Another aspect of hydrogen metal-hydride activation is the emission of excited hydrogen particles
from the metal hydride surface to the gas phase. In this case, the flow of particles emitted from the surface
includes nonequilibrium concentrations of vibrational and rotationally excited molecules H*2, molecules
with excess translational kinetic energy, nonequilibrium concentrations of ortho- and steam-modifications of
hydrogen. In this case, the most probable cause of the formation of excited molecules is the recombination of
hydrogen atoms diffused from the volume to the surface of a solid, accompanied by the release of energy [3].
The purpose of this work is to study the energy characteristics of hydrogen associated with the het-
erogeneous activation of hydrogen and its isotopes by metal hydride systems.
Mass-spectrometric studies of hydrogen-hydride forming intermetallic compounds
At the first stage of the study, the mass spectra of hydrogen (deuterium), activated as a result of het-
erogeneous interaction with LaNi5 powder, were measured. The LaNi5 powder (granules with dimensions of
2 − 10 μm) was placed in a flow quartz ampoule with a heater and a thermocouple. One side of the ampoule
was connected to a metering system for hydrogen input from an outer container with the possibility of auton-
omous pumping with a diffusion pump equipped with a liquid nitrogen trap. Its other side was connected to
the ionization chamber of a mass spectrometer, in which the incoming gas was ionized by an electron beam
and sent to the magnetic mass analyzer chamber. Before the measurements, the LaNi5 sample was heated to
700 K in a dynamic vacuum of 10-2 Pa. After that, the mass spectra of hydrogen were recorded at various
temperatures of LaNi5 [4].
When comparing the mass spectra of the hydrogen gas supplied to the analyzer (up to the pressure P)
directly from the cylinder (reference gas) with an additional gas line and through a sample of LaNi5 (through
a flow ampoule), it was established that after hydrogen contacting LaNi5, an increase in the intensities of ion
peaks H + and H3
+ takes place (Table 1). Thus, for the metal hydride temperature of 708 K, the ratio of the
intensities of the measured peaks is 1.67 and 2.92 for H + and H3
+, respectively (the pressure of hydrogen
supplied in both cases is the same).
Table 1. Mass-spectra of H2 in the atmosphere (P = 6.3·10–4 Pa)
Temperature of LaNi5, K
Peak intensity or mass numbers, relative units
1 (H+) 2 (H+
2) 3 (H3
+)
300 16.7 186 0.19
378 18.5 186 0.26
453 20.4 187 0.25
561 23.0 188 0.35
708 27.5 189 0.35
Reference H2 16.5 185 0.12
If deuterium (with a small admixture of hydrogen, D2 + 5 % of volumetric H2) is fed into the system
instead of hydrogen, then at LaNi5 temperature of 730 K, one can observe the increase in the concentration of
H +, D + and HD + ions by 1.4, 2.0 and 3.9 times, respectively (Table 2). A possible cause of this effect can be
an increase in the internal energy of molecules and hydrogen atoms (deuterium) after their contact with LaNi5.
Table 2. Mass-spectra of D2 + 5 % H2 (P = 6.3·10–4 Pa) in the atmosphere
Temperature of LaNi5,
K
Peak intensity of mass numbers, relative units
1 (H+) 2 (D+) 3 (HD+) 4 (D2
+) 6 (D3
+)
316 18.4 12.7 2.5 326 2.0
565 23.2 13.2 3.2 326 2.5
731 25.5 25.5 8.9 341 3.0
Reference D2 + 5 % H2 18.2 12.5 2.3 325 1.9
The following experiment was performed at a temperature of 393 − 403 K and a deuterium pressure
of 7·10-4 – 2·10-3 Pa. Under these conditions, the formation of the hydride phase of LaNi5 does not occur.
The ampoule with LaNi5 activator was connected to the ionization chamber of the mass spectrometer by
means of a teflon tube in order to reduce the probability of the active particles losing excitation when collid-
НЕТРАДИЦІЙНІ ЕНЕРГОТЕХНОЛОГІЇ
ISSN 0131–2928. Проблеми машинобудування, 2018, Т. 21, № 1 51
ing with the inner surface of the metal tube. In this case, a sharp increase in the intensity of the ion peaks
with masses m/e = 2 (by 15 times) and m/e = 3 (by 20 times) is observed, a slight increase in the intensity of
the ion peaks with m/e = 1 and some decrease in the intensity of the ion peaks with m/e = 4 (Table 3). The
results obtained show that even under the conditions where the hydride phase is not formed, finely dispersed
LaNi5 exhibits high catalytic activity, especially with respect to deuterium.
Table 3. Mass-spectra of D2 ( P = 1.7·10–5 Pa) in the atmosphere
Sample
Peak intensity of mass numbers, relative units
1 (H+) 2 (D+) 3 (HD+) 4 (D2
+) 5 (HD2
+) 6 (D3
+)
Reference D2 8.3 12.5 17.7 59.7 2.0 14.5
D2 which passed through La-
Ni5 at 393 – 403 K
49.1 193 345 50.5 7.5 5.5
To study the possibility of activation processes on other materials, experiments were conducted on
mass spectrometric analysis of the degassed products received from the samples of sintered powders of getter
titanium and titanium nickelide Ti2Ni supplemented with deuterium-presaturated nickel. The saturation of
the samples was carried out in two ways: by barothermal treatment with technical deuterium and by satura-
tion an arc discharge in a deuterium-plasma jet. The saturated samples were placed in an ampoule connected
to the ionization chamber of the mass spectrometer and heated to 713 K at a rate of 44 K / min. In doing that,
the mass spectrum of the gas being desorbed was registered. The results given in Table. 4 show that whenev-
er the gas is desorbed from the volume phases of Ti−D and Ti2Ni−D obtained by both methods, an increased
yield of energetically excited D*2 molecules is observed in comparison with the reference deuterium. This is
manifested by an increase in the content of HD + and D + components and a decrease in D2
+. The decrease in
the yield of D2
+ (m/e = 4) is due to the fact that in the gaseous phase reaction
H + D2 → HD + D
can occur.
The analysis of the obtained data suggests that desorption products from deuterium-saturated sam-
ples of titanium and titanium nickelide contain deuterium molecules in a thermodynamically nonequilibrium
state.
Table 4. Mass-spectra of the gas disorbed from Ti and Ti2Ni/Ni samples
Sample
Abundance of ion components, %
1 (H+) 2 (D+) 3 (HD+) 4 (D2
+) 5 (HD2
+) 6 (D3
+)
Barotherm. Ti 0.02 0.77 6.64 92.19 0.03 0.35
Barotherm.T2Ni/Ni 0.78 10.00 7.29 81.09 0.63 0.23
Plasma Ti 0.01 0.69 5.98 93.19 0.01 0.32
Plasma T2Ni/Ni 0.01 1.65 5.32 92.48 0.04 0.50
Reference D2 0.46 0.23 0.32 98.99 – –
Investigations of the energy state of hydrogen desorbed from a metal hydride
There are a number of experimental studies that give indirect reasons to believe that the excitation of
molecules of hydrogen desorbed from the surface of metal hydrides has an oscillatory character [5, 6]. To
obtain direct experimental proof of this fact, mass spectrometric measurements of the energy states of hydro-
gen and deuterium molecules desorbed from metal hydrides were carried out.
The investigations were carried out using the method of measuring the ionization efficiency curves
(IEC) of hydrogen and deuterium molecules by electron impact. The experimentally measured IECs were the
dependencies of the registered current of ions H2
+ (D2
+) on the energy of ionizing electrons. By mathemati-
cal processing of such dependences, the effect of the thermal spread of the energies of ionizing electrons on
the shape of the IEC was eliminated, and sets of values of the vertical ionization potentials of the equilibrium
and desorbed hydrogen (deuterium) molecules were determined [7].
The calculated values of the vertical ionization potentials corresponding to the transitions of the H2
molecule from the state with the vibrational quantum number v to the state of the molecular ion H2
+ with the
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vibrational quantum number v 'in accordance with the Franck-Condon principle can be determined using an
approximate analytical expression (assuming that we can neglect possible shifts and the splitting of the vibra-
tional levels)
ν'ν)'νν( EEPIPI a ,
where PIa is the adiabatic ionization potential of the hydrogen molecule; νE and ν'E are the vibrational ener-
gies of a neutral molecule at the level ν and molecular ion at the level 'ν , respectively. For the first
4 − 5 vibrational levels of the molecular ion H2
+ or D2
+, the vibrational energy ν'E of the molecular ion
H2
+(D2
+) can be expressed in accordance with [8] by the following formula:
2
'ν )
2
1
'ν('ω)
2
1
'ν('ω eee kE ,
where ωe' is the energy of the vibrational quantum; κeωe'is the anharmonicity constant.
A similar expression is also valid for the vibrational energy of a neutral molecule
2
ν )
2
1
ν(ω)
2
1
ν(ω eee kE ,
where ωe is the energy of the vibrational quantum; keωe is the anharmonicity constant.
The calculations from the above formulas (taking into account the reference data [9]) give a calculat-
ed set of vertical ionization potentials, which is uniquely determined by the vibrational state of the original
neutral molecule. Thus, a comparison of these calculated data with a set of vertical ionization potentials ob-
tained experimentally makes it possible to identify the levels between which the transition occurs. The com-
parison of the results for equilibrium hydrogen and for hydrogen desorbed from the surface of a metal hy-
dride makes it possible to draw conclusions about the states of the original hydrogen molecule, which is ion-
ized by an electron beam. An example of the corresponding data for equilibrium hydrogen and hydrogen de-
sorbed from (Zr-V-Fe) Hx is shown in Table 5.
Таблица 5. Table 5. Vertical ionization potentials of the H2 molecule with the formation of the H2
+molecular ion
The vibrational
quantum number
v of the H2 mole-
cule
The vibrational
quantum number
v' of the H2
+
The values of vertical ionization potentials, eV
Calculation
according to the
data of [9]
The result of pro-
cessing the experi-
mental IEC for equilib-
rium hydrogen
The result of processing the
experimental IEC for hydro-
gen desorbed from the sam-
ple (Zr–V–Fe) Hx
0 0 15.426 15.420 15.43
0 1 15.697 15.685 –
0 2 15.952 15.943 15.94
0 3 16.191 16.184 16.18
0 4 16.413 16.400 16.40
1 0 14.910 – 14.90
1 1 15.182 – 15.17
1 2 15.436 – –
1 3 15.675 – 15.66
1 4 15.897 – –
From the data given in Table , it is evident that for equilibrium molecular hydrogen there exist fixed
ionization potentials corresponding to transitions from only ground ( ν = 0) states of the initial molecules to
different vibrationally excited levels of molecular ions. For the hydrogen desorbed from a metal hydride,
there exist fixed ionization potentials corresponding to transitions from both the ground state (to the states
with 'ν = 0, 'ν = 2, 'ν = 3, 'ν = 4) and the first vibrational level of the desorbed molecule (to the states
with 'ν = 0, 'ν = 1, 'ν = 3). This allows us to conclude that the hydrogen desorbed from a metal hydride
surface has an anomalously large group of vibrationally excited molecules. Proceeding from this, desorbed
hydrogen (deuterium) can be represented as a mixture of molecules located at the main and first vibrational
levels.
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Conclusion
For hydride-forming materials, one of the possible factors leading to the activation of hydrogen fol-
lowed by its desorption into the gas phase is isobaric hysteresis. In practice, hysteresis in metal-hydrogen
systems occurs when the pressure of hydride formation is higher than the pressure of its decomposition. As is
known [10, 11], the above-mentioned effect arises because of different parameters of the crystal lattices of
the initial matrix of metal and metal hydride, which leads to the appearance of elastic stresses in the matrix
during the formation (decomposition) of a hydride. As a result, the metal matrix acquires excess energy,
which can be transferred to hydrogen atoms diffusing to the surface with subsequent desorption. The absorp-
tion of hydrogen by a metal is accompanied by the appearance of defects, cracks as well as by crushing the
original matrix, which leads to the formation of surface regions that are extremely active with respect to the
emission of excited and charged particles. The more intensive the dispersion is, the greater the localization of
the crystal lattice excess energy is. This causes the excitation of nonequilibrium electrons and activation of
the desorption process of hydrogen particles since the scattering of this energy in a solid becomes ineffective.
When analyzing the above effects, it should be borne in mind that mechanochemical reactions similar to
those described in [12] can occur too.
Thus, taking into account the above, it is possible to single out the following reasons, leading to the
activation of hydrogen in its interaction with hydride-forming materials.
1. Isolation of the energy of the induced elastic and plastic deformation of the material matrix (hyste-
resis) and its transfer to hydrogen being desorbed.
2. Exoemission of charged and excited particles as a result of such actions as:
− chemical (the decomposition of the hydroxide film on a metal surface in a hydrogen atmosphere,
segregation of clusters of transition metals on the surface);
− physical (the appearance of defects, structural and micropore irregularities as a result of intensive
charge exchange and acceleration of particles in local electric fields);
− mechanical (the destruction of the metal matrix, the appearance of cracks and, as a result, an in-
crease in free energy and the appearance of 'broken' chemical bonds);
3. Desorption (without recombination) of hydrogen protons or atoms diffusing to the surface.
4. Recombination (associative) of desorbed hydrogen atoms with excitation of various degrees of
freedom into the H2 molecules.
5. Processes of nonequilibrium energy exchange in collisions between the emitted particles (second-
ary processes).
All the above-mentioned mechanisms for the formation of activated hydrogen are interrelated and, as
a rule, accompany each other. When hydrogen is desorbed from a metal hydride, the main factor is hystere-
sis. The difference between the chemical potentials of hydrogen in the gas phase and in the metal matrix,
where it is 'conserved' in metastable nonequilibrium (α + β) or β-phases, is responsible for the thermodynam-
ic prerequisites for activation [13].
The results obtained with a high degree of reliability make it possible to confidently assert that the
use of the phenomenon of metal hydride activation allows one to improve the energy characteristics of virtu-
ally all types of energy-converting devices using hydrogen as a working fluid. In gas-discharge electrophysi-
cal devices, metal hydride activation makes it possible to reduce the ignition and burning voltages of the dis-
charge in activated hydrogen, increase the reliability of start-up and operation of the systems, as well as re-
duce energy consumption for the implementation of their operation.
On the basis of the obtained experimental results, it can be concluded that the hydride-forming in-
termetallide LaNi5 in the dispersed state exhibits a high reserve of activity. Under the conditions of the exist-
ence of the α-phase in the regime of gas flowing through LaNi5, the fine-grained LaNi5 powder facilitates the
production of atoms and excited molecules from hydrogen (deuterium) without the formation of a hydride
phase.
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Received 24 January 2018
Introduction
Hydrogen metal-hydride activation
Mass-spectrometric studies of hydrogen-hydride forming intermetallic compounds
Investigations of the energy state of hydrogen desorbed from a metal hydride
Conclusion
References
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