Effect of adsorbed impurities on catalytic CO oxidation
The effect of inactive adsorbed impurities on kinetics of catalytic synthesis of carbon dioxide is investigated
 in the framework of the lattice-gas model. Namely, two cases of equilibrium impurities with fast, compared
 with the reaction's rate, and slow self dynamics are analy...
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| Zitieren: | Effect of adsorbed impurities on catalytic CO oxidation / I.S. Bzovska, I.M. Mryglod // Condensed Matter Physics. — 2009. — Т. 12, № 2. — С. 183-191. — Бібліогр.: 15 назв. — англ. |
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| citation_txt | Effect of adsorbed impurities on catalytic CO oxidation / I.S. Bzovska, I.M. Mryglod // Condensed Matter Physics. — 2009. — Т. 12, № 2. — С. 183-191. — Бібліогр.: 15 назв. — англ. |
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| description | The effect of inactive adsorbed impurities on kinetics of catalytic synthesis of carbon dioxide is investigated
in the framework of the lattice-gas model. Namely, two cases of equilibrium impurities with fast, compared
with the reaction's rate, and slow self dynamics are analyzed. It is revealed that the adsorbed impurities
shift the phase diagram to the region of lower temperatures and higher pressures pCO. In the case of slow
impurities the bistable region is narrowed far more than in the case when their dynamics is fast and their
distribution on the surface can be assumed to be equilibrium. The critical concentration of impurities at which
the bistable region disappears, is found. From analysis of the kinetic equations the condition of the existence
of the bifurcation region is analytically obtained.
В рамках ґраткової моделi дослiджується вплив неактивних домiшок на кiнетику реакцiї каталiтичного синтезу вуглекислого газу, зокрема аналiзуються випадки рiвноважної домiшки з швидкою (в порiвняннi зi швидкiстю реакцiї) та повiльною власними динамiками. Показано, що домiшки на поверхнi змiщують фазову дiаграму до областi нижчих температур i вищих тискiв pCO. У випадку, коли концентрацiя домiшки змiнюється на поверхнi досить повiльно, область бiстабiльностi звужується значно бiльше, нiж коли динамiка домiшки є швидкою i її розподiл на поверхнi можна вважати рiвноважним. Знайдено критичну концентрацiю домiшок, при якiй ще спостерiгається область бiстабiльностi. З кiнетичних рiвнянь аналiтично знайдено умову iснування областi бiстабiльностi.
|
| first_indexed | 2025-12-07T17:54:17Z |
| format | Article |
| fulltext |
Condensed Matter Physics 2009, Vol. 12, No 2, pp. 183–191
Effect of adsorbed impurities on catalytic CO oxidation
I.S.Bzovska, I.M.Mryglod
Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine,
1 Svientsitskii Str., 79011 Lviv, Ukraine
Received April 10, 2009, in final form May 8, 2009
The effect of inactive adsorbed impurities on kinetics of catalytic synthesis of carbon dioxide is investigated
in the framework of the lattice-gas model. Namely, two cases of equilibrium impurities with fast, compared
with the reaction’s rate, and slow self dynamics are analyzed. It is revealed that the adsorbed impurities
shift the phase diagram to the region of lower temperatures and higher pressures pCO. In the case of slow
impurities the bistable region is narrowed far more than in the case when their dynamics is fast and their
distribution on the surface can be assumed to be equilibrium. The critical concentration of impurities at which
the bistable region disappears, is found. From analysis of the kinetic equations the condition of the existence
of the bifurcation region is analytically obtained.
Key words: lattice-gas model, catalysis, oxidation, carbon monoxide, oxygen
PACS: 05.50.+q, 68.43.-h, 82.65.+r
1. Introduction
Poisoning phenomenon has played a great role in the development of the theory of catalysis.
Considering heterogeneous catalytic reactions one often speaks about poisons which reduce the
activity of catalysts. These impurities can exist in raw materials which are used for preparation
of catalysts or can be entered together with the reactants. It is usually assumed that they are
chemosorbed at active sites of the surface, block up interactions between reagent and the surface
and are inhibitors for the reaction. Mexted [1] mentioned that metals are the most sensitive to
poisoning. Oxides and sulfides used as catalysts are more persistent. Metallic catalysts can be
poisoned by: 1) molecules which consist of elements of groups VB and VIB if their active atoms are
not completely saturated; 2) compounds or ions of some metals; 3) molecules or ions with multiple
bonds. Typical catalytic poisons are sulphur compounds (H2S, CS2, mercaptan), hydrocyanic acid
(HCN), carbon monoxide (CO), free halides (J2, Cl2, Br2), mercury and mercury salts (HgCl2,
Hg(CN)2), compounds of phosphorus, arsenic, lead. Since sorption of impurities can be reversible
and irreversible, one can distinguish reversible and irreversible poisoning. For example, Pt catalyst
is poisoned in the presence of CO and CS2 but its activity can be quickly restored in pure initial
mixture of gases. At H2S and PH3 poisoning Pt deactivates irreversibly and completely.
To prevent catalysts from poisoning, special demands are set to the equipment and to the
cleaning of initial reactants. However, it is practically impossible to remove all the impurities in a
real crystal sample. Considering catalytic reactions theoretically we take into account the presence
of impurity atoms or molecules which do not take part in the reaction course but decrease the
number of active sites on the catalyst’s surface and lower its activity [2–4]. It is experimentally
known [5–7] that active reaction-diffusion media can be constructed containing poisons and that
the scale and nature of these poisons can drastically affect spontaneous pattern formation on the
modified substrate. Increments of the density of impurities lead to a smaller regions of existence
of oscillations [2]. Eventually a critical concentration of inert sites is reached at which the region
vanishes and oscillations are no longer possible, due to inability of the lattice to reach the minimum
local concentration of adsorbate required to trigger the surface reconstruction mechanism.
An attempt to investigate the effect of impurity atoms on one of the catalytic reactions, namely
the reaction of catalytic CO oxidation on Pt surface [8–14], is made in the paper. Specifically, our
c© I.S.Bzovska, I.M.Mryglod 183
I.S.Bzovska, I.M.Mryglod
purpose is to take into account the effect of equilibrium impurities with fast and slow self-dynamics
on the reaction within the lattice-gas model with interactions on a surface.
2. Lattice-gas model of CO oxidation reaction with equilibrium impurities
2.1. A case of equilibrium impurities with fast self dynamics
Let us consider a model of the reaction of catalytic CO oxidation by incorporating the effect of
passive impurities on a surface. In the case when impurities can be considered as equilibrium ones
the Hamiltonian of the system is
H = −µ1
∑
i
n1
i − µ2
∑
i
n2
i − µ3
∑
i
n3
i + w1
∑
〈ij〉
n1
i n
1
j + w2
∑
〈ij〉
n2
i n
2
j + ε12
∑
〈ij〉
n1
i n
2
j
+ ε13
∑
〈ij〉
n1
i n
3
j + ε23
∑
〈ij〉
n2
i n
3
j , (1)
where µ1, µ2 and µ3 denote the chemical potentials of CO, O and impurity respectively, and w1,
w2, ε12, ε13 and ε23 are the interaction energies between the nearest-neighbor CO–CO, O–O, CO–
O, CO-impurity and O-impurity respectively. The following notations for three types of adsorbate
occupancies of ith surface site are: n1
i for an adsorbed CO molecule, n2
i for adsorbed oxygen and
n3
i for adsorbed impurity, nl
i = [0, 1] and l=1,2,3. The condition n1
i + n2
i + n3
i 6 1 precludes the
adsorbed particles from occupation of the same adsorption site.
∑
〈ij〉 means the sum over the
nearest-neighbor pairs.
The Hamiltonian of the system in the mean-field approximation looks like
H = −µ̃1
∑
i
n1
i − µ̃2
∑
i
n2
i − µ̃3
∑
i
n3
i + AN, (2)
where the following notations are introduced:
A = −w1〈n
1〉2 − w2〈n
2〉2 − ε12〈n
1〉〈n2〉 − ε13〈n
1〉〈n3〉 − ε23〈n
2〉〈n3〉, (3)
µ̃1 = µ1 − 2w1〈n
1〉 − ε12〈n
2〉 − ε13〈n
3〉, (4)
µ̃2 = µ2 − 2w2〈n
2〉 − ε12〈n
1〉 − ε23〈n
3〉, (5)
µ̃3 = µ3 − ε13〈n
1〉 − ε23〈n
2〉. (6)
The grand partition function of the whole system is equal to
Ξ = exp
(
−
AN
kT
)[
1 + exp
(
µ̃1
kT
)
+ exp
(
µ̃2
kT
)
+ exp
(
µ̃3
kT
)]N
, (7)
whence we obtain the following expression for the grand thermodynamic potential:
Ω = −kT ln Ξ = −Nw1θ
2
1 − Nw2θ
2
2 − ε12θ1θ2N − ε13θ1θ3N − ε23θ2θ3N
− kTN ln
[
1 + exp
(
µ̃1
kT
)
+ exp
(
µ̃2
kT
)
+ exp
(
µ̃3
kT
)]
. (8)
Making use of this formula, we can calculate all the thermodynamic functions of the system in the
mean-field approximation.
Using the thermodynamic formula
θi = −
1
N
(
∂Ω
∂µi
)
T
, (9)
184
Effect of adsorbed impurities on catalytic CO oxidation
we obtain the following system of equations for the coverages θi:
θi =
exp
(
µ̃i
kT
)
1 +
3∑
i=1
exp
(
µ̃i
kT
) , i = 1, 2, 3. (10)
In the case when the reaction rate is higher than the rates of adsorbate adsorption and desorption,
the evolutions of the CO and O coverages in time are determined by the kinetic equations
dθ1
dt
= pCOkCOsCO(1 − θ1 − θ2 − θ3) − dθ1 − kθ1θ2 , (11)
dθ2
dt
= 2pO2
kOsO(1 − θ1 − θ2 − θ3)
2 − kθ1θ2 , (12)
where pCO and pO2
are the partial pressures of CO and oxygen respectively, kCO and kO are
the CO and oxygen impingement rates, sCO and sO are the corresponding sticking coefficients.
The coefficient k denotes the reaction rate constant and is given by: k = kCO2
exp(−βE0) where
E0 is the activation energy of the reaction. The coefficient d = d0 exp(−βEd) is the rate of CO
desorption. The first equation, equation (11), describes variations in the amount of adsorbed CO,
chemical reaction with adsorbed oxygen, and desorption of CO with desorption constant d. The
first term in equation (12) describes the dissociative adsorption of oxygen, and the second one refers
to the reaction between adsorbed oxygen and CO. Then, in order to analyse the stable states, it
is necessary to solve the equations dθ1/dt = 0 and dθ2/dt = 0 together with equations (10) with
respect to the average coverages for CO and oxygen.
2.2. A case of equilibrium impurities with slow self dynamics
Let us now consider a case of equilibrium impurities with slow self-dynamics on a catalyst sur-
face. In this case, the distribution of impurities on the surface can not be assumed to be equilibrium
as in the previous case. So, the kinetic equation for such impurities can be written as
dθ3
dt
= ka(1 − θ1 − θ2 − θ3) − kdθ3 , (13)
where the coefficients ka and kd are the rates of adsorption and desorption of the impurities. Again,
to analyse the stable states of the system, it is necessary to solve the equation dθ3/dt = 0 together
with equations (10)–(12) with respect to the average coverages for CO and oxygen.
3. Results and discussion
3.1. Phase diagrams of the model
In figure 1 phase diagrams (pCO, 1/T ) for various values of sCO and sO in the cases of clean Pt
surface (case a) and the surface containing equilibrium impurities with fast self-dynamics (cases
b − d) are shown. According to the known experimental results, we can make allowance for the
variation of the sticking factors for CO and oxygen, which is caused by the presence of impurity
atoms. Notice that in the case of modified sticking coefficients (case b in the figure) the bistable
region is shifted towards higher CO pressures. On the other hand, taking into account the impurities
via the average coverage θd in the kinetic equations with unaltered sticking coefficients (case c)
causes a shift of the bistable region towards lower pressures and lower temperatures. Finally, taking
into account the impurities on the surface via both the coverage θd and the modification of the
coefficients sCO and sO (case d) shifts the phase diagram to the region of lower temperatures and
higher pressures pCO in comparison with the case of pure surface (case a). We also note that the
phase diagram of equilibrium lattice model (1)–(9) does not contain the region of bistability.
185
I.S.Bzovska, I.M.Mryglod
Figure 1. Phase diagrams (pCO, 1/T ) for various values of θd, sCO and sO.
In figure 2 the dependences of the CO and oxygen coverages on the pressure pCO are exhibited
for two cases. In the first case the catalyst’s surface is pure and in the second case it is poisoned by
fast impurities. It is clearly seen from the figure, that impurities give rise to a significant shift of the
region of bistability. The shift of the region is also accompanied by a reduction of the average CO
coverage and by an increase of the oxygen one, which is in agreement with experimental results.
Figure 2. Average CO and oxygen coverages as the functions of pCO at T=466 K and for various
values of θd, sCO and sO.
At some rather high concentration of impurities, the bistable region disappears and we have only
a monotonous dependence θCO,O = f(pCO). This phenomenon is accompanied by an increase of the
CO coverage and a decrease of the oxygen one. It is interesting to find, in the same approximation,
the highest possible concentration of impurities, at which the region of bistability still exists.
Figure 3 demonstrates that θd = 0.7 is the critical value, at which the bifurcation of the solution
is still observed. At higher values of θd, the bistable region disappears. Taking into account the
interactions between impurities we should expect a decrement of concentration θd.
In figure 4 the dependencies of the average CO and oxygen coverages as the functions of pCO are
shown for three different cases – for a pure surface without any impurities, for the surface with fast
186
Effect of adsorbed impurities on catalytic CO oxidation
Figure 3. Average CO and oxygen coverages as the functions of pCO at T=466 K and for various
values of concentrations θd.
Figure 4. Average CO and oxygen coverages as the functions of pCO at T=466 K and for various
values of concentrations θd.
impurities when their concentration θd on the surface is constant, θd = 0.1, and for the surface with
slow impurities, the concentration of which is determined by kinetic equation (13). The sticking
coefficients sCO, sO are constants for all three cases and have the following values: sCO = 0.9 and
sO = 0.06. We can see from the figure that the presence of the impurities narrows the bistable
region and shifts it to the region of lower pressures pCO, but in the case of impurities with slow
self-dynamics the bistable region is narrowed far more than in the case when their dynamics is
fast.
Thus, the presence of impurities on the surface significantly affects the kinetics of the catalytic
CO oxidation reaction. Impurities shift the bistable region and change the average coverages on
the surface. The variations of sCO and sO, caused by the presence of impurity atoms, play an
important role.
3.2. Analysis of the kinetic equations
To analyse the system of kinetic equations (11)–(13) it is convenient to rewrite it in dimensi-
onless form:
dθCO
dτ
=
pCOkCOsCO
d
(1 − θCO − θO − θd) − θCO −
k
d
θCOθO , (14)
187
I.S.Bzovska, I.M.Mryglod
dθO
dτ
=
2pO2
kOsO
d
(1 − θCO − θO − θd)2 −
k
d
θCOθO , (15)
dθd
d(kdt)
=
ka
kd
(1 − θCO − θO − θd) − θd , (16)
where τ = d · t is a new scale of time for θCO and θO.
Let us find stationary points of the model described by equations (14)–(16). One is given by
θs
CO = 0, θs
O = 1, θs
d = 0, (17)
which corresponds to oxygen poisoning on the substrate. It should be noted that this solution is
never observed experimentally. The others are given by the roots of cubic equation for θCO,
Aθ3
CO + Bθ2
CO + CθCO + D = 0, (18)
and the corresponding oxygen and impurities concentrations are given by
θO =
hCO
kid
(1 − θCO) − θCO
hCO
kid
+
k
d
θCO
, θd =
ki − 1
ki
(1 − θCO − θO) , (19)
where the following notations hO = 2pO2
kOsO, hCO = pCOkCOsCO, ki = ka/kd + 1 are introduced
for convenience. The coefficients of the cubic equation are
A =
hOk2
k2
i
1
d3
,
B = −
2hOk2
k2
i
1
d3
+
hCOk2
ki
1
d3
−
2hOk
k2
i
1
d2
+ k2
1
d2
,
C =
hOk2
k2
i
1
d3
+
h2
CO
k
k2
i
1
d3
−
hCOk2
ki
1
d3
+
2hOk
k2
i
1
d2
+
hCOk
ki
1
d2
+
hO
k2
i
1
d
,
D = −
h2
CO
k
k2
i
1
d3
. (20)
All the roots of cubic equation (18) can be real when the following condition
(
C
3A
−
(
B
3A
)2
)3
+
((
B
3A
)3
−
BC
6A2
+
D
2A
)2
< 0 (21)
is satisfied. From the physical point of view, in this case we have a bistable region in the phase
diagram. So, inequality (21) is the condition of the existence of the bifurcation region obtained
from the kinetic level of description. In linear approximation for small desorption constants this
condition can be rewritten as follows:
d < −
c1 + c2
c3 + c4
, (22)
where
c1 =
(
1
3
+
h2
CO
3hOk
−
hCOki
3hO
−
(
−
2
3
+
hCOki
3hO
)2
)3
, (23)
c2 =
((
−
2
3
+
hCOki
3hO
)3
+
1
3
−
h2
CO
3hOk
−
hCOki
2hO
−
h3
CO
ki
6h2
O
k
+
h2
CO
k2
i
6h2
O
)2
, (24)
c3 = 3
(
1
3
+
h2
CO
3hOk
−
hCOki
3hO
−
(
−
2
3
+
hCOki
3hO
)2
)2(
2
3k
+
hCOki
3hOk
−
2
9
(
−2 +
hCOki
hO
)
188
Effect of adsorbed impurities on catalytic CO oxidation
×
(
k2
i
hO
−
2
k
))
, (25)
c4 = 2
((
−
2
3
+
hCOki
3hO
)3
+
1
3
−
h2
CO
3hOk
−
hCOki
2hO
−
h3
CO
ki
6h2
O
k
+
h2
CO
k2
i
6h2
O
)((
−
2
3
+
hCOki
3hO
)2
×
(
k2
i
hO
−
2
k
)
+
1
k
−
h2
CO
k2
i
3h2
O
k
+
h2
CO
3hOk2
−
hCOki
3hOk
−
k2
i
6hO
+
hCOk3
i
6h2
O
)
. (26)
Relation (22) works well for the parameter range considered at hCO/hO 6 0.7.
We take the following values of our model parameters which correspond to Pt(111) surface:
pO2
= 1.5 ·10−5Torr, kO = 7.8 ·105c−1Torr−1, kCO = 7 ·106c−1Torr−1, k = 598c−1, d = 0.27c−1,
sCO = 0.9, sO = 0.06. Coefficients ka = 0.05c−1, kd = 0.2c−1 are chosen under the condition
that keeps the impurities concentration on a surface sufficiently small. This allows us to study the
effect of impurities on the bistable range. Since this model is formulated at the phenomenological
level, these coefficients can be adjusted to different kinds of impurities if experimental data are
available. Then, the bistable region exists at the following values of pressure pCO:
1.42 · 10−7 Torr < pCO < 1.67 · 10−7 Torr. (27)
The characteristic equation for eigenvalues is as follows:
det
∣∣∣∣
∣∣∣∣λ −
(
∂(FθCO
, FθO
, Fθd
)
∂(θCO, θO, θd)
)
ss
∣∣∣∣
∣∣∣∣ = 0 (28)
or for the system considered
det
∣∣∣∣∣∣∣∣∣
∣∣∣∣∣∣∣∣∣
−
hCO
d
− 1 −
k
d
θs
O − λ −
hCO
d
−
k
d
θs
CO −
hCO
d
−
2hO
d
vs −
k
d
θs
O −
2hO
d
vs −
k
d
θs
CO − λ −
2hO
d
vs
−ki + 1 −ki + 1 −ki − λ
∣∣∣∣∣∣∣∣∣
∣∣∣∣∣∣∣∣∣
= 0 (29)
with vs = 1 − θs
d
− θs
O
− θs
CO
the stationary density of empty adsorption sites.
Determination of eigenvalues of stationary points of the model allows us to analyse the type of
their stability. Let us consider three cases. One case is when the partial pressure pCO has such a
value that we are in the bistable region at the phase diagram. The other two cases are presented
when we consider the regions situated lower or higher than the region of bistability. The stationary
points, their eigenvalues and the corresponding types of their stability are shown in table 1. As
expected, at the intermediate values of pressure pCO the system has four stationary points, but
only two of them are stable. In other cases, there is only one stable point in the system, i. e., a
stable node.
There should be noted a great difference in the eigenvalues for the stationary solutions by two
or even by three orders of magnitude. It actually determines the relaxation times of the model.
However, it is unlikely that this phenomenon has anything to do with the presence of impurities on
the catalyst’s surface. In paper [15] where the reaction kinetics on a pure metal surface is studied,
a similar situation is observed. Speaking about the width of the bistability region we observe a
tendency to its narrowing as a result of a presence of impurities. For comparison, we can give the
results of calculations for the boundaries of the bistable region for the model of the reaction of
catalytic CO oxidation without impurities: pmin
CO
= 1.53× 10−7 Torr and pmax
CO
= 2.05× 10−7 Torr.
As we see, the impurities considerably narrow the bistable region.
4. Conclusions
We have investigated the effect of impurities on the kinetics of catalytic reaction of carbon
dioxide synthesis. For the lattice-gas model in the mean-field approximation we have obtained
kinetic phase diagrams (pCO, 1/T ) which contain bistable regions. Modification of the sticking
189
I.S.Bzovska, I.M.Mryglod
Table 1. Analysis of the stability of the stationary points at different values of pressure pCO .
Pressure pCO Stationary points Eigenvalues Stability
–2221.9
(θCO = 0, θO = 1, θd = 0) –1.06 saddle
1.3 · 10−7 Torr 2.84
–609.7
(θCO = 0.003, θO = 0.269, θd = 0.146) –3.3 stable node
–0.89
–2222.8
(θCO = 0, θO = 1, θd = 0) –1.06 saddle
3.3
–364.9
(θCO = 0.007, θO = 0.154, θd = 0.168) –3.5 stable node
1.5 · 10−7 Torr –0.91
–603.5
(θCO = 0.264, θO = 0.003, θd = 0.147) –1 saddle
1.26
–1312.3
(θCO = 0.589, θO = 0.0004, θd = 0.082) –1.33 stable node
–1
–2224.2
(θCO = 0, θO = 1, θd = 0) –1.05 saddle
1.8 · 10−7 Torr 3.98
–1555.8
(θCO = 0.7, θO = 0.0002, θd = 0.06) –2.95 stable node
–1
coefficients sCO and sO induced by the presence of impurities plays an important role. There is
observed a shift of the diagram to the region of higher pressures pCO. It leads to a decrease of the
CO and to an increase of the oxygen coverages which agrees well with the experimental results.
Taking into account the impurities on the surface via both the coverage θd and the modification
of the coefficients sCO and sO shifts the phase diagram to the region of lower temperatures and
higher pressures pCO. In the case of slow impurities, the bistable region is narrowed far more than
in the case when their dynamics is fast and their distribution on the surface can be assumed to
be equilibrium. The critical concentration of impurities at which the bistable region still exists, as
follows from our estimations, is θd = 0.7. Taking into account the interactions between impurities
we should expect a decrement of concentration θd. From the analysis of kinetic equations, the
condition of the existence of bifurcation region has been analytically found.
In our work the interactions between the impurities and coadsorbates have been taken into
account within the mean field approximation for the Hamiltonian (1). In general, it is also possible
to include such interactions into the level of kinetic equations and to use more sophisticated ap-
proximations that allow one to consider more in detail the surface modifications (phase transitions,
inhomogeneous patterns, etc) and diffusion effects. Some of these problems will be considered in
our further studies.
190
Effect of adsorbed impurities on catalytic CO oxidation
References
1. Ioffe I.I., Reshetov V.A., Dobrotvorskyj A.M. Heterogeneous Catalysis. Leningrad, 1985.
2. Chavez F., Vicente L., and Perera A., J. Phys. Chem., 2000, 113, 10353.
3. Pavlenko N., Kostrobij P.P., Suchorski Yu., Imbihl R., Surf. Sci., 2001, 489, 29.
4. Mryglod I.M., Bzovska I.S., Ukr. J. Phys., 2007, 52, No. 5, 468.
5. Asakura K., Lauterbach J., Rotermund H.H., and Ertl G., Phys. Rev. B, 1994, 50, 8043.
6. Asakura K., Lauterbach J., Rotermund H.H., and Ertl G., Surf. Sci., 1997, 374, 125.
7. Bär M., Kevrekidis G., Rotermund H.H., and Ertl G., Phys. Rev. E, 1995, 52, R5739; Bär M., Ban-
gia A.K., Kevrekidis G., Haas G., Rotermund H.H., and Ertl G., J. Phys. Chem., 1996, 100, 19106.
8. Kostrobii P.P., Tokarchuk M.V., Alekseyev V.I., Phys. and Chem. of Solid State, 2006, 7, No. 1, 25.
9. Zhdanov V.P., Surf. Sci., 2002, 500, 966.
10. Chavez F. and Vicente L., Perera A. and Moreau M., J. Chem. Phys., 1998, 109, No.19, 8617.
11. Suchorski Yu., Beben J., Imbihl R., James E.W., Da-Jiang Lin and Evans J.W., Phys. Rev. B, 2001,
63, No.16, 165417.
12. Grandi B.C.S. and Figueiredo W., Phys. Rev. E, 2002, 65, 036135.
13. Nekhamkina O., Digilov R., Sheintuch M., J. Chem. Phys., 2003, 119, 2322.
14. Cisternas Y., Holmes Ph., Kevrekidis I.G., Li X., J. Chem. Phys., 2003, 118, 3312.
15. Mryglod I.M., Bzovska I.S., Ukr. J. Phys. 2008, 53, No. 6, 529.
Вплив домiшок на реакцiю каталiтичного окислення СО
I.С.Бзовська, I.М.Мриглод
Iнститут фiзики конденсованих систем НАН України, вул. Свєнцiцького, 1, 79011 Львiв, Україна
Отримано 10 квiтня 2009 р., в остаточному виглядi – 8 травня 2009 р.
В рамках ґраткової моделi дослiджується вплив неактивних домiшок на кiнетику реакцiї каталiти-
чного синтезу вуглекислого газу, зокрема аналiзуються випадки рiвноважної домiшки з швидкою
(в порiвняннi зi швидкiстю реакцiї) та повiльною власними динамiками. Показано, що домiшки на
поверхнi змiщують фазову дiаграму до областi нижчих температур i вищих тискiв pCO. У випадку,
коли концентрацiя домiшки змiнюється на поверхнi досить повiльно, область бiстабiльностi звужує-
ться значно бiльше, нiж коли динамiка домiшки є швидкою i її розподiл на поверхнi можна вважати
рiвноважним. Знайдено критичну концентрацiю домiшок, при якiй ще спостерiгається область бi-
стабiльностi. З кiнетичних рiвнянь аналiтично знайдено умову iснування областi бiстабiльностi.
Ключовi слова: модель ґраткового газу, каталiз, окислення, монооксид вуглецю, кисень
PACS: 05.50.+q, 68.43.-h, 82.65.+r
191
192
|
| id | nasplib_isofts_kiev_ua-123456789-119968 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1607-324X |
| language | English |
| last_indexed | 2025-12-07T17:54:17Z |
| publishDate | 2009 |
| publisher | Інститут фізики конденсованих систем НАН України |
| record_format | dspace |
| spelling | Bzovska, I.S. Mryglod, I.M. 2017-06-10T14:01:36Z 2017-06-10T14:01:36Z 2009 Effect of adsorbed impurities on catalytic CO oxidation / I.S. Bzovska, I.M. Mryglod // Condensed Matter Physics. — 2009. — Т. 12, № 2. — С. 183-191. — Бібліогр.: 15 назв. — англ. 1607-324X PACS: 05.50.+q, 68.43.-h, 82.65.+r DOI:10.5488/CMP.12.2.183 https://nasplib.isofts.kiev.ua/handle/123456789/119968 The effect of inactive adsorbed impurities on kinetics of catalytic synthesis of carbon dioxide is investigated
 in the framework of the lattice-gas model. Namely, two cases of equilibrium impurities with fast, compared
 with the reaction's rate, and slow self dynamics are analyzed. It is revealed that the adsorbed impurities
 shift the phase diagram to the region of lower temperatures and higher pressures pCO. In the case of slow
 impurities the bistable region is narrowed far more than in the case when their dynamics is fast and their
 distribution on the surface can be assumed to be equilibrium. The critical concentration of impurities at which
 the bistable region disappears, is found. From analysis of the kinetic equations the condition of the existence
 of the bifurcation region is analytically obtained. В рамках ґраткової моделi дослiджується вплив неактивних домiшок на кiнетику реакцiї каталiтичного синтезу вуглекислого газу, зокрема аналiзуються випадки рiвноважної домiшки з швидкою (в порiвняннi зi швидкiстю реакцiї) та повiльною власними динамiками. Показано, що домiшки на поверхнi змiщують фазову дiаграму до областi нижчих температур i вищих тискiв pCO. У випадку, коли концентрацiя домiшки змiнюється на поверхнi досить повiльно, область бiстабiльностi звужується значно бiльше, нiж коли динамiка домiшки є швидкою i її розподiл на поверхнi можна вважати рiвноважним. Знайдено критичну концентрацiю домiшок, при якiй ще спостерiгається область бiстабiльностi. З кiнетичних рiвнянь аналiтично знайдено умову iснування областi бiстабiльностi. en Інститут фізики конденсованих систем НАН України Condensed Matter Physics Effect of adsorbed impurities on catalytic CO oxidation Вплив домiшок на реакцiю каталiтичного окислення СО Article published earlier |
| spellingShingle | Effect of adsorbed impurities on catalytic CO oxidation Bzovska, I.S. Mryglod, I.M. |
| title | Effect of adsorbed impurities on catalytic CO oxidation |
| title_alt | Вплив домiшок на реакцiю каталiтичного окислення СО |
| title_full | Effect of adsorbed impurities on catalytic CO oxidation |
| title_fullStr | Effect of adsorbed impurities on catalytic CO oxidation |
| title_full_unstemmed | Effect of adsorbed impurities on catalytic CO oxidation |
| title_short | Effect of adsorbed impurities on catalytic CO oxidation |
| title_sort | effect of adsorbed impurities on catalytic co oxidation |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/119968 |
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