Subsolidus of the MO-Cr2O3-V2O5 systems, where M=Ni, Mg

Article abstract of DOI:10.1016/j.jpcs.2006.12.006

Phase relations in the system: MO-Cr₂O₃-V₂O₅, where M=Ni and Mg, were determined up to the solidus lines over the whole components concentration range. On the basis of this, a division of both systems into subsidiary subsystems was performed. The melting temperatures of individual areas were also established.

Full text of DOI:10.1016/j.jpcs.2006.12.006

ARTICLE IN PRESS
Journal of Physics and Chemistry of Solids 68 (2007) 1193–1197
www.elsevier.com/locate/jpcs
Subsolidus of the MO–Cr O –V O systems, where M ¼ Ni, Mg
2
3
2 5
Ã
I. Rychlowska-Himmel, M. Bosacka
Department of Inorganic and Analytical Chemistry, Szczecin University of Technology, Al. Piast o´ w 42, 71-065 Szczecin, Poland
Abstract
Phase relations in the system: MO–Cr
2
O
3
–V
2
O
5
, where M ¼ Ni and Mg, were determined up to the solidus lines over the whole
components concentration range. On the basis of this, a division of both systems into subsidiary subsystems was performed. The melting
temperatures of individual areas were also established.
r 2007 Elsevier Ltd. All rights reserved.
Keywords: A. Inorganic compounds; A. Oxides; C. X-ray diffraction; D. Phase equilibria
1
. Introduction
congruently at the temperatures: Ni CrV O –94075 1C
2
3
11
[
5], Mg CrV O –90075 1C [3].
2
3
11
The development of industry poses a considerable threat.
Until today, phase relations corresponding to the solidus
Therefore, increasingly, all sorts of enterprises aiming at
minimizing the negative consequences of industrial activity
are undertaken. Owing to the fact that norms permitting
line, settling in three intersections of the ternary NiO–
Cr O –V O , i.e. NiV O –NiCr O , Ni V O –CrVO and
Ni V O –NiCr O system [4,5] have been examined. The
2
3
2
5
2
6
2
4
2
2
7
4
3
2
8
2
4
the values of harmful HCl, NO molecules and others are
x
results of these investigations made it possible to draw a
few lines of the division of the triangle of the ternary
NiO–Cr O –V O system concentrations (Fig. 1a) [4,5].
being tightened, one can expect much stricter boundary
values of exhaust gas emissions. Therefore, their effective
purification, thanks to DENOX filters and catalysts, will
become highly necessary. In the years 1970–1980, the bloc
d metal oxides, implemented as catalysts removing NO2,
were found to be highly selective [1]; thus, the research on
further improvement of the catalysts’ selectivity is far flung.
The oxide multicomponent systems are the area of search
for the catalysts characterized by high selectivity and
activity. For many years, the vanadates of bivalent metals
2
3
2
5
This figure implies that the NiV O —NiCr O system is the
4
2
6
2
actual bivalent system up to the 25 mol% NiCr O content
2
4
only. Above the content of 25 mol% NiCr O , the
2
4
NiV O –NiCr O system constitutes the cross-section of
4
2
6
2
the NiO–Cr O –V O , going through two subsidiary
2
3
2
5
subsystems: Ni CrV O –Ni V O –Cr O and Ni V O –
3
2
4
11
3
2
8
2
3
2
8
NiCr O –Cr O . The investigation into the Ni V O –
7
2
4
2
3
2
2
CrVO4 system demonstrated that it is the real binary
system where the Ni CrV O compound is formed.
[
2] have been known owing to their interesting properties.
2
3
11
Thoroughly conducted studies have revealed that the
catalytic characteristics are connected with the presence
of isolated tetrahedra VO in vanadates’(V) molecules [2].
The studies on the three intersections, MgV O –
2 6
MgCr O , Mg V O –CrVO and Mg V O , [3] allowed
2
4
2
2
7
4
3
2
8
the determination of the partial division of the components
concentration triangle of the MgO–V O –Cr O system
4
During the works conducted on M V O reactivity in
2
2
7
2
5
2
3
relation to CrVO , where M ¼ Ni, Mg, Zn, it was
into subsidiary subsystems (Fig. 1b.) The figure implies
that the MgV O –MgCr O system is not the real binary
one. In the samples containing up to 50.00% mol MgV O ,
4
demonstrated that, in the solid phase, these compounds
react with forming a new phase of the general formula
M CrV O [3–5]. The M CrV O compounds, where
2
6
2
4
2
6
Mg V O , Cr O and MgCr O coexist at equilibrium,
4
2
3
11
2
3
11
2
2
7
2
3
2
M ¼ Ni, Mg crystallize in the triclinic system and melt
while within the concentration range from 50.00 up to
5.00% mol MgV O the products of Mg CrV O ,
Mg V O and Cr O reactions coexist at equilibrium,
7
2
6
2
3
11
Ã
Corresponding author.
E-mail address: bossm@ps.pl (M. Bosacka).
2
2
7
2
3
whereas above 75.00% mol MgV O : MgCrV O and
2 6 3 11
0022-3697/$ - see front matter r 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jpcs.2006.12.006

ARTICLE IN PRESS
I. Rychlowska-Himmel, M. Bosacka / Journal of Physics and Chemistry of Solids 68 (2007) 1193–1197
1194
a
b
NiO
MgO
Mg V O
3
Ni V O
8
2
8
3
2
Ni V O
2
Mg V O
2
2
7
2
7
MgV O
2
Mg CrV O
2
Ni CrV O
2
NiCr O
2
6
3
11
·
MgCr O
2
NiV O
2
3
11
4
4
6
·
·
·
V O 10 20 30 40 50 60 70 80 90 Cr O
V O 10 20 30 40 50 60 70 80 90 Cr O
2 5 2
2
5
2
3
3
Cr V O
2
CrVO4
Cr V O
2
CrVO4
mol % Cr O
4
13
4
13
mol % Cr O
2
3
2
3
Fig. 1. Preliminary division of the investigated ternary systems into subsidiary subsystems: a— NiO–V
O
2 5
–Cr
2
O
3
, b—MgO–V
2
O
5
2 3
–Cr O .
MgV O [3]. However, the Mg V O –CrVO is the real
2
syntheses of the mentioned compounds have been related
in works [3,5–8].
6
2
2
7
4
binary system where the Mg CrV O compound is formed
11
2
3
[
3]. Also, the Mg V O –MgCr O system is binary, in
3
Adequate weighed amount of substrates were homo-
genized by grinding, forming into pellets and heating in air
atmosphere in several stages, until the state of equilibrium
was obtained. After each heating stage, the samples were
homogenized and examined by the X-ray diffraction
(XRD) method and later formed into pellets and heated
once again. The conditions of heating particular samples,
depending on the composition of the initial mixtures,
differed by both the heating temperature and the time of
heating at a given temperature.
After the final heating stage, all samples and the furnace
were slowly cooled down to ambient temperature. Next,
they were ground and tests were applied by means of the
DTA and XRD methods. The samples were then pelletized
again and further heated at the temperature of the last
stage of the synthesis within 24 h. Later, they were rapidly
cooled down to room temperature and, after grinding, were
DTA tested. Their composition was determined with the
XRD method. This procedure allowed the establishment of
types of phases being generated in the investigated system
and also the ranges of their coexistence in the concentra-
tion solid state.
The DTA tests were carried out with the help of the
F. Paulik—L. Paulik—L. Erdey derivatograph (MOM,
Budapest). The samples weighing 1000 mg each were
placed in quartz crucibles. All measurements were run in
air atmosphere, in the temperature range 293–1273 K, at
the samples’ heating rate 10 K/min. Some chosen samples
were examined by DTA method using an instrument of
METLER TOLEDO TGA/SDTA 851. Samples of 5 mg
each, measured by DTA method in air, in the temperature
2
8
2
4
which the components do not react with one another [4].
The aim of this work was to complete the phase relations
determined so far, settling to the solidus line in two ternary
systems: MO–Cr O –V O , where M ¼ Ni, Mg all over
2
3
2
5
their components concentration range. On the basis of this
data, a division of these two systems into subsidiary
subsystems was carried out. Another objective was to
obtain samples, at equilibrium, of the compositions
belonging to particular subsidiary subsystems and binary
intersections of the investigated ternary systems, and next
determining the melting temperatures of both the sub-
sidiary subsystems and the binary intersections.
2
. Experimental
The following compounds were used in the investiga-
tions:
ꢀ
ꢀ
ꢀ
ꢀ
2 5
¨
V O , analytically pure, Riedel-de Haen, Germany—
manufacturer;
Cr O , analytically pure, Aldrich, Germany—manufac-
turer;
2
3
2NiCO ꢁ 3Ni(OH) ꢁ H O, analytically pure, POCh Gli-
3
2
2
wice; Poland—manufacturer;
3MgCO ꢁ Mg(OH) ꢁ 3H O, analytically pure, POCh
3
2
2
Gliwice, Poland—manufacturer.
Also, MV O , M V O , M V O , MCr O , where
2
6
2
2
7
3
2
8
2
4
M ¼ Ni, Mg as well as CrVO and Cr V O were used
4
2
4
13
as reacting substances in the conducted studies. The

ARTICLE IN PRESS
I. Rychlowska-Himmel, M. Bosacka / Journal of Physics and Chemistry of Solids 68 (2007) 1193–1197
1195
range 1173–1673 K, were placed in platinum crucibles and
heated at a rate of 10 K/min.
The phases occurring in the samples were identified on
the basis of the results of the XRD investigations
The results of these studies allowed to determine the
division of the polygon into two subsidiary subsystems,
NiV O –NiCrV O –CrVO and NiV O –CrVO –V O ,
2
6
3
11
4
2
6
4
2
5
and finally state that, in the solidus area of the investigated
(
DRON—3 diffractometer, CoKa radiation Fe filter),
and the information included in the PDF cards [9] and
works [3,5]. When a diffraction pattern was being worked
on, a package of computer programs DHN/PDS (Program
Packing for Powder Diffraction) was used.
NiO
I
Ni V O
8
3
2
3
. Results and discussion
1493
IV
Ni V O
2
·
2
7
3
.1. The NiO–Cr O –V O system
5
2
3
2
9
93
V
Ni CrV O
2
II
3
11
In order to carry out the studies, 22 samples of
993
NiCr O4
2
NiV O6
2
1213
1398
compositions exhibited in Table 1 were prepared. Table 1
demonstrates the heating conditions of particular samples
and the phases detected in the equilibrium state as well.
The information obtained by means of the XRD method,
concerning the samples with compositions lying within the
area of a polygon characterized by the CrVO , Cr V O ,
III
VI
9
33
VII
VIII
4
2
4
13
913
1103
V O , NiV O and Ni CrV O compounds (samples 1–5),
2
2
5
2
6
3
11
implies that reaction:
·
V O
2
5
10
20
30
40
50
60
70
80
2
90 Cr O3
2
CrVO4ðsÞ þ V2O5ðsÞ ¼ Cr2V4O13ðsÞ
(1)
Cr V O
2
CrVO4
4
13
does not occur, while other components of the examined
polygon react with one another according to the following
reaction:
mol % Cr O3
2
Fig. 2. The division of concentration components triangle of the
NiO–V –Cr system into subsidiary subsystems and the melting
temperatures (K) of the subsidiary subsystems and binary systems.
2
O
3
2 3
O
V O þ Ni CrV O
¼ CrVO4ðsÞ þ 2NiV O
:
6ðsÞ
(2)
2
5ðsÞ
2
3
11ðsÞ
2
Table 1
The composition of initial mixtures per system’s components, heating stages and phases detected in the samples in the state of equilibrium in binary and
ternary systems belonging to the NiO–Cr –V system
2
O
3
2 5
O
Sample no Mixtures’ composition per system’s components [mol%]
Heating conditions (K ꢂ 24 h)
Phases detected in the state of equilibrium
NiO
V
2
O
5
2 3
Cr O
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
85.00
60.00
40.00
10.00
37.00
60.00
45.00
30.00
65.00
53.00
28.00
60.00
85.00
70.00
60.00
35.00
15.00
33.00
15.00
55.00
60.00
25.00
10.00
15.00
55.00
80.00
54.00
35.00
35.00
27.00
15.00
17.00
22.00
20.00
10.00
10.00
15.00
20.00
10.00
33.00
30.00
40.00
30.00
42.00
5.00
25.00
5.00
863-923-973
863-923-943
863-923-943-993
863-( ꢂ )
CrVO
4
, NiV
2
O
6
4
4
, Ni
2
CrV
3
O
11
NiV
2
O
6
, CrVO
, V
2
O
5
10.00
9.00
989 ( ꢂ 4)
NiV
2
O
6
, CrVO
, Ni
, V
2
O
5
5.00
973
973-1073
Ni
2
Ni
2
Ni
2
Ni
3
Ni
3
Ni
2
Ni
3
V
2
O
7
2
CrV
11, Cr
11, CrVO
3 11
O
20.00
43.00
20.00
30.00
50.00
20.00
5.00
CrV
CrV
3
O
O
2 3
O
3
4
973-1073-1093
973-1073
973
V
V
2
O
O
8
, NiCr
, Cr
11, Cr
, Cr
2
O
4
1
1
1
1
1
1
1
1
1
1
2
2
2
2
8
2
O
3
CrV
3
O
2
O
3
973-1073
863-923-1073-1123-1223 NiO, Ni
V
2
O
8
2
O
3
3
V
2
O
8
, NiCr
2
O
4
20.00
25.00
45.00
75.00
34.00
55.00
5.00
863-923-943-1123
863-923-943-1073-1093 Ni
Ni
3
V
V
2
O
O
8
, NiCr
2
O
4
, Cr
2
O
3
3
2
8
, Ni CrV
2
3
O
11, Cr
, CrVO
11, NiV
2
O
3
863-923-973-943
Ni
2
CrV
3
O11, Cr
2
O
3
4
863-923-943-993
973-1073-1093
Ni
2
Ni
2
Ni
2
V
2
O
7
, Ni
2
CrV
3
O
2
O
6
10.00
33.00
CrV
CrV
3
O
11, Cr
11, Cr
2
O
O
3
, Ni
3
V
, CrVO
2
O
8
3
O
2
3
4

ARTICLE IN PRESS
I. Rychlowska-Himmel, M. Bosacka / Journal of Physics and Chemistry of Solids 68 (2007) 1193–1197
1196
NiO–Cr O –V O system, eight subsidiary subsystems,
2
The investigations conducted resulted in isolating, in the
ternary MgO–Cr O –V O system, nine subsidiary sub-
systems, where in the equilibrium state there coexist three
solid phases. These are the following subsidiary subsys-
tems:
2
3
5
where three solid phases coexist, can be distinguished
Fig. 2).
2
3
2
5
(
Area I
NiO–NiCr O –Ni V O
2 4 3 2 8
Area II
Area III
Area IV
Area V
NiCr O –Cr O –Ni V O
2 4 2 3 3 2 8
Cr O –Ni CrV O –Ni V O
3
Area I
MgO–MgCr O –Mg V O
2 4 3 2 8
2
3
2
3
11
2
8
Ni CrV O –Ni V O –Ni V O
3
Area II
Area III
Area IV
Area V
Mg V O –MgCr O –Mg V O
3 2 8 2 4 2 2
2
3
11
2
2
7
2
8
7
Ni CrV O –NiV O –Ni V O
2
Mg V O –MgCr O –Cr O
2 2 7 2 4 2 3
2
3
11
2
6
2
7
Area VI
Area VII
Area VIII
NiV O –CrVO –Ni CrV O
3
Mg V O –Cr O –Mg CrV O
2 2 7 2 3 2 3 11
2
6
4
2
11
NiV O –V O –CrVO
5
Mg CrV O –Cr O –CrVO
3
2
6
2
4
2
3
11
2
4
Ni CrV O –CrVO –Cr O
3
2
3
11
4
2
MgO
3
.2. The MgO–Cr O –V O system
2 3 2 5
Fourteen samples of the compositions presented in
1453
I
Mg V O
8
Table 2 were prepared. Table 2 also has the heating
conditions of particular samples and the phases detected in
the equilibrium state. In order to determine the phase
relations establishing in the quadrilateral described by the
V O , MgV O , Mg CrV O and CrVO phases, it was
3
2
II
Mg V O
2
2
7
1393
1003
IX
Mg2CrV3O11
IV
2
5
2
6
2
3
11
4
1028
MgV O6
2
MgCr O4
2
necessary to investigate the mutual reactivity of Mg CrV O
3
2
11
III
1093
1083
towards V O and Mg CrV O towards Cr V O . Thus,
2
2
5
2
3
11
4
13
VI
1003
two samples 1 and 2 were subjected to the reactivity
investigations (Table 2). After obtaining the samples in the
equilibrium state, it was concluded that substrates of sample
903
V
1
responded completely, according to equation:
VIII
1113
VII
883
Mg2CrV3O11ðsÞ þ V2O5ðsÞ ¼ 2 MgV2O6 þ CrVO4ðsÞ;
(3)
whereas sample 2 responded in accordance with equation:
Mg CrV O
þ 3V O ¼ 4MgV O þ Cr V O :( 4)
V O 10
20
30
40
50
60
70
80
90 Cr O3
2
2
5
2
Cr V O
13
CrVO4
2
3
11ðsÞ
2
5ðsÞ
2
6ðsÞ
2
4
13ðsÞ
2
4
mol % Cr O3
2
It can be concluded that the quadrilateral described by the
V O –MgV O –CrVO Cr V O compounds can be divided
into two subsidiary subsystems: V O –MgV O –Cr V O
2
5
2
6
4
2 4 13
Fig. 3. The division of concentration components triangle of the
MgO–V –Cr system into subsidiary systems and the melting
temperatures (K) of subsidiary and binary systems.
2
5
2
6
2
4
13
2
O
5
2 3
O
and Cr V O –MgV O –CrVO .
6
2
4
13
2
4
Table 2
The composition of initial mixtures per system’s components, the heating stages and the phases detected in the samples in the state of equilibrium in binary
and ternary systems belonging to the MgO–Cr –V system
2
O
3
2 5
O
Sample no Mixtures’ composition per system’s components [mol%]
Heating conditions (K ꢂ 24 h) Phases detected in the state of equilibrium
MgO
V
2
O
5
2 3
Cr O
1
2
3
4
5
6
7
8
9
0
1
2
3
4
40.00
28.57
36.36
66.66
60.00
50.00
40.00
80.00
65.00
55.00
40.00
20.00
25.00
20.00
50.00
50.00
54.54
16.67
20.00
25.00
30.00
10.00
20.00
40.00
45.00
65.00
55.00
30.00
10.00
21.43
9.09
823-853-873
868-893-903
868-868-893
923-973-1023-1073
MgV
2
2
O
6
6
, CrVO
4
MgV
O
, Cr
2
V
4
O
13
16.67
20.00
25.00
30.00
10.00
15.00
5.00
Mg
Mg
Mg
Mg
3
2
2
2
V
V
V
2
2
2
O
O
O
8
7
7
, MgCr
, MgCr
, Cr
11, Cr
2
O
4
2
O
4
2
O
3
CrV
3
O
2
O
3
MgO, Mg
3
V
2
O
8
, MgCr
, MgCr , Mg
, Mg CrV
CrV
, Cr
, Cr
2
O
4
Mg
Mg
3
V
V
2
2
O
O
8
2
O
4
2
V
2
O
7
1
1
1
1
1
923-973-1023
2
7
2
3
O
11, MgV
2
O
6
15.00
15.00
20.00
50.00
MgV
2
O
6
, Mg
2
3
O
11, CrVO
4
823-853-873-883
823-873-923-948
V
MgV
2
O
5
, MgV
2
O
6
2
V
4
O
13
2
O
6
, CrVO
11, Cr
4
2
V
4
O
13
Mg CrV
2
3
O
2
O
3
, CrVO
4

ARTICLE IN PRESS
I. Rychlowska-Himmel, M. Bosacka / Journal of Physics and Chemistry of Solids 68 (2007) 1193–1197
1197
Area VI
Area VII
Area VIII
Area IX
Mg CrV O –CrVO –MgV O
6
References
2
3
11
4
2
MgV O –CrVO –Cr V O
11
2
6
4
2
4
[
[
[
1] V.N. Parmon, G.I. Panov, A. Uriarte, A.S. Noskov, Nitrous oxide in
oxidation chemistry and catalysis: application and production, Catal.
Today 100 (2005) 115.
MgV O –Cr V O –V O
5
2
6
2
4
13
2
MgV O –Mg V O –CrVO
4
2
6
2
2
7
2] M.A. Charr, D. Patel, M.C. King, H.H. Kung, Selective oxidative
dehydrogenation of butane over V–Mg–O catalysts, J. Catal. 105
In order to determine the melting temperatures of
particular subsidiary subsystems in the ternary MO–
Cr O –V O systems, where M ¼ Ni, Mg, the melting
(
1987) 181.
3] M. Kurzawa, I. Rychlowska-Himmel, A. Blonska-Tabero, M.
Bosacka, G. Dabrowska, A new compound Mg CrV O and phase
2
3
2
5
2
3
11
temperatures of all samples prepared for particular systems
of the compositions demonstrated in Tables 1 and 2, were
determined. The melting temperatures of phases, being at
equilibrium in a given binary or ternary system, were
marked out on the basis of the onset temperatures of first
endothermic effects, not being the temperatures of poly-
morphous transformations, recorded on the DTA curves.
The conducted measurements, completed with the results
of the tests run earlier, facilitated working out complete
relations in the MgV
2 6 2 4
O –MgCr O system in solid state, Solid State
Phenom. 90-91 (2003) 353–358.
4] M. Bosacka, M. Kurzawa, I. Rychlowska-Himmel, M. Laskowska,
I. Naniewicz, Phase equilibria in the selected intersections of
[
the ternary oxide system NiO–V
(
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Acknowledgements
2 4
V O
[
This scientific work is financed from budget resources
allocated to science in the years 2005–2008.
3