Synthesis of TiO2-ZrO2 binary oxides by hydrolysis of tetrabutoxytitanium and tetrabutoxyzirconium mixtures under water-ammonia atmosphere

Article abstract of DOI:10.1134/S0036023615090156

TiO₂-ZrO₂ binary oxides were prepared by joint hydrolysis of tetrabutoxytitanium (TBT) and tetrabutoxyzirconium (TBZ) mixtures under an atmosphere of H₂O vapor and 10% aqueous NH₃ in the batch mode. The physical

Full text of DOI:10.1134/S0036023615090156

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2015, Vol. 60, No. 9, pp. 1059–1067. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © A.B. Shishmakov, Yu.V. Mikushina, O.V. Koryakova, L.A. Petrov, 2015, published in Zhurnal Neorganicheskoi Khimii, 2015, Vol. 60, No. 9, pp. 1166–1174.
SYNTHESIS AND PROPERTIES
OF INORGANIC COMPOUNDS
Synthesis of TiO2–ZrO2 Binary Oxides by Hydrolysis
of Tetrabutoxytitanium and Tetrabutoxyzirconium Mixtures
under Water–Ammonia Atmosphere
A. B. Shishmakov, Yu. V. Mikushina, O. V. Koryakova, and L. A. Petrov
Institute of Organic Synthesis, Ural Branch, Russian Academy of Sciences,
ul. S. Kovalevskoi 22/Akademicheskaya 20, Yekaterinburg, 620990 Russia
eꢀmail: mikushina@ios.uran.ru
Received September 24, 2014
Abstract—TiO2–ZrO2 binary oxides were prepared by joint hydrolysis of tetrabutoxytitanium (TBT) and tetꢀ
rabutoxyzirconium (TBZ) mixtures under an atmosphere of H2O vapor and 10% aqueous NH3 in the batch
mode. The physical and chemical properties of the thusꢀprepared samples were studied as dependent on the
synthesis parameters.
DOI: 10.1134/S0036023615090156
TiO2–ZrO2 binary systems are of interest as cataꢀ we attempted at preparing TiO2–ZrO2 by this technolꢀ
lysts and catalyst supports in organic synthesis and in ogy. The batch hydrolysis of precursors excludes some
air and water decontamination [1–10]. These systems of the factors that influence the properties of the final
can be prepared by various methods, via the precipitaꢀ product, and thereby enhances the reproducibility of
tion of hydroxides from salt solutions (hydrothermal the characteristics of oxide materials.
synthesis, sol–gel technology) or vapor phase deposiꢀ
tion (electrochemical synthesis and other processes)
[11–14]. Synthesis parameters determine particle
sizes, pore sizes, the ratio between ZrO2 and TiO2 polyꢀ
morphs in the binary material, and, accordingly, the
scope of practical use of these systems.
The goals of this study were to prepare binary
oxides in a wide range of ratios TiO2/ZrO2 by joint
hydrolysis of TBT and tetrabutoxyzirconium (TBZ)
mixtures in the presence of water vapor (the first set)
and in a water–ammonium atmosphere (second set)
and to carry out a comparative analysis of the effects of
synthesis parameters on physical and chemical propꢀ
erties of the prepared samples.
Sol–gel technology stands out from many synthesis
methods in that it does not require complex hardware
design and ensures a homogeneous distribution of
components on an atomic level. The conventional
synthesis of binary oxides by this technology comꢀ
prises the hydrolysis of a mixture of metal alkoxides in
an aqueous alcohol in the presence of catalysts (acids
and alkalis), followed by controlled drying. However,
the sol–gel synthesis of a material having tailored
properties is made difficult by many significant factors
that influence the final result, so that the main paramꢀ
eters of the binary system are frequently poorly reproꢀ
ducible.
EXPERIMENTAL
The organometallic precursors were hydrolyzed
inside a 3000ꢀcm3 desiccator, where a beaker was
mounted containing 80 mL H2O in the first set of runs
(A) and the same volume of 10% aq. ammonia in the
second set (B). Tetrabutyltitanium (SigmaꢀAldrich,
Titanium(IV)butoxide, reagent grade, 97%), TBZ
(SigmaꢀAldrich. Zirconium(IV)butoxide solution,
80 wt % in 1ꢀbutanol), or mixtures of the two, 10 mL
in volume, were poured into roundꢀbottomed porceꢀ
lain bowls 60 mm in diameter and 30 mL in capacity,
and the bowls were placed into the desiccator.
Our earlier studies showed the feasibility to prepare
TiO2–SiO2 binary xerogels by joint hydrolysis of tetꢀ
rabutoxytitanium (TBT) and tetraethoxysilane mixꢀ
In order to prepare TiO2–ZrO2 binary oxides where
tures in the presence of water vapor or under a water– the TiO2 molar percentage was 7 (sample 1), 13 (samꢀ
ammonia atmosphere without stirring [15–19]. This ple 2), 25 (sample 3), 47 (sample 4), or 84 (sample 5),
technology is distinguished by simple hardware and TBT and TBZ were mixed so that the solution conꢀ
offers a way to prepare TiO2–SiO2 mixed oxides with a tained 0.5, 1, 2, 4, or 8 mL TBT per 10 mL, respecꢀ
wide range of physical and chemical properties. Here, tively.
1059

1060
SHISHMAKOV et al.
I
ZrO2(A)
1070
1068
1042
1039
1(A)
1378
1556
1038
1378
1556
3352
3362
2(A)
3(A)
1071
1069
1378
1556
1038
1378
3360
3292
1556
1581
1120
1376
1464
4(A)
5(A)
1038
1081
1630
1125
3334
1376
1376
1462
1635
1037
1098
1635
1462
3318
1037
1098
1126
2872
2933
TiO2(A)
3330
2958
40003600320028002400200018001600140012001000 800 600 390
, cm–1
ν
Fig. 1. IR spectra of Set A oxides after drying at 90°C.
The precursors were exposed in the desiccator for using special programs from the spectrometer softꢀ
ware.
The specific areas Ssp of samples were determined
3 days at 24 С; after this time elapsed, liquid hydrolyꢀ
°
sis products were decanted from the bowls where a
precipitate remained. Elemental analysis did not
detect metalꢀcontaining components in the liquid
phase. The bowls with the precipitate were again
placed into the desiccator for 2 days, dried under air at
by thermal nitrogen desorption on a SoftSorbiꢀII
ver.1.0 instrument (determination precision was
5%).
Xꢀray powder diffraction patterns of oxides were
recorded on Rigaku DNAX 2200PC.
24
°
С
for 96 h and then in a drying cabinet at 90 С for
°
96 h (to attain a constant weight). After this, samples
were loaded into a quartz reactor and calcined at
RESULTS AND DISCUSSION
850 С (the heating rate was 10 K/min) in flowing air
°
(the flow rate was 0.075 m3/h) for 1 h. Atomicꢀabsorpꢀ
tion analysis confirmed that the experimentally
obtained ratios TiO2/ZrO2 corresponded to equimolar
ratios in samples of both sets (within the error of the 90
method).
Oxide samples of Sets A and B after drying were
loose white powders.
In the IR spectrum of a ZrO2(А) sample dried at
°
С (Fig. 1), absorption bands of the Zr–O stretchꢀ
ing vibrations appear in the range 1000–400 cm–1. In
this case, a composite band with peaks at 1070 and
1042 cm–1 can be assigned to the bending vibrations of
hydroxide groups of the oxide. Absorption bands at
1556 and 1378 cm–1 can be assigned to either the bendꢀ
ing vibrations of hydroxide groups (that differ in the
degree of being hydrogen bonded from those OH groups
The IR spectra of solid powders were recorded on a
PerkinElmer Spectrum One FTꢀIR spectrometer in
the frequency range 4000–400 cm–1 using a diffuse
reflectance unit (DRA). Band assignment was perꢀ
formed with reference to literature data [20, 21]. The
spectra were processed and intensities were calculated that have absorption bands at 1070 and 1042 cm–1) and
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 9 2015

SYNTHESIS OF TiO2–ZrO2 BINARY OXIDES BY HYDROLYSIS
1061
I
ZrO2(B)
1138
1093
1031
1(B)
1354
1342
1375
1093
1031
1563
1561
3352
3350
2(B)
3(B)
1093
1031
1556
1118
1074
1040
1377
1466
3339
1557
1038
1124
1376
1462
4(B) 3334
1631
1077
5(B)
1376
1633
1462
1037
1096
1126
3326
2874
2932
3281
TiO2(B)
2960
1633
1376
1461
1036
1096
1126
3222
4000 3600320028002400200018001600140012001000 800 600 390
, cm–1
ν
Fig. 2. IR spectra of Set B oxides after drying at 90°C.
hydroxideꢀstructured water [22–24], or to the stretchꢀ 1037 cm–1 arise from the bending vibrations of Ti–OH
ing vibrations of the monodentate carbonate ion
which is formed due to the sorption of atmospheric
carbon dioxide on the oxide surface [25]. Substantiaꢀ
tion to the second assignment variant is provided by
the presence of 0.8–1 wt % carbon as determined by
elemental analysis in the ZrO2 xerogel which was preꢀ
pared by hydrolyzing zirconium(IV) chloroxide by
groups. The organic products of TBT hydrolysis conꢀ
tained in the oxide appear as absorption bands in the
region 3000–2800 cm–1 (C–H stretching vibrations)
and the region 1500–1300 cm–1 (
bending vibrations).
⎯CH2– and –СН3
The IR spectra of binary samples 1(A)–3(A) and
aqueous ammonia and featured identical IR absorpꢀ 5(A) are almost identical to the spectra of ZrO2(А) and
tion bands in the region 1300–1600 cm–1 [26]. The
TiO2(А), respectively. The spectral pattern of sample
stretching vibrations of water and hydroxide groups
appear as a strong band with a peak at 3352 cm–1; the
bending vibrations of adsorbate Н2О appear as a highꢀ
frequency shoulder on the band at 1556 cm–1.
4(A) is the superposition of the spectra of individual
TiO2 and ZrO2
.
Samples ZrO2(B) and 1(B)–3(B) after drying conꢀ
tain a greater amount of remnant organic matter than
in similar Set A samples (Fig. 2). The effect of the titaꢀ
nium component in Set B spectra in the region of the
bending vibrations of hydroxide groups persists up to
sample 3(B) (Fig. 2), whereas in the first set, spectrum
of sample 3(A) is fully identical to the spectrum of
sample ZrO2(А) (Fig. 1). In other respects, the IR
In the spectrum of sample TiO2(А) (Fig. 1), there is
a broad and strong absorption band in the region
1000–400 cm–1, which corresponds to the Ti–O
stretching vibrations. A broad band with a peak at
3300 cm–1 corresponds to the absorptions of hydroxꢀ
ide groups and oxideꢀbound water; the band with a
peak at 1635 cm–1 is due to the bending vibrations of
water; and three bands with peaks at 1126, 1098, and spectra of both sets of oxides have similar patterns.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 9 2015

1062
SHISHMAKOV et al.
I
ZrO2(A)
1105
1557
1569
3385
2342
1112
720
568
475
1(A)
1113
1111
3364
2(A)
1573
1653
3736
3354
571
479
3(A)
3394
456
1111
1109
4(A)
1641
1652
506
5(A)
3347
3354
519
523
TiO2(A)
2856
2925
3366
40003600320028002400200018001600140012001000 800 600 390
, cm–1
ν
Fig. 3. IR spectra of calcined Set A oxides.
ο
Calcination of Set A oxides at 850 С induces a bands of binary oxides and ZrO2(B) in this region have
considerable reduction in intensities of the absorption lower intensities than in Set A spectra. The samples of
bands of C–H stretching vibrations in samples the second set have lower contents of adsorbate water.
TiO2(А), 4(A), and 5(A) (Fig. 3). The appearance of
The data shown in Figs. 3 and 4 were used to calcuꢀ
the stretching and bending vibrations of water in the
late the intensity ratios for the absorption bands that correꢀ
spectra results from the sorption of atmospheric moisꢀ
spond to the vibrations of adsorbate СО2 (I
(2342 cm–1))
ture by the oxides. In this case, the absorption band at
1105–1112 cm–1 is due to the vibrations of surface catꢀ
ion–oxygen bonds of various strengths [19, 22, 25].
The spectral appearance of this band is most likely to
indicate the formation of strongly bonded aggregates of
dioxide particles [22]. The absorption band with a peak at
2342 cm–1 corresponds to the vibrations of carbon dioxꢀ
ide physisorbed by the surface of oxides [27–31].
and to the Zr–O and Ti–O stretching vibrations
(
I
(500 cm–1)), as functions of titanium dioxide perꢀ
centage (Fig. 5). The curves for both sets run in the
same manner; they each have two peaks at 13% (7–
13% B) and 84% TiO2. Thus, the binary oxides where
the fraction of one component is 90 5% have higher
amounts of adsorbate carbon dioxide.
The IR spectrum of sample TiO2(B) (Fig. 4) feaꢀ
The Ssp versus titanium percentage plots for binary
tures no absorption band at 1109 cm–1; the absorption oxide samples of both sets have nonlinear trends (Fig. 6).
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 9 2015

SYNTHESIS OF TiO2–ZrO2 BINARY OXIDES BY HYDROLYSIS
1063
I
1110
ZrO2(B)
1572
1564
720
1110
3426
575
1(B)
486
3383
1110
1120
2(B)
575
1584
1589
491
491
3383
3(B)
579
3372
4(B)
3399
5(B)
3352
TiO2(B)
3395
491
510
1589
2342
2856
2925
4000 3600320028002400200018001600140012001000 800 600 390
, cm–1
ν
Fig. 4. IR spectra of calcined Set B oxides.
Initially Ssp decreases, as the titanium component in it from transition to the monoclinic phase. The Xꢀray
the oxide grows, to reach a minimal value at 25% TiO2 diffraction patterns of samples 4(A) and 4(B) correꢀ
in Set A samples and at 47% TiO2 in Set B samples. As spond to ZrTiO4. The shifts of ZrO2 lines in the diffracꢀ
the titanium fraction increases further, the Ssp of tion patterns of samples 3(A) and 3(B) imply the forꢀ
binary oxides increases. The maximal Ssp values in mation of solid solutions. The result from the presence
both sets are attained in samples containing 84% titaꢀ of 16 mol % zirconium in samples 5(A) and 5(B) conꢀ
nium dioxides. The high values of
Ssp in samples 5(A) and sists in the stabilization of the anatase phase in the titaꢀ
5(B) are likely to be responsible for the higher sorptive nium dioxide (~90%). In the absence of zirconium (in
capacity of this composition toward CO2 (Fig. 5).
samples TiO2(А) and TiO2(B)), rutile is formed as the
only phase.
Figures 7 and 8 show fragments of Xꢀray diffraction
patterns for calcined oxides. A rise in titanium perꢀ
The rise in adsorbate CO2 amount observed in the
centage in samples 1–3 of both sets is accompanied by series of samples ZrO2(А)–2(А) and ZrO2(B)–2(B)
a rise in the fraction of the tetragonal phase in zircoꢀ (Fig. 5) occurs on the background of the increasing
nium dioxide. The fraction of tetragonal ZrO2 phase in fraction of the tetragonal ZrO2 phase in the sample. In
Set B samples is higher (Fig. 9). It follows that the the range of 13–25 mol % TiO2 (2(A)–3(A) and 2(B)–
presence of 7–25 mol % TiO2 in a binary sample favors 3(B)), the absolute content of the tetragonal phase is
the stabilization of the tetragonal ZrO2 phase, keeping reduced, for its percentage in the zirconium dioxide
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 9 2015

1064
SHISHMAKOV et al.
0.4
0.3
0.2
0.1
I
, arb. units
А
R
R
TiO2(A)
5(A)
15000
A
B
R
Z
Т
Z
Z
Z
Z
4(A)
10000
5000
0
0
10 20 30 40 50 60 70 80 90 100
TiO2, mol %
М
М
3(A)
2(A)
Fig. 5. Intensity ratio versus titanium dioxide percentage in
the sample for the absorption band of adsorbate СО
(I(2342 cm )) and the Zr–O and Ti–O stretching vibraꢀ
Т
2
–1
–1
М
М
tion band (
I
(500 cm )).
М
Т
Т
М
М
М
М
М
1(A)
8
М
7
6
5
4
3
2
1
B
ZrO2(A)
20
30
, deg
40
2
θ
А
Fig. 7. Fragment of Xꢀray diffraction pattern of Set A
oxides. Notations: R stands for rutile, A for anatase, Z for
ZrTiO , M for monoclinic ZrO ), and T for tetragonal
4
2
ZrO
.
2
0
20
40 60
TiO2, mol %
80
100
(Fig. 10). The percentages of spheres in samples are
5–20%. The spheres consist of spheroids with crossꢀ
sections of 0.04–0.15
(Fig. 11) and sample TiO2(А)) and 0.15–0.4
µ
m (in samples 4(A) and 5(A)
m (in
Fig. 6.
S versus titanium dioxide percentage in oxides.
sp
µ
sample ZrO2(А)). The absorption bands of –СН2–
and –СН3 stretching vibrations observed in the IR
spectra of oxides after highꢀtemperature treatment
(Figs. 3, 4) apparently imply the carbonization of
organic products of precursor hydrolysis in the inferior
regions of oxide microparticles. Likely, the access of
air into the interior of the microparticles is difficult,
which causes pyrolysis of the organic matter and preꢀ
ceases to increase (Fig. 9) and the total fraction of the
zirconium component in TiO2–ZrO2 decreases, with
an attendant reduction in carbon dioxide sorption by
the powder (Fig. 5). Therefore, we may assume that
the tetragonal ZrO2 phase in TiO2–ZrO2 has a higher
CO2 sorptive capacity than the other phases.
On the microscopic level, calcined oxides are comꢀ
positions of irregularly shaped particles and spheres vents burning out of the carbonizate. Presumably,
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 9 2015

SYNTHESIS OF TiO2–ZrO2 BINARY OXIDES BY HYDROLYSIS
, arb. units
1065
I
10000
8000
6000
4000
2000
R
R
A
Z
TiO (B)
2
R
5(B)
Z
Z
Z
Z
4(B)
Т
3(B)
2(B)
1(B)
Т
М
М
М
Т
М
М
М
М
ZrO (B)
2
0
20
30
θ, deg
40
2
Fig. 8. Fragment of Xꢀray diffraction pattern of calcined Set B oxides.
100
90
80
70
60
50
40
30
20
10
B
A
0
10
20
TiO , mol %
30
2
Fig. 9. Tetragonal phase percentage in ZrO versus titanium dioxide percentage in the binary oxide.
2
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 9 2015

1066
SHISHMAKOV et al.
(b)
(а)
(d)
(c)
Fig. 10. Micrographs of samples: (a) ZrO (A), (b) 4(A), (c) 5(A), and (d) TiO (A). Frame width: 15 µm.
2
2
a considerable part of the carbonizate is encapsulated ical properties of the binary sample. IR spectra show
in microspheres, which have hard shells (Fig. 11).
adsorbate carbon dioxide on the surface of oxides; the
maximal carbon dioxide amount is found in the samꢀ
ples where the fraction of one of the components is
90 5%. Xꢀray powder diffraction shows that, for the
composition where TiO2–ZrO2 = 0.47 : 0.53, the
In summary, we have developed a method for preꢀ
paring binary oxides with a wide range of ratios
TiO2/ZrO2 through joint hydrolysis of TBT and TBZ
mixtures under an atmosphere of H2O vapor and 10%
aqueous NH3 in the batch mode. The presence of
ammonia at the stage of hydrolysis of the precursors
structure of the binary material corresponds to ZrTiO4
.
In the compositions where TiO2–ZrO2 = 0.07 : 0.93–
has no significant influence on the physical and chemꢀ 0.25 : 0.75, the presence of titanium favors the stabiliꢀ
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 60 No. 9 2015

SYNTHESIS OF TiO2–ZrO2 BINARY OXIDES BY HYDROLYSIS
1067
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