Synthesis of zirconyl polyolates and their conversion to nanosized zirconia

Article abstract of DOI:10.1007/s11172-009-0143-y

Three new methods for the synthesis of zirconyl polyolates by the sol-gel process from zirconyl salts in aqueous media are developed. The polyolates produced are suitable precursors for zirconia nanopowders. ; 2009 Springer Science+Business Media, Inc.

Full text of DOI:10.1007/s11172-009-0143-y

1
106
Russian Chemical Bulletin, International Edition, Vol. 58, No. 6, pp. 1106—1113, June, 2009
Synthesis of zirconyl polyolates and their conversion to nanosized zirconia
I. S. Puzyrev,а A. V. Alyabyshev, A. S. Lipilin, V. V. Ivanov, and Y. G. Yatluk
а
b
b
а
аI. Ya. Postovsky Institute of Organic Synthesis, Urals Branch of the Russian Academy of Sciences,
2
2/20 ul. S. Кovalevskoy, 620041 Ekaterinburg, Russian Federation.
Fax: +7 (343) 3741189. Eꢀmail: puzyrev@ios.uran.ru
b
Institute of Electrophysics, Urals Branch of the Russian Academy of Sciences,
1
06 ul. Amundsena, 620016 Ekaterinburg, Russian Federation.
Fax:: +7 (343) 2678794. Eꢀmail: lipilin@iep.uran.ru
Three new methods for the synthesis of zirconyl polyolates by the solꢀgel process from
zirconyl salts in aqueous media are developed. The polyolates produced are suitable precursors
for zirconia nanopowders.
Key words: zirconia, solꢀgel technology, polyols, glycerol, nanopowders.
1
Nanosized zirconia finds application in the producꢀ
glycerolate was precipitated with an ammonia solution
from aqueous zirconyl chloride or nitrate at room temꢀ
perature or with heating:
tion of ceramic oxide electrolytes for fuel cells, technical,
refractory and structural bioceramics, abrasives and dyes,
plastics and coatings, pharmaceutical and cosmetic forꢀ
mulations, jewellery, etc.
The methods used to prepare zirconia nanopowders
are commonly classified into two categories, physical and
chemical. The former are exemplified by laserꢀinduced
evaporation of ZrO (see Ref. 2), and the latter, by preꢀ
2
cipitation and solꢀgel processes. The starting materials for
3
X = Cl or NO3.
precipitation methods are typically zirconium salts , while
4
,5
6—8
zirconium propoxide and butoxide, as well as zirconyl
The reaction product, the zirconyl glycerolate gel
chloride9 or nitrate, for the solꢀgel processes.
Zirconium is known12 to readily form, with the oxyꢀ
genꢀcontaining ligands, complexes stable in aqueous
solutions. Hence, such compounds appear as very suitꢀ
able to be exploited for hydrolysis control (as inhibitors).
At the same time, zirconium alkoxides (monoatomic
alcohol derivatives) are readily hydrolyzed and thus
are used in the solꢀgel process conducted in an alcohol
medium. This study focuses on the search for moderately
hydrolyzable zirconium derivatives that would allow the
solꢀgel process to be carried out directly in an aqueous
solution.
,10
11
(
ZGG), was dried and calcined. Upon drying, the synꢀ
thesized ZGG is converted to zirconyl glycerolate xerogel
ZGX) whose calcination yields ZrO nanopowders. In
(
2
the case of zirconyl chloride, calcination was conducted
at 650 °C since at lower temperatures some particles reꢀ
mained unburned (carbonized) due to the presence of
chlorine. The results of analysis are given in Table 1.
When using zirconyl nitrate as the starting material,
the calcination temperature was 550 °C, no carbonized
products were observed. Characteristics of the ZrO2
nanopowders obtained are listed in Table 2. The size
Table 1. Elemental composition of ZGX derived from ZrOCl2a
Results and Discussion
Entry Тb/°C ZGX composition (%) Cl : Zr
Yield of
1
. Synthesis of zirconyl glycerolates by the exchange
reaction method. A method for glycerol concentration by
precipitating as a complex with zirconium is known.
The method was patented rather long ago and has no
alternative applications. On the basis of this method, we
have developed and implemented the precipitation proꢀ
C
Cl
Zr
ZGX (%)
1
3
1
2
20
70
18.4 6.9
17.4 5.6
36.3
37.1
0.49
0.39
∼ 100
∼ 100
a
b
ZrOCl : C H O = 1 : 2.
2
3
8
3
ZGG synthesis temperature.
cess for the synthesis of nanosized ZrO . First, zirconyl
2
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1078—1085, June, 2009.
066ꢀ5285/09/5806ꢀ1106 © 2009 Springer Science+Business Media, Inc.
1

Synthesis of nanosized zirconia from zirconyl polyolates Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
1107
Table 2. Specific surface area (S) and diameter of particles (D)
Table 3. Specific surface area (S) and diameter of particles (D)
a
of ZrO nanopowders derived from ZrO(NO )
of ZrO nanopowders derived from ZrO(NO ) with introducing
2
3 2
2
3 2
a
the amine from the gas phase
b
2
–1
Entry
Т /°C
Yield of ZGX (%) S/m g
D/nm
2
–1
Entry
Amine
NH3
Yield of ZGX (%) S/m g
D/nm
1
2
20
70
∼ 100
∼ 100
25
27
21
19
1
2
3
~100
~100
~100
31
10
8
17
52
65
CH NH
2
a
3
ZrO(NO ) : C H O = 1 : 2. Calcination at 550 °C.
3
2
3
8
3
(CH ) NH
3 2
b
ZGG synthesis temperature.
a
ZrOCl : C H O = 1 : 2.
2
3
8
3
of particles was determined assuming their spherical
geometry:
2. Synthesis of zirconyl polyolates at the interface of
aqueous and organic phases. The results considered clearly
indicate that the introduction of a base directly to the
waterꢀglycerol solution results in gelation only in the case
of ammonia delivered through the gas phase, the gel
formation takes several days.
D = 3•10–6/Sρ ,
2
–1
where D (m) is the particle diameter, S (m g ) is the
–
3
specific surface area, ρ (g cm ) is the material density.
As follows from the data of Table 2, the specific surꢀ
face area of the final nanopowders increases with increasꢀ
ing the synthesis temperature. As is seen from the microꢀ
graph (Fig. 1), the powder is formed by strongly agglomꢀ
erated particles with the size in the range 20—40 nm.
The aboveꢀdescribed synthesis method for nanosized
In order to accelerate the process, we suggested to
remove ammonium salts by extraction with an organic
4
solvent. As pointed above, the solꢀgel process for zircoꢀ
nia nanopowder production makes use of zirconium
alkoxides, which can be synthesized only in anhydrous
media. If proceed from the accessible zirconyl salts, this
approach appears laborꢀconsuming and multistep (typiꢀ
cally, four steps):
3
ZrO is comparable to the known process in which zircoꢀ
2
nium hydroxide is precipitated as a precursor, and the
2
–1
final product has a surface area of ∼ 40 m g under
the same calcination conditions.
While conducting synthesis with introduction of amꢀ
monia or an amine from the gas phase, we found that in
this case no precipitate formation took place but, instead,
ZGG was formed (in 5 days). The higher the amine
basicity (the substitution degree) the smaller the specific
It also should be kept in mind that the solꢀgel process can
be carried out only in an anhydrous alcohol. Zirconium
alkoxide could be converted to glycerolate but the
complexes formed by glycerol and zirconium are water
insoluble. Furthermore, commercial zirconium alkoxides
are rather expensive.
surface area of the ZrO powder formed upon ZGG calciꢀ
2
nation, and, correspondingly, the larger the particle
size (Table 3). Thus, ammonia is the base of choice for
the solꢀgel process.
The process that we propose includes two steps:
As a result, the acid is extracted into the organic phase,
and the waterꢀglycerol solution transforms to the gel:
2
00 nm
Fig.1. Micrograph of ZrO2 powder produced by calcination
of ZGX synthesized by the method of exchange reactions (see
2
–1
Table 1, entry 2, S = 27 m g ). Magnification is 100000.
X = Cl or NO3.

1
108
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
Puzyrev et al.
a
Table 4. Effect of Zr : C H O ratio on ZGX composition
increase in amount and hence consumption of glycerol is
unreasonable, being virtually of no use for improvement
of the quality of the final product.
3
8
3
Entry Zr : C H O ZGX composition (%) Cl : Zr
Yield of
3
8 3
ZGX (%)
Selection of the amine for the extraction of anions. In
the reaction carried out at the interface, the acid correꢀ
sponding to the zirconyl salt anion forms the salt with the
organic base, i.e., amine, and is extracted into the organic
phase:
C
Cl
Zr
1
2
3
4
5
1 : 0
1 : 1
1 : 2
1 : 4
1 : 6
0
10.2 43.1
5.8 36.7
4.9 36.2
3.6 27.1
2.2 16.8
0.61
0.41
0.35
0.34
0.34
54
74
89
98
∼ 100
17.6
20.2
27.4
31.7
1
2 3
ZrOCl2 aq + C H O + NR R R
3
8
3
org
a
–
Extractant of Cl ꢀions is a 15% NH(C H ) solution in chloꢀ
9
19 2
1
2 3
roform. ZrOCl2 : NH(C H ) = 1 : 2. ZGG synthesis time
ZrOCl (C H O ) (C H O )
+ NR R R HCl
.
org
n
3
7
3 m
3
6
3 (2 – n – m)/2
9
19 2
(
hereinafter unless otherwise noted) is 30 min.
In this process, the strength of the base, as well as
the length of its hydrocarbon radical, are of substantial
importance. To choose the extracting base, we assayed
triethylamine, tributylamine, nonylamine, dinonylamine,
and a mixture of alkylamines С —С and analyzed their
As can be seen, the reaction of zirconyl salt in aqueous
glycerol with an organic base dissolved in an organic
solvent consists of the following processes: extraction of
the inorganic acid into the organic phase, extraction
of the organic amine into the aqueous phase, extraction of
1
0
14
effect on the composition of ZGX (Table 5).
The much higher carbon and nitrogen content in
samples 1 and 5 as compared to others suggests that triꢀ
ethylamine is strongly extracted into the aqueous
solution. Hence, it does not remove acid from the aqueꢀ
ous phase, which is inacceptable. The effciciency of HCl
extraction decreases in the series: dinonylamine > nonylꢀ
amine > tributylamine ≈ amines С —С . Being a strong
1
2
3
zirconium in the form of complexes (HNR R R ) ZrX
2
6
1
2
3
or 2NR R R •ZrX into the organic phase with ZGG
4
formation in the aqueous phase. For the target product to
be successfully obtained, optimization of the process
conditions is needed.
Optimization of the zirconium : glycerol ratio. Table 4
illustrates the effect of the zirconium : glycerol molar
ratio (Zr : C H O ) in the reaction system
1
0
14
base, dinonylamine provides the minimum chlorine conꢀ
tent in ZGX, and owing to its long radical (C : N = 18) it
is not extracted into the aqueous phase as evidenced by
the zero nitrogen content in ZGX. The product yields
obtained with dinonylamine are among the highest of all
amines tested.
3
8
3
ZrOCl2 aq + C H O + NH(C H )
19 2 org
3
8
3
9
ZrOCl (C H O ) (C H O )
+ NH Cl(C H )
2 9 19 2 org
n
3
7
3 m
3
6
3 (2 – n – m)/2
on the composition of ZGX formed upon ZGG drying.
With the increase in the glycerol mole fraction, the
relative content of chlorine in ZGX decreases and the prodꢀ
uct yield increases. Increasing the glycerol content after
the ratio Zr : C H O = 1 : 2 is reached does not result in
Selection of synthesis time. In the reaction occurring
at the interface, along with the extraction of inorganic
acid into organic phase, extraction of zirconium in the
form of hexachloroꢀ or hexanitrozirconate of the correꢀ
sponding amine takes place, which reduces the product
yield. Since the extraction of the acid is kinetically faster
than the extraction of the metal, the product yield can be
optimized by adjusting the synthesis time:
3
8
3
substantial decerase in chlorine content, while the product
yields are still rather high (89—98%) for the Zr : C H O
3
3
8
ratios within the range 1 : 2—1 : 4. Accordingly, further
1
2
3
a
Table 5. Effect of anionꢀextracting amine (NR R R ) structure on ZGX composition
Entry Zr : C H O Amine composition
ZGX composition (%)
Cl : Zr
Yield of
3
8 3
R1
R2
R3
ZGX (%)
C : N
С
N
Cl
Zr
1
2
3
4
5
6
7
8
1 : 2
C H
C H
H
C H
H
6
29.5
20.0
20.0
20.2
31.7
30.6
27.7
27.4
4.2
1.4
1.3
0
3.3
1.5
0.5
0
9.3
4.9
4.3
22.6
33.5
31.1
36.2
18.0
16.9
28.8
27.1
1.06
0.38
0.35
0.35
1.78
1.55
0.60
0.34
∼ 100
92
92
89
99
82
81
98
2
5
2
5
2
5
9
1 : 2
1 : 2
1 : 2
1 : 4
1 : 4
1 : 4
1 : 4
С —С
14
12
12
18
6
12
9
1
0
C H
C H
C H
4
9
4
9
4
C H
C H
H
4.9
9
19
9
19
C H
C H
C H
12.5
10.2
6.7
2
5
2
5
2
5
9
C H
C H
C H
4
9
4
9
4
C H
H
H
H
9
19
19
C H
C H
18
3.6
9
9
19
a
ZrOCl : N(amine) = 1 : 2. Amine concentration 15%. The solvent is CHCl .
2
3

Synthesis of nanosized zirconia from zirconyl polyolates Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
1109
Table 6. Effect of ZGG synthesis time (t) on elemental composiꢀ
tion of ZGX
Table 8. Effect of dinonylamine concentration in CHCl (С) on
ZGX composition
3
a
a
Entry
X
t/min ZGX composition (%) Cl : Zr Yield of
Entry C (%) ZGX composition (%)
Cl : Zr
Yield of
ZGX (%)
С
N
Cl
Zr
ZGX (%)
C
Cl
Zr
–
1
2
3
4
5
6
7
Cl
Cl
Cl
Cl
Cl
15
30
45
60
30.0
27.4
31.5
30.3
0
0
0
0
0
0
1.2
4.1 32.1 0.33
3.6 27.1 0.34
3.2 24.7 0.33
4.6 25.0 0.47
4.5 18.6 0.62
0.2 22.4 0.02
73
98
60
31
30
87
55
1
2
3
5
15
25
29.2 5.3
27.4 3.6
27.8 3.0
17.0
27.1
22.2
0.81
0.34
0.35
93
98
80
–
–
–
–
a
ZrOCl : C H O = 1 : 4, ZrOCl : NH(C H ) = 1 : 2.
1440 28.9
30 26.8
1440 28.6
2
3
8
3
2
9
19 2
3
3
–
–
NO
NO
0
17.6
0
Selection of dinonylamine concentration. In the similar
manner, the reaction is controlled by the amine concenꢀ
tration in chloroform. The increase in the amine conꢀ
centration decreases the density of organic phase and the
increase in the chloroform content results in its increase.
The data on the effect of dinonylamine concentration in
chloroform on the characteristics of xerogels obtained are
given in Table 8. Chlorine becomes better extractable
from ZGG with increase in the amine concentration.
However, its increase from 15 to 25% results in a decrease
in the yield, most likely due to predominant zirconium
transfer in the form of a complex to the organic phase,
which is favored by high amine concentration. The optiꢀ
mum dinonylamine concentration is 15% where satisfacꢀ
tory chlorine extraction occurs along with the maximum
product yield.
Extraction of xerogels. The asꢀformed ZGG still conꢀ
tains some residual anions, as well as excess of glycerol.
Diethylamine was used to extract these remaining anions
and remove nonbound glycerol.
On examining the extraction of ZGX derived from
zirconyl chloride, the extraction was found to reduce
considerably the chlorine content in ZGX (Table 9,
cf. entries 1 and 3). It allows reducing the calcination
temperature from 650 to 600 °С for the preparation of
a
ZrOX2 : C H O = 1 : 4; ZrOX2 : NH(C H ) = 1 : 2.
19 2
3
8
3
9
Dinonylamine concentration 15%. Solvent is CHCl3.
ZrOX2 aq + C H O + NH(C H )
3
8
3
9
19 2 org
ZrOX (C H O ) (C H O )
+ NH X(C H )
.
n
3
7
3 m
3
6
3 (2 – n – m)/2
2
9
19 2 org
Table 6 lists the data demonstrating the effect of ZGG
synthesis time on the final ZGX composition. In the case
of zirconyl chloride, the increase in the synthesis time
from 15 to 45 min results in a decrease in the chlorine
content in the xerogel, and after 45 min the increase in
the chlorine content starts. Probably, at this stage chloꢀ
ride in the amine salt undergoes partial replacement by
the hexachlorozirconate anion. Correspondingly, the prodꢀ
uct yields are first increased and then start to decrease, the
maximum been attained at the reaction time of 30 min.
If the synthesis time lasts for 60 min and longer, the yields
are lower considerably. The similar dynamics was
observed with zirconyl nitrate.
The effect of solvent. The next optimization step
was selection of the organic solvent. The density of the
organic phase appreciably affects the character of gelation
(
Table 7). The lower the solvent permittivity the more
efficient the chlorine removal, yet the highest yield was
obtained with a solution of dinonylamine in chloroform.
In this case, the density of the amine solution is approxiꢀ
mately equal to that of the waterꢀglycerol solution of the
zirconyl salt, this naturally facilitating dispersion and proꢀ
viding larger phase contact surface. When other solvents
were used, ZGG either sedimented or accumulated at the
surface. Thus chloroform was a solvent of choice.
ZrO nanopowders from xerogels. Extraction of ZGX also
reduces the glycerol concentration. Before extraction,
decreasing the zirconium : glycerol ratio results in deꢀ
2
crease in the surface area of ZrO nanopowders (increase
2
in particle size). Removal of excess glycerol by the
extraction of ZGX results in the increase in the specific
surface area at Zr : C H O = 1 : 2 and in its decrease at
3
8
3
Zr : C H O = 1 : 4.
3
8
3
Table 7. Effect of organic solvent (with the density, ρ and dielectric constant, ε) on elemental composition of ZGXa
Entry
Characteristics of solvent
ZGX composition (%)
Cl : Zr
Yield of
ρ/g cm–3
ZGX (%)
Compound
ε
C
Cl
Zr
1
2
3
CH Cl
CHCl3
CCl4
1.33
1.49
1.59
9.08
4.81
2.24
30.8
27.4
29.5
3.8
3.6
0.9
21.0
27.1
20.1
0.47
0.34
0.12
52
98
70
2
2
a
ZrOCl : C H O = 1 : 4, ZrOCl : NH(C H ) = 1 : 2. Dinonylamine concentration 15%.
2
3
8
3
2
9
19 2

1
110
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
Puzyrev et al.
Table 9. Effect of extractant on ZGX composition and morphology of ZrO nanopowders (specific surface area, S and
2
a
diameter of particles, D)
2
–1
Entry
Extractant
Zr : C H O
3
ZGX composition (%)
Cl : Zr
S/m g
D/nm
3
8
C
Cl
Zr
1
2
3
4
—
—
1 : 2
20.2
27.4
22.3
24.2
4.9
3.6
—
36.2
27.1
35.1
35.8
0.35
0.34
—
11
10
21
6
48
52
25
87
1 : 4
1 : 2
1 : 4
(С H ) NH
2
5 2
(С H ) NH
0.5
0.04
2
5 2
a
ZrOCl : NH(C H ) = 1 : 2. Solvent is CHCl .
2
9
19 2
3
a
Table 10. Effect of extractant on ZGX composition and morphology of ZrO nanopowders
2
2
–1
Entry
Extractant
Zr : C H O
ZGX composition (%)
S/m g
D/nm
3
8
3
C
N
Zr
1
2
3
4
—
—
1 : 2
1 : 4
1 : 2
1 : 4
23.4
26.8
19.5
21.6
0.7
0
0.4
0.7
29.0
22.4
38.1
37.8
27
20
19
19
19
26
28
28
(С H ) NH
2
5 2
(С H ) NH
2
5 2
a
ZrO(NO ) : NH(C H ) = 1 : 2. Solvent is CHCl .
3
2
9
19 2
3
The analogous data for zirconyl nitrate are listed in
Table 10. ZGG extraction reduces the specific surface
increases (Table 11) in the similar manner as with the
glycerol content increase (see Tables 4, 9, 10). And again,
area of the target ZrO powders. As was observed for
the particle size of ZrO powder formed after calcination
2
2
zirconyl chloride, the decrease in the Zr : C H O ratio
increases. The maximum specific surface area was found
for zirconia prepared using glycerol.
3
8
3
resulted in formation of larger ZrO particles. The best
2
results were obtained at the equimolar ratio of zirconium
and glycerol. The samples formed had the surface area of
On the whole, the general features of formation of
zirconyl polyolate gels, as well as nanosized zirconia, in
the twoꢀphase systems are as follows:
2
–1
3
0 m g , which is quite sufficient for most applications.
Zirconia nanopowders for oxygenꢀconducting ceramics,
produced by laser evaporation have specific surface area
of 30—33 m g .
— the optimum zirconium : polyol ratio (that provides
the maximum product yield at minimum polyol consumpꢀ
tion) lies in the range 1 : 2—1 : 4;
2
–1
Using other polyols for production of zirconia nanoꢀ
powders. Besides glycerol, there are other polyatomic
alcohols that can form organic compounds with zircoꢀ
nium. When we move from ethylene glycol and diethylꢀ
ene glycol to tetraethylene glycol, the product yield
— the quantitative extraction of anions requires the
use of amines containing at least 18 carbon atoms;
— the optimum synthesis time is 15—30 min (if aging
lasts for one day or longer, the gel is formed in a much
smaller yield);
a
Table 11. Effect of polyol structure on ZGX composition and morphology of ZrO nanopowders
2
2
–1
Entry
Polyol
ZGX composition (%)
Yield of
S/m g
D/nm
ZGX (%)
C
N
Zr
1
2
3
4
5
6
Glycerol
EG
DiEG
TriEG
TetraEG
Glucitol
23.4
13.1
18.7
20.9
27.5
29.3
0.7
29.0
40.5
34.3
32.2
26.3
20.2
80
75
77
89
85
98
27
21
21
16
16
24
19
25
25
33
33
22
b
1.2
0.9
1.2
1.1
0.8
a
ZrO(NO ) : alcohol = 1 : 2, ZrO(NO ) : NH(C H ) = 1 : 2. Dinonylamine concentration 15%. Calcination
3
2
3 2
9
19 2
temperature 550 °C.
b
EG is ethylene glycol.

Synthesis of nanosized zirconia from zirconyl polyolates Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
1111
3
. Oxidative synthesis of zirconyl glycerolates. While
examining solubility of zirconyl nitrate in waterꢀglycerol
systems, it was found that these solutions are transformed
to gels on heating.
Based on this phenomenon, a new method for the
synthesis of nanosized zirconia was developed. In
1
4
aqueous solutions, zirconyl nitrate is known to undergo
hydrolysis:
ZrO(NO ) + H O
ZrO(OH) (NO )
+ HNO3.
3
2
2
n
3 2 – n
The nitric acid formed can oxidize glycerol (C H (OH) )
3
5
3
1
5
to glyceric acid :
2
00 nm
C H (OH) + HNO
C H (OH) COOH + NO + H O.
2 3 2 2 2
3
5
3
3
Fig. 2. Microphotograph of ZrO powder produced by calcinaꢀ
Thus, in the reaction, some anions NO3– are removed
leading finally to gel formation:
2
tion of ZGX synthesized by solꢀgel process at the interface (see
2
–1
Table 10, entry 1, S = 27 m g ). Magnification is 100000.
ZrO(NO ) + C H (OH)
3
3
2
3
5
—
as organic solvent, chlorinated hydrocarbons showed
ZrO(OH) (Y) (NO )
(gel) + NO (gas)
2
n
m
3 2 – n – m
best, while the amine is taken in such a concentration that
to provide equal densities of the aqueous and organic
phases;
Y = OC H (OH) or C H (OH) COO .
3
5
2
2
3
2
Gel drying likely involves further hydrolysis as well as
glycerol esterification:
—
extraction of xerogels allows calcination to be carꢀ
ried out at a lower temperature avoiding carbonization of
ZGX derived from ZrOCl (extraction of ZGX derived
2
ZrO(OH) (Y) (NO )
+ H O
2
from ZrO(NO ) is unreasonable as resulting in the deꢀ
n
m
3 2 – n – m
3
2
creased specific surface area of final nanopowders);
the polyols suitable for the process can be sorted
into two groups: those providing maximum product yield
glycerol, glucitol, triꢀ and tetraethylene glycols) and those
ZrO(OH) (Y)
NO + HNO ,
3 3
k
2 – k
—
(
C H (OH) + n HNO
C H (OH)
(NO ) + n H O .
3
5
3
3
3
5
3 – n 3 n 2
providing maximum surface area (glycerol, glucitol).
It should also be mentioned that after the process is
finished, the amines used for extraction can be easily
regenerated by washing the organic phase with an alkali.
Calcination of ZGX is accompanied by explosive
decomposition of glycerol nitrates present as an admixꢀ
ture with microflare (microexplosion). As follows from
As can be seen from the micrograph of ZrO (Fig. 2)
experimental data (Table 12), the resulting ZrO nanoꢀ
2
2
produced from ZGX (see Table 11, entry 1), the powder
is a densely packed structure of nanoparticles with the
sizes ranging from 30 to 35 nm.
powders are characterized by the same particle size irreꢀ
spective of Zr : C H O ratio as opposed to the two other
3
8
3
methods considered. The ZrO powder is weakly agglomꢀ
2
The solꢀgel process developed yields the comparable
erated spherical particles, 30—35 nm in diameter (Fig. 3).
The oxidative synthesis of ZGG with its subsequent
2
–1
results (specific surface area of particles is 20—27 m g )
4
with the method based on hydrolysis of zirconyl isoꢀ
conversion to nanosized ZrO is a particularly advantaꢀ
2
propoxide, given the gel aging time in both methods is
the same. Our method, however, rests on more available
starting materials.
geous process since it is the simplest, requires neither
expensive equipment, nor reagents, nor strictly approved
conditions. However, due to a strongly exothermic charꢀ
a
Table 12. Composition of ZGX produced by oxidation method and morphology of ZrO nanopowders
2
2
–1
Entry
Zr : C H O
ZGX composition (%)
N : Zr
Yield of
S/m g
D/nm
3
8
3
ZGX (%)
C
N
Zr
1
2
3
1 : 2
1 : 6
1 : 10
32.3
31.6
31.6
0.8
0.8
0.8
12.8
13.9
7.3
0.4
0.4
0.7
∼ 100
∼ 100
∼ 100
24
23
23
22
23
23
a
Calcination temperature 550 °C.

1
112
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
Puzyrev et al.
(
see Fig. 4, 2) shows the same bands. In the IR spectrum
of ZGX produced using precipitation (exchange reaction)
method (see Fig. 4, 3) there are two absorption bands at
–
1
1
098 and 1039 cm , the former being more intensive.
The same two bands with equal intensities are present
in the spectrum of ZGX produced at the interface at
Zr : C H O = 1 : 2 (spectrum 4). In the IR spectrum of
3
8
3
ZGX produced by the oxidative process (spectrum 5), the
band at 1039 cm— is more intensive. Spectrum 2 is almost
equivalent to spectrum 5. The band shape in the spectrum
1
4
is intermediary between the spectra 3 and 5. Thus, preꢀ
sumably, the gelation at the interface yields glycerolate
first, which is followed by its partial hydrolysis. ZGG
formation in the oxidative process is due to hydrolysis
only. This conclusion is also confirmed by the spectrum 6
of ZGX obtained at the interface at Zr : C H O = 1 : 4.
2
00 nm
Fig. 3. Microphotograph of ZrO powder produced by calcinaꢀ
2
3
8
3
tion of ZGX synthesized by oxidation method (see Table 11,
2
–1
This spectrum is virtually identical to the spectrum 3 of
ZGX since in excess of glycerol hydrolysis is slowed
down. Certain changes in the spectra are observed in
the 600—400 cm– region, which is characteristic
of Zr—O—Zr, Zr=O, and Zr—OH vibrations. These
changes, however, are not very informative because of
using zirconyl alkoxides rather than zirconium alkoxides
as the starting materials.
entry 1, S = 23 m g ). Magnification is 100000.
acter of the calcination reaction, it is not advisable to
manufacture the product in large batches.
The ZGX samples were analyzed by IR spectroscopy
to explore the effect of synthesis conditions on ZGG
formation. Figure 4 shows the IR spectra of ZGX obꢀ
tained by different methods, as well as of model systems.
1
The results discussed demonstrate that the developed
1
6
The Zr—O—C bonds absorption are known to lie beꢀ
methods for synthesizing nanosized ZrO via zirconyl
–
1
2
tween 1200 and 1000 cm . There are strong absorption
bands due to glycerol in this region (see Fig. 4, 1). The
spectrum of a zirconia nanopowder dispersed in glycerol
polyolates can easily be realized in aqueous medium with
available reagents. In all cases, the ZrO powder formed
2
upon polyolate calcination was free of carbon, nitrogen
and chlorine. Therefore, no elemental analysis data for
each individual sample are presented.
I (%)
The chemical methods for the synthesis of nanooxides
are much cheaper than the physical ones. Nonetheless,
the quality of resultant oxide ceramics being the criterion
for choosing the production process, the goals of further
research can be specified only after detailed analysis of
different methods.
1
2
3
4
Experimental
Elemental analysis was carried out on a Perkin Elmer
elemental analyzer. For IR spectra, Perkin Elmer IR/FTIR
Spectrum One spectrometer was used. The surface area for
zirconia powders was measured using the BET technique of gas
5
(
nitrogen) adsorption, with a TriStar 3000 V.6.03A analyzer.
The instrument for micrographs was the LEO 982 electron
scanning microscope.
6
1
098
1039
Synthesis of ZGG by precipitation method. Zirconyl nitrate
(9.94 g, 0.0043 mol) was dissolved in 3 mL of water. Then
glycerol (0.31 g, 0.0086 mol) was added. The mixture was stirred
until its homogenization. To the homogeneous mixture, 25%
ammonia solution (5 mL) was added dropwise at 20 °С. The
same procedure was performed at 70 °С. The mixture was stirred
for 5 min. The precipitate obtained was washed with water to
neutral pH of wastewater.
1
810.4 1600 1400 1200 1000 800 600 λ/cm–1
Fig. 4. IR spectra of glycerol (1); nanosized ZrO2 dispersed
in glycerol (2); ZGX prepared by the precipitation method of
exchange reactions (3), solꢀgel process at the interface at
Zr : C H O = 1 : 2 (4), oxidative method (5), solꢀgel process
3
8
3
at the interface at Zr : C H O = 1 : 4 (6).
3
8
3

Synthesis of nanosized zirconia from zirconyl polyolates Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
1113
Synthesis of ZGG by the method of exchange reactions (from
the gas phase). Zirconyl nitrate (5.00 g, 0.021 mol) was dissolved
in 3 mL of water. Then glycerol (3.98 g, 0.043 mol) was added
with stirring. Another beaker (volume 200 mL) with 5 mL of
2. Yu. A. Kotov, V. V. Osipov, O. M. Samatov, M. G. Ivanov,
V. V. Platonov, A. M. Murzakaev, E. I. Azarkevich, A. I.
Medvedev, A. K. Shtolts, O. R. Timoshenkova, Techn. Phys.,
2004, 49, 352.
2
5% ammonia solution was held with the former in the closed
3. D. Tichit, D. E. Alami, F. Figueras, Appl. Cat. A: General.,
1996, 145, 195.
space for 5 days.
Synthesis of ZGG by the solꢀgel process at the interface.
Zirconyl chloride (or nitrate) (0.0062 mol) was dissolved in 2 (or
4. G. K. Chuah, S. H. Liu, S. Jaenicke, J. Li, Microporous and
Mesoporous Materials, 2000, 39, 381.
4
mL) of water. Then the required amount of glycerol or other
5. A. Aronne, A. Marotta, P. Pernice, M. Catauro, Thermochim.
Acta, 1996, 275, 75.
6. X. Bokhimi, E. Munos, J. L. Boldu, E. Adem, O. Novaro,
J. SolꢀGel Sci. Technol., 2000, 17, 219.
7. S. Kim, S. W. Nam, S. Yoon, S. Hyun, J. Han, T. Lim,
S. Hong, J. Mat. Sci. Lett., 2004, 39, 2683.
polyol was added. The mixture was homogenized by stirring,
then the amine dissolved in the organic solvent was added (the
ratios are given in Tables). After gel was formed (no more stirring
could be performed) the pure solvent (25 mL) was added to the
mixture, which was further stirred magnetically for additional
5
min. The gel that formed was filtered through the kapron net,
8. R. Gomez, T. Lopez, X. Bokhimi, J. SolꢀGel Sci. Technol.,
1998, 11, 309.
then put in the beaker and stirred with 20 mL of chloroform to
remove residual amine, which was followed by second filtration
and washing with 15 mL of chloroform.
9. J. Shen, Q. Zhang, J. Wang, T. Yang, Z. Deng, B. Zhou,
L. Chen, J. SolꢀGel Sci. Technol., 2000, 19, 271.
10. O. Vasylkiv, Y. Sakka, Scr. mater., 2001, 44, 2219.
11. G. Stefanic, S. Popovic, S. Music, Termochim. Acta, 1997,
303, 31.
Synthesis of ZGG by the oxidative method. Zirconyl nitrate
(
9.94 g, 0.0043 mol) was dissolved in a saturated waterꢀglycerol
solution at varied Zr : C H O ratios. The mixture was heated
3
8
3
until the gel was formed.
Synthesis of ZGX from ZGG. The zirconyl glycerolate gels
were dried at 70 °С to constant mass.
12. A. A. Grinberg, Vvedenie v khimiyu kompleksnykh soedinenii
[Introduction to the Chemistry of Complexes], Khimiya,
Moscow, 1971, 632 pp. (in Russian).
Extraction of xerogels. Xerogels were placed in an extractor
for extraction with hot solvent, and subjected to extraction with
diethylamine for 24 h.
13. DE Pat. 501110; Chem. Abstrs., 1998.
14. W. B. Blumenthal, The Chemical Behavior of Zirconium,
Princeton: Van Nostrand, 1958.
Synthesis of ZrO2 by ZGX decomposition. Xerogels were
placed in the ceramic plates and calcined in a muffle (the
temperature is given in Tables).
15. A. N. Nesmeyanov, N. A. Nesmeyanov, Nachala organicheskoi
khimii [Elements of Organic Chemistry], Khimiya,
Moscow, 1970, 824 pp. (in Russian).
1
6. F. Rubio, J. Rubio, J. L. Oteo, J. Mat. Sci. Lett., 1998, 17,
839.
1
References
1
. T. E. Konstantinova, I. A. Danilenko, V. V. Tokii, V. A.
Glazunova, Ot novatsii k innovatsii [From discovery to innoꢀ
vation], Nauka i innovatsii [Science and Innovations], 2005,
Received April 9, 2009;
1
, 76 (in Russian).
in revised form April 22, 2009