Acetone condensation over CaO—SnO2 catalyst

Article abstract of DOI:10.1007/s11172-017-1760-5

Aldol condensation of acetone was studied over solid base CaO—SnO₂ catalyst in the 300—450 °C temperature range and at 15—75 atm pressure in a fixed-bed reactor. The main products are mesityl oxide and isophorone. The high stability of CaO—SnO₂ catalyst performance was observed at pressure of 75 atm giving the acetone conversion of 36—41%. Increase in the temperature and pressure led to a simultaneous raise in acetone conversion. The maximum conversion of 41% was achieved at 400 °C, 75 atm and a flow rate of acetone of 8.1 g h^–1 (g catalyst)^–1.

Full text of DOI:10.1007/s11172-017-1760-5

488
Russian Chemical Bulletin, International Edition, Vol. 66, No. 3, pp. 488—490, March, 2017
Acetone condensation over CaO—SnO catalyst
2
A. E. Koklin, G. M. Hasyanova, L. M. Glukhov, and V. I. Bogdan
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
4
7 Leninsky prosp., 119991 Moscow, Russian Federation.
Eꢀmail: koklin@ioc.ac.ru, vibogdan@gmail.com
Aldol condensation of acetone was studied over solid base CaO—SnO2 catalyst in the
3
00—450 °C temperature range and at 15—75 atm pressure in a fixedꢀbed reactor. The main
products are mesityl oxide and isophorone. The high stability of CaO—SnO2 catalyst perꢀ
formance was observed at pressure of 75 atm giving the acetone conversion of 36—41%. Inꢀ
crease in the temperature and pressure led to a simultaneous raise in acetone conversion.
The maximum conversion of 41% was achieved at 400 °C, 75 atm and a flow rate of acetone of
–
1
–1
8
.1 g h (g catalyst)
.
Key words: acetone, mesityl oxide, isophorone, aldol condensation, CaO—SnO2.
Acetone is a coꢀproduct in the largeꢀscale cumene proꢀ
sion varied from 58 to 78% depending on the Mg AlO
x
cess for phenol synthesis and is generally used as a solvent
as well as a feedstock for the manufacture of a number of
important chemicals, such as diacetone alcohol, mesityl
oxide, methyl isobutyl ketone, isophorone, and others.
These chemicals are produced via aldol condensation of
acetone in the presence of basic catalysts, such as alkaline
and alkaline earth metal hydroxides, followed by acid deꢀ
hydration of intermediate products.1 Product purificaꢀ
tion, catalyst regeneration, and waste treatment processes
have the most significant contributions to the final product
catalyst composition, and the selectivity towards isophorꢀ
–
1
–1
one varied from 70 to 80% (VW = 1.2 g h (g catalyst) ).
It should be noted that the catalyst deactivation is a signifꢀ
icant problem when solid base catalysts are used in aldol
condensation. The main reason of deactivation of the catꢀ
alysts is coke formation and blockage of the active sites of
1
1,12
the catalyst.
Therefore, considering low stability of
—3
the known solid base catalysts for aldol condensation
screening of new catalytic systems showing high perforꢀ
mance and stability remains a topical issue.
4
price. Thereby, the development of novel effective heteroꢀ
The purpose of the present work is to reveal the feaꢀ
geneous catalytic processes of aldol condensation of
acetone is of special interest.
tures of acetone condensation over CaO—SnO oxide catꢀ
alysts. According to our data, this catalytic system has not
been used as a catalyst for aldol condensation.
2
5
Earlier, several alkaline earth metal oxides, MgO and
6
,7
8
TiO promoted with alkaline metals, as well as Mg—Al
and Mg—Zr
2
9
,10
mixed oxides have been tested as solid
Experimental
base catalysts in acetone condensation. The reaction was
performed in a gas phase in a flow of inert carrier gas at
temperatures ranged from 250 to 450 °C.5—10 Much attenꢀ
The CaO—SnO2 catalyst was prepared by coprecipitation of
metal hydroxides with 3 M aqueous NaOH from the mixed soluꢀ
tion of the researchers has been focused on magnesiumꢀ
containing catalysts. At 300 °C, acetone conversion over
tion containing equimolar amounts of SnCl4 and Ca(NO3)2
–1
(
overall concentration was 1.1 mol L ). The obtained gel was
–
1
MgO was 17% (acetone flow rate V = 1.2 g h (g cataꢀ
W
aged for 24 h in a closed flask, filtered, resuspended in water,
filtered again (these two steps were repeated two more times),
dried at 120 °С, and calcined at 600 °С for 4 h. According to the
Xꢀray diffraction analysis data (DRONꢀ2 diffractometer, CuКα
irradiation, 2θ range from 10 to 40°), the obtained solid was Xꢀray
amorphous. The catalyst powder was pressed in pellets, granuꢀ
lated and a 0.10—0.45 mm fraction was selected for the experiments.
Acetone condensation was performed in a stainless steel
fixedꢀbed reactor with the inner diameter of 10 mm. The reacꢀ
tion temperature was 300—450 °C and pressure was 15—75 atm.
Acetone (reagent grade) was used without additional purificaꢀ
–
1
lyst) ) and selectivity towards mesityl oxide and isophorꢀ
one was 85 and 15%, respectively. However, after 6 h run,
the catalytic activity decreased nearly twice. Acetone conꢀ
6
version over Mg—Zr mixed oxide reached 32% at 450 °С
VW = 8 g h–1 (g catalyst) ). Nevertheless, it could be
–1
9
(
improved up to 50% by supporting the catalyst on graphite
9
materials with high specific surface area. At the same
time, the activity of Mg—Zr oxide catalyst1 was reported
0
to decrease by nearly 50% after 8 h run (350 °C, 1 atm). Jia
8
3
3
and coꢀworkers revealed high catalytic performance of
tion. A mixture of 1.0 cm of the catalyst (1.47 g) and 1.0 cm of
quartz chips of the same size was placed in the middle of the
Mg—Al mixture oxides. At 300 °C, the acetone converꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 0488—0490, March, 2017.
066ꢀ5285/17/6603ꢀ0488 © 2017 Springer Science+Business Media, Inc.
1

Acetone condensation over CaO—SnO2
Russ.Chem.Bull., Int.Ed., Vol. 66, No. 3, March, 2017
489
reactor. The remained volume of the reactor was loaded with
K (%)
quartz chips. Acetone feed rate was 0.25, 0.5 and 1.0 mL min–
1
,
5
4
0
that corresponds to the weight space velocities (V ) of 8.1, 16.1 and
W
–
1
–1
3
2.2 g h (g catalyst) . Acetone was fed using a liquid highꢀ
pressure Knauer pump. The flow rate was controlled by a valve
installed after the reactor. The reaction products were collected
in a cold trap (and sampled every 30 min) and then analyzed on
a Varian 3700 gas chromatograph using an OVꢀ101 capillary colꢀ
umn. The products were identified by GC/MS on a Thermo
Focus DSQꢀII instrument using a Thermo TRꢀ5ms column.
0
3
2
30
2
1
0
0
Results and Discussion
1
Figure 1 illustrates the time dependences of the aceꢀ
tone conversion at 400 °C on pressures of 15, 50 and
6
0
120
180
240 t/min
7
5 atm. At 15 atm, the acetone conversion showed a twoꢀ
fold decrease within 3 h, from 12 to 6%. Higher pressure
improved the acetone conversion and the stability of the
catalyst. Thus, at 75 atm acetone conversion remained
between 36 and 41% during the entire experiment. Mesityl
oxide and isophorone were found to be the main products
of the reaction. The results of the analysis of the products
Fig. 1. Acetone conversion (K) as a function of the reaction time
(t) over CaO—SnO catalyst at pressures of 15 (1), 50 (2), and
2
–
1
–1
75 atm (3) (T = 400 °C, VW = 8.1 g h (g catalyst) ).
K (%)
S (%)
1
8
6
4
2
00
of the acetone condensation over CaO—SnO catalyst are
2
4
3
0
summarized in Table 1. As it can be seen, pressure posiꢀ
tively affects not only acetone conversion but also the comꢀ
position of the products. As pressure increases, a fraction
of the compounds formed from three or more acetone
molecules grows. Thus, at 15 atm the selectivity towards
isophorone was 1%, whereas at 75 atm it reached 24%.
The effect of temperature on acetone conversion is
illustrated in Fig. 2. The experimental data show that at
temperatures below 350 °C the acetone conversion is inꢀ
significant (only several perсents). Raising the reaction
temperature significantly increases the acetone converꢀ
sion up to 18 and 40% at 400 and 450 °C, respectively. In
comparison, the conversion at 350 °C was only 3%
0
2
0
1
0
20
0
3
4
1
0
0
3
00
350
400
T/°С
Fig. 2. Temperature dependences of acetone conversion (1) and
selectivity towards mesityl and isomesityl oxides (2), αꢀisophorꢀ
one (3), and other reaction products (4) over CaO—SnO cataꢀ
–
1
–1
2
(
P = 75 atm, VW = 16.1 g h (g catalyst) ). At the same
–1
–1
lyst (P = 75 atm, VW = 16.1 g h (g catalyst) , t = 60 min).
time, the total selectivity towards two isomers of mesityl
oxide decreases from 90 to 60%.
In addition, we examined the effect of an acetone feed
rate on the acetone conversion and composition of the
product mixture (see Table 1). At 400 °C and a weight
version reached its maximum value of 41%. When a weight
space velocity increases twice, i.e., the contact time beꢀ
tween the substrate and the catalyst is reduced, nearly
linear decrease in the conversion (up to 18%) is observed.
–
1
–1
space velocity of 8.1 g h (g catalyst) , the acetone conꢀ
Table 1. Acetone condensation over CaO—SnO catalyst (T = 400 °C)
2
Entry
P/atm
Vw
Conversion
(%)
Selectivity (%)
g h–1 (g catalyst)
–1
/
Mesityl
oxide
Isomesityl
oxide
Phorone
αꢀIsoꢀ
Mesitylene
Other
phorone
products
1
2
3
4
5
15
50
75
75
75
18.1
18.1
18.1
16.1
32.2
12
32
41
18
12
70
51
43
62
68
23
18
15
21
23
0
1
1
1
0
11
16
24
10
13
1
4
3
1
0
15
10
14
15
16

4
90
Russ.Chem.Bull., Int.Ed., Vol. 66, No. 3, March, 2017
Koklin et al.
Scheme 1
one via intramolecular aldol condensation. The main prodꢀ
uct of the process is mesityl oxide. At low pressure (15 atm)
and low temperature (350 °C), the total selectivity towards
mesityl and isomesityl oxides exceeds 90%. An increase in
the reaction temperature and pressure or decrease in the
weight space velocity improve the conversion of acetone.
Herewith, the selectivity towards isophorone via condenꢀ
sation of three acetone molecules increases.
In summary, the performance of CaO—SnO catalyst has
2
been studied in aldol condensation of acetone. Mesityl
oxide and isophorone were found to be the main reaction
products. High acetone conversion (36—41%) and stable
work of the catalyst were observed at 75 atm. With inꢀ
creasing temperature and pressure, a simbate increase in
acetone conversion was demonstrated. The maximum acꢀ
etone conversion of 41% was achieved at 400 °C, 75 atm, and
–1
–1
the acetone weight space velocity of 8.1 g h (g catalyst)
.
References
1
. G. S. Salvapati, K. V. Ramanamurty, M. Janardanarao,
J. Mol. Catal., 1989, 54, 9.
2
3
. H. Dabbach, B. H. Davis, J. Mol. Catal., 1988, 48, 117.
. Y. Ono, H. Hattori, Solid Base Catalysis, Springer, Berlin—
Heidelberg, 2011, 421 pp.
4
5
6
. G. J. Kelly, F. King, M. Kett, Green Chem., 2002, 4, 392.
. G. Zhang, H. Hattori, K. Tanabe, Appl. Catal., 1988, 36, 189.
. J. I. Di Cosimo, V. K. Díez, C. R. Apesteguía, Appl. Catal., A,
1
996, 137, 149.
7
. M. Zamora, T. López, R. Gómez, M. Asomoza, R. Melenꢀ
drez, Catal. Today, 2005, 107—108, 289.
Moreover, the selectivity towards isophorone decreases
8. C. Ma, G. Liu, Z. Wang, Y. Li, J. Zheng, W. Zhang, M. Jia,
React. Kinet. Catal. Lett., 2009, 98, 149.
–
1
–1
from 24 to 10%. At VW = 32.2 g h (g catalyst) , the
conversion was only 2%.
Based on the literature data7,9 and the present results,
we suggest the following scheme of acetone transformaꢀ
9
. L. Faba, E. Díaz, S. Ordóñez, Appl. Catal., B, 2013,
142—143, 387.
1
1
1
0. J. Quesada, L. Faba, E. Díaz, S. Bennici, A. Auroux,
S. Ordóñez, J. Catal., 2015, 329, 1.
1. J. I. Di Cosimo, C. R. Apesteguía, J. Mol. Catal., 1998,
tions over CaO—SnO catalyst (Scheme 1). At the first
2
step, the aldol condensation between two acetone moleꢀ
cules yields diacetone alcohol, which then, transforms to
mesityl oxide via dehydration. The subsequent addition of
an acetone molecule results in either phorone or 4,6ꢀdiꢀ
methylheptaꢀ3,5ꢀdienꢀ2ꢀone. Isophorone is formed from
phorone via intramolecular Michael reaction, and mesiꢀ
tylene is produced from 4,6ꢀdimethylheptaꢀ3,5ꢀdienꢀ2ꢀ
1
30, 177.
2. V. K. Díez, C. R. Apesteguía, J. I. Di Cosimo, Stud. Surf.
Sci. Catal., 2001, 139, 303.
Received April 8, 2016;
in revised form August 22, 2016