Oxidative conversion of ethane involving lattice oxygen of molybdenum systems modified with aluminum, gallium, or yttrium oxide

Article abstract of DOI:10.1134/S0965544116090218

Oxidative conversion of ethane on the molybdenum oxide MoO₃ mixed with 0–95% Al₂O₃, Ga₂O₃, or Y₂O₃ has been studied in the pulse mode at 600°C. It has been revealed that the components of these systems undergo strong interaction, which leads to enhanced ethane conversion and an increased selectivity for ethylene with a decrease in the MoO₃ content. The 5%MoO₃–95%Al₂O₃ system has proved the most effective in the oxidative dehydrogenation of ethane, with the selectivity for ethylene reaching 90% at an ethane conversion of 30 wt %.

Full text of DOI:10.1134/S0965544116090218

ISSN 0965-5441, Petroleum Chemistry, 2016, Vol. 56, No. 9, pp. 841–845. © Pleiades Publishing, Ltd., 2016.
Original Russian Text © N.Ya. Usachev, I.M. Gerzeliev, V.V. Kharlamov, V.P. Kalinin, E.P. Belanova, S.A. Kanaev, A.V. Kazakov, T.S. Starostina, 2016, published in Neftekhimiya,
2016, Vol. 56, No. 6, pp. 622–627.
Oxidative Conversion of Ethane Involving Lattice Oxygen
of Molybdenum Systems Modified with Aluminum, Gallium,
or Yttrium Oxide
a,
b,
a
a
a
a
N. Ya. Usachev *, I. M. Gerzeliev **, V. V. Kharlamov , V. P. Kalinin , E. P. Belanova , S. A. Kanaev ,
a
a
A. V. Kazakov , and T. S. Starostina
a
Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia
Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, 119991 Russia
e-mail: ny@ioc.ac.ru
b
*
*
*e-mail: gerzeliev@ips.ac.ru
Received May 30, 2016
Abstract⎯ Oxidative conversion of ethane on the molybdenum oxide MoO mixed with 0–95% Al O ,
3
2
3
Ga O , or Y O has been studied in the pulse mode at 600°C. It has been revealed that the components of
2
3
2
3
these systems undergo strong interaction, which leads to enhanced ethane conversion and an increased selec-
tivity for ethylene with a decrease in the MoO content. The 5%MoO –95%Al O system has proved the
3
3
2
3
most effective in the oxidative dehydrogenation of ethane, with the selectivity for ethylene reaching 90% at
an ethane conversion of 30 wt %.
Keywords: ethane, ethylene, oxidative dehydrogenation, oxides, molybdenum, aluminum, gallium, yttrium
DOI: 10.1134/S0965544116090218
INTRODUCTION
pounds [9] were tested in the dehydrogenation of eth-
ane along with oxides. Among a large series of such
substances, the highest yield of ethylene (4.47%) was
One of the central places among catalysts for the
dehydrogenation of alkanes is occupied by systems
containing molybdenum oxide [1–4]. When studying
the Mo-containing catalysts in the dehydrogenation of
C -C alkanes, it was shown that molybdenum oxide
observed over Cs Cu
H
PVMo O at 425°C for
2.5
0.08 1.34 11 40
the reaction mixture of the following composition
vol %): ethane, 57; O , 9; and N , 34. γ-Al O is often
(
2
2
2
3
3
4
used as a support of active ingredients. The modified
support contained 17.5 wt % of V O –γ-Al O was
could be represented by mono- or polymeric particles
MoO and crystallites MoO , which depends on the
2
5
2
3
x
3
Mo content, carrier type, and catalyst preparation applied in [10], which was coated with a precursor of
method [5]. In [6] it has been noted that the optimum Mo—molybdophosphoric acid (10 wt %). At 600°C
activity is achieved at monolayer coating of alumina the maximum values of conversion (35%) and ethene
surface with molybdenum oxide. The fresh catalyst selectivity (65%) was achieved for a mixture of
6+
C H /O /He = 15/10/35 (mol). Mezoporous material
contains molybdenum in the state Mo ; however, in
2
6
2
4+
SBA-16 containing MoO is known to be used, which
contact with hydrocarbons it is reduced to Mo and
x
5
+
was synthesized by deposition or hydrothermal
Mo ions. Some authors note [1] that the catalyst
deactivation results from the formation of catalytically method [11]. In the latter case, the catalyst had a
inactive crystallites Al (MoO ) . To prevent the for- greater selectivity for ethylene caused by high disper-
2
4 3
sion of MoO . The ability of MoO to decrease the
mation of these mixed oxides, Mo-systems are modi-
x
3
fied with magnesium oxide, resulting in the formation degree of oxidation, i.e. act as an oxygen carrier, opens
of Mo–Mg–O compounds, which exhibit dehydroge- the possibility to use molybdenum systems in the oxi-
nation activity. It was found that an additional positive dative dehydrogenation of lower alkanes. This is cru-
effect, which is observed when MgO is added, is cial for ethane, because the elimination of hydrogen
caused by a decrease in the acidity of the catalyst, a from its molecule is hard to achieve. Oxygen recovery
decrease in coke formation, and an increase in the proceeds by the interaction between the catalyst
selectivity for olefins.
reduced and O . In particular, this process is expected
2
Modifiers are used to improve the efficiency of to proceed according to the Mars–van Krevelen
Mo-catalysts, namely oxides of different transition mechanism [7]. Different Mo systems, their structure,
and non-transition elements [8]. Heteropoly com- and mechanism of oxidation reactions of hydrocar-
841

8
42
USACHEV et al.
bons were discussed in detail in [12]. The oxidative of Al O was practically unchanged, although S to eth-
2
3
dehydrogenation of alkanes with gaseous oxygen ylene was increased to the level of 63–70%. Further
allows one to recover the lattice oxygen in the reduced increase of the Al O content (up to 90%) led to a nat-
2
3
catalyst oxides. However, the presence of O in the
2
ural increase in the conversion of ethane to ~20%
reaction mixture results in a number of problems: (a) a (during first pulse) with a simultaneous increase of S
deep oxidation of olefins, which have higher reactivity for ethylene to 75%. The value of S in a series of five
as compared to alkanes; (b) the explosion hazard of pulses of ethane increased to 88.8%. It is important
such mixtures, which requires the introduction of inert that system 10%MoO –90%Al O was hardly
3
2
3
diluents in the reaction zone, complicating the selec-
tion of target products. In this regard, another
approach is proposed involving separate dehydrogena-
changed the nature of the oxidation of ethane to eth-
ylene after three oxidative regenerations at 600°C. This
indicates its high stability in a series of reaction–
regeneration cycles. At the same time, according to the
tion steps in the absence of O and the oxidation of the
2
reduced catalyst by air oxygen [3, 4, 13]. The cyclic first pulse data the fresh sample is more active in the
operation mode of the reaction–regeneration process deep oxidation as compared with the regenerated sam-
opens the possibility to increase the selectivity for ole- ple: total S to CO is decreased from 25.4 to 14.7%.
x
fins and their concentration in the reaction products.
In alternate supply of ethane and air to the reactor and
regenerator with a fixed catalyst layer results in tech-
nological complications associated with the switching
of gas flows. The system with a microspherical catalyst
circulating between the reactor and regenerator is free
from these disadvantages [4]. In [4] we developed a
procedure for preparing a microspherical Mo-con-
taining catalyst, on which the selectivity for ethylene
exceeded 90% and made it promising for use.
In this study, we investigated the dependence of
molybdenum oxide properties on the nature and con-
centration of the modifiers (aluminum, gallium, and
yttrium oxides) in oxidative transformations of ethane.
This may indicate a strengthening of the interaction
between the components of the system in high-tem-
perature treatments.
Interesting results were obtained for the catalyst
containing only 5% of MoO (Table 1). This sample in
3
the first pulse reaches maximum conversion of ethane
(
50%) at S to ethylene being 82.5%, i.e. the ethylene
yield exceeded 40%. This is probably due to the high
dispersion of MoO particles. It should also be noted
3
that with increasing the number of pulses, the conver-
sion is reduced and in the fifth pulse, it is equal to 24%
with S being 90%. Obviously, this is due to the con-
sumption of lattice oxygen, which is indicated by a
decrease in S for CO by 2.5 times. Moreover, methane
x
appears in reaction products, whose formation can
take place at the reduced Mo-component.
EXPERIMENTAL
In the next series of Mo catalysts, Ga O was stud-
2
3
Catalyst Preparation and Testing
ied as the second component (Table 2). The conver-
Ammonium heptamolybdate (AHM) and crystal
hydrates of nitrates of aluminum, gallium, and yttrium
sion of ethane on individual oxide Ga O was previ-
2
3
ously studied. It is clear that Ga O has a quite high
2
3
(analytically pure) were used as reagents. Mixture
oxidizing power: during five pulses, the ethane con-
version varied from 55 to 44%, although the selectivity
for ethylene was low (26–31%). In the deep oxidation
products, carbon monoxide dominated, the selectivity
for which was 21–27%. It should be emphasized that
the basic product of the ethane conversion was meth-
thereof in certain proportions were triturated in a por-
celain mortar, heated in an air atmosphere to 600°C at
a rate of 100 K/h, and allowed to stand at this tempera-
ture for 1 h. The resulting mixed oxides were ground in
a porcelain mortar, and the resulting powders were
pressed into tablets (3 × 8 × 30 mm), which were
crushed; the fraction of particles with dimensions of
ane (the selectivity for CH reached ~50%).
4
These results are obviously determined by the abil-
5
0–160 μm was collected. Samples were tested in a
ity of Ga O to reduce in the given experimental con-
pulse setup described in [3]. The methods for analysis
of the resulting products and a formula for calculating
the ethane conversion and selectivities for ethylene,
methane, and carbon oxides are also reported in [3].
2
3
ditions, leading to oxidation, dehydrogenation, and
hydrogenolysis of ethane. It is possible that the latter
reaction proceeds according to the scheme: 2C H =
2
6
C H + 2CH In the number of oxide systems MoO –
2
4
4.
3
Ga O containing 82–10% MoO (Table 2), the fol-
2
3
3
RESULTS AND DISCUSSION
lowing general rules are observed. As compared to
Results of the ethane conversion over MoO – simple oxide Ga O , the conversion of ethane is twice
3
3
2
3
Al O systems in a series of consecutive pulses are decreased using the system with 82.2% MoO with
2
3
shown in Table 1. For comparison, the data for indi- simultaneous almost threefold increase in the ethylene
vidual oxide MoO are also shown. A low conversion selectivity because of the complete suppression of
3
of ethane (1.1–0.7%) with the selectivity (S) for eth- methane formation. Further increase in MoO con-
3
ylene of 49–70% was observed for this sample. The tent to ~70% causes an increase in the conversion of
activity of the 6MoO –Al O system containing 10.6% ethane (to 40%), while the selectivity for ethylene
3
2
3
PETROLEUM CHEMISTRY
Vol. 56
No. 9
2016

OXIDATIVE CONVERSION OF ETHANE INVOLVING LATTICE OXYGEN
843
Table 1. Ethane conversions in a series of pulses over MoO –Al O systems. Catalyst charge, 500 mg; V
= 0.85 mL;
3
2
3
pulse
carrier gas flow rate, 20 mL/min; 600°C
Selectivity for, %
Ethane
conversion, %
Catalyst
C H
CH4
CO
CO2
2
4
MoO3
prepared by decomposition
of AHM at 600°C, 1 h)
1.1
0.9
48.9
57.0
57.8
60.8
70.1
62.2
67.5
70.0
73.0
70.8
65.9
65.9
67.9
67.6
65.7
69.2
69.4
69.9
69.3
69.9
74.6
84.1
84.4
87.9
88.8
85.3
86.5
86.9
87.7
88.3
82.5
89.4
90.8
89.2
89.4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
35.2
24.3
24.4
19.5
12.2
24.0
22.5
20.5
17.8
17.1
20.3
19.9
16.8
18.7
20.1
14.3
13.9
14.1
14.8
14.1
19.9
12.8
12.4
10.1
10.1
11.6
10.7
9.9
15.9
18.6
18.2
19.7
17.7
13.8
10.0
9.5
(
0.9
0.8
0.7
6
MoO –Al O (mol)
1.1
1.0
3
2
3
8
9.4%MoO –10.6%Al O (wt)
3
2
3
1
.0
.0
.0
1
9.2
1
12.1
13.8
14.2
15.3
13.7
14.2
16.5
16.7
16.0
15.9
16.0
5.5
3.1
3.2
2.0
1.1
3.1
2.8
3.2
2.5
3
MoO –Al O (mol)
3.3
3.3
3
2
3
8
0.9%MoO –19.1%Al O (wt)
3
2
3
3.1
3.2
3.1
0
.66MoO –Al O (mol)
5.6
5.3
3
2
3
4
8.2%MoO –51.8%Al O (wt)
3
2
3
5.1
5.0
4.9
0
.08MoO –Al O (mol)
19.7
15.0
14.5
3
2
3
1
0%MoO –90%Al O (wt)
3
2
3
experiment 1
14.4
12.7
0
.08MoO –Al O (mol)
18.6
16.4
15.0
3
2
3
1
0%MoO –90%Al O (wt)
3
2
3
after regeneration, experiment 4
14.3
9.8
9.0
12.4
6.7
4.2
1
3.6
2.7
5.1
3.9
3.0
3.1
3.2
0
.04MoO –Al O (mol)
50.3
40.7
3
2
3
5
%MoO –95%Al O (wt)
3
2
3
31.3
2.0
2.7
3.7
2
2
6.2
4.0
5.0
3.7
remains at the level of ~62%. Interestingly, similar accompanied by a decrease in the selectivity for eth-
results were obtained on a sample with the same com- ylene with a simultaneous increase in the yield of CO .
x
position but prepared from mechanical mixtures of
molybdenum and gallium oxides. This indicates a sig-
nificant interaction of these compounds at elevated
temperatures.
Noteworthy is the fact that after three pulses of ethane,
i.e. as the system is reduced, significant amounts of
methane appear in the reaction products. Marked
trends are amplified when reducing the content of
MoO to 10%. Thus, regular trends were revealed for
For the sample containing 34% of MoO , the eth-
3
3
ane conversion reaches 60%, which is naturally the MoO
–Ga O systems, which are expressed in an
3
2 3
PETROLEUM CHEMISTRY Vol. 56 No. 9 2016

8
44
USACHEV et al.
Table 2. Ethane conversions in a series of pulses over MoO –Ga O systems. Catalyst charge 500 mg; V
pulse
= 0.85 mL;
CO2
3
2
3
carrier gas flow rate, 20 mL/min; 600°C
Selectivity for, %
CH4
Ethane
conversion, %
Catalyst
C H
2 4
CO
Ga O3
54.8
50.3
48.4
26.0
25.9
26.5
28.4
31.0
63.9
76.0
76.3
77.6
76.9
62.6
71.5
65.6
63.8
63.2
62.8
72.3
66.5
65.4
65.6
31.5
45.3
41.7
41.8
41.2
40.7
45.9
38.8
32.9
28.3
48.0
46.1
43.0
41.4
40.9
45.6
44.4
47.7
47.7
47.0
0
0
0
0
0
0
0
0
0
0
0
0
0
23.0
27.4
24.5
23.0
21.3
28.8
18.0
19.2
17.8
19.2
30.1
22.7
27.4
28.6
29.0
30.3
22.2
26.7
27.5
27.3
49.0
40.0
42.7
38.6
32.8
27.1
17.2
17.6
19.5
21.2
10.4
14.1
17.9
19.1
20.9
5.4
2.3
1.3
0.9
0.7
7.3
6.0
4.5
4.6
3.9
7.3
5.8
7.0
7.6
7.8
6.9
5.5
2
(
prepared by decomposition
of Ga(NO ) ⋅ 8H O at 600°C, 1 h)
3
3
2
4
4
6.3
4.0
6
MoO –Ga O (mol)
25.9
20.3
3
2
3
82.2%MoO –17.8%Ga O (wt)
3
2
3
2
2
2
0.1
1.8
0.4
3
MoO –Ga O (mol)
40.8
35.2
3
2
3
69.7%MoO –30.3%Ga O (wt)
3
2
3
4
4
3
1.0
1.8
9.9
3
MoO –Ga O
3
39.5
33.4
35.9
3
2
69.7%MoO –30.3%Ga O (wt)
3
2
3
from mixture of oxides
6.8
7.1
7.1
3
3
3.1
2.4
0
0
0
0
0.67MoO –Ga O (mol)
71.9
62.7
19.5
14.7
15.6
16.0
15.9
23.8
20.4
20.3
19.6
17.2
20.3
12.0
7.8
3
2
3
33.8%MoO –66.2%Ga O (wt)
3
2
3
6
6
3.8
2.5
0
3.6
10.1
8.4
16.5
23.3
28.0
33.3
21.3
27.8
31.3
34.1
34.0
6
1.1
0.145MoO –Ga O (mol)
65.3
59.7
3
2
3
10%MoO –90%Ga O (wt)
3 2 3
63.5
63.6
60.5
0.16MoO –0.55Ga O – Al O (mol)
61.0
52.8
3
2
3
2
3
10%MoO + 45%Ga O + 45%Al O (wt)
3 2 3 2 3
48.9
48.8
48.2
5.4
4.2
increase in their oxidizing activity with increasing the lyst remains active in the entire series of ethane pulses
MoO content. This is accompanied by a decrease in at an ethane in the range of 60–65%, with the ethylene
3
the selectivity for ethylene due to more intense forma- selectivity decreasing from 45 to 28%. Under the same
tion of carbon oxides and methane.
conditions, the catalyst based on Al O loses its activ-
2
3
ity from 20 to 13%, but S (ethylene) remained at a high
The comparison of oxidative properties of
1
9
0%MoO –90%Ga O (Table 2) and 10%MoO – level (~85%). Replacement of half the weight of
3 2 3 3
0%Al O samples (Table 1) containing the same Ga O with Al O (sample 10%MoO + 45%Ga O +
2 3 2 3 3 2 3
2
3
amount of MoO shows that the Ga-containing cata- 45%Al O ) reduces its stability in the oxidation of eth-
3
2
3
PETROLEUM CHEMISTRY
Vol. 56
No. 9
2016

OXIDATIVE CONVERSION OF ETHANE INVOLVING LATTICE OXYGEN
845
Table 3. Ethane conversions in a series of pulses over MoO –Y O systems. Catalyst charge 500 mg; V
= 0.85 mL; car-
3
2
3
pulse
rier gas flow rate, 20 mL/min; 600°C
Selectivity for, %
Ethane
conversion, %
Catalyst
C H
CH4
CO
CO2
2
4
6
MoO –Y O (mol)
0.6
0.6
36.4
43.7
40.3
42.5
50.8
52.8
39.4
46.2
46.5
52.7
80.6
85.6
85.1
86.1
86.0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
26.8
27.1
25.0
29.8
25.0
27.2
29.3
31.0
27.9
25.8
9.4
36.8
29.2
34.7
27.7
24.2
20.0
31.3
22.8
25.6
21.5
10.0
7.2
3
2
3
79.2%MoO –20.8%Y O (wt)
3
2
3
0.6
0.6
0.5
3MoO –Y O (mol)
0.7
0.7
3
2
3
65.6%MoO –34.4%Y O (wt)
3
2
3
0.5
0.5
0.6
0.67MoO –Y O (mol)
11.2
10.6
3
2
3
29.8%MoO –70.2%Y O (wt)
7.2
8.7
9.3
8.2
3
2
3
9.6
8.6
8.9
6.2
4.6
5.8
ane, although ethylene S decreases only from 48 to ment № 14.607.21.0054, unique applied research
4
1%. Thus, the properties of MoO -containing sys- identifier RFMEFI60714X0054).
3
tems depend on the nature of the components and the
catalyst composition.
REFERENCES
. J. H. B. Sattler, J. R. Martinez, E. Santillan-Jimenez,
and B. M. Weckhuysen, Chem. Rev. 114, 10613 (2014).
. C. A. Gartner, A. van Veen, and J. A. Lercher, Chem-
CatChem 5, 3196 (2013).
. S. N. Khadzhiev, N. Ya. Usachev, I. M. Gerzeliev,
et al., Pet. Chem. 55, 640 (2015).
. S. N. Khadzhiev, N. Ya. Usachev, I. M. Gerzeliev,
et al., Pet. Chem. 55, 651 (2015).
. S. Xie, K. Chen, A. T. Bell, and E. Iglesia, J. Phys.
Chem. B 104, 10059 (2000).
. M. E. Harlin, L. B. Backman, A. O. I. Krause, and
O. J. T. Jylha, J. Catal. 183, 300 (1999).
. P. Mars and van D. W. Krevelen, Chem. Eng. Sci. 3, 41
The MoO –Y O systems (Table 3) containing
3
2
3
1
2
3
4
5
6
7
8
9
yttrium oxide are similar to the MoO –Al O samples
3
2
3
to a certain extent (Table 1). Apparently, this is
because both oxides (Al O and Y O ) are inactive in
2
3
2
3
the conversion of ethane, in contrast to Ga O . The
2
3
greatest differences in oxidative properties occur in the
case of the samples containing 0.67 moles of MoO .
3
This manifests itself in a high conversion of ethane (9–
1
1%) and high selectivity for ethylene (80–86%) over
0
.67MoO –Y O . Perhaps, this results from a signifi-
3 2 3
cant difference in the molecular masses of Y O and
2
3
Al O , which leads to a decrease in the molybdenum
2
3
oxide content of the MoO –Y O samples.
3
2
3
The results obtained show a strong influence of
aluminum, gallium, and yttrium oxides on the oxidiz-
ing properties of Mo systems in the conversion of eth-
ane in the absence of gaseous oxygen. General trends
in their activity manifested themselves in the increased
ethane conversion and ethylene selectivity with a
(
1954).
. M. H. Al-Hazmi, T. Odedairo, A. S. Al-Dossari, and
Y. M. Choi, Arabian J. Sci. Eng. 24, 41 (1999).
. M. Sun, J. Zhang, P. Putaj, et al., Chem. Rev. 114, 981
(
2014).
decrease in the MoO content because of dispersion of 10. A. S. H. Kumar, K. Upendar, A. Qiao, et al., Catal.
3
Commun. 33, 76 (2013).
MoO particles. The interaction between the compo-
3
1
1. L. Kong, J. Li, Zh. Zhao, et al., Appl. Catal., A 510, 84
2016).
2. J. C. Vedrine and I. Fechete, C. R. Chim.
http://dx.doi.org/. doi 10.1016/j.crci.2015.09.021
nents in the MoO –90Ga O system causes signifi-
3
2
3
(
cant suppression of the methane formation, which
occurs over gallium oxide.
1
1
3. I. A. Bakare, S. A. Mohamed, S. Al-Ghamdi, et al.,
ACKNOWLEDGMENTS
Chem. Eng. J. 278, 207 (2015).
This work was supported by the Ministry of Educa-
tion and Science of the Russian Federation (agree-
Translated by V. Avdeeva
PETROLEUM CHEMISTRY Vol. 56 No. 9 2016