Deoxygenation of propionic acid in gas phase over cobalt molybdenum catalyst

Article abstract of DOI:10.14233/ajchem.2016.20107

The gas-phase deoxygenation of propionic acid was investigated in the presence of Co-Mo catalysts in N₂ or H₂ flow at 200-400°C. In the presence of N₂, the main product was 3-pentanone with other deoxygenates and some ligh

Full text of DOI:10.14233/ajchem.2016.20107

Asian Journal of Chemistry; Vol. 28, No. 12 (2016), 2745-2748
A
SIAN
J
OURNAL OF HEMISTRY
C
http://dx.doi.org/10.14233/ajchem.2016.20107
Deoxygenation of Propionic Acid in Gas Phase over Cobalt Molybdenum Catalyst
HOSSEIN BAYAHIA
Department of Chemistry, Faculty of Science, Albaha University, P.O. Box 1988, Albaha 65431, Saudi Arabia
Corresponding author: Tel: +966 555622767; E-mail: hbayahia@bu.edu.sa
Received: 28 May 2016;
Accepted: 22 July 2016;
Published online: 1 September 2016;
AJC-18072
The gas-phase deoxygenation of propionic acid was investigated in the presence of Co-Mo catalysts in N
2
or H
2
flow at 200-400 °C. In the
flow,
presence of N , the main product was 3-pentanone with other deoxygenates and some light gases e.g., ethane and ethene. Using H
2
2
the catalyst was active for decarboxylation and decarbonylation of acid and the yields of ethane and ethene. The decarboxylation and
decarbonylation reactions increased with increasing temperature. Cobalt-molybdenum supported on alumina showed better performance
than bulk catalyst, especially at 400 °C in the presence of N for the ketonization of propionic acid to form 3-pentanone as the main
2
product. Bulk and supported catalysts were characterized by surface area porosity (BET), thermogravimetric analysis and diffuse reflectance
infrared Fourier transform spectroscopy (DRIFTS) of pyridine adsorption.
Keywords: Deoxygenation, Propionic acid, Gas-phase, Cobalt-molybdenum catalyst.
INTRODUCTION
EXPERIMENTAL
Value-added chemicals and biofuel components have been
produced from carboxylic acids because these are renewable
raw materials attractively and readily available from natural
sources [1-6]. Deoxygenation of carboxylic acids has been
used in the production of fuel [1-6]. Heterogeneous catalysis
has recently received attention in these deoxygenation reactions
All chemicals were used as received from Sigma-Aldrich
without further purification. The purity of propionic acid was
≥ 99.5 %. The aluminium oxide used for supporting catalysts
was obtained from Degussa. Throughout the experiments,
double distilled water was used to prepare catalysts.
Catalyst preparation: Cobalt-molybdenum catalyst was
prepared by dissolving cobalt acetate and 12-molybdophos-
[7-9]. Propionic acid, which can be derived from carbohydrate
feed stocks, is chosen as an illustrative carboxylic acid with
six carbon atoms [10].
phoric acid H
3
PMo12
O
40·13H O in a minimum amount of water
2
separately at room temperature. The solutions were mixed by
adding them simultaneously to a vessel at room temperature
and stirred for at least 3 h. The mixture was rotary evaporated
at 35 °C and the resulting material was dried overnight in an
Molybdenum and cobalt or nickel, supported on γ-Al
2
O ,
3
have been used in hydro treating reactions. Molybdenum
sulfide supported catalysts were more active in hydro treatment
for removing sulfur, nitrogen and oxygen than others such as
Co and Ni sulfide. Cobalt and nickel were used as active
promoters [11]. Co(Ni)Mo(W) supported on alumina has been
used to catalyze commercial petroleum refining for a century
oven at 110 °C. Co–Mo was supported on γ-Al
2
O using the
3
impregnation method. The amount of Co–Mo bulk catalyst
was added to the support and the mixture was stirred for 3 h at
room temperature, then the catalyst was dried at 110 °C over-
night. The products were finally calcined at 400 °C for 2 h to
form metal oxides.
[12]. Fe–Co/sulfonated polystyrene was an efficient catalyst for
heterogeneous reactions of cyclic ketones and H to lactones.
O
2 2
Yield and selectivity of lactones were high [13]. Molybdenum
catalysts based on carbide have attracted attention for reactions
including the synthesis of ammonia [14], hydrogenation,
dehydrogenation, hydrodenitrogenation, hydrodesulfurization
and isomerization [11,15-18]. In the current work, cobalt
molybdenum catalysts in bulk form and supported on alumina
were tested in the gas-phase deoxygenation of propionic acid
at 200-400 °C at ambient pressure.
Catalyst characterization: The specific surface area and
porosity of catalysts were measured by the BET method from
nitrogen physisorption determined at -196 °C on a Micro-
meritics ASAP2010 instrument. Prior to analysis, the catalyst
was evacuated in situ at 250 °C for 3 h. Thermogravimetric
analysis of 20-50 mg sample was carried out on a Perkin-Elmer
TGA 7 instrument, under nitrogen flow at a heating rate of
–1
20 °C min to raise the temperature from room temperature

2746 Bayahia
Asian J. Chem.
to 700 °C. Diffuse reflectance infrared Fourier transform
spectroscopy (DRIFTS) of adsorbed pyridine was performed
on the Nico-let Nexus FTIR spectrometer in Professor Ivan
Kozhevnikov’s Laboratory. Catalyst samples were ground with
9
0
75
60
–5
KBr (10 wt % in KBr) and pretreated at 150 °C/10 bar for
1
h. The samples were then exposed to pyridine vapour at room
4
3
1
5
0
5
0
–5
temperature for 1 h, followed by pumping out at 150 °C/10
bar for 1 h to remove physisorbed pyridine, as explained else-
where [3,4,19-21]. The DRIFT spectra of adsorbed pyridine
–1
were recorded at room temperature at a resolution of 5 cm .
Catalyst testing:The gas-phase deoxygenation of propionic
acid was performed in flowing N
2
or H at 200-400 °C under atmos-
2
4
000 3500 3000 2500 2000 1750 1500 1250 1000 750 500
pheric pressure using a down flow quartz fixed-bed reactor (9
mm i.d.) with online GC analysis (Varian 3800 instrument with
a 30 m × 0.32 mm × 0.5 µm Zebron ZB-WAX capillary column
and a flame ionization detector). For hydrocarbon products, a
–
1
Wavelength (cm )
Fig. 1. IR spectra of H PMo12 40·13H O
3
O
2
6
0 m × 0.32 mm GS-GasPro capillary column was used, which
1
12.5
allowed for full separation of these hydrocarbons. The reaction
temperature was controlled by using a thermocouple placed at
the top of the catalyst bed inside the glass reactor. Propionic acid
was fed into the carrier gas and the flow of acid was controlled by
a Brooks mass flow controller through a stainless steel saturator,
which held the liquid acid at an appropriate temperature to
maintain the chosen reactant concentration in the gas flow. All
system lines and GC valves were maintained at 180 °C to prevent
downstream condensation of propionic acid and its reaction
products. The reactor was packed with 0.2 g catalyst powder of
100.0
9
9
82.5
7
6
60.0
5
4
37.5
3
2
1
7.5
0.0
5.0
7.5
2.5
5.0
0.0
2.5
5.0
7
.5
0
-7.5
45-180 µm particle size. Typically, the reaction was carried out
with 0.2 g of catalyst and 2 vol % of propionic acid concentration
-1
–
1
under N
2
or H at a flow rate of 20 mL min . Before the reaction
2
Wavelength (cm )
started, the catalysts were pretreated at the same conditions of
temperature and flow rate for 1 h. The products were analyzed
using the gas chromatography equipment in Kozhevnikov’s
laboratory at Liverpool University, UK.
Fig. 2. IR spectra of Co1.5PMo12 40·13H O
O
2
Figs. 3 and 4 show the TGA results for H
3
PMo12
2
O40·13H O
and Co1.5PMo12
2
O40·13H O respectively. From Fig. 3 it can be
RESULTS AND DISCUSSION
seen that the bulk catalyst had two thermal areas. The first,
from 50-240 °C, may be attributed to loss of physisorbed water
or hydration water. The peak at 240-450 °C is due to the
decomposition of the catalyst’s Keggin structure [10,22,23].
Catalyst acidity was determined by pyridine adsorption.
Both bulk and supported catalysts had very high numbers of
Lewis acid sites, but fewer Brønsted acid sites. The acidity
Table-1 shows the resulting catalyst porosity in terms of
BET surface area, pore size and pore diameter. Co–Mo had
2
-1
3
-1
only 45 m g of surface area, 0.06 cm g of pore volume and
3 Å pore diameter, whereas the values for the supported
2
2
1
3
-1
catalyst were 97 m g , 0.12 cm g and 49 Å, respectively.
was not affected by supporting Co–Mo on Al
Fig. 5.
O
2 3
as shown in
TABLE-1
CATALYST CHARACTERIZATION
b
c
Pore volume
Pore diameter
a
2
-1
Catalyst
Co–Mo
SBET (m g )
3
-1
(cm g )
(Å)
23
53
49
100
45
164
97
0.06
0.22
0.12
Al O3
2
95
90
85
80
75
Co–Mo/Al O3
2
a
b
c
BET surface area; Single point total pore volume; Average BET pore
diameter.
Figs. 1 and 2 show infrared adsorption bands for heteropoly-
oxometalate catalysts H
3H O respectively. Keggin structure can be assigned in the
range of 750-1150 cm [10]. It can be seen that there are some
bands in 1,080-1,060, 990-960, 900-870 and 810-760 cm region,
which are assigned to (P–O), (M–O), (M–O–M) and (M–O–M)
vibrations respectively, whereas M is Co or Mo [10,22].
3
PMo12
O40·13H
2
O and Co1.5PMo12
40
O ·
1
2
–1
–1
0
100
200
300
400
500
600
700
Temperature (°C)
Fig. 3. TGA analysis for H PMo12
3
O
40·13H
2
O

Vol. 28, No. 12 (2016)
Deoxygenation of Propionic Acid in Gas Phase over Cobalt Molybdenum Catalyst 2747
177.0
176.8
176.6
176.4
176.2
176.0
175.8
175.6
175.4
175.2
175.0
TABLE-2
DEOXYGENATION OF PROPIONIC ACID
OVER BULK Co–Mo AND Co–Mo/Al O
2
3
Selectivity (%)
Temp.
(°C)
Conv.
(%)
a
2
2
00
4
9
15
22
31
5
4
6
14
65
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
8
8
9
6
1
7
8
6
3
5
5
87
81
69
65
35
93
92
71
32
28
a
50
11
22
29
64
0
a
300
a
350
a
4
00
50
100 150 200 250 300 350 400 450 500 550 600 650
Temperature (°C)
b
b
2
2
3
3
4
00
50
0
2
Fig. 4. TGA analysis for Co1.5PMo12O40·13H O
b
00
11
65
67
b
50
b
00
a
-1
0
.2 g catalyst, 20 mL min N flow rate and 2 vol % PA for 4 h over
2
b
-1
Co–Mo. 0.2 g catalyst, 20 mL min N flow rate and 2 vol % PA for 4
2
c
h over Co–Mo/Al O . Isopropanol and acetone together.
2
3
TABLE-3
DEOXYGENATION OF PROPIONIC ACID
OVER BULK Co–Mo AND Co–Mo/Al O3
2
Selectivity (%)
Temp.
Conv.
(%)
(°C)
a
2
2
3
3
00
50
00
50
7
18
47
90
99
9
12
32
96
100
5
8
9
13
12
2
2
5
2
5
9
12
14
13
16
4
7
9
10
8
20
42
38
18
10
8
19
39
31
18
0
2
0
25
45
0
22
34
25
16
66
36
39
31
16
86
50
13
32
53
a
a
a
a
1
540
1520
1500
Wavenumber (cm )
Fig. 5. DRIFT spectra for (a) bulk Co–Mo and (b) Co–Mo/Al
1480
1460
1440
1420
–
1
2
O
3
400
b
b
b
b
b
200
250
300
Catalyst performance
Deoxygenation of propionic acid over Co–Mo bulk
catalyst and N flow: Table-2 lists the conversion and selec-
350
400
0
2
a
-1
.2 g of catalyst, 20 mL min of H flow rate and 2 vol % of PA for 4
h over Co–Mo. 0.2 g of catalyst, 20 mL min of H flow rate and 2
vol % of PA for 4 h over Co–Mo/Al O . Isopropanol and acetone
tivity results for the deoxygenation of propionic acid over bulk
and supported cobalt/molybdenum catalysts under various
2
b
-1
2
c
2
3
conditions. The flow of N was used and the reactor was packed
2
together.
with 0.2 g of catalyst and 2 vol % of acid in the temperature
range of 200-400 °C. It can be seen that catalyst performance
improved as temperature increased. At 400 °C, bulk catalyst
gave 65 % selectivity of 3-pentanone at 31 % conversion and
no hydrocarbons were produced at any temperature. Co–Mo/
Stability of Co–Mo/Al
was that of 0.2 g Co–Mo/Al
shows that supported Co–Mo/Al
2
O
3
:The best catalytic performance
at 400 °C under N flow. Fig. 6
was stable for at least 15 h
2
O
3
2
O
2 3
st
on stream. The catalyst reached the steady state in the 1 h. In
the last 3 h there was only a slight drift in acid conversion
from 58 to 52 %, while selectivity of the product remained
stable. Loss of conversion may have resulted from the depo-
sition of carbon on the catalyst as coke. C, N, H measurement
showed that 4 % of carbon and 2 % of hydrogen were deposited
on the catalyst. In addition, the surface area may have decreased
at higher reaction temperature, thus reducing catalytic activity.
2
-1
3
-1
Al
2
O ,with 97 m g surface area, 0.12 cm g pore volume and
3
49 Å pore diameter showed better performance, giving 67 %
and 5 % selectivity of 3-pentanone and propanal, respectively
at 65 % propionic acid conversion (44 % yield of 3-pentanone).
Deoxygenation of propionic acid over Co–Mo bulk
catalyst and H flow: Similar reaction conditions for tempe-
2
rature, concentration of acid and catalyst weight were applied
to the gas-phase deoxygenation of propionic acid, using
Conclusion
H
2
instead of N
2
. Table-3 shows that the conversion of acid
at 400 °C,
increased with increasing temperature. Under H
2
This work has demonstrated that Co–Mo in bulk and
supported on alumina are active and durable catalysts for the
gas-phase deoxygenation of propionic acid at 200-400 °C and
Co–Mo bulk catalyst gave45 % and 10 % of 3-pentanone and
propanal selectivity respectively, at 99 % of propionic acid
conversion. The supported catalyst gave only 16 % 3-penanone
and 18 % propanal selectivity at 100 % acid conversion.
1 bar of pressure under N
2
and H
2
flow. Co–Mo/Al
2
O showed
3
the best performance at 400 °C and it was stable for at least

2748 Bayahia
Asian J. Chem.
1
00
3. H. Bayahia, E. Kozhevnikova and I. Kozhevnikov, Chem. Commun., 49,
Propionic acid conversion (%)
-Pentanone selectivity (%)
3
842 (2013).
H. Bayahia, E. Kozhevnikova and I. Kozhevnikov, Appl. Catal. B, 165,
53 (2015).
5. P.T. Do, M. Chiappero, L.L. Lobban and D. Resasco, Catal. Lett., 130,
(2009).
3
4
.
Propanal selectivity (%)
Others selectivity (%)
2
8
6
4
2
0
0
0
0
0
9
6
.
M. Arend, T. Nonnen, W.F. Hoelderich, J. Fischer and J. Groos, Appl.
Catal. A Gen., 399, 198 (2011).
7
.
H. Bernas, K. Eränen, I. Simakova, A.-R. Leino, K. Kordás, J. Myllyoja,
P. Mäki-Arvela, T. Salmi and D.Y. Murzin, Fuel, 89, 2033 (2010).
J.G. Immer, M.J. Kelly and H.H. Lamb, Appl. Catal. A, 375, 134 (2010).
M. Arend, T. Nonnen, W.F. Hoelderich, J. Fischer and J. Groos, Appl.
Catal. A, 399, 198 (2011).
8
9
.
.
10. M.A. Alotaibi, E.F. Kozhevnikova and I.V. Kozhevnikov, Appl. Catal. A,
47, 32 (2013).
4
1
1. G. Ertl, H. Knozinger, F. Schüth and J. Weitkamp, Handbook of Hetero-
geneous Catalysis, Wiley-VCH, edn 2, vol. 8 (2008).
0
2
4
6
8
10
12
14
16
1
2. X.-H. Wang, M.-H. Zhang, W. Li and K.-Y. Tao, Catal. Today, 131, 111
Time on stream (h)
(
2008).
Fig. 6. Deoxygenation of propionic acid on Co–Mo/Al
2
O
3
(0.2 g catalyst,
13. Y. Wang, J. Huang, X. Xia and X. Peng, J. Saudi Chem. Soc., (2016);
doi:10.1016/j.jscs.2016.01.006.
-
1
4
00 °C, 1 bar pressure, 20 mL min
2
N flow rate and 2 vol %
propionic acid)
14. R. Kojima and K. Aika, Appl. Catal. A, 215, 149 (2001).
1
5. A.M. de Jong,V.H.J.S. de Beer, J.A.R. vanVeen and J.W.H. Niemantsverdriet,
J. Phys. Chem., 100, 17722 (1996).
1
5 h on stream, with a small decrease in the last 3 h, probably
1
1
6. J.H. Ashley and P.C.H. Mitchell, J. Chem. Soc. A, 2821 (1968).
7. L. Cedeño, D. Hernandez, T. Klimova and J. Ramirez, Appl. Catal. A,
241, 39 (2003).
because of catalyst deactivation by coking. Co–Mo and its
metal oxide supports were characterized by BET, TGA and
DRIFTS of pyridine.
18. M. de Boer, E.P. Koch, R.J. Blaauw, E.R. Stobbe, A.N.J.M. Hoffmann, L.A.
Boot, A.J. van Dillen and J.W. Geus, Solid State Ion., 63-65, 736 (1993).
9. F. Al-Wadaani, E.F. Kozhevnikova and I.V. Kozhevnikov, Appl. Catal.
A, 363, 153 (2009).
0. A.M. Alsalme, P.V. Wiper, Y.Z. Khimyak, E.F. Kozhevnikova and I.V.
Kozhevnikov, J. Catal., 276, 181 (2010).
1
2
2
ACKNOWLEDGEMENTS
The author thanks Prof. Ivan Kozhevnikov, Chemistry
Department, The University of Liverpool for the opportunity
to work in his laboratory. Thanks are also due to Prof. Ahmed
Aouissi, Chemistry Department, King Saud University, Saudi
Arabia for his help and advice. Finally, sincere thanks toAlbaha
University for its financial support.
1. F. Al-Wadaani, E.F. Kozhevnikova and I.V. Kozhevnikov, J. Catal., 257,
199 (2008).
22. A. Aouissi, A.W. Apblett, Z.A. Al-Othman and A. Al-Amro, Transition
Met. Chem., 35, 927 (2010).
2
3. C.S. Song, C.S. Hsu and I. Mochida, Chemistry for Diesel, Applied
Energy Technology series, p. 140 (2000).
REFERENCES
1
2
.
.
A. Corma, S. Iborra and A. Velty, Chem. Rev., 107, 2411 (2007).
E.L. Kunkes, D.A. Simonetti, R.M. West, J.C. Serrano-Ruiz, C.A. Gartner
and J.A. Dumesic, Science, 322, 417 (2008).