Oxidation of ethylene glycol on oxide catalysts

Article abstract of DOI:10.1023/A:1022268610417

The catalytic activity of a series of metal oxides in oxidation of ethylene glycol was studied.

Full text of DOI:10.1023/A:1022268610417

Russian Journal of Applied Chemistry, Vol. 75, No. 9, 2002, pp. 1424 1426. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 9,
002, pp. 1456 1458.
Original Russian Text Copyright
2
2002 by Kopeikina, Vodyankina, Golovko, Kurina.
CATALYSIS
Oxidation of Ethylene Glycol on Oxide Catalysts
L. Yu. Kopeikina, O. V. Vodyankina, A. K. Golovko, and L. N. Kurina
Institute of Petroleum Chemistry, Siberian Division, Russian Academy of Sciences, Tomsk, Russia
Tomsk State University, Tomsk, Russia
Received March 13, 2001; in final form, June 2002
Abstract The catalytic activity of a series of metal oxides in oxidation of ethylene glycol was studied.
Transformations of alcohols into lower aliphatic
carbonyl compounds are performed in industry on
a large scale [1]. These reactions are catalyzed by
d-metal oxides (V O , MoO , etc.) and complex sys-
precipitated with NH OH from metal nitrate solutions,
4
followed by drying of the precipitates at 200 C and
calcination at 450 500 C for 3 h. The specific surface
area of the resulting oxide systems was 7.6, 5.0, 7.6,
2
5
3
2
1
tems based on them [2].
and 20.0 m g for WO , MoO , V O , and Cr O ,
3 3 2 5 2 3
respectively.
Partial oxidation of lower alcohols (methanol,
ethanol) into carbonyl compounds on oxide catalysts
has been extensively studied [3 5]. However, only
scarce data are available on oxidation of dihydric alco-
hols on oxide catalysts. In particular, for oxidation of
ethylene glycol (EG) on complex molybdenum-con-
taining catalysts, only the composition of the reaction
products was reported [6], without detailed discussion.
In this work, we studied selective oxidation of EG on
a series of individual oxide catalysts.
Experiments were performed in a flow quartz reac-
tor (d = 20 mm) with a fixed bed of a catalyst (bed
height 1 cm). The contact time of the reaction mixture
with the catalyst was 0.1 s, and the content of EG in
air, 3.5 vol %. Liquid reaction products were analyzed
with a Chrom-5 chromatograph (flame ionization de-
tector, 1.6-m column, stationary phase 15% Reoplex-
4
00 on Chromaton N, carrier gas nitrogen; flow rates,
1
ml min : nitrogen 25, hydrogen 40, and air 500;
temperatures, C: column 146, vaporizer 200, and
detector 190). Analyses were performed by the proce-
dure described in [12] for determination of glyoxal in
scrubber waters in the form of quinoxaline.
EXPERIMENTAL
We tested as catalysts V O , MoO , WO , CuO,
2
5
3
3
Gaseous reaction products were analyzed on an
LKhM-80 chromatograph (thermal conductivity detec-
tor; 2-m column packed with silica gel or 3-m column
packed with CaA molecular sieves; carrier gas argon;
temperature, C: columns 80 and detector 150; detec-
tor current 120 mA) [13].
and Cr O . This choice was governed by the follow-
2
3
ing factors. According to published data on catalytic
oxidation of monohydric alcohols to carbonyl com-
pounds [7], these individual oxide catalysts exhibit
acid properties, i.e., they readily adsorb alcohols.
Furthermore, the oxygen binding energy in the crystal
lattice of these oxides is high, which favors partial
oxidation of organic compounds [2, 7]. It is also
known that addition of Cr O or WO to vanadium
Figure 1 shows that the EG conversion increases
with temperature on all the catalysts tested, reaching
1
00% at 350 C (except MoO , on which the conver-
3
2
3
3
sion, though growing with temperature, does not reach
catalytic systems appreciably enhances the catalytic
activity of V O in oxidation of methanol into formal-
100% even at 400 450 C).
2
3
dehyde [8, 9]. Supported copper oxide catalyst is
fairly active in oxidation of EG to glyoxal [10, 11].
With respect to the product composition, the oxide
systems can be subdivided into the following groups:
(
(
1) CuO and Cr O , on which EG is oxidized to CO ;
The catalysts were prepared as follows: WO , by
2 3 2
3
2) V O and WO , on which EG undergoes partial
decomposition of (NH ) WO at 600 C for 4 h;
2
5
3
4
2
4
oxidation to formaldehyde, formic acid, methyl for-
mate, and CO; and (3) MoO , on which EG undergoes
polycondensation to give polyethylene glycols.
MoO , by decomposition of (NH ) Mo O at 350
3
4 6
7 24
4
00 C; V O , by decomposition of NH VO at 450 C
3
2
5
4
3
for 3 h; and Cr O and CuO, by decomposition of
the corresponding hydroxides, Cr(OH) and Cu(OH) ,
2
3
Deep oxidation of EG to CO on the first group of
3
2
2
1
070-4272/02/7509-1424$27.00 2002 MAIK Nauka/Interperiodica

OXIDATION OF ETHYLENE GLYCOL ON OXIDE CATALYSTS
1425
oxide catalysts (Cr O , CuO) is due to the presence
on their surface of molecular weakly bonded oxygen
2
3
K, wt %
responsible for deep oxidation of organic compounds
[14]. Figure 2a shows experimental data on the cata-
lytic activity of Cr O . At low temperatures ( 200 C),
2
3
the EG conversion on Cr O is low ( 10%), with the
2
3
main product being formaldehyde. As the temperature
is increased to 250 C, the conversion of EG increases
to 60%, with formation of CO becoming prevalent.
2
At 300 350 C, the EG conversion reaches 100%.
The low activity of Cr O at 200 C may be due to
2
3
rapid reduction of the catalyst surface to Cr(II) under
the action of the reaction medium [15]. Under such
conditions, transformation of EG is limited by reoxi-
dation of the surface, and the process attenuates with
time. Since the main product of EG conversion on
Cr O is formaldehyde, the active centers of partial
2
00 250 300 350 T, C
Fig. 1. Temperature dependence of EG conversion K in
vapor-phase oxidation on oxides: (1) Cr O , (2) V O ,
3) MoO , and (4) WO .
2
3
2
5
(
3
3
Y, %
(a)
Y, % Y, %
(b)
Y, %
2
3
2+
oxidation of EG are, presumably, Cr ions [16]. At
50 400 C, the catalyst surface is reoxidized faster,
and deep oxidation of EG to CO becomes prevalent
3
2
(
(
Fig. 2a). The yield of CO passes through a maximum
12%) at approximately 300 C. At higher tempera-
tures, the CO yield decreases to 4%, which may be
due to the fact that CO is formed from formaldehyde
in a consecutive process; note that the yield of form-
aldehyde passes through a maximum at 250 300 C.
T, C
T, C
Y, %
(
c)
Y, % Y, %
(d)
Figure 2b illustrates the activity of V O in EG
2
5
Y, %
oxidation. With increasing temperature, the yields of
formaldehyde and CO pass through a maximum at
2
2
50 300 C. The yield of formic acid decreases with
temperature, which is due to its further oxidation to
CO . The consecutive-parallel reaction pattern in-
2
cludes the initial formation of formaldehyde (by scis-
sion of the C C bond in EG), whose secondary ad-
sorption on the catalyst surface is followed by oxida-
T, C
T, C
tion to formic acid and CO . The yield of CO mono-
2
Fig. 2. Oxidation of EG on (a) Cr O , (b) V O , (c) MoO ,
and (d) WO . (Y) Yield and (T) temperature. (1) CO ,
2) H CO, (3) CO, (4) HCOOH, and (5) EG ethers.
tonically increases with temperature, which may be
due to thermal decomposition of formaldehyde.
2
3
2
5
3
2
3
(
2
Among all the oxide systems studied, V O is the
2
5
most selective with respect to formation of formalde-
hyde and formic acid. The yield of HCOOH reaches
to the plane of the bipyramid network layer) to 3.42
(along cogged chains formed by distorted VO tetra-
4
1
0% (Fig. 2b). The major product of EG oxidation at
hedra) [18]. In view of preferableness of EG adsorp-
tion on paired centers [19], it can be presumed that,
in the precatalysis stage, EG and its carbonyl deriva-
tives are adsorbed via two hydroxy (or aldehyde)
groups, extending the C C bond whose length is 1.54
and 1.47 in EG and glyoxal, respectively. Stabiliza-
tion of the system should involve scission of the C C
bond and formation of formaldehyde as the major
product of vapor-phase oxidation of EG.
elevated temperatures is CO.
At low temperatures ( 200 250 C), up to 5% of
glyoxal is formed. The low yield of glyoxal may be
due to structural features of EG, which mainly exists
in the conformation with an intramolecular hydrogen
bond and cis location of the hydroxy groups at the
C C bond [16]. In the excited state, the cis configura-
tion of glyoxal is the most stable [17]. The distance
between the vanadium cations in the V O lattice
These assumptions are supported by the fact that
the yield of glyoxal decreases with increasing temper-
2
5
varies from 4.369 (the longest distance, perpendicular
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 9 2002

1426
KOPEIKINA et al.
ature. It is interesting that, at 350 400 C, glycolalde-
hyde is formed (i.e., only one functional group is
oxidized). Dehydration in the course of EG oxidation
can be ruled out, since no olefins were detected in the
gas phase.
nie uglevodorodov (Heterogeneous Catalytic Oxida-
tion of Hydrocarbons), Moscow: Khimiya, 1967.
3. Boreskov, G.K., Popov, B.I., Bibin, V.N., and Kozish-
nikova, E.S., Kinet. Katal., 1968, vol. 9, no. 4,
pp. 796 803.
4
5
. Ai, M., J. Catal., 1983, vol. 3, no. 1, pp. 141 150.
. Allakhverdova, N.Kh., Kerimov, Kh.M., and Alkha-
zov, T.G., Kinet. Katal., 1992, vol. 33, no. 3, pp. 586
Experimental data on the temperature dependence
of the catalytic activity of MoO are shown in Fig. 2c.
3
The major products of EG conversion are di- and tri-
5
90.
ethylene glycols. MoO is less active than the other
3
6
. Volkov, V.L., Skobeleva, V.D., Buldakova, L.Yu.,
and Zakharova, G.S., Zh. Obshch. Khim., 1989,
vol. 59, no. 10, pp. 2307 2310.
oxides tested (Fig. 1). The EG conversion at 400 C is
as low as 60%. The activity of MoO in partial oxida-
3
tion of monohydric alcohols (methanol, ethanol) is
also low [5, 20], but the selectivity reaches 90%. It is
known [21] that WO and MoO effect fast isomeriza-
7. Golodets, G.I., Teor. Eksp. Khim., 1982, vol. 18,
no. 1, pp. 37 45.
3
3
tion of 1-butene, which is the model process for deter-
mining the surface acidity function. However, the nec-
essary condition for high activity of a catalyst is low
strength of oxygen bonding with the catalyst surface,
8. Ediseeva, O.N. and Kurina, L.N., Kinet. Katal.,
1973, vol. 14, no. 1, pp. 267 270.
9. Kurina, L.N. and Sterligova, T.I., Kinet. Katal., 1972,
vol. 13, no. 4, pp. 942 948.
Q . In pure MoO , on the contrary, Q is fairly high.
10. Bohmfalk, J.F., Ind. Eng. Chem., 1951, vol. 43, no. 4,
s
3
s
In WO , Q is somewhat lower but still not optimal
pp. 786 794.
3
s
for the process [7]. Since etherification involves pro-
1
1
1
1. Ioffe, I.I., Brodskii, M.S., and Tishchenko, A.I., Meto-
dy proizvodstva monomerov (Methods for Production
of Monomers), Moscow: Nauka, 1964, p. 205.
2. Medonos, V., Ruzicka, V., Kalina, Y., and Mar-
noln, A., Coll. Czech. Chem. Commun., 1968, vol. 33,
no. 12, pp. 4393 4395.
ton transfer, the strong surface acidity of MoO and
3
WO presumably results in predominant polyconden-
3
sation of EG to form polyethers.
The activity of WO is illustrated by Fig. 2d. The
3
major products of EG oxidation are formaldehyde and
CO. The yield of formic acid passes through a max-
imum at 300 350 C. Presumably, HCOOH is formed
after readsorption of formaldehyde on the catalyst
surface. With increasing temperature, the yield of
partial oxidation products decreases, and the yield
of EG condensation products grows.
3. Vodyankina, O.V. and Galanov, S.I., Zavod. Lab.,
1
995, no. 8, pp. 12 13.
14. Popovskii, V.V., in Mekhanizmy geterogenno-kataliti-
cheskikh reaktsii okisleniya (Mechanisms of Hetero-
geneous-Catalytic Oxidation Reactions), Novosibirsk:
Inst. Kataliza, Sib. Otd. Ross. Akad. Nauk, 1993,
pp. 37 48.
1
1
1
1
5. Kurina, L.N., Koval’, L.M., and Kotenko, N.F.,
CONCLUSIONS
Zh. Fiz. Khim., 1975, vol. 49, no. 6, pp. 1494 1497.
6. Strelkova, L.F. and Ginzburg, I.M., Zh. Obshch.
Khim., 1986, vol. 56, no. 8, pp. 1884 1887.
(
1) With respect to the activity in partial oxida-
tion of ethylene glycol, oxide catalysts can be ranked
in the following order: V O > WO > MoO >
7. Le Khyu Kho and Tyulin, V.I., Zh. Strukt. Khim.,
2
5
3
3
1
975, vol. 16, no. 1, pp. 63 70.
Cr O > CuO. The major products are formaldehyde
2
3
8. Fotiev, A.A., Glazyrin, M.P., Volkov, V.L., et al.,
Issledovaniya kislorodnykh vanadievykh soedinenii
(Studies of Oxygen Compounds of Vanadium), Sverd-
lovsk: Ural. Otd. Akad. Nauk SSSR, 1970.
and formic acid.
(
2) The low ( 5%) yield of glyoxal on V O is
presumably due to scission of the C C bond upon
adsorption of ethylene glycol on the catalyst surface.
2
5
1
9. Vodyankina, O.V., Kurina, L.N., Sudakova, N.N.,
et al., Zh. Fiz. Khim., 1998, vol. 72, no. 3, pp. 521
5
24.
REFERENCES
2
2
0. Osipova, N.A., Kurina, L.N., Belousova, V.N., et al.,
Zh. Fiz. Khim., 1984, vol. 58, no. 4, pp. 1000 1003.
1
2
. Golodets, G.I., Probl. Kinet. Katal., 1985, vol. 19,
pp. 28 58.
1. Golodets, G.I. and Roiter, V.A., Ukr. Khim. Zh., 1963,
. Margolis, L.Ya., Geterogennoe kataliticheskoe okisle-
vol. 29, no. 7, pp. 667 685.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 75 No. 9 2002