Effect of the Nature of the Catalyst on Catalytic Activity and Selectivity in the Formaldehyde Hydrogenation

Article abstract of DOI:10.1134/S0036024418090297

The effect the nature of the carrier and supported metal on the activity and selectivity of the catalyst in the reaction of formaldehyde hydrogenation to methanol is studied. The formation of such oxygenates as ethanol, formic acid, and diethyl formal is observed. It is found that ethanol forms on Fe-containing alloyed catalyst, while formic acid forms on the catalysts containing Au. Thermodynamic calculations are performed for a series of side reactions that confirm the formation of the resulting oxygenates.

Full text of DOI:10.1134/S0036024418090297

ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2018, Vol. 92, No. 9, pp. 1670–1674. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © A.L. Tarasov, 2018, published in Zhurnal Fizicheskoi Khimii, 2018, Vol. 92, No. 9, pp. 1396–1401.
CHEMICAL KINETICS
AND CATALYSIS
Effect of the Nature of the Catalyst on Catalytic Activity
and Selectivity in the Formaldehyde Hydrogenation
A. L. Tarasova,*
aZelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, 119991 Russia
*e-mail: atarasov@ioc.ac.ru
Received November 24, 2017
Abstract—The effect the nature of the carrier and supported metal on the activity and selectivity of the catalyst
in the reaction of formaldehyde hydrogenation to methanol is studied. The formation of such oxygenates as
ethanol, formic acid, and diethyl formal is observed. It is found that ethanol forms on Fe-containing alloyed
catalyst, while formic acid forms on the catalysts containing Au. Thermodynamic calculations are performed
for a series of side reactions that confirm the formation of the resulting oxygenates.
Keywords: formaldehyde, methanol, ethanol, formic acid, hydrogenation
DOI: 10.1134/S0036024418090297
INTRODUCTION
adsorption and catalytic methods of removing FA
from gas discharges [17, 18]. However, the FA hydro-
genation itself is of particular interest, from the view-
point of both forming other valuable oxygenates (e.g.,
ethanol, formic acid, and diethyl formal) and under-
standing FA’s role in numerous reactions with the par-
ticipation of carbon oxides and H2. The main product
of FA hydrogenation is methanol. The authors of [19]
investigated the effect the nature of supports,
VIII group metals, and different alkaline promoters
have on the selectivity of methanol formation in FA
hydrogenation.
However, the reactions providing other oxygenates
from FA are also known. For example, scientists from
the Institute of Catalysis, Siberian Branch, Russian
Academy of Sciences, have developed a new way of
preparing formic acid via the catalytic oxidation of
formaldehyde with atmospheric oxygen in the gas
phase. A key component of this processing is a vana-
dium–titanium oxide catalyst that shows high selec-
tivity in the temperature range of 110–140°С [20].
Microbiological FA conversion to methanol and for-
mic acid catalyzed by a highly active enzyme, dis-
mutase [21], is also known.
Supported catalysts are widely used to obtain valu-
able products [1–6], while physicochemical studies of
the nature of active phases allows us to improve the
activity and selectivity of catalysts and replace their
expensive components [7–11]. Formaldehyde is a
multi-tonnage product, so the design of new, more
effective means of its synthesis using nanosize and
hybrid materials as catalysts [12–14] is highly
required. The subsequent synthesis of valuable prod-
ucts from formaldehyde is a most important problem,
but its production is the key step. Formaldehyde is
currently produced in industry in two ways [15]. A sil-
ver or copper catalyst and a rich mixture of methanol
and air are used in the first classic variant, where waste
gases are 18–20% hydrogen and less than 1% oxygen,
along with small amounts of methane and carbon
oxides. In the second way, where oxide catalysts (e.g.,
Fe and Mo oxides) are employed, poor mixtures of
methanol and air are used. Waste gases then contain
unreacted oxygen and virtually no hydrogen. Nonoxi-
dative methanol dehydrogenation on zinc-copper cat-
alysts at 600°C has yet to be thoroughly developed, but
it is promising because it allows water-free formalde-
hyde to be produced.
The aim of this work was to determine the depen-
The catalytic formaldehyde (FA) hydrogenation dence of product distribution of the formaldehyde
reaction remains virtually unstudied. Industrial prac- hydrogenation reaction on the nature of the carrier
tice shows that the hydrogenation of higher aldehydes and supported metal for the catalysts, which are most
(e.g., butanal and pentanal) is of more interest. The promising in the reactions of carbon oxides. To
most promising catalysts of these processes are mixed explain the results of our catalytic experiments, ther-
copper–zinc–chromium oxides [16]. In contrast, dif- modynamic calculations of equilibrium concentra-
ferent reactions involving FA, i.e., production of phe- tions of products and reactants are performed for the
nol–formaldehyde resins and other valuable organic side reactions giving different oxygenates in FA hydro-
products are now being widely studied, along with genation.
1670

EFFECT OF THE NATURE OF THE CATALYST ON CATALYTIC ACTIVITY
1671
Catalytic Testing
kmol
1.0
A mixture of hydrogen and formaldehyde at atmo-
spheric pressure was fed into a flow reactor in the form
of a quartz tube 7 mm in diameter. A saturator was
positioned upstream of the reactor, charged with para-
formaldehyde, and heated to 170°C. H2 was then fed
through it at a rate of 10 mL/min. The catalyst charge
was 1 cm3. The molar ratio was H2/CH2O = 5/1. A
trap cooled to −10°C was placed at the reactor’s outlet
to condense the liquid products. The gas at the trap
output was analyzed on a 3700 model chromatograph
(NPO Granat) equipped with two columns packed
HayeSep-Q (H2 + СО, CH4, СО2, С2) and 5A molec-
ular sieves (H2, CH4, СО). Liquid products were ana-
lyzed on the same chromatograph equipped with a
flame-ionization detector, using an SE-30 capillary
column (50 m) in the isothermal mode at 65°C. The
carrier gas was helium.
H2(g) CO(g)
0.9
~
~
0.1
CH2O(g)
200
0
400
600
800
1000
T, °C
Fig. 1. Thermodynamic equilibrium concentrations of
products and reactants in the reaction CO + H = CH O
at 100 atm.
2
2
EXPERIMENTAL
Catalysts and Their Preparation
For our investigations, we selected a number of the
catalysts which are most promising in carbon oxides
hydrogenation.
Thermodynamic Calculations
Fe–K Alloyed
Thermodynamic calculations of the equilibrium
concentrations of the reactants and products in differ-
ent direct and accompanied reactions were performed
using the HSC-4 computer program designed by Hal-
dor Topsøe company.
Conventional catalyst for the Fischer–Tropsch
(F–T) process was prepared by alloying iron oxide
(magnetite) with chemical promoter K2O and struc-
tural promoters MgO and Al2O3 in an electric-arc fur-
nace at 1650°C. The specific surface measured via
BET method was 95 m2/g.
RESULTS AND DISCUSSION
Table 1 presents the results from formaldehyde
(FA) catalytic conversion in mixtures with hydrogen
on the investigated catalysts.
СuО–ZпО–Аl2О3
Industrial methanol synthesis catalyst (C-79-7GL,
Süd Chemie) with the composition 56% CuO,
32% ZnO, and 12% Аl2О3 was used. The specific sur-
It should be noted that on all of the investigated
catalysts, the main reaction was formaldehyde decom-
position to carbon oxides (CO and CO2). The selectiv-
ity toward carbon oxides was quite high (50–80%).
This agrees with our thermodynamic calculations of
the equilibrium concentrations presented in Fig. 1 for
the products and reactants in the reversible reaction
CO + H2 = CH2O.
face of the catalyst was 160 m2/g.
2% Au/S–ZrO2
Industrial catalyst of the water-shift reaction
(Chevron Co.), produced according to the procedure
in [22]. The specific surface is 140 m2/g.
It is clear from Fig. 1 that even at an elevated pres-
sure (100 atm), the equilibrium of the reaction was
strongly shifted toward CO formation. The equilib-
rium concentration of formaldehyde was no higher
than 2%. Additional calculations showed that at atmo-
2% Au/Аl2О3
Gold nanoparticles were supported on the surface spheric pressure within the investigated range of tem-
of γ-Al2О3 microspheres (IKT-02-6M, produced by peratures, it is generally measured in hundredths and
thousandths of a fraction of a percent, and the reaction
of the formation FA in that of CO2 hydrogenationis
not thermodynamically favorable. We may therefore
conclude that formaldehyde cannot be considered an
intermediate compound in the reaction of methanol
synthesis from synthesis gas containing CO and CO2.
This is important for understanding the mechanism of
reactions with the participation of CO, CO2, and
hydrogen.
AO Katalizator). The specific surface are of the cata-
lyst was 138 m2/g. The catalyst was prepared accord-
ing to the procedure described in [23] using HAuCl4 as
gold precursor by precipitation with NaOH until
pH 7.0. The obtained suspension was agitated for 1 h at
70°C. The resulting catalyst precursor was collected by
filtration, washed with distilled water, dried in air for
24 h, and calcined at 300°C under an inert atmosphere
for 3 h.
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 92 No. 9 2018

1672
TARASOV
Table 1. Results from formaldehyde conversion in the hydrogenation at atmospheric pressure at the molar ratio
H2/CH2O = 5/1 and GHSV of 720 h−1
Conversion, mol %
Distribution of oxygenates, mol %
,
K
CH2O
СО/СО2
Catalyst
Т, °С
СО
+ СО2
oxyge-
nates
metha- formic
diethyl
formal
%
СН4
С2–С4
ethanol
nol
acid
Fe–K-Alloyed
260
310
360
180
220
260
180
220
260
360
180
220
260
360
66.1
80.2
99.8
50.8
60.4
69.8
66.1
72.6
80.8
45.1
56.3
64.4
60.1
55.6
69.4
61.4
53.2
—
3.1
10.0
8.5
9.3
10.1
2.0
Traces
0.6
1.8
—
—
—
—
—
0.5
2.2
—
15.3
16.1
18.2
25.4
18.1
9.1
52.9
36.6
19.7
16.0
35.0
22.7
25.6
24.6
6.1
7.3
8.2
2.6
3.5
4.8
4.2
5.2
7.0
9.5
2.0
2.4
2.8
3.1
—
—
—
100
100
100
—
—
—
—
—
62.2
85.0
97.8
—
—
—
37.8
15.0
2.2
—
—
—
Traces
7.0
3.1
0.9
2.9
1.8
CuО–ZnO–
Аl2О3
100
100
100
100
100
100
100
90.6
97.8
100
100
—
2% Au/S-ZrO2
10.1
80.9
55.2
58.1
74.2
29.9
19.4
34.5
42.8
9.0
7.1
13.3
15.8
10.1
62.1
67.0
40.5
26.3
24.5
23.0
14.8
5.1
11.8
24.0
30.1
15.4
21.7
Traces
5.7
12.8
21.4
2% Au/Аl2О3
—
0.2
0.8
1.0
0.8
Along with the carbon oxides in the reaction prod- studied for methanol synthesis, as the results pre-
ucts, we observed the formation of different oxygen- sented in Fig. 2 show.
ates such as methanol, ethanol, formic acid, diethyl
It is strange that fairly high selectivity toward meth-
formal (DEF) on all the investigated catalysts. The
ane (25%) was observed for the CuO–ZnO–Al2O3
selectivity of their formation depended largely on the
catalyst at a fairly low temperature (180°С), as this is
nature of the catalyst (Table 1). It is obvious from
not characteristic of catalysts for methanol synthesis.
Table 1 that the reaction on the Fe–K alloyed catalyst
As noted earlier, however, FA cannot be an intermedi-
resulted in the preferential formation of ethanol and
ate in synthesizing methanol from CO and H2, and in
diethyl formal—the product of FA and ethanol con-
our case, methane apparently formed through the
densation. The yield of ethanol grew with tempera-
hydrogenation of FA itself, not during the hydrogena-
ture, while the yield of DEF fell. At elevated reaction
temperatures (higher than 310°C), small amounts of
different C1–C4 gaseous hydrocarbons also formed,
%
including the C2–C4 olefins that are precursors of high-
molecular paraffins and olefins in F–T synthesis.
CuO−ZnO−Al2O3
2% Au/Al2O3
2% Au/S−ZrO2
25
Thermodynamic calculations of the equilibrium
concentrations of products and reactants in reaction
CH2О +H2 = С2Н5ОН + H2О confirmed the forma-
tion of ethanol from FA. In the investigated range of
temperatures (180–360°С), the thermodynamics of
this reaction favored the complete conversion of FA to
ethanol.
20
15
10
Along with the main reaction of FA decomposition
to form carbon oxides, the reaction on the CuO–
ZnO–Al2O3 catalyst yielded methanol and methane.
Total conversion took place in the investigated range
of temperatures from 180 to 260°C. The yield of meth-
anol fell with temperature, corresponding to patterns
known from the literature for the methanol synthesis
from CO and H2 (though in our case, methanol
formed via the FA hydrogenation reaction). Note that
this tendency was characteristic of all the catalysts
5
0
150
200
250
300
350
400
T, °C
Fig. 2. Dependences of the methanol yield on temperature
on different catalysts.
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EFFECT OF THE NATURE OF THE CATALYST ON CATALYTIC ACTIVITY
%
1673
kmol
3.0
40
(а)
H2(g)
2% Au/S−ZrO2
2% Au/Al2O3
30
2.0
1.0
CO(g)
20
10
0
CH4(g)
HCOOH(g)
0
200
400
600
800
1000
T, °C
kmol
1.0
150
200
250
300
350
400
T, °C
(b)
HCOOH(g)
CH4(g)
Fig. 4. Dependence of the formic acid yield on tempera-
ture on different catalysts.
0.8
0.2
~
CH2O(g)
H2(g)
~
(180–360°С), the formation of formic acid preferen-
tially occurs during FA hydrogenation, not in the
hydrogenation of the CO that forms during FA
decomposition. The data in Fig. 3 agree with the
experimental results we obtained for Au-containing
catalysts. We can see from Table 1 that along with
formic acid, the products of the reaction on the
2% Au/S−ZrO2 and 2% Аu/Al2O3 catalysts contained
comparable amounts of methane throughout the
investigated range of temperatures (180–360°С). Fig-
ure 4 presents the dependences for the yield of formic
acid on the temperature of the reaction on different Au
catalysts.
0
200
400
600
800
1000
T, °C
Fig. 3. Thermodynamic equilibrium concentrations of
products and reactants in reactions (a) 2CO + 3H =
2
HCOOH + CH and (b) CH O + H = HCOOH + CH
4
2
2
4
at 1 atm.
tion of carbon oxides that form intensely in the pro-
cess. This is important for understand mechanisms of
side reactions.
It is clear that the yield of formic acid on the
2% Au/S−ZrO2 catalyst was very high (43%) at a mod-
erate temperature (180°С). The yield of acid on the
2% Аu/Al2O3 sample the investigated range of tem-
peratures was much lower (around 10%). It is seen that
the yield of formic acid on the 2% Au/S−ZrO2 sample
fell sharply when the temperature was raised to 260°С,
and then stabilized at the level of 10%. The sharp drop
in the yield agrees with the calculated data presented in
Fig. 3, from which we can see that at a temperatures
higher than 200°С the equilibrium of the reaction is
shifted towards formic acid decomposition with for-
mation of CO and H2. Note too that this decomposi-
tion is catalyzed by acid catalysts (e.g., phosphomo-
lybdic acid supported on silica gel [24]), and such sup-
ports as sulfated zirconia in 2% Au/S−ZrO2 have
pronounced acidity [25].
The investigated gold-containing 2% Au/S-ZrO2
and 2% Аu/Al2O3 catalysts catalyzed the reaction of
formic acid formation with high selectivity along with
FA decomposition to form carbon oxides and alcohols
(methanol and ethanol). Note especially that nothing
is known about the formation of formic acid during FA
hydrogenation. According to [15], FA in the hydroge-
nation reaction first converts to methanol, and then to
methane. Note too that the synthesis of formic acid
from carbon oxides according to reactions CO2 + H2 =
HCOOH and СО + H2O = HCOOH is not thermo-
dynamically favorable because the equilibrium in
these reactions is strongly shifted to the left. Our ther-
modynamic calculations show that on the other hand,
formic acid can easily form in the hydrogenation of
both FA (Fig. 3b) and the carbon oxide (Fig. 3a) that
forms during FA decomposition (Table 1). In both
cases, however, methane must surely present in reac-
tion products.
The results presented in Table 1 also show that in
addition to formic acid, ethanol forms on both gold-
The calculated data (Fig. 3) show clearly that in the containing and Fe–K alloyed catalysts. Figure 5 shows
range of temperatures selected for our experiments the dependence of the ethanol yield on the tempera-
RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A Vol. 92 No. 9 2018

1674
%
TARASOV
3. V. P. Ananikov, D. B. Eremin, and S. A. Yakukhnov,
Mendeleev Commun. 27, 425 (2017).
Fe-K alloyed
2% Au/S−ZrO2
2% Au/Al2O3
4. A. V. Tokarev, E. V. Murzina, and J. P. Mikkola,
16
12
8
J. Chem. Eng. 134, 153 (2007).
5. L. M. Kustov, E. D. Finashina, and E. V. Shuvalova,
Environ. Int. 37, 1044 (2011).
6. M. P. Vorob’eva, A. A. Greish, A. V. Ivanov, and
L. M. Kustov, Appl. Catal., A 199, 257 (2000).
7. E. Sulman, V. Doluda, and S. Dzwigaj, J. Mol. Catal. A
278, 112 (2007).
8. V. P. Ananikov, ACS Catal. 5, 1964 (2015).
9. A. Yu. Khodakov, C. Williams, L. M. Kustov, and
V. B. Kazansky, J. Chem. Soc., Faraday Trans. 89, 1393
(1993).
4
0
10. A. V. Ivanov and L. M. Kustov, Ross. Khim. Zh. 44, 21
(2000).
150
200
250
300
350
400
T, °C
11. V. Kanazirev, R. Dimitrova, and G. L. Price, J. Mol.
Catal. 70, 111 (1991).
12. I. P. Beletskaya and L. M. Kustov, Russ. Chem. Rev.
Fig. 5. Dependence of the ethanol yield on temperature on
different catalysts.
79, 441 (2010).
13. E. A. Redina, A. A. Greish, and I. V. Mishin, Catal.
Today 241, 246 (2015).
14. L. M. Kustov and H. W. M. Sachtler, J. Mol. Catal. 71,
ture of the reaction for two Au-containing and Fe–K
alloyed catalysts.
233 (1992).
15. S. K. Ogorodnikov, Formaldehyde (Khimiya, Moscow,
As is seen from Fig. 5, the yield of ethanol on the
Fe−K alloyed catalyst tends toward stable growth
along with temperature, and this agrees with our ther-
modynamic calculations. On Au-containing catalysts
supported on different carriers, this tendency ends
abruptly at temperatures higher than 250°С. C2–C4
hydrocarbons (including ethylene) appeared in the
reaction products at 260 and 360°С, clearly indicating
the reaction of ethanol dehydration to form ethylene.
This was obviously associated with the pronounced
1984) [in Russian].
16. V. M. Evgrashin, A. E. Shkol’nik, and V. M. Pered-
ernin, RF Patent No. 2148433 (2000).
17. Yaobin Li, Z. Changbin, and H. Hong, Catal. Today
281, 412 (2017).
18. E. Ventura-Macias, J. Guerrero-Sanchez, and
N. Takeuchi, Comp. Theor. Chem. 1117, 119 (2017).
19. R. Hirschl, A. Eichler, and J. Hafner, J. Catal. 226, 273
(2004).
acidity of the carriers that were used (2% Au/S−ZrO2 20. E. V. Danilevich, G. Ya. Popova, I. A. Zolotarskii,
A. Ermakova, and T. V. Andrushkevich, Catal. Ind. 2,
and 2% Au/Al2O3), which agrees with the findings in
[25]. In our case, this was most pronounced for the
2% Au/S−ZrO2 catalyst.
320 (2017).
21. I. M. Artsukevich, Vestn. Grodn. Univ. im. Yanki
Kupaly, Ser. 5., No. 2, 142 (2012).
22. A. Kuperman and M. E. Moir, WO Patent
No. 2005005032 (2005).
ACKNOWLEDGMENTS
23. V. V. Smirnov, S. A. Nikolaev, and G. P. Murav’eva,
L. A. Tyurina, and A. Yu. Vasil’kov, Kinet. Catal. 48,
265 (2007).
This work was supported by Russian Science Foun-
dation, project no. 14-50-00126.
24. G. G. Garifzyanova and A. Z. Gainutdinova, Vestn.
REFERENCES
Kazan. Univ. 20, 11 (2017).
25. L. M. Kustov, V. B. Kazansky, F. Figueras, and
1. A. V. Kirilin, A. V. Tokarev, and L. M. Kustov, Appl.
D. Tichit, J. Catal. 150, 143 (1994).
Catal., A 172, 435 (2012).
2. V. P. Ananikov, E. G. Gordeev, and M. P. Egorov,
Translated by S. Lebedev
Mendeleev Commun. 26, 365 (2016).
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