One-step catalytic conversion of ethanol into 1,3-butadiene using zinc-containing talc

Article abstract of DOI:10.1016/j.catcom.2015.04.023

Compared with previously reported catalysts, zinc-containing talc exhibited the highest formation rate of 1,3-butadiene in one-step conversion of ethanol at 673 K. Our results showed that talc containing just 1.4 wt.% of ZnO produced 1,3-butadiene at a rate of 1.9 × 10^{- 2} mol g^{- 1} h^{- 1}.

Full text of DOI:10.1016/j.catcom.2015.04.023

One-step catalytic conversion of ethanol into 1,3-butadiene using zinc-
containing talc
Yasumasa Sekiguchi, Sohta Akiyama, Wataru Urakawa, To-ru Koyama,
Akimitsu Miyaji, Ken Motokura, Toshihide Baba
PII:
DOI:
Reference:
S1566-7367(15)00169-7
doi: 10.1016/j.catcom.2015.04.023
CATCOM 4307
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
27 January 2015
19 March 2015
21 April 2015
Please cite this article as: Yasumasa Sekiguchi, Sohta Akiyama, Wataru Urakawa, To-ru
Koyama, Akimitsu Miyaji, Ken Motokura, Toshihide Baba, One-step catalytic conversion
of ethanol into 1,3-butadiene using zinc-containing talc, Catalysis Communications (2015),
doi: 10.1016/j.catcom.2015.04.023
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ACCEPTED MANUSCRIPT
Short Communications
One-step catalytic conversion of ethanol into 1,3-butadiene using
zinc-containing talc
Yasumasa Sekiguchi,a,b Sohta Akiyama,a Wataru Urakawa,a To-ru Koyama,a Akimitsu
Miyaji,a Ken Motokuraa and Toshihide Baba*a
a Department of Environmental Chemistry and Engineering, Interdisciplinary
Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259
Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
b Press Kogyo Co., Ltd., 1-1-1 Shiohama, Kawasaki 210-8512, Japan
Abstract
Compared with previously reported catalysts, zinc-containing talc exhibited the
highest formation rate of 1,3-butadiene in one-step conversion of ethanol at 673 K.
Our results showed that talc containing just 1.4 wt% of ZnO produced 1,3-butadiene
at a rate of 1.9 × 10-2 mol g-1 h-1.
Keywords:
Ethanol
1,3-Butadiene
Zinc-containing talc
High production rate
* Corresponding author. Tel: +81-459245480; Fax: +81-459245441.
E-mail address: tbaba@chemenv.titech.ac.jp
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1. Introduction
Ethanol is mainly produced by fermentation of sugars and is considered one of the
most abundant and sustainable raw materials, especially in view of the CO2
emissions and man-made global warming resulting from the production and
processing of most industrial feedstock. The conversion of ethanol into industrial
materials is an important application of the chemical. Among the converted products,
1,3-butadiene is widely used in the production of polymers and polymer
intermediates such as styrene–butadiene rubbers. At present, 1,3-butadiene (referred
to herein as butadiene) is mainly produced as the isolation product from
naphtha-steam-cracker fractions of paraffinic hydrocarbons for manufacturing
ethylene and its homologues.
The industrial process for the catalytic conversion of ethanol into butadiene was
initially attempted in the 1950s when the US and the former USSR tried to produce
rubber using non-petrochemical-based methods.1 Since then, the effects of reaction
conditions on the conversion of ethanol, butadiene yield, and the selectivity of the
process have been examined using various catalysts to produce butadiene with higher
space–time yield, while various reaction mechanisms have also been proposed for
butadiene formation.1
Corson et al. examined the catalytic activities of various kinds of single, binary,
and ternary metal oxides such as MgO–SiO2, while the effects of operating
parameters on the yield of butadiene were also investigated.2,3 Bhattcharya et al.
investigated various features of ethanol conversion to butadiene by testing binary
metal oxides catalysts such as Al2O3–ZnO.4
In other studies, ternary metal oxides were also used to increase the catalytic
activity and selectivity for butadiene.1,2,5 For example, ZnO, Cr2O3, and Ta2O3
were used as dopants in the binary MgO–SiO2 system. Compared with the catalytic
activity of binary MgO–SiO2, the addition of a small amount of ZnO led to a very
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high yield of butadiene and suppressed ethylene formation.5 Impregnating the
MgO–SiO2 catalyst with NaOH or KOH instead of ZnO also increased the
butadiene yield.6
A recent investigation by Jones et al. focused on bi- and tri-metallic systems
such as zirconia–zinc supported on silica (Zr–Zn/SiO2).7 Among these catalysts,
Zr–Zn/SiO2 showed the highest butadiene yield from ethanol at 648 K. Ag or Cu
supported on the MgO–SiO2 catalyst was also reported to produce butadiene at 673
K.8
The catalysts mentioned above either do not have specific crystal structures or
consist of mixtures of various metal oxides. On the other hand, catalysts that have
specific crystal structures have also generated butadiene from ethanol.9–11 For
example, sepiolite,9,10 which is a fibrous silica–magnesia clay material, and
hydroxyapatite (Ca10(PO4)(OH)2) catalyzed the conversion of ethanol into
butadiene.11
Among the constituents of previously reported catalysts, MgO and SiO2 appear
to play important roles in the production of butadiene with high yield in one-step
conversion of ethanol. Compared with earlier catalysts, we found zinc-containing
talc the most active for butadiene production. Talc is one of the minerals consisting
of magnesium silicate; a model of its structure is shown in Fig. 1. Talc has a 1:2
layered structure, where one octahedral sheet is sandwiched between two
tetrahedral sheets. The unit cell of talc includes six octahedral sites and eight
tetrahedral sites. As shown in Fig. 1, the tetrahedral cations are Si4+, while the
octahedral cations are Mg2+. The Si4+ cations are coordinated to four oxygen atoms
and linked to the adjacent tetrahedron by sharing three corners (the basal oxygen
atoms, Ob). The corners (the tetrahedral apical oxygen atoms, Oa) of all tetrahedra
point toward the same side of the sheet, and they connect the tetrahedral and
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octahedral sheets to form a common plane at the octahedral positions (the
octahedral oxygen atoms, Ooct).
In this work, we examined the catalytic performance of talc in one-step
conversion of ethanol to butadiene, while the effects of the talc structure and the
amount of Zn contained in the talc on catalytic activities were examined.
2. Experimental
Three kinds of talc were obtained from Mizusawa Industrial Chemicals, Ltd.,
Japan,12 which were sold under the trade name MIZUKALIFE P-1. They contained
Zn and are referred to as P1-(I), P1-(II), and P1-(III) in this study. Talc was also
synthesized according to the preparation method reported in Ref. 12; this catalyst is
referred to as P1-(IV). MgO was prepared by calcination of magnesium hydroxide
(Wako Pure Chemicals Co. Ltd., Japan) at 873 K for 6 h, and P1-(IV) was prepared
using the prepared MgO and colloidal silica (Nissan Chemicals Co. Ltd., Japan).
The powder X-ray diffraction (XRD) patterns of P1-(IV) are in good agreement
with that of talc reported in Ref. 12. Furthermore, the XRD patterns of P1-(I),
P1-(II), and P1-(III) are not different from those of P1-(IV), as shown in Fig. 2.
The amounts of Mg, Si, and other elements contained in these materials were
determined by inductively coupled plasma atomic emission spectroscopy. The
compositions of these materials are summarized in Table 1; P1-(I), P1-(II), and
P1-(III) contained Zn, while P1-(IV) did not contain any Zn.
A binary oxide, referred to as MgO–SiO2 in this manuscript, was prepared by
kneading magnesium hydroxide (Wako Pure Chemicals Co. Ltd.) and colloidal
silica (Nissan Chemicals Co. Ltd.) for 3 h at room temperature.13 The resulting gel
was dried at 393 K in an oven for 24 h. The amounts of Mg and Si in MgO–SiO2
are also shown in Table 1.
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The conversion reaction was carried out in a continuous-flow reactor at
atmospheric pressure. Prior to the reaction, all of the catalysts were pressed,
crushed, and sorted into grains using 16-32 mesh. The grains were packed into a
reactor of silica-tubing (internal diameter: 8 mm). The reactor was placed in a
vertical furnace, where they were heated under a nitrogen stream (flow rate of 500
cm3 min-1) at a heating rate 1 K min-1 from room temperature to 673 K. The
catalyst was then heated at the same temperature for 8 h. In the case of MgO–SiO2,
the material was heated at 673 K under air (flow rate of 500 cm3 min-1) at a heating
rate 1 K min-1 from room temperature to 673 K; the catalyst was then heated at the
same temperature for 3 h.
After heating the catalysts, the conversion of ethanol was carried out in a
continuous-flow reactor under atmospheric pressure at 673 K. Ethanol was
continuously delivered by a syringe infusion micro pump to a preheating zone of
the reactor containing quartz sand, where it would be vaporized. The contact time
(W/F) was 5.49 g h mol-1, where W is the weight of the catalyst (g) and F is the total
flow rate (mol h-1). The pressure of ethanol was 101.3 kPa.
To determine the amounts of the reaction products and that of ethanol, effluent
gas was periodically withdrawn in sampling tubes and directly injected into a gas
chromatograph. Thus, ethanol, acetaldehyde, and lower hydrocarbons (with three
carbon atoms) were quantitatively analyzed using a Porapak Q column, while the
hydrocarbons and oxygenates with more than four carbon atoms were also
quantitatively analyzed by a DB-1 column. Furthermore, the amounts of CO and
CO2 were measured by a Unicarbon column. The product distributions are
expressed on a carbon-number basis.
3. Results and Discussion
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The conversion of ethanol was carried out to examine the catalytic performance
of P1-(I) at 673 K. The distributions of all products together with the conversion of
ethanol and the rate of butadiene formation, expressed as moles of butadiene per
g-catalyst per hour (mol g-1 h-1), are summarized in Table 2. The conversion of
ethanol and the rate of butadiene formation were almost constant at about 43% and
1.9 × 10-2 mol g-1 h-1 after 7 h on stream. The predominant products were butadiene
and acetaldehyde. The selectivities for butadiene and acetaldehyde were also
almost constant at about 49 and 22%, respectively, after 7 h on stream.
As shown in Table 2, the other products were ethylene and diethyl ether, while
butenes and butanols were also produced. The main oxygenates produced were
acetaldehyde and diethyl ether, and the distributions of other oxygenates such as
butanols and butyraldehyde were very low. The formation of croton aldehyde was
observed; however, only a very small amount of this compound was detected and
crotyl alcohol (2-butene-1-ol) was not observed. These results show that croton
aldehyde was quickly converted to butadiene via crotyl alcohol. The distributions
of CO2 and CO were very small.
The catalytic activity of P1-(I) gradually decreased after it was on stream for
more than 9 h. Thus, the conversion of ethanol decreased to 35.6% after 9 h and
became 24.2% after 14 h, along with a decrease in the distribution of butadiene. On
the contrary, the distribution of acetaldehyde increased to 30.8% after 9 h, and
further increased to 34.7% after 14 h. The distributions of other reaction products
such as ethylene and butanols remained almost unchanged with increasing reaction
time.
To examine the effect of Zn and the crystal structure on the rate of conversion,
the reaction was carried out using Zn-containing talc P1-(I), P1-(II), and P1-(III),
and Zn-free talc P1-(IV) as catalysts. The results are summarized in Table 3. The
effect of the amount of Zn in talc on the formation rate of butadiene was crucial.
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Thus, the rate of butadiene formation was considerably increased by the presence
of a small amount of Zn in talc. For example, the rate was 1.9 × 10-2 mol g-1 h-1 at
673 K when P1-(I), which contained 1.4 wt% ZnO, was used as a catalyst, while it
was drastically decreased to 7.8 × 10-4 mol g-1 h-1 after 1 h on stream and the
selectivity for butadiene was very low when Zn-free P1-(IV) was used as the
catalyst. The catalytic activity of P1-(IV) also quickly decreased from 28.0%
ethanol conversion after 1 h on stream to 17.2 % after 2 h on stream. These results
show that the very small amount of Zn was essential to generating the catalytic
activity of talc for butadiene formation. In the case of catalytic conversion with
P1-(IV), mostly ethylene was produced, even though the concentrations of Mg and
Si in P1-(IV) were almost equal to those in P1-(I). The very small amount of Zn
also prolonged the catalyst life.
Furthermore, among the Zn-containing talc, the catalytic activity for butadiene
formation strongly depended on the amount of Zn. The rate of butadiene formation
was decreased from 1.9 × 10-2 to 1.3 × 10-2 mol g-1 h-1 when the ZnO content
decreased from 1.4 to 0.3 wt% with the switch from P1-(I) to P1-(II) as the catalyst,
while the composition of other constituents remained almost constant.
The rate of butadiene formation was decreased from 1.3 × 10-2 to 9.1 × 10-3 mol
g-1 h-1 by decreasing the composition of MgO from 34.1 to 32.8 wt% with the
change from P1-(II) to P1-(III), while the composition of ZnO remained constant at
0.3 wt%. These results show that the amounts of Mg and Zn in the talc affected the
catalytic activity for butadiene formation.
Although the catalytic activity strongly depends on the presence of Zn in the
talc, the XRD spectrum of Zn-free P1-(IV) was not different from those of
Zn-containing P1-(I), P1-(II), and P1-(III) as shown on Fig. 2. However, P1-(IV)
showed butadiene selectivity of 25.8% and a butadiene formation rate of 3.2 × 10-4
mol g-1 h-1, which are much lower than the values for P1-(I), P1-(II), and P1-(III).
7

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Therefore, the presence of Zn in talc is presumably an important criterion for
generating high catalytic activity in butadiene formation.
To examine the effect of the crystal structure on the catalytic activity for ethanol
conversion to butadiene, MgO–SiO2 was prepared by kneading magnesium
hydroxide and colloidal silica, according to the procedure reported in Ref. 13.
When the effect of the MgO/SiO2 ratio on the catalytic activity was independently
examined at 673 K and 101.3 kPa of ethanol in this work, the MgO–SiO2 with
MgO/SiO2 ratio of 9.5:0.5 showed the highest catalytic activity for butadiene
formation. The rate of butadiene formation was 2.8 × 10-3 mol g-1 h-1 for up to 3 h
on stream, and it decreased with time and reached 1.7 × 10-3 mol g-1 h-1 after 4 h on
stream.
In Ref. 13, Niiyama et al. reported that MgO–SiO2 (Mg/Si = 3) yielded butadiene
at a rate of 1.7 × 10-3) mol g-1 h-1 at 653 K. This catalytic activity was a little lower
than that of the catalyst of MgO–SiO2 with MgO/SiO2 ratio of 9.5:0.5.
However, the Zn-containing talc showed much higher catalytic activity for
butadiene formation than MgO–SiO2, suggesting that the Zn-containing talc
crystal structure was an important factor for generating the catalytic activity for
butadiene formation.
To further compare the catalytic activity of P1-(I) with those of previously reported
catalysts, their rates of butadiene formation are also summarized in Table 3, together with
the reaction conditions as well as the ethanol conversion, and butadiene yield or
selectivity. The MgO–SiO2 catalysts co-existing with Ag,8 Cu,8 and Na2O 6 showed lower
rates of butadiene formation than P1-(I), P1-(II), and P1-(III). The rate of butadiene
formation using P1-(I) as the catalyst was also higher than those using Zr–Zn/SiO2 and
Al2O3–ZnO. These results again confirm that the Zn-containing talc structure is essential
to the catalytic activity required for butadiene production. However, the XRD patterns do
not show features that can be used to distinguish the structures of P1-(I) and P1-(IV).
8

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These results presumably show that chemical properties of talc, such as the electron
density of O2- or Mg2+, are influenced by the introduction of Zn2+ in talc. At the current
stage, the elucidation of the role of Zn2+ has progressed through measuring the X-ray
photoelectron (XP) spectra of oxygen, Mg, and Si, and magic-angle spinning nuclear
magnetic resonance (MAS NMR) spectra of Mg.
4. Conclusions
Both talc structure and the presence of Zn in talc are crucial to producing
butadiene at a high formation rate in one-step conversion of ethanol. Moreover, Zn
in talc drastically prolongs the catalyst life.
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References
[1] C. Angelici, B. M. Weckhuysen and P. C. A. Bruijnincx, ChemSusChem, 6
(2013) 1595-1614.
[2] B. B. Corson, H. E. Jones, C. E. Welling, J. A. Hinckley and E. E. Stahly, Ind. Eng.
Chem. 42 (1950) 359-373.
[3] B. B. Corson, E. E. Stahly, H. E. Jones and H. D. Bishop, Ind. Eng. Chem. 41 (1949)
1012-1017.
[4] S. K. Bhattacharyya and B. N. Avasthi, Ind. Eng. Chem. Process Des. Dev. 2 (1963)
45-51.
[5] J. M. Brerak, R. Guczalski and J. Wojcik, Acta Chimica Academiae Scientarum
Hungaricae, 50 (1966) 163-166.
[6] R. Ohnishi, T. Akimoto and K. Tanabe, J. Chem. Soc. Chem. Commun. (1985)
1613-1614.
[7] M. D. Jones, C. G. Keir, C. D. Iulio, R. A. M. Robertson, C. V. Williams and D. C.
Apperley, Catal. Sci. Technol. 1 (2011) 267-272.
[8] E. V. Makshina, W. Jarssens, B. F. Sels and P. A. Jacobs, Catal. Today, 198 (2012)
338-344.
[9] V. Gruve, A. Sun and J. J. Fripiat, Catal. Lett., 34, (1995) 359-364.
[10] Y. Kitayama and A. Michishita, J. Chem. Soc. Chem. Commun. (1981) 401-402.
[11] K. Tsuchida, J. Kubo, T. Yoshida, S. Sakuma, T. Takeguchi and W. Ueda, J. Catal.
259 (2008) 183-189.
[12] N. Takahashi, M. Tanaka, T. Sato and T. Endo, Bull. Chem. Soc. Jpn. 67 (1994)
2463-2467.
[13] H. Niiyama, S. Morii and E. Echigoya, Bull. Chem. Soc. Jpn. 45 (1972) 655-659.
10

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Ob
Si4+
Oa,
Mg2+
Ooct
Si4+
Ob
Fig. 1 Model of the structure of talc
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P1-(Ⅰ)
P1-(Ⅱ)
P1-(Ⅲ)
P1-(Ⅳ)
5
10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
2theta(deg)
Fig.2 XRD spectra of talc-based catalysts
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Table 1 Composition and surface area of catalysts used in this work
Composition / wt%
Mg/ Surf
Si ace
MgO SiO2
ZnO Na2O CaO Al2O B2O3
mol area
3
ar
rati
o
/ m2
g-1
P1-(I)
34.1
34.1
32.8
63.6
1.4
0.3
0.3
0.4
0.3
0.2
0.1
0.1
0.2
0.3
0.1
0.1
0.1 3.2/ 390
4.0
P1-(II)
P1-(III)
P1-(IV)
65.0
66.3
0.1 3.1/ 407
4.0
0.1 3.0/ 482
4.0
35.5
64.5 NOa) NOa) NOa) NOa) NOa) 3.3/ 364
4.0
9.5/
0.5
7.3 NOa)
0.3
NOa) NOa) NOa)
285
MgbO) –S
iO2
92.0
a) NO means that the composition was not observed by ICP analysis.
b) MgO–SiO2 was prepared by kneading magnesium hydroxide and colloidal silica.
13

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Table 2 Ethanol conversion, product distribution, and rate of 1,3-butadiene formation using P1-(I) at 673 K
Time on stream / h
C2H5OH conversion / %
Product distribution / C-atm%
1,3-Butadiene
Acetaldehyde
Crotonaldehyde
Ethylene
1
2
3
7
9
11
15
41.8
44.5
43.2
45.7
35.6
25.6
24.2
50.1
21.4
0.2
8.3
8.0
0.2
1.2
3.4
0.3
0.2
5.7
1.0
49.1
22.9
0.2
8.1
8.0
0.2
1.1
3.3
0.1
0.1
5.8
0.8
49.4
23.7
0.2
8.3
7.3
0.2
1.1
3.3
0.2
0.1
4.8
1.4
48.3
21.6
0.2
7.8
7.7
0.3
0.9
3.5
2.2
0
41.8
30.8
0.3
9.2
7.7
0.3
0.6
2.9
1.8
0
38.2
31.9
0.4
8.2
8.0
0.4
1.5
2.9
1.2
0
37.3
34.7
0.4
8.9
7.1
0.3
1.9
3.0
1.0
0
Diethyl ether
Butyraldehyde
Butanols
Butenes
CO
CO2
Other hydrocarbons
Other oxygenates
5.7
1.8
3.1
1.5
4.0
3.3
2.5
2.9
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Rate of 1,3-butadiene
formation
1.9 × 10-2
2.0 × 10-2
1.9 × 10-2
2.0 × 10-2
1.4 × 10-2
8.9 × 10-3
8.2 × 10-3
/ mol g-1 h-1
Reaction conditions: Ethanol pressure = 101.3 kPa; W/F = 5.49 g h mol-1
15

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Table 3 Catalytic activities of MIZUKALIFE P1 and previously reported catalysts
Catalyst
React.
temp.a)
Catal.
weight b)
Ethanol feed rate
Ethanol
conversion c)
1,3-Butadiene yield or
selectivity d)
Rate of 1,3-butadiene
formation
Reference
/ %
/ %
P1-(I)
673 K
673 K
673 K
673 K
673 K
673 K
673 K
0.30 g
0.30 g
0.30 g
0.30 g
0.30 g
0.30 g
0.30 g
5.5 × 10-2 mol h-1
43.2 % (3 h)
45.7% (7 h)
33.1% (3 h)
25.9% (3 h)
23.1% (3 h)
14.1% (7 h)
11.8% (3 h)
49.1% (selectivity)
48.3% (selectivity)
44.5% (selectivity)
38.4% (selectivity)
5.1% (selectivity)
4.8% (selectivity)
25.8% (selectivity)
1.9 × 10-2 mol g-1 h-1
2.0 × 10-2 mol g-1 h-1
1.3 × 10-2 mol g-1 h-1
9.1 × 10-3 mol g-1 h-1
5.5 × 10-4 mol g-1 h-1
3.2 × 10-4 mol g-1 h-1
2.8 × 10-3 mol g-1 h-1
This work
This work
This work
This work
This work
This work
This work
P1-(I)
5.5 × 10-2 mol h-1
5.5 × 10-2 mol h-1
5.5 × 10-2 mol h-1
2.8 × 10-2 mol h-1
2.8 × 10-2 mol h-1
5.5 × 10-2 mol h-1
P1-(II)
P1-(III)
P1-(IV)
P1-(IV)
MgO–SiO2h) (Mg/Si = 9.5:0.5)
Zr (1.5 wt%):Zn(0.5 wt%)/SiO2
Al2O3 (60 wt%):ZnO (40 wt%)
648 K
698 K
1.0 g
0.1 mL min-1
48.0 (1 h)
100 (1 h)
47.9% (selectivity)
55.8% (yield)
1.2 × 10-2 mol g-1 h-1 f)
7
4
(1.0 × 10-1 mol h-1)e)
1.875 mL g-cat-1 h-1
(3.2 × 10-2 mol g-cat-1 h-1)e)
not shown
8.9 × 10-3 mol g-1 h-1 f)
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Ag/MgO - SiO2
673 K
673 K
623 K
553 K
573 K
0.20 g
0.20 g
5.7 × 104 ppm in Ar 20 mL min-1
91.8 (7–8 h)
98.7 (7–8 h)
100 (10 min)
63
49.2% (yield)
0.20 g g-1 h-1
8
8
(Ag/Si = 0.05, Mg/Si = 3)
(2.8 × 10-3 mol h-1)e)
5.7 × 104 ppm in Ar 20 mL min-1
(2.8 × 10-3 mol h-1)e)
3.7 × 10-3 mol g-1 h-1 f)
0.20 g g-cat-1 h-1
Cu/MgO–SiO2
45.4% (yield)
(Cu/Si = 0.05, Mg/Si = 3)
3.7 × 10-3 mol g-1 h-1 f)
1.4 × 10-3 mol g-1 h-1 f)
MgO–SiO2–Na2O (1 wt%)
(MgO/SiO2 = 1)
0.20 g
6.5 × 10-4 mol h-1
87% (yield)
6
Ag–Sepiolite
Not shown
Contact time 75 min
6% (yield) (20 min)
5.2 × 10-4 mol g-1 h-1 f)
9
1.7 × 10-2 mol g-cat-1 h-1 e)
20 mmHg (240 cm3)g)
Mn–Sepiolite
0.30 g
Not shown
27.9% (yield) (30 min)
1.4 × 10-4 mol g-1 h-1 f)
10
a) Reaction temperature in K; b) Catalyst weight in g; c) Ethanol conversion at time on stream shown in parenthesis; d) Selectivity based on carbon
number basis; e) Ethanol feed rate was re-calculated by the authors; f) Rate of 1,3-butadiene formation was re-calculated by the authors; g) Batch
reactor in the gas circulation system
h) MgO–SiO2 was prepared by kneading magnesium hydroxide and colloidal silica.
17