Chemoselective hydrogenation of 3-nitrostyrene over Ag/TiO2-SiO2 catalyst in a flow reactor

Article abstract of DOI:10.1016/j.mencom.2019.09.025

Hydrogenation of 3-nitrostyrene in a flow reactor over silver nanoparticles on TiO₂-modified silica affords 3-vinylaniline with selectivity of 97% at the full conversion of the substrate.

Full text of DOI:10.1016/j.mencom.2019.09.025

Mendeleev
Communications
Mendeleev Commun., 2019, 29, 553–555
Chemoselective hydrogenation of 3-nitrostyrene over Ag/TiO -SiO2
2
catalyst in a flow reactor
Alexey L. Nuzhdin,* Galina A. Bukhtiyarova, Tingting Lin, Evgeny Yu. Gerasimov and Valerii I. Bukhtiyarov
G. K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, 630090
Novosibirsk, Russian Federation. Fax: +7 383 330 8056; e-mail: anuzhdin@catalysis.ru
DOI: 10.1016/j.mencom.2019.09.025
Flow reactor
N+
Hydrogenation of 3-nitrostyrene in a flow reactor over silver
O−
H
H
N
O
H
H
nanoparticles on TiO -modified silica affords 3-vinylaniline
with selectivity of 97% at the full conversion of the substrate.
Ag
2
H2
TiO2
SiO2
Conversion >99.5%
Selectivity 97%
Functionalized anilines are widely used in the manufacture of
pharmaceuticals, agrochemicals, and fine chemicals.
Conventional techniques for their production are based on the
reduction of nitroaromatic compounds with stoichiometric
According to transmission electron microscopy (TEM), the
average diameter of silver nanoparticles in Ag/Al O -A and Ag/
2
3
Al O -H samples was 3.7 and 2.9 nm, respectively. However,
2
3
Ag/SiO -A, Ag/SiO -H andAg/TiO -SiO -A samples comprised
2
2
2
2
amounts of reducing agents, such as iron in acid media, H S or
bigger Ag particles (see Table 1). This can be explained by a
2
NaHS. Hydrogenation of nitroarenes over heterogeneous
catalysts is a more cost-effective and environmentally friendly
alternative for the production of functionalized anilines.
stronger interaction of silver(i) ions with the γ-Al O surface,
2
3
which contributes to a more uniform distribution of the active
1
–3
22
constituent. The use of hydrogen for reduction of silver nitrate
However, chemoselective hydro-genation of the nitro moiety of
a molecule that contains an easily reduced C=C bond (for
example, 3-nitrostyrene) is a challenge.3
supported on TiO -SiO allows one to decrease the calcination
2
2
temperature from 500 to 300°C that provides smaller silver
–5
8,12
particles due to slower sintering. The TEM data of Ag/TiO2-
4
–10
Several catalytic systems containing noble metals (Au,
SiO -H show mainly Ag particles of 1.5–9.5 nm in diameter
2
Pt,3
,4,11
Ag,
12,13
Au–Pt and Pt–Zn ), as well as Co or Fe
14
15
(Figure 1).
1
6,17
particles embedded in mesoporous nitrogen-doped carbon,
The catalytic activity of the silver catalysts was evaluated in the
hydrogenation of 3-nitrostyrene 1 in a packed-bed flow reactor
were proposed for hydrogenation of nitrostyrenes to
corresponding anilines. Silver catalysts such as the Al O - or
‡
using toluene as a solvent. In addition to 3-vinylaniline
2
3
12
TiO -supported silver nanoparticles and Ag@CeO core-shell
2, undesired 3-ethylaniline 3 and the derivatives of azobenzene 4a
and azoxybenzene 4b were observed among the reaction products
2
2
1
3
nanocomposite provide high selectivity in a batch reactor
hydrogenation. Meanwhile, continuous flow synthesis is an
attractive alternative to traditional batch protocols. Potential
benefits of flow chemistry include excellent interfacial mass and
energy transfer properties, suppression of by-product formation
through a better control over reaction parameters, simplified
scaling, and enhanced safety profile.18–20 Here we report on the
hydrogenation of 3-nitrostyrene 1 in a flow reactor over
Table 1 Physico-chemical properties of the catalysts.
Catalyst
Content Tcal/ °Ca
of Ag
S
m g
/
V
cm g
/
Particle size
distribution/
nm
BET
2
pore
3
–1
–1
(wt%)
Ag/Al O -A
1.9
500 (air)
300 (H2)
500 (air)
300 (H2)
500 (air)
300 (H2)
170
172
271
274
256
255
0.62
0.62
0.76
0.77
0.62
0.62
1.5–7.5 (3.7b)
1–5 (2.9b)
2–40
2
3
supported silver catalysts.
Ag/Al O -H
1.9
2
3
Previously, titania,4
–6,12,14
alumina,6–9,12 and silica21 were
Ag/SiO -A
2.0
2
applied to the preparation of supported metal catalysts used for
chemoselective hydrogenation of nitroarenes. However, it is
difficult to form granules from individual titanium dioxide;
Ag/SiO -H
2.0
2–30
2
Ag/TiO
Ag/TiO -SiO -H
-SiO
-A
1.8
1–16
2
2
therefore, we synthesized the TiO -modified silica (TiO -SiO )
1.5–12 (4.2b)
2
2
2
1.8
2
2
support containing 8.8 wt% TiO , with TiO occupying
approximately half of the silica surface.
2
2
a
b
Calcination temperature. Average diameter of Ag nanoparticles.
22
The catalysts containing approximately 2 wt% Ag were
prepared by the incipient wetness impregnation of the support
with an aqueous solution of silver nitrate with a subsequent
drying and calcination in air23 or in hydrogen flow. The catalysts
†
Supported silver catalysts were prepared by impregnating γ-Al O , SiO
2
2
3
and TiO -SiO (grain size of 250–500 μm) with an aqueous solution of
silver nitrate followed by drying at 60 °C in vacuo and calcination in air
at 500 °C or in hydrogen flow at 300 °C for 3 h (for details, see refs. 12,
2
2
2
†
calcined in air and H are denoted as Ag/support-A and Ag/
2
3 and 26). The solids were then cooled to room temperature, purged
support-H, respectively. The physico-chemical characteristics of
the catalysts are given in Table 1.
with N and stored in a glass flask before being used.
2
©
2019 Mendeleev Communications. Published by ELSEVIER B.V.
–
553 –
on behalf of the N. D. Zelinsky Institute of Organic Chemistry of the
Russian Academy of Sciences.

Mendeleev Commun., 2019, 29, 553–555
Table 2 Hydrogenation of 3-nitrostyrene 1 over supported silver catalysts
in a flow reactor. a
Entry Catalyst
Mass of the
catalyst/
mg
T
°C
/
Conversion Selectivity (%)
b
of 1 (%)
2
3
Σ4a,b
42
1
2
3
4
5
6
7
8
9
0
Ag/Al O -A
190
190
195
195
162
163
170
170
170
170
170
80
88
99
50
8
2
3
Ag/Al O -A
90
80
59 18
59 3
23
38
20
1
2
3
Ag/Al O -H
89
2
3
Ag/Al O -H
90
100
97
70 10
71 28
76 23
87 12
2
3
Ag/SiO -A
120
120
120
120
125
110
110
2
Ag/SiO -H
99
1
2
Ag/TiO -SiO -A
98
1
2
2
Ag/TiO -SiO -H
99
96
97
97
92
3
3
1
8
1
2
2
Figure 1 Transmission electron micrograph of the Ag/TiO -SiO -H
Ag/TiO -SiO -H
>99.5
69
<0.5
2
2
2
2
2
catalyst.
1
Ag/TiO -SiO -H
2 2
Scheme 1).2–4 It was found that hydrogenation of
substrate 1 over silver nanoparticles supported on γ-alumina and
silica occurs with low selectivity towards 2 due to the formation of
a large amount of diazenes 4a,b and/or hydrogenation of 2 to 3
11c
Ag/TiO -SiO -H
97
<0.5
(
2
2
a
Reaction conditions: 3-nitrostyrene (0.025 m), toluene, p(H ) = 3.0 MPa,
2
–1
flow rates of the liquid phase and of H were 0.5 and 60 ml min ,
2
respectively. b For the complete filling of the reactor. c Reaction in methanol.
(
Table 2, entries 1–6).
The modification of silica with titanium dioxide and the
conversion of substrate (entries 8–10). Consequently, the
hydrogenation rate of the carbon–carbon double bond on
Ag/TiO -SiO -H is very low under the reaction conditions. The
reduction of active component with hydrogen during the catalyst
preparation ensure the better reaction selectivity. The Ag/TiO2-
SiO -A catalyst provides the formation of 3-vinylaniline with
selectivity of 87% at substrate conversion of 98% (see Table 2,
entry 7). At the same time, the Ag/TiO -SiO -H catalyst
demonstrates excellent selectivity towards 2, which is 96–97% at
conversion of 99–100% (entries 8 and 9). Interestingly, the
selectivity to the desired product is almost not affected by the
2
2
observed chemoselectivity exceeds the results obtained both on
7
,8
the Au/Al O catalysts in a flow reactor and on Ag/Al O3
2
2
3
2
1
2
catalyst in a batch reactor. In addition, the reaction proceeds in
a flow reactor at a much lower temperature than in a batch
2
2
1
2
reactor.
The use of methanol instead of toluene accelerated the
hydrogenation, but the selectivity was low (see Table 2, entries
1
0 and 11). This can be explained by a decrease in the selectivity
NO2
NH2
NH2
H2 (3.0 MPa),
toluene
(a)
+
100
100
99
98
97
96
95
Catalyst
80
60
40
20
Me
1
2
3
(
O)n
N
N
+
4
a,b
0
a n = 0
b n = 1
30
50
70
t/min
90
110
130
Scheme 1
(
b)
‡
The investigation of the catalytic properties was performed using
1
00
100
99
continuous flow device H-Cube Pro™ (Thalesnano, Hungary) equipped
with stainless-steel CatCart®30 reactors of 30 mm in length and 4.0 mm
in inner diameter.7 Before catalytic run, toluene was fed to the reactor
loaded with catalyst (162–195 mg) until the required reaction parameters
were reached. Afterwards, the inlet was switched to the flask filled with a
,8
80
6
4
2
0
0
0
98
0
.025 m solution of 3-nitrostyrene in toluene. This point in time was
chosen as the starting point of the reaction. The catalytic tests were
carried out within the 80–125 °C range with a hydrogen pressure of
97
96
3
6
.0 MPa, where liquid and hydrogen feed rates were set to 0.5 and
−
1
0 ml min , respectively. We found earlier that there was no influence of
0
7
external or internal mass transfer limitations under the conditions used.
The performance of catalyst was evaluated by analysis of the samples
taken 30–34 min after the start of the experiment. The reaction products
were analyzed by GC (Agilent 6890N instrument with a capillary
HP 5-MS column 60 m × 0.32 mm, 0.25 μm) using n-decane as the
internal standard. Identification of the products was performed by GC–
MS (Agilent 7000B Triple Quad System).
30
50
70
90
110
130
t/min
Figure 2 Time dependence of conversion and selectivity to 3-vinylaniline
during hydrogenation of 3-nitrostyrene 1 at 120 °C over the Ag/TiO2-
SiO -H catalyst: (a) fresh sample and (b) regenerated sample.
2
–
554 –

Mendeleev Commun., 2019, 29, 553–555
7
A. L. Nuzhdin, B. L. Moroz, G. A. Bukhtiyarova, S. I. Reshetnikov,
P. A. Pyrjaev, P. V. Aleksandrov and V. I. Bukhtiyarov, ChemPlusChem,
015, 80, 1741.
of 3-nitrostyrene 1 adsorption through nitro group on active
4
,6,9,12
sites
due to competition with methanol molecules. The
2
active sites occupied by solvent molecules probably become
available to the vinyl group of compound 2 that is hydrogenated
yielding product 3.
8 A. L. Nuzhdin, S. I. Reshetnikov, G. A. Bukhtiyarova, B. L. Moroz,
E. Yu. Gerasimov, P. A. Pyrjaev and V. I. Bukhtiyarov, Catal. Lett.,
2
017, 147, 572.
9
S. S. Yakushkin, A. L. Nuzhdin, E. A. Artiukha, P. E. Plyusnin, G. A.
The evolution of the reaction products over the Ag/TiO2-
Bukhtiyarova and O. N. Martyanov, Mendeleev Commun., 2018, 28,
SiO -H catalyst in the course of hydrogenation of 1 showed a
2
5
36.
deactivation of the catalyst with time-on-stream [Figure 2(a)],
1
0 Y. Matsushima, R. Nishiyabu, N. Takanashi, M. Haruta, H. Kimura and
Y. Kubo, J. Mater. Chem., 2012, 22, 24124.
11 Y. Motoyama, Y. Lee, K. Tsuji, S.-H. Yoon, I. Mochida and
H. Nagashima, ChemCatChem, 2011, 3, 1578.
12 K. Shimizu, Y. Miyamoto and A. Satsuma, J. Catal., 2010, 270, 86.
3 T. Mitsudome, Y. Mikami, M. Matoba, T. Mizugaki, K. Jitsukawa and
K. Kaneda, Angew. Chem., Int. Ed., 2012, 51, 136.
which can be explained by the formation of carbonaceous
deposits on the catalyst surface.7
,8,23,24
The rinsing of the spent
–1
catalyst by flowing methanol (1 ml min ) for 30 min results in
the removal of these deposits25 and restores the catalytic activity
1
[Figure 2(b)]. The study of the regenerated catalyst by the
methods of elemental analysis and TEM allows one to conclude
that the leaching of Ag and Ti from this catalyst and the increase
in silver particle size do not occur during the reaction and
regeneration (see Online Supplementary Materials).
1
4 P. Serna, P. Concepcion and A. Corma, J. Catal., 2009, 265, 19.
15 A.Yarulin, C. Berguerand, I.Yuranov, F. Cardenas-Lizana, I. Prokopyeva
and L. Kiwi-Minsker, J. Catal., 2015, 321, 7.
1
1
1
6 D. Formenti, F. Ferretti, F. K. Scharnagl and M. Beller, Chem. Rev.,
019, 119, 2611.
7 P. Zhou, L. Jiang, F. Wang, K. Deng, K. Lv and Z. Zhang, Sci. Adv.,
017, 3, e1601945.
2
In summary, silver nanoparticles supported on TiO -modified
2
silica catalyze highly chemoselective hydrogenation of
2
3
-nitrostyreneinaflowreactor. Selectivitytowards3-vinylaniline
8 K. Masuda, T. Ichitsuka, N. Koumura, K. Sato and S. Kobayashi,
is 97% at the full conversion of the substrate.
Tetrahedron, 2018, 74, 1705.
1
2
2
2
9 M. Irfan, T. N. Glasnov and C. O. Kappe, ChemSusChem, 2011, 4, 300.
0 C. Wiles and P. Watts, Green Chem., 2014, 16, 55.
1 Y. Chen, J. Qiu, X. Wang and J. Xiu, J. Catal., 2006, 242, 227.
2 E.A.Artyukha,A. L. Nuzhdin, G.A. Bukhtiyarova, E.A. Derevyannikova,
E. Yu. Gerasimov, A. Yu. Gladkii and V. I. Bukhtiyarov, Kinet. Catal.,
This study was conducted within the framework of the budget
project no. AAAA-A17-117041710083-5 for G. K. Boreskov
Institute of Catalysis.
2
018, 59, 593 (Kinet. Katal., 2018, 59, 583).
Online Supplementary Materials
23 E.A.Artiukha,A. L. Nuzhdin, G.A. Bukhtiyarova andV. I. Bukhtiyarov,
Supplementary data associated with this article can be found
in the online version at doi: 10.1016/j.mencom.2019.09.025.
RSC Adv., 2017, 7, 45856.
4 F. Cardenas-Lizana, D. Lamey, M. Li, M. A. Keane and L. Kiwi-Minsker,
Chem. Eng. J., 2014, 255, 695.
2
2
5 E. A. Artiukha, A. L. Nuzhdin, G. A. Bukhtiyarova, S. Yu. Zaytsev,
P. E. Pluysnin, Yu. V. Shubin and V. I. Bukhtiyarov, Catal. Sci. Technol.,
References
1
R. S. Downing, P. J. Kunkeler and H. van Bekkum, Catal. Today, 1997,
7, 121.
2
015, 5, 4741.
3
2
6 C. Paun, G. Słowik, E. Lewin and J. Sa, RSC Adv., 2016, 6, 87564.
2
3
4
5
6
F. Cardenas-Lizana and M. A. Keane, J. Mater. Sci., 2013, 48, 543.
H.-U. Blaser, H. Steiner and M. Studer, ChemCatChem, 2009, 1, 210.
P. Serna, M. Boronat and A. Corma, Top. Catal., 2011, 54, 439.
A. Corma and P. Serna, Science, 2006, 313, 332.
K. Shimizu, Y. Miyamoto, T. Kawasaki, T. Tanji, Y. Tai and A. Satsuma,
J. Phys. Chem. C, 2009, 113, 17803.
Received: 18th April 2018; Com. 19/5892
–
555 –