Catalytic hydrogenation of 2,4-dinitroethylbenzene to 2,4- diaminoethylbenzene over Ni/HY catalysts: The solvent effect

Article abstract of DOI:10.1016/j.catcom.2014.02.029

Catalytic hydrogenation of 2,4-dinitroethylbenzene over Ni/HY catalysts in different solvents was studied, which demonstrated that the reaction exhibits the best performance in protic solvents. The reason is hypothesized to be the strong hydrogen-bond interaction between the protic solvents with the reactant, intermediates and product due to their excellent hydrogen-bond donating capability, which favors the desorption of the adsorbed intermediates and product from the catalysts and helps to polarize the NO bonds of the reactant and intermediates. Subsequently, the hydrogenation in the mixed solvents of water and ethanol was investigated, which showed that the reaction can be significantly accelerated by adding water into ethanol and the optimum volume percentage of water is verified to be 40%.

Full text of DOI:10.1016/j.catcom.2014.02.029

Catalysis Communications 50 (2014) 92–96
Contents lists available at ScienceDirect
Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short Communication
Catalytic hydrogenation of 2,4-dinitroethylbenzene to
2,4-diaminoethylbenzene over Ni/HY catalysts: The solvent effect
Bin Ren a,b, Minghui Zhao a,b, Lichun Dong a,b, , Guixian Li
⁎
c,⁎⁎
a
School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, PR China
Key Laboratory of Low-grade Energy Utilization Technologies & Systems of the Ministry of Education, Chongqing University, Chongqing 400044, PR China
School of Petrochemical Technology, Lanzhou University of Technology, Lanzhou 730050, PR China
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 27 June 2013
Received in revised form 26 February 2014
Accepted 28 February 2014
Available online 7 March 2014
Catalytic hydrogenation of 2,4-dinitroethylbenzene over Ni/HY catalysts in different solvents was studied, which
demonstrated that the reaction exhibits the best performance in protic solvents. The reason is hypothesized to be
the strong hydrogen-bond interaction between the protic solvents with the reactant, intermediates and product
due to their excellent hydrogen-bond donating capability, which favors the desorption of the adsorbed interme-
diates and product from the catalysts and helps to polarize the N_O bonds of the reactant and intermediates.
Subsequently, the hydrogenation in the mixed solvents of water and ethanol was investigated, which showed
that the reaction can be significantly accelerated by adding water into ethanol and the optimum volume percent-
age of water is verified to be 40%.
Keywords:
Catalytic hydrogenation
2,4-Dinitroethylbenzene
2,4-Diaminoethylbenzene
Solvent effect
© 2014 Elsevier B.V. All rights reserved.
Mixed solvent
1. Introduction
Catalytic hydrogenation of organic compounds is a typical group of
reactions that are required to carry out in solvents; accordingly, solvent
Liquid-phase reactions over heterogeneous catalysts often involve
the use of solvents, whose selection usually has a crucial impact on
catalytic activity and selectivity [1–5]. An inappropriate solvent may re-
sult in a remarkable decrease in reaction rate and product yield. A signif-
icant number of studies have demonstrated the solvent effect to activate
the reactant by forming hydrogen bond in a variety of organic reactions,
e.g. conjugate addition, cyclocondensation, epoxide phenolysis, and N-
tert-butyloxycarbonylation of amines [6–10]. Khatik et al. [5] studied
the catalyst-free conjugate addition of thiols to α,β-unsaturated carbon-
yl compounds in water, and reported that water can activate the α,β-
unsaturated carbonyl compound and the thiol by forming hydrogen
bonds. Chebolu et al. [6] investigated the selectivity control during the
cyclocondensation of o-phenylenediamine with aldehydes, and found
that the selectivity of 1,2-disubstituted benzimidazoles can be promoted
by using trifluoroethanol or hexafluoro-2-propanol as the solvent due to
the hydrogen-bond-driven electrophilic activation of aldehydes. Kommi
et al. [7] reported that water plays a crucial and indispensable role
through the hydrogen bond driven “synergistic electrophile–nucleophile
dual activation” during the arylaminoarylation/arylaminoalkylation of
o-fluoroanilines.
effect in these reactions has been extensively investigated in literatures
[11–15]. Wan et al. [11] studied the hydrogenation of 2-butanone over
Ru/C catalysts in different solvents and obtained an exceptionally high
activity in protic solvents. Wolfson et al. [12] investigated the asymmet-
ric hydrogenation of methyl acetoacetate over Ru–diphosphine com-
plexes and found that the reaction in alcoholic solvents is much faster
than that in aprotic solvents. Bertero et al. [13] reported a similar obser-
vation for the liquid-phase catalytic hydrogenation of acetophenone
over Ni catalysts. They explained the high activity in alcoholic solvents
by the dissociative chemisorption of alcohols on Ni surface to generate
extra active hydrogens, and the polarized activation of the C = O
bonds of ace-tophenones by forming hydrogen bonds with alcohols.
Akpa et al. [14] and Kluson et al. [15] demonstrated that the hydrogena-
tion of carbonyl groups are particularly efficient with the presence of
water, the reason of which was believed to be the active hydrogens gen-
erated by the dissociative chemisorption of water on metal surfaces.
2,4-diaminoethylbenzene (2,4-DAEB) is an important chemical in-
termediate for a variety of applications, of which the most important
is for dyestuff manufacture. The liquid-phase catalytic hydrogenation
of 2,4-dinitroethylbenzene (2,4-DNEB) over supported Ni or Pd cata-
lysts [16–18] is the primary industrial method for 2,4-DAEB production.
In previous studies, we reported a high-efficiency Ni/HY catalyst for the
catalytic hydrogenation of 2,4-DNEB to 2,4-DAEB [19,20]. In this paper,
2,4-DNEB hydrogenation over Ni/HY catalysts was studied in different
types of solvents, i.e. protic solvent (water, ethanol, n-butyl alcohol,
⁎
Correspondence to: L. Dong, School of Chemistry and Chemical Engineering,
Chongqing University, Chongqing 400044, China. Tel.: +86 23 65106051.
⁎⁎ Corresponding author. Tel.: +86 931 2973560.
E-mail addresses: lcdong72@cqu.edu.cn (L. Dong), lgxwyf@163.com (G. Li).
http://dx.doi.org/10.1016/j.catcom.2014.02.029
1566-7367/© 2014 Elsevier B.V. All rights reserved.

B. Ren et al. / Catalysis Communications 50 (2014) 92–96
93
CH2CH3
formamide), aprotic polar solvent (tetrahydrofuran, dimethyl formam-
ide, ethyl acetate) and apolar solvent (benzene, toluene, hexane). The
results demonstrated that hydrogenation exhibits the best performance
in the protic solvents. The addition of an appropriate amount of water in
ethanol (formamide) can significantly increase the reaction rate. Conse-
quently, the mixture of ethanol and water (the volume percentage of
water = 40%) is the most suitable solvent for the catalytic hydrogena-
tion of 2,4-DNEB.
NO2
NH2
2A4NEB
3H2
3H2
Ni
Ni
Ni
H2
2. Experimental
CH2CH3
CH2CH3
CH2CH3
2.1. Reagents and materials
NO2
NH2
NO2
2H2
Ni
2,4-DAEB and 2,4-DNEB were purchased from Sinopharm Chemical
Reagent Company (Shanghai, China); 2-ami-no-4-nitroethylbenzene
and 4-ami-no-2-nitroethylbenzene were from Johnson Mattey Compa-
ny (London, UK); HY support (silica:alumina ratio = 5.4, BET surface =
408.93 m2/g) was from Nankai University Catalyst Co. Ltd. (Tianjin,
China); ethanol was purchased from Anhui Ante Food Company Co.,
Ltd. (Suzhou, Anhui Province, China); n-butyl-alcohol (NBA), benzene,
dimethyl formamide (DMF), hexane were from Chongqing Chuandong
Chemical Co., Ltd. (Chongqing, China); tetrahydrofuran (THF) and tolu-
ene were from Tianjin FuYu Fine Chemical Co., Ltd. (Tianjin, China);
ethyl acetate (EtOAc) and formamide were from Chengdu Kelong
Chemical Reagent Company (Chengdu, Sichuan Province, China);
Ni(NO3)2·6H2O and (NH4)2CO3 were from Tianjin Yatai Co. Ltd. (Tianjin,
China). All the reagents are of analytical grade and were used without
further purification.
NO2
2,4-DNEB
NH2
2,4-DAEB
NHOH
4HA2NEB
3H2
3H2
Ni
CH2CH3
Ni
NH2
NO2
4A2NEB
Fig. 1. The schematic diagram of the catalytic hydrogenation of 2,4-DNEB to 2,4-DAEB.
2.2. Catalyst preparation
DNEB and the intermediates (2A4NEB or 4A2NEB) over Ni/HY catalysts
via a nitro group [17] as well as the dissociative chemisorption of H2 to
generate active hydrogens; the reduction of the adsorbed nitro group to
amino group by the active hydrogens, through which, the product and
intermediates are generated; the desorption of 2,4-DAEB and the inter-
mediates from the catalysts. Consequently, the hydrogenation is affect-
ed by the adsorption of 2,4-DNEB and the intermediates on Ni/HY
catalysts, the reduction of the nitro groups as well as the desorption of
the intermediates and 2,4-DAEB from the catalysts. Moreover, the re-
duction of 2,4-DNEB to 2A4NEB could possibly go through the interme-
diate of 4-hydroxylamino-2-nitroethylbenzene (4HA2NEB) as showed
in Fig. 1, however, the percentage of 2,4-DNEB converting to 4HA2NEB
is very small (less than 1%), it is rational to neglect its effect during the
discussion of the hydrogenation mechanism [16].
Ni/HY catalyst was prepared by the conventional precipitation
method. HY support was firstly pretreated at 773 k for 4 h, then put
into a specific amount of Ni(NO3)2·6H2O solution (1.0 mol/L). After stir-
ring the suspension at 333 K for 1 h, a same volume of (NH4)2CO3 solu-
tion (1.0 mol/L) was added drop-wisely. Afterwards, the mixture was
continuously stirred at 333 K for 22 h. The resulting solid was subse-
quently filtered, washed, and dried at 333 K overnight, and then milled
and screened to obtain the expected catalysts.
2.3. Catalytic reaction
Under a H2 atmosphere and in a fixed-bed reactor, the catalysts were
reduced for 3 h at 773 K, and then cooled to room temperature. Subse-
quently, H2 was switched to N2 containing 0.7% O2, under which, the
catalysts were surface-passivated to prevent their rapid oxidation
when suddenly exposing to the air.
3.2. Catalytic hydrogenation in pure solvents
The hydrogenation was carried out in a stainless steel reactor
equipped with a magnetic stirrer. After 5 g 2,4-DNEB, 0.5 g Ni/HY cata-
lysts and 300 ml solvent were added, the reactor was heated to and
thermostated at 363 K under a H2 atmosphere (2.2 MPa) and stirring
(750 rpm). During the reaction, the reaction liquid was sampled regu-
larly and analyzed by using GC (Tianmei, GC 7890II) and GC–MS
(Agilent 6890/5973 N).
In this study, the hydrogenation in ten solvents was compared,
which could be classified into three categories: protic solvents (water,
ethanol, n-butyl alcohol, formamide), aprotic polar solvent (THF, DMF,
Table 1
Polarity, hydrogen-bond donating and accepting parameters of the solvents [33,34].
Solvent
Z
ET(30)
α
β
3. Results and discussion
Ethanol
NBA
Water
Formamide
DMF
THF
EtOAc
Benzene
Toluene
Hexane
79.6
77.7
95
83.3
68.4
58.8
64.0
54.0
56.1
–
51.9
48.6
63
56.6
43.8
37.4
38.1
34.3
33.9
31.1
0.86
0.79
1.17
0.71
0
0
0
0
0
0.75
0.84
0.46
0.48
0.69
0.55
0.45
0.10
0.11
0
3.1. Reaction mechanism
The hydrogenation of 2,4-DNEB to 2,4-DAEB (Fig. 1) over Ni/HY cat-
alysts can occur in two routines [16,17]. In the first routine, the ortho-
nitro group was firstly reduced to generate the intermediate: 2-
amino-4-nitroethylbenzene (2A4NEB); while in the second routine,
the para-nitro group was firstly reduced to generate 4-amino-2-
nitroethylbenzene (4A2NEB). In either routine, the reaction includes
several steps as most of the catalytic reactions: the adsorption of 2,4-
0
Note: Z, ET(30): Dimroth–Reichardt's polarity parameter, α: Hydrogen-bond donating
parameter, β:Hydrogen-bond accepting parameter.

94
B. Ren et al. / Catalysis Communications 50 (2014) 92–96
Ethanol
NBA
Formamide
Water
THF
DMF
EtOAc
Benzene
Toluene
Hexane
ethyl acetate), and apolar solvent (benzene, toluene, hexane). The po-
larity and hydrogen-bond donating/accepting parameters of the sol-
vents are listed in Table 1, which shows that the protic solvents
possess the highest polarity (indicated by the Z and ET(30) parameters)
as well as the highest hydrogen-bond donating capability (indicated by
the α value), while their hydrogen-bond accepting capability (indicated
by the β value) is not always higher than that of the aprotic polar sol-
vents. Moreover, 2,4-DNEB has good solubility in all the solvents but
water.
Figs. 2 and 3 compared 2,4-DNEB conversion and 2,4-DAEB yield of
the hydrogenation in different solvents at different reaction time. The
results showed that the reaction exhibits good performance in the
protic solvents; 2,4-DNEB conversion and 2,4-DAEB yield could reach
nearly 100% in less than 70 min and 135 min, respectively, in all the
protic solvents. In contrast, the catalytic reaction exhibits poor perfor-
mance in the aprotic polar solvents and apolar solvents. 2,4-DNEB con-
version and 2,4-DAEB yield in the apolar solvents can only reach around
65% and 25% after 240 min, and even worse, those in polar aprotic sol-
vents are only around 38% and 5% after 240 min, respectively. Table 1
shows that all the polar aprotic solvents have higher polarity than
apolar solvents and equivalent and two polar aprotic solvents (DMF
and THF) have even higher hydrogen-bond accepting capability than
some protic solvents (water and formamide). The experimental results
demonstrated that the best performance of 2,4-DNEB hydrogenation in
protic solvents is not due to their polarity and hydrogen-bond accepting
capability, but closely correlated with their higher hydrogen-bond do-
nating capability.
100
80
60
40
20
0
0
30
60
90 120 150 180 210 240
Time (min)
Fig. 3. 2,4-DAEB yield of the catalytic hydrogenation in different solvents.
absorption of ethanol and water does not play a significant role in this
reaction [29].
For clarifying the diffusion effect in the hydrogenation, the reactions
were also carried out at the diffusion-free condition, in which, a small
amount of catalysts (10 mg) was used to limit the conversion of 2,4-
DNEB lower than 5%. The results in Fig. 4 demonstrated that the reaction
exhibits the same trend at the diffusion-free condition as that in Figs. 2
and 3, i.e. the reaction exhibits the best performance in protic solvents,
while the poorest performance in the aprotic polar solvents [11].
As discussed in the reaction mechanism, the efficient hydrogenation
of 2,4-DNEB requires the prompt desorption of the intermediates and
2,4-DAEB from the catalysts. Since hydrogen bonds can be easily formed
between the intermediates and product with the protic solvents due to
their excellent hydrogen-bond donating capability [21], a strong inter-
action lies between them, which is beneficial to the desorption of the in-
termediates and 2,4-DAEB from the catalysts and therefore the catalytic
hydrogenation [22]. Moreover, the protic solvents can interact with the
adsorbed nitro groups of 2,4-DNEB and the intermediates by forming
hydrogen bonds, which helps to polarize the N = O bonds and makes
them easy to be attacked by the active hydrogens on the catalyst [22].
Water has better hydrogen-bond donating capability among the protic
solvents. The low hydrogenation rate in water is mainly due to the
low solubility of 2,4-DNEB in water.
It has been reported that water [23] and ethanol [24–27] can be
absorbed on Ni catalysts dissociatively to generate active hydrogens, fa-
cilitating the hydrogenation [28]. In order to verify this hypothesis, ex-
periments of the catalytic hydrogenation of 2,4-DNEB were carried out
with the same conditions except that of replacing H2 with N2. The re-
sults showed that after 180 min, 2,4-DNEB exhibits a negligible conver-
sion in both water and ethanol, indicating that the dissociative
3.3. Hydrogenation in mixed solvents
In this section, we examined the hydrogenation of 2,4-DNEB over Ni/
HY catalysts in the mixed solvents of water and ethanol with different
water content with the intention to overcome the low solubility of
2,4-DNEB in water. In the mixed solvents, the hydrogenation exhibits
better performance than that in pure water and ethanol, indicated by
the higher reaction rate. Fig. 5 shows that the time required to reach
equilibrium (TRE) for the hydrogenation, at which 2,4-DAEB yield
reaches nearly 100%, was significantly decreased in the mixed solvents
compared with that in pure water and ethanol. The mixed solvents
with the volume percentage of water = 40% leads to the best hydroge-
nation performance, in which it only takes 16 min for the 2,4-DAEB
yield to reach equilibrium, 22% of the TRE in pure ethanol. However,
when the volume percentage of water in the mixed solvents exceeds
40%, the rate of 2,4-DNEB hydrogenation decreases with an further in-
crease in water content due to the decrease of 2,4-DNEB solubility in
the mixed solvents. A similar phenomenon was also found for the
mixed solvents of water and formamide (inset in Fig. 5), where the
5
Ethanol
Ethanol
100
80
60
40
20
0
NBA
Formamide
Water
THF
DMF
EtOAc
Benzene
Toluene
Hexane
NBA
Formamide
Water
THF
DMF
EtOAc
Benzene
Toluene
4
3
2
Hexane
1
0
0
30
60
90 120 150 180 210 240
0
10
20
30
40
50
60
Time (min)
Time (min)
Fig. 2. 2,4-DNEB conversion of the catalytic hydrogenation in different solvents.
Fig. 4. 2,4-DNEB conversion of the catalytic hydrogenation at diffusion-free conditions.

B. Ren et al. / Catalysis Communications 50 (2014) 92–96
95
80
70
60
50
40
30
20
10
0
4. Conclusion
120
100
80
60
40
20
0
Catalytic hydrogenation of 2,4-DNEB to 2,4-DAEB over Ni/HY cata-
lysts in different solvents was studied, which demonstrated that the re-
action exhibits the best activity in protic solvents, i.e. ethanol, NBA,
formamide and water, and even the low solubility of 2,4-DNEB in
water. The reason is hypothesized to be the stronger hydrogen-bond in-
teraction between the protic solvents with the reactant, intermediates
and product, which facilitates the desorption of intermediates and prod-
uct from the catalysts and helps to polarize the N_O bonds of the reac-
tant and intermediates adsorbed on the catalysts. Subsequently, the
hydrogenation in the mixed solvents of water and ethanol was investi-
gated, and the experimental results showed that the reaction can be sig-
nificantly accelerated by adding water into ethanol and the optimum
volume percentage of water was demonstrated to be 40%.
0
10
20
30
40
Water Content (%)
0
10
20
30
40
50
Water Content (%)
The current study is, however, limited by the fact that we were not
able to give some direct experimental proofs confirming the proposed
mechanism of the solvent effect. Therefore, it is a natural extension of
this study by using in-situ IR to confirm the H-bond between the reac-
tant, intermediates and product with the solvent or comparing the hy-
drogenation performance in D2O with that in H2O [7].
Fig. 5. TRE of the catalytic hydrogenation in the mixed solvent of water and ethanol (inset:
TRE of the catalytic hydrogenation in the mixed solvent of water and formamide).
hydrogenation exhibits higher activity in the mixed solvents than that
in pure water and formamide.
The mixed solvents of water and ethanol (or formamide), on one
side, have a better solubility of 2,4-DNEB than water, on the other
side, possess higher hydrogen-bond donating capability than ethanol
(or formamide). Consequently, the mixed solvents have a stronger
hydrogen-bond interaction with the reactant, intermediates and prod-
uct, which enhances the hydrogen-bond driven polarization of the
N_O bonds of the adsorbed nitro group and favors the desorption of
the adsorbed intermediates and product from the catalysts.
Acknowledgment
This work is financially supported by the National Science Founda-
tion of China (21176270,51272296).
Appendix A. Supplementary data
Another possible reason why the addition of water can signifi-
cantly accelerate the hydrogenation is that it can facilitate the diffu-
sion of active hydrogens on the Ni/HY catalyst [30,31]. Our study has
demonstrated that in the 2,4-DNEB hydrogenation over Ni/HY cata-
lysts, there exists obvious “hydrogen spillover” effect (please see
the supporting material), while previous studies have demonstrated
that the addition of water can elevate the mobility of bridging hy-
droxyl on the catalyst surface and promote the transport of “spill-
over” hydrogens between Ni particles across the HY surface [31].
Accordingly, the addition of water can facilitate the transport of ac-
tive hydrogens on the Ni/HY catalysts, which is crucial to increase
the hydrogenation activity [32].
The same observation was also demonstrated in the hydrogenation
of other aromatic nitro-compounds, i.e. paranitrotoluene (PNT), m-
nitrophenol (MNP), and o-nitroaniline (ONA) over the Ni/HY catalyst.
The experimental results (Fig. 6) showed that all the three reactions re-
quire about 30 min to reach equilibrium when pure ethanol was used as
the solvent. However, when the mixed solvents of ethanol and water
with the volume percentage of water = 40% were used, the reactions
were completed within 10 min.
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.catcom.2014.02.029.
References
[1] M. Hronec, K. Fulajtarová, T. Liptaj, Appl. Catal. A Gen. 437–438 (2012) 104–111.
[2] L. Vanoye, M.L. Zanota, A. Desgranges, A. Favre-Reguillon, C.D. Bellefona, Appl. Catal.
A Gen. 394 (2011) 276–280.
[3] C.E. Ramachandran, H. Du, Y.J. Kim, M.C. Kung, J. Catal. 253 (2008) 148–158.
[4] T. Kim, R.S. Assary, H. Kim, C.L. Marshall, D.J. Gosztola, L.A. Curtiss, P.C. Stair, Catal.
Today 205 (2013) 60–66.
[5] G.L. Khatik, R. Kumar, A.K. Chakraborti, Org. Lett. 8 (2006) 2433–2436.
[6] R. Chebolu, D.N. Kommi, D. Kumar, N. Bollineni, A.K. Chakraborti, J. Org. Chem. 77
(2012) 10158–10167.
[7] D.N. Kommi, P.S. Jadhavar, D. Kumar, A.K. Chakraborti, Green Chem. 15 (2013)
798–810;
D.N. Kommi, D. Kumar, K. Seth, A.K. Chakraborti, Org. Lett. 15 (2013) 1158–1161;
D.N. Kommi, D. Kumar, A.K. Chakraborti, Green Chem. 5 (2013) 756–767;
D.N. Kommi, D. Kumar, R. Bansal, R. Chebolu, A.K. Chakraborti, Green Chem. 14
(2012) 3329–3335.
[8] I. Vilotijevic, T.F. Jamison, Science 371 (2007) 1189–1192.
[9] N. Parikh, D. Kumar, S.R. Roya, A.K. Chakraborti, Chem. Commun. 47 (2011)
1797–1799.
[10] S.V. Chankeshwara, A.K. Chakraborti, Org. Lett. 8 (2006) 3259–3262.
[11] H.J. Wan, A. Vitterb, R.V. Chaudhari, B. Subramaniam, J. Catal. 309 (2014) 174–184.
[12] A. Wolfson, I.F.J. Vankelecom, S. Geresh, P.A. Jacobs, J. Mol. Catal. A Chem. 198 (2003)
39–45.
Ethanol
Mixed solvent
[13] N.M. Bertero, A.F. Trasarti, C.R. Apesteguía, A.J. Marchi, Appl. Catal. A Gen. 394
(2011) 228–238.
30
[14] B.S. Akpa, C. D'Agostino, L.F. Gladden, K. Hindle, H. Manyar, J. McGregor, R. Li, M.
Neurock, J. Catal. 289 (2012) 30–41.
[15] P. Kluson, L. Cerveny, Appl. Catal. A Gen. 128 (1995) 13–31.
[16] R.V. Malyala, R.V. Chaudhari, Ind. Eng. Chem. Res. 38 (1999) 906–915.
[17] M.V. Rajashekharam, D.D. Nikalje, R. Jaganathan, R.V. Chaudhari, Ind. Eng. Chem.
Res. 36 (1997) 592–604.
[18] G. Neri, M.G. Musolino, C. Milone, S. Galvagno, Ind. Eng. Chem. Res. 34 (1995)
2226–2231.
[19] G.X. Li, X.M. Zhang, B. Ren, C.N. Patent 102240571A, 2011 (in Chinese).
[20] G.X. Li, Y.D. Xu, X.M. Zhang, B. Ren, C.N. Patent 102909047A, 2013 (in Chinese).
[21] J.B. Ning, J. Xu, J. Liu, H. Miao, H. Ma, C. Chen, X.Q. Li, L.P. Zhou, W.Q. Yu, Catal.
Commun. 8 (2007) 1763–1766.
25
20
15
10
5
[22] N. Yao, J.X. Chen, J.X. Zhang, J.Y. Zhang, Catal. Commun. 9 (2008) 1510–1516.
[23] B.W. Callen, K. Griffiths, R.V. Kasza, M.B. Jensen, P.A. Thiel, J. Chem. Phys. 97 (1992)
3760–3774.
0
PNT
MNP
ONA
[24] A.R. Alemozafar, R.J. Madix, J. Phys. Chem. 109 (2005) 11307–11313.
[25] G. Blyholder, W.V. Wyatt, J. Phys. Chem. 70 (1966) 1745–1750.
[26] S.C. Street, A.J. Gellman, Surf. Sci. 372 (1997) 223–238.
Fig. 6. TRE of the hydrogenation of other aromatic nitro-compounds in the mixed solvent
and pure ethanol.

96
B. Ren et al. / Catalysis Communications 50 (2014) 92–96
[27] J. Zawadzki, M. Wisniewski, J. Weber, O. Heintz, B. Azambre, Carbon 39 (2001)
187–192.
[31] J. Kanellopoulos, C. Gottert, D. Schneider, B. Knorr, D. Prager, H. Ernst, D. Freude, J.
Catal. 255 (2008) 68–78.
[28] F. Alonso, P. Riente, J.A. Sirvent, M. Yus, Appl. Catal. A Gen. 378 (2010) 42–51.
[29] V. Mohan, C.V. Pramod, M. Suresh, K.H.P. Reddy, B.D. Raju, K.S.R. Rao, Catal.
Commun. 18 (2012) 89–92.
[32] L.R. Merte, G.W. Peng, R. Bechstein, F. Rieboldt, C.A. Farberow, L.C. Grabow, W.
Kudernatsch, S. Wendt, E. Lægsgaard, M. Mavrikakis, F. Besenbacher, Science 18
(2012) 889–893.
[30] F. Zaera, G.A. Somojai, Hydrogen Effects in Catalysis: Fundamental and Practical Ap-
plications, Marcel Dekker, New York, 1988.
[33] Y. Marcus, Chem. Soc. Rev. 22 (1993) 409–416.
[34] C. Reichardt, Chem. Rev. 94 (1994) 2319–2358.