Coupling of ortho-chloronitrobenzene hydrogenation with 1,4-butanediol dehydrogenation over Cu[sbnd]MgO catalysts: A hydrogen free process

Article abstract of DOI:10.1016/j.catcom.2017.02.029

Aiming at an efficient method for the hydrogenation of o-chloronitrobenzene to o-chloroaniline under hydrogen free environment, the reaction was coupled with 1,4-butanediol dehydrogenation over Cu[sbnd]MgO catalysts containing various amounts of copper lo

Full text of DOI:10.1016/j.catcom.2017.02.029

Accepted Manuscript
Coupling of ortho-chloronitrobenzene hydrogenation with
1,4-butanediol dehydrogenation over Cu-MgO catalysts: A
hydrogen free process
Kannapu Hari Prasad Reddy, Young-Woong Suh, Narani Anand,
Burri David Raju, Kamaraju Seetha Rama Rao
PII:
DOI:
Reference:
S1566-7367(17)30080-8
doi: 10.1016/j.catcom.2017.02.029
CATCOM 4957
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
21 September 2016
27 February 2017
28 February 2017
Please cite this article as: Kannapu Hari Prasad Reddy, Young-Woong Suh, Narani Anand,
Burri David Raju, Kamaraju Seetha Rama Rao , Coupling of ortho-chloronitrobenzene
hydrogenation with 1,4-butanediol dehydrogenation over Cu-MgO catalysts: A hydrogen
free process. The address for the corresponding author was captured as affiliation for all
authors. Please check if appropriate. Catcom(2016), doi: 10.1016/j.catcom.2017.02.029
This is a PDF file of an unedited manuscript that has been accepted for publication. As
a service to our customers we are providing this early version of the manuscript. The
manuscript will undergo copyediting, typesetting, and review of the resulting proof before
it is published in its final form. Please note that during the production process errors may
be discovered which could affect the content, and all legal disclaimers that apply to the
journal pertain.

ACCEPTED MANUSCRIPT
Coupling of ortho-chloronitrobenzene hydrogenation with 1,4-butanediol
dehydrogenation over Cu-MgO catalysts: A hydrogen free process
Kannapu Hari Prasad Reddya,b,c,*, Young-Woong Suhb,c,*, Narani Ananda, Burri David Rajua,
Kamaraju seetha Rama Raoa
a Catalysis, Indian Institute of Chemical Technology, Hyderabad-500007, India
b Department of Chemical Engineering, Hanyang University, Seoul 04763, Republic of Korea
c Research Institute of Industrial Science, Hanyang University, Seoul 04763, Republic of Korea
*Corresponding author.
E-mail address: kannapuhari@gmail.com (H.P.R Kannapu), ywsuh@hanyang.ac.kr (Y.-W. Suh).
Abstract
Aiming at an efficient method for the hydrogenation of o-chloronitrobenzene to o-chloroaniline under
hydrogen free environment, the reaction was coupled with 1,4-butanediol dehydrogenation over Cu-
MgO catalysts containing various amounts of copper loadings (5–20 wt%). o-Chloroaniline and γ-
butyrolactone were the main products with the yield of 85% and 90%, respectively. The main
advantage of the coupling process was that the hydrogenation reaction was conducted at the lower
temperature (523 K) without external hydrogen supply when compared to the independent
hydrogenation (648 K). Catalysts were characterized using various analytical techniques such as
BET, XRD, N2O pulse chemisorption, TPR-H2, XPS and CHNS analysis. From N2O characterization
results, it was found that 10 wt% Cu-MgO catalyst containing more surface Cu species (Cu0/Cu+1)
showed a superior performance in the coupling process.
Keywords:
Cu-MgO; ortho-chloronitrobenzene; ortho-chloroaniline; in-situ hydrogen; 1,4-
butanediol; γ-butyrolactone
– 1 –

ACCEPTED MANUSCRIPT
1. Introduction
Due to enormous use of aromatic haloamines in the chemical industry especially for the
manufacture of herbicides, dyes, drugs, and pesticides, the haloamines synthesis from
halonitrobenzenes is of great importance [1–9]. Typically, the hydrogenation of ortho-
chloronitrobenzene (o-CNB) to ortho-chloroaniline (o-CAN) has been studied extensively
using various precious metals such as platinum, palladium, nickel, rhodium, ruthenium and
iridium [1–9]. Moreover, o-CNB hydrogenation is carried out under external hydrogen at
high pressures and high temperatures, making the process very complex and expensive in the
industrial point of view. The hydrodechlorination and ring hydrogenation of o-CNB are major
side reactions yielding aniline and cyclohexylamine, respectively. Hence, in order to avoid
operation problems and increase the yield of o-CAN, an alternative method, i.e., an
economically cheap and environmentally friendly method has to be developed.
Currently, the coupling of hydrogenation and dehydrogenation [10] is a promising method
to conduct the hydrogenation reaction without external hydrogen. In this method two
reactions can be carried out simultaneously under the same reaction condition over the same
catalyst bed. Copper based catalysts have been tested in this coupling reaction [10–14]. To
the best of our knowledge, selective o-CNB hydrogenation to o-CAN has not been reported
over copper catalysts using 1,4-butanediol (BDO) as a hydrogen donor. Here, BDO
cyclodehydrogenation can produce γ-butyrolactone (GBL) along with 2 moles of hydrogen.
Also, GBL can use as green solvent [12, 13].
Herein, we have studied the coupling of o-CNB hydrogenation and BDO
dehydrogenation for the simultaneous synthesis of o-CAN and GBL over Cu-MgO catalysts
under hydrogen free atmosphere. All catalysts developed by co-precipitation were
characterized using various analytical techniques such as BET, N2O pulse chemisorption,
XRD, TPR-H2, TEM, XPS and CHNS analysis.
– 2 –

ACCEPTED MANUSCRIPT
2. Experimental
2.1. Catalyst preparation
Typically, an aqueous solution containing Cu(NO3)2·3H2O and Mg(NO3)2·6H2O (Loba
Chemie, India, 99.5%) was subjected to co-precipitation with 10 wt% aq. K2CO3·3H2O (Loba
Chemie, India, 99%) solution at a constant pH of 9 under vigorous stirring. Subsequently, the
suspension was aged at 373 K for 12 h. The resulting precipitate was filtered and washed
several times until pH 7, ensuring the total removal of K+. The wet filter cake was dried at
393 K for 12 h, followed by calcination at 723 K for 5 h in air. The obtained samples were
labelled as 5CM, 10CM, 15CM and 20CM, where the numerical value indicates the copper
weight percentage, and C and M stand for copper and MgO, respectively.
2.2. Catalyst characterization
Brunauer, Emmett and Teller (BET) surface area was measured by N2 physisorption at 77
K using a Quadrasorb-SI surface area analyzer (Quantachrome Instruments, USA), after
degassing at 473 K for 4 h. The surface properties such as Cu metal surface area (MSA), Cu
dispersion (DCu), particle size (PCu) and surface coverage of Cu atoms (SCu) were estimated
by N2O pulse chemisorption on pre-reduced (553 K for 3 h) catalyst, where the detailed
procedure was described elsewhere [10–13]. X-ray diffraction (XRD) patterns were recorded
on a Miniflex diffractometer (Rigaku Instruments, Japan) using a Ni filtered Cu Kα radiation
in the 2 range 10–80° at a scan rate of 2° min−1. The average copper crystallite size was
calculated by Debye-Scherrer principle. Transmission electron microscopy (TEM) images
were taken using a Phillips Tecnai G2 FEI F12 electron microscope. The reduction behavior
of the catalysts was determined by temperature programmed reduction (TPR) experiments on
a home-made system as per the procedure described elsewhere [10]. X-ray photoelectron
– 3 –

ACCEPTED MANUSCRIPT
spectroscopy (XPS) was conducted for reduced catalysts using a Kratos-Axis 165 instrument
with Mg Kα radiation (hν = 1253.6 eV) at 75 W. CHNS elemental analysis was carried out on
an Elementar’s vario MICRO cube to estimate the carbon content in fresh and spent catalysts.
2.3. Activity measurement
A down-flow fixed-bed reactor was used to investigate the activity of Cu-MgO catalysts.
Individual reactions, i.e., hydrogenation of o-CNB (dissolved in ethanol) to o-CAN and
dehydrogenation of BDO to GBL, were first examined. Then, the best reaction condition
obtained from the individual reactions was applied for the coupling of o-CNB hydrogenation
and BDO dehydrogenation. Approximately 500 mg of the catalyst powder (sieved to < 200
µm) with an equal amount of quartz beads was loaded to the reactor. After the catalyst was
reduced at 553 K for 3 h under hydrogen, o-CNB was fed with H2 (18 ml min−1). Similarly,
the dehydrogenation of BDO was conducted under N2 atmosphere. The coupling of o-CNB
hydrogenation and BDO dehydrogenation was performed at the molar ratio of 2:3 under N2
atmosphere. The liquid products such as o-CAN and GBL were analyzed using a GC-17A
(Shimadzu, Japan) equipped with a ZB-wax capillary column and a FID. The product
identification was done using a GCMS–QP5050 (Shimadzu, Japan) equipped with a ZB-5
capillary column (25 m × 0.32 mm).
3. Results and discussion
3.1. Physicochemical properties of Cu-MgO
The BET surface area of the Cu-MgO catalysts increases with copper loading from 5 to
10 wt%, but it decreases above 10 wt% of copper loading (Table 1). It was reported that the
increase in the surface area is mainly due to the presence of smaller copper particles over
MgO [12]. The reason for the decrease in the surface area for 15CM and 20CM is due to the
– 4 –

ACCEPTED MANUSCRIPT
formation of bigger copper particles, which can be seen clearly from the copper crystallite
size (Table 1). In addition, TEM images show the structural transformation from needle
shaped particles to cylindrical particles with increasing copper loading (Fig. S2, ESI). This
structural modification is additional cause for the change in the surface area of the catalysts.
The estimated surface properties of Cu-MgO catalysts such as (i) the number of surface
copper atoms, (ii) copper dispersion, (iii) copper surface area, and (iv) copper particle size are
summarized in Table 1. The trend of the above properties is affected by copper loading as
observed in BET surface area. The copper surface area is the highest over 10CM and it
becomes lower above 10 wt% copper loading. The smaller copper particle size of ca. 5 nm in
10CM is a possible reason for the highest BET surface area (70 m2 g−1) among all catalysts.
The metal-support interaction can also play a critical role in the above surface properties, as
mentioned later in TPR and XPS (Fig. S3, Fig. S4, ESI) results.
3.2. X-Ray diffraction (XRD) studies
XRD patterns of the calcined catalysts (Fig. S1, ESI) show the major diffractions of CuO
(d-spacing values of 2.52, 2.32 and 2.53 Å at 2 = 35.6°, 38.78° and 35.45°, respectively;
ICDD Card No.5-661) and MgO (d-spacing values of 2.11, 1.49 and 1.22 Å at 2 = 42.82°,
62.25° and 78.30°, respectively; ASTM card No. 4-829). For the reduced catalysts, all XRD
patterns show the reflections of Cu0 phase (d-spacing values of 2.09, 1.81 and 1.28 Å at 2 =
43.25°, 50.37° and 73.99°, respectively; ICDD Card No. 4-836), where the reflection around
2 = 43.25° is not separated well due to overlapped Cu0 and MgO diffractions (Fig. 1).
When calculated by Debye-Scherrer equation, the crystallite Cu0 sizes of the reduced
catalysts (10 to 35 nm) are smaller than those of the spent catalysts (18 to 56 nm). However,
the crystallite size of 10CM does not increase after the reaction as much as the other catalysts.
Cu particle sizes from N2O pulse chemisorption are not the same as the crystallite sizes from
– 5 –

ACCEPTED MANUSCRIPT
XRD patterns. This is caused by the fact that there is possibility that some parts of Cu might
have oxidized to an amorphous form since the reduced catalysts are exposed to air for XRD
analysis. Since in-situ reduction done prior to N2O pulse chemisorption explains the
difference of copper sizes from these two techniques, it is appropriate to use N2O pulse
chemisorption for the measurement of Cu particle sizes.
3.3. Temperature programmed reduction (TPR) studies
The reduction behavior of all Cu-MgO catalysts is investigated by TPR experiments (Fig.
2). While the reduction profile of 5CM shows a single stage reduction at Tmax of 690 K,
copper oxide is reduced in two steps for 10CM. Although the stepwise reduction of copper
oxide over MgO supported catalysts is still unclear, CuO is first reduced to Cu2O and then to
Cu0, and surface CuO is reduced at lower temperature compared to bulk CuO. Hence, the low
temperature shoulder peaks at 600 K and 650 K are ascribed to the reduction of surface
copper species, whereas a shoulder peak at 680 K is attributed to the reduction of residual
bulk CuO in the 10CM. These results are consistent well with the literature reported by Yuan
et al. [15]. Moreover, the study on the reduction behavior of copper oxide on MgO, Al2O3,
SiO2-Al2O3 and SiO2-MgO confirmed that only Cu/MgO showed the two stage reduction and
it exhibited a higher catalytic activity in the low temperature water gas shift reaction than the
other supported copper catalysts [16]. Therefore, the two step reduction of 10CM is
associated with the interaction between copper and magnesia. At 15 and 20 wt% copper
loadings, the single stage reduction is ascribed to the reduction of CuO species in a single
step (CuO + H2 → Cu0 + H2O). While the calculated hydrogen consumption increases with
copper loading, it is estimated as 3.2 µmol gcat−1 for 5CM and 16.8 µmol gcat−1 for 20CM. In
contrast, the degree of copper reduction decreases from 88% to 69% with the increase of
copper loading from 5 to 20 wt%. This result might be associated with the decreased activity
– 6 –

ACCEPTED MANUSCRIPT
of Cu-MgO catalysts, particularly 15CM and 20CM.
3.4. Catalytic activity
3.4.1. Catalytic hydrogenation of o-CNB
All Cu-MgO catalysts were examined in o-CNB hydrogenation to o-CAN under
hydrogen at ambient pressure in the temperature range 548–723 K. According to Scheme 1a,
the hydrogenation of o-CNB to o-CAN consumes 3 moles of H2 and forms o-CAN and H2O.
Fig. 3 shows that the conversion of o-CNB to o-CAN increases with the reaction temperature
up to 648 K over all catalysts. However, the activity decreases at higher temperatures than
648 K, except 10CM. The catalytic activity decreases in the order of 10CM > 15CM > 20CM
> 5CM, where the selectivity of o-CAN is nearly >99% over all catalysts. The higher activity
of 10CM is mainly attributed to the higher copper dispersion (9%) and higher metal surface
area (12.9 m2 g−1). The catalytic performance of 10CM at high temperatures can be assigned
to strong metal-support interaction as observed in TPR results. The poor activity of 5CM is
caused by the very low copper surface area (3.2 m2 g−1), and the lower activities of 15CM
and 20CM at higher temperatures are due to agglomeration of copper particles and oxidation
of copper species by water molecules released by the reaction. Moreover, as per the TPR
analysis the reducibility of copper was very low for 15CM and 20CM, so that more Cu+2
present on the surface of these catalysts can lead to the poor catalytic performance compared
to 10CM. XPS analysis reveals that 5CM and 10CM contain the higher amounts of surface
Cu0 species whereas 15CM and 20CM have more amounts of Cu+2 species (Fig. S3, ESI).
Thus, 10CM is the best catalyst in the conversion of o-CNB at 648 K in the presence of
external hydrogen.
3.4.2. Dehydrogenation of BDO to GBL
– 7 –

ACCEPTED MANUSCRIPT
Dehydrogenation of BDO to GBL releases two moles of hydrogen (Scheme 1b). Under
nitrogen atmosphere in the temperature range 473–573 K, the dehydrogenation activity
follows in the order of 10CM > 15CM > 20CM > 5CM (Fig. 4). The BDO conversion over
10CM is >99% at 523 K. Remarkably, the selectivity of GBL was near 99% over all
temperatures. In case of 15CM and 20CM, the activity decreases gradually when the
temperature increases above 523 K, mainly due to agglomeration of copper particles [11–13].
3.4.3. Coupling of o-CNB hydrogenation and BDO dehydrogenation
According to Scheme 1c, the molar ratio of o-CNB and BDO should be maintained at 2:3
for the coupling reaction. Based on the results obtained from the above single reactions, the
coupling experiment of o-CNB hydrogenation and BDO dehydrogenation was conducted
under N2 atmosphere at 523 K over 10CM catalyst for 10 h time on stream. In the initial run,
the conversion of o-CNB to o-CAN is above 80%, however it decreases steadily with
increasing the reaction time. The conversion of o-CNB is above 60% for the first 5 h and then
decreases to 10% at the end of the experiment. The conversion of BDO is close to 90% in the
first hour and then it decreases gradually for 10 h course of the reaction. The deactivation is
possibly due to coke formation (Table S1, ESI) and agglomeration of copper particles (cf.
Table 1).
The advantage of the coupling process is that the hydrogenation of o-CNB to o-CAN can
be successfully carried out by H2 released from BDO dehydrogenation. The yield of o-CAN
(ca. 85%) in the coupling reaction is approximately equal to the yield obtained in the single
hydrogenation reaction at 648 K where external hydrogen is used. Also, the selectivity of o-
CAN was 99% in the coupling reaction. The high conversion of o-CNB at 523 K is explained
in the following plausible manner: the hydrogenation of o-CNB under molecular hydrogen
requires a high temperature, whereas in coupling process the active hydrogen obtained by
– 8 –

ACCEPTED MANUSCRIPT
BDO dehydrogenation is more effective even at a lower temperature [17–19]. It was reported
that the coupling of maleic anhydride (MA) hydrogenation and BDO dehydrogenation
exhibited high yields at lower temperatures than single reactions because activated hydrogen
species on the catalysts surface from BDO dehydrogenation could promote MA
hydrogenation easily [18]. In addition, since the hydrogenation reaction is exothermic and the
dehydrogenation is endothermic, the coupling process would be in better thermal balance by
heat exchange between the two reactions. The same phenomenon is possible in the present
study to show the high yield of o-CAN (>85%) even at the lower temperature of 523 K.
Although the hydrogenation of o-CNB under external hydrogen pressure over noble metal
catalysts exhibits 100 % conversion with 100 % selectivity of o-CAN (Table S2, ESI), Cu-
MgO catalyst is very active in the coupling reaction (no external H2 supply). However, the
reason for a high activity of Cu-MgO catalyst is not clear from the present study alone and
further works will be required to explain the results in detail.
4. Conclusions
The coupling experiment of o-CNB hydrogenation and BDO dehydrogenation is
conducted successfully over Cu-MgO catalysts under a hydrogen free condition. Among all
catalysts, 10CM shows the excellent performance at the yields of 85% o-CAN and 90% GBL
with 99% selectivity. A better thermal balance and in-situ produced hydrogen play a key role
in the coupling process to obtain the high yield of o-CAN even at a lower temperature.
More number of surface copper atoms (Cu0/Cu+1) and strong metal-support interaction in
10CM contribute to the overwhelming catalytic performance in both the single and coupled
reactions. Hence, the coupling of hydrogenation and dehydrogenation processes over Cu-
MgO can be an environmentally friendly process.
– 9 –

ACCEPTED MANUSCRIPT
Acknowledgement
Authors are gratefully thanks to CSIR-UGC (INDIA) for the financial support. This
research was also financially supported by Basic Science Research Program through the
National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-
2016R1A6A1A03013422) and New & Renewable Energy Core Technology Program of the
Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial
resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No.
20143030091040).
References
[1] X.L. Yang, Z.L. Deng, H.F. Liu, J. Mol. Catal. A: Chem. 144 (1999) 123.
[2] V.L. Khilnani, S.B. Chandalia, Org. Process Res. Dev. 5 (2001) 257.
[3] M.H. Liang, X.D. Wang, H.Q. Liu, H.C. Liu and Y. Wang, J. Catal. 255 (2008) 335.
[4] Y. Motoyama, K. Kamo, H. Nagashima, Org. Lett. 11 (2009) 1345.
[5] X. Yuan, N. Yan, C.X. Xiao, C.N. Li, Z.F. Fei, Z.P. Cai, Y. Kou, P.J. Dyson, Green
Chem. 12 (2010) 228.
[6] X.L. Yang, H.F. Liu, H. Zhong, J. Mol. Catal. A: Chem. 147(1999) 55.
[7] B. Sreedhar, P.S. Reddy, D.K. Devi, J. Org. Chem. 74 (2009) 8806.
[8] M.H. Liu, W.Y. Yu, H.F. Liu, J. Mol. Catal. A: Chem. 138 (1999) 295.
[9] V. Kratky, M. Kralik, M. Mecarova, M. Stolcova, L. Zalibera, M. Hronec, Appl. Catal.
A: Gen. 235 (2002) 225.
[10] K.H.P. Reddy, C.A. Mullen, Y. Elkasabi, A.A. Boateng, Fuel Proc. Technol.
137 (2015) 220–228.
[11] K.H.P. Reddy, N.C. K. Prasad, K.S.R. Rao, V.N. Kalevaru, A. Martin, B.D. Raju,
Catal. Sci. Technol. 6 (2016) 5494.
– 10 –

ACCEPTED MANUSCRIPT
[12] K.H.P. Reddy, R. Rahul, S.S. Reddy, B.D. Raju, K.S.R. Rao, Catal. Commun. 108
(2009) 879.
[13] K.H.P. Reddy, N. Anand, V. Venkateswarlu, K.S.R. Rao, B.D. Raju, J. Mol. Catal. A:
Chem. 355 (2012) 180.
[14] M. Pietrowski, Green Chem. 13 (2011) 1633.
[15] Z. Yuan, J. Wang, L. Wang , W. Xie , P. Chen, Z. Hou , X. Zheng, Bioresource
Technol. 101 (2010) 7088.
[16] H. Yahiro , K. Murawaki, K. Saiki, T. Yamamoto, H. Yamaura, Catal. Today 126
(2007) 436.
[17] Y.-L. Zhu, H.-W. Xiang, G.-S. Wu, L. Bai, Y.-W. Li, Chem. Commun. (2002) 254.
[18] Y.-L. Zhu, J. Yang, G.-Q. Dong, H.-Y. Zheng, H.-H. Zhang, H.-W. Xiang, Y.-W. Li,
Appl. Catal. B: Environ. 57 (2005) 183.
[19] B.M. Nagaraja, A.H. Padmasri, P. Seetharamulu, K.H.P. Reddy, B. David Raju, K.S.R.
Rao, J. Mol. Catal. A: Chem. 278 (2007) 29.
[20] K.N. Rao, B.M. Reddy, S.-E. Park, Catal. Commun. 11 (2009) 142.
[21] Y. Fang, H. Xiao, N. Sui, M. Liu, W.W. Yu, RSC Adv. 4 (2014) 11788.
[22] A.B. Dongil, C. Rivera-Carcamoa, L. Pastor-Pérez, A. Sepúlveda-Escribanob, P.
Reyes, Catal. Today 249 (2015) 72.
[23] C.H. Camposa, M. Jofréa, C.C. Torresa, B. Pawelecb, J.L.G. Fierrob, P. Reyes, Appl.
Catal. A: Gen. 482 (2014) 127.
[24] Z. Zhang, Y. Suo, J. He, G. Li, G. Hu, Y. Zheng, Ind. Eng. Chem. Res. 55 (2016)
7061.
– 11 –

ACCEPTED MANUSCRIPT
# MgO
#
* Cu0
*
#
#
20CM
*
*
15CM
10CM
5CM
10
20
30
40
50
60
70
80
2 theta (deg.)
Fig. 1.
– 12 –

ACCEPTED MANUSCRIPT
20CM
15CM
10CM
5CM
400
500
600
700
800
900
1000
Temperature (K)
Fig. 2.
– 13 –

ACCEPTED MANUSCRIPT
100
90
80
70
60
50
40
30
20
10
0
5CM
10CM
15CM
20CM
540 560 580 600 620 640 660 680 700 720 740
Temperature (K)
Fig. 3.
– 14 –

ACCEPTED MANUSCRIPT
100
90
80
70
60
50
40
30
20
10
5CM
10CM
15CM
20CM
GBL selectivity
460
480
500
520
540
560
580
Temperature (K)
Fig. 4.
– 15 –

ACCEPTED MANUSCRIPT
BDO conversion
GBL selectivity
o-CNB conversion
o-CAN selectivity
100
80
60
40
20
0
1
2
3
4
5
6
7
8
9
10
Time ,h
Fig. 5.
– 16 –

ACCEPTED MANUSCRIPT
Scheme-1: o-CNB hydrogenation (a), BDO dehydrogenation (b) and coupling of both reactions (c)
– 17 –

ACCEPTED MANUSCRIPT
Graphical Abstract:
– 18 –

ACCEPTED MANUSCRIPT
Table 1
Crystallite size
of Cu0 from XRD
BET
Surface
Cu
Cu
Cu0
surface
Cu atoms dispersion surface
c
particle
(nm)
c
c
c
Catalyst
area
area
size
− 1
− 1
− 1
(m2 g )
(1019 g ) (%)
(m2 g ) (nm)
a
Reduced Spent
5CM
44
70
60
55
10
20
25
35
18
26 (28 b)
4.8
8.8
10.0
9.2
03.2
12.9
6.4
10
5
10CM
15CM
20CM
35
9.5
6.6
16
20
56
10.2
5.3
6.8
c
a after hydrogenation of o-CNB. b after coupling process.
N2O pulse chemisorption.
– 19 –

ACCEPTED MANUSCRIPT
Research highlights:
 Coupling of o-CNB hydrogenation and BDO dehydrogenation is first reported.
 Both reactions occur simultaneously at same reaction conditions over the Cu-MgO.
 o-CAN with 85 % yield achieved without external hydrogen at low temperature.
 Synergistic effect can lead to an increment in the surface copper sites (Cu0/Cu+1).
 The coupling process can be a hydrogen free and environmentally benign process.
– 20 –

ACCEPTED MANUSCRIPT
Table captions:
Table 1: Physicochemical characterization of reduced and spent Cu-MgO catalyst
Figure captions
Fig. 1.
Fig. 2.
Fig. 3.
XRD pattern of reduced Cu-MgO catalysts.
TPR profiles of calcined Cu-MgO catalysts.
Effect of reaction temperature on the hydrogenation of o-CNB to o-CAN over
Cu-MgO catalysts; Reaction condition: 500 mg catalyst (reduced at 553 K for 3
h under H2 flow), 1 ml h−1 o-CNB feed, 548–723 K, 18 ml min−1 H2 flow.
Effect of reaction temperature on the dehydrogenation of BDO to GBL over Cu-
MgO catalysts; Reaction condition: 500 mg catalyst (reduced at 553 K for 3 h
under H2 flow), 1 ml h−1 BDO feed, 473–573 K, 18 ml min−1 N2 flow.
Activity results in the coupling of o-CNB hydrogenation and BDO
dehydrogenation over 10CM as a function of time on stream; Reaction condition:
500 mg catalyst (reduced at 553 K for 3 h under H2 flow), 1 ml h−1 feed
consisting of o-CNB/BDO = 2:3, 523 K, 18 ml min−1 N2 flow.
Fig. 4.
Fig. 5.
– 21 –