High-stable CuPd-Cu2O/Ti-powder catalyst for low-temperature gas-phase selective oxidation of alcohols

Article abstract of DOI:10.1016/j.catcom.2015.04.001

Abstract The oxidation of alcohols to carbonyl compounds in gas-phase is of great importance in organic chemistry and industrial process. Herein, the catalyst CuPd-Cu₂O/Ti-powder is prepared by depositing Cu(NO₃)₂ and Pd(NO₃)₂ on Ti powder support followed by in-situ activation in reaction stream, which delivers high-performance for the gas-phase oxidation of alcohols. Compared with Cu/Ti-powder and Pd/Ti-powder, CuPd-Cu₂O/Ti-powder exhibits higher stability and activity in alcohol oxidation reaction. The catalyst is characterized by XRD, XPS, TEM and ICP. The results indicate that CuPd(alloy)-Cu₂O formed during the reaction contributes to the high activity and stability.

Full text of DOI:10.1016/j.catcom.2015.04.001

Catalysis Communications 67 (2015) 54–58
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Catalysis Communications
journal homepage: www.elsevier.com/locate/catcom
Short communication
High-stable CuPd–Cu2O/Ti-powder catalyst for low-temperature
gas-phase selective oxidation of alcohols
⁎
⁎
Kun Liu, Zhaoxiang Chen, Peipei Zou, Yuanyuan Wang , Liyi Dai
Department of Chemistry, East China Normal University, Shanghai 200241, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
The oxidation of alcohols to carbonyl compounds in gas-phase is of great importance in organic chemistry and
industrial process. Herein, the catalyst CuPd–Cu2O/Ti-powder is prepared by depositing Cu(NO3)2 and
Pd(NO3)2 on Ti powder support followed by in-situ activation in reaction stream, which delivers high-
performance for the gas-phase oxidation of alcohols. Compared with Cu/Ti-powder and Pd/Ti-powder, CuPd–
Cu2O/Ti-powder exhibits higher stability and activity in alcohol oxidation reaction. The catalyst is characterized
by XRD, XPS, TEM and ICP. The results indicate that CuPd(alloy)–Cu2O formed during the reaction contributes to
the high activity and stability.
Received 20 October 2014
Received in revised form 19 March 2015
Accepted 1 April 2015
Available online 2 April 2015
Keywords:
CuPd–Cu2O/Ti-powder
Alcohol oxidation
Stability
© 2015 Elsevier B.V. All rights reserved.
CuPd(alloy)–Cu2O
1. Introduction
transfer ability of TiO2 [15]. In order to improve the catalyst heat-
transfer ability, Zhao et al. develop a microstructured Au/Cu-fiber
Oxidation of alcohols to aldehydes or ketones is of great importance
due to the wide applications of carbonyl compounds in dyestuff,
pharmaceutical and agrochemical industries [1]. Conventionally,
stoichiometric oxidants, such as dichromate and permanganate are
employed in the process of alcohol oxidation, which are toxic and ex-
pensive. There needs to be an exigent fundamental shift from methods
based on the toxic and expensive inorganic oxidants to greener and
more atom-efficient methods which adopt recyclable catalysts and
molecular oxygen as oxidant [2].
Many noble metals such as Au [3,4], Pd [2], Pt [5], and Ru [6] have
been used as catalysts in the oxidation of alcohols. However, the short
lifetime and the high price impede their applications [7,8]. Other metals
such as Mn [9], Cu [10], and heteropoly acid [1] are also used. Cu is
beneficial to industrial application due to its low price compared with
other metal catalysts. Cu-based catalyst shows high catalytic efficiency
in oxidation or reduction reactions [11–13], but still faces some prob-
lems. For example, the loss of silica from Cu/SiO2 catalyst in the form
of TMOS leads to the decrease of copper surface area and the aggrega-
tion of copper particle, which are adverse in the hydrogenation of di-
methyl oxalate [14]. Furthermore, the temperature-increase in catalyst
bed is great over K–Cu–TiO2 in gas-phase alcohol oxidation because of
the strong-exothermicity of alcohol oxidation and the weak heat-
catalyst with high heat-transfer ability in alcohol oxidation reaction [3].
Moreover, the active composites of AuCu(alloy)–Cu2O are in-situ
formed in the reaction stream and the synergic effect between AuCu
and Cu2O contributes to promoting the activity and stability.
Cu2O is active in alcohol oxidation, however, it is unstable in the re-
action conditions because of the reduction of unstable Cu2O [15]. As a
continuation of previous research, the strategy of stabilizing Cu2O by
PdCu alloy delivers a catalyst CuPd–Cu2O/Ti-powder with high activity,
high stability, and low Pd content. Metal support such as Ti powder, Cu
powder and thin-sheet sinter-locked Al fiber has been used in oxidation
or reduction reactions due to its thermal conductivity [16–18]. Ti pow-
der is chosen as support because of its high heat-transfer ability, low
price and high oxidation/acid corrosion resistance behavior toward
the alcohol oxidation. Control-experiments indicate that CuPd(alloy)–
Cu2O composites formed during the reaction contribute to the activity
and stability.
2. Experimental
2.1. Materials and methods
Ti powder (A. R.), Pd(NO3)2·2H2O (A. R.), Cu(NO3)2·3H2O (A. R.),
AgNO3 (A. R.), Co(NO3)2·6H2O (A. R.), HAuCl4·4H2O and
Ni(NO3)2·6H2O (A. R.) are obtained from Sinopharm Chemical
Reagent Co. Ltd. Alcohols such as 1-phenylethanol (C. P.) and 2-
⁎
Corresponding authors.
E-mail addresses: yywang@chem.ecnu.edu.cn (Y. Wang), lydai@chem.ecnu.edu.cn
(L. Dai).
http://dx.doi.org/10.1016/j.catcom.2015.04.001
1566-7367/© 2015 Elsevier B.V. All rights reserved.

K. Liu et al. / Catalysis Communications 67 (2015) 54–58
55
Table 1
phenylethanol (C. P.) are supplied by Aladdin Reagent Co. Ltd.,
Influence of metal content and Cu/Pd molar ratio.
other materials are purchased from local companies.
Entry
Catalysts
Weight ratio (%)c
Conv. (%)d
Sel. (%)e
2.2. Catalyst preparation
1
Ti powder
Cu/Ti-powder
Cu/Ti-powder
Cu/Ti-powder
CuPd–Cu2O-4/Ti-powder
CuPd–Cu2O-3/Ti-powder
CuPd–Cu2O-2/Ti-powder
CuPd–Cu2O-1/Ti-powder
CuPd–Cu2O-4/Ti-powder
CuPd–Cu2O-4/Ti-powder
CuPd–Cu2O-1/Ti-powder
Pd/Ti-powder
–
5
65
78
89
66
60
53
8
81
87
11
44
13
46
32
31
85
99
98
98
98
99
99
98
99
98
99
98
98
98
84
98
95
99
98
98
2a
Cu4.8
Cu6.7
Cu8.9
CuPd–Cu2O-4/Ti-powder catalyst (the metal weight is 9% and the
molar ratio of Cu/Pd is 4/1) is prepared by impregnation of 1 g Ti pow-
der, 70 mg Cu(NO3)2, 20 mg Pd(NO3)2 and 10 mL H2O followed by dry-
ing at 100 °C overnight and calcined at 300 °C in air for 1 h, which is
abbreviated as CuPd–Cu2O-4/Ti-powder fresh. Additionally, other cata-
lysts such as CuPd–Cu2O-x/Ti-powder (the molar ratio of Cu/Pd is x),
Cu/Ti-powder and Pd/Ti-powder are prepared by following the same
procedure and simply tuning the amount of Pd(NO3)2 and copper
salts in the corresponding solutions. CuAg-4/Ti-powder (the metal
weight is 9% and the molar ratio of Cu/Ag is 4/1), CoPd-4/Ti-powder
and NiPd-4/Ti-powder are prepared by the same method using their
corresponding nitrite salts. Au/Ti-powder (Au weight is 9%) is prepared
using HAuCl4 as material.
3b
4
5a
Cu3.5Pd1.5
Cu3.2Pd1.8
Cu2.8Pd2.2
Cu1.8Pd3.2
Cu5Pd2
Cu6.5Pd2.5
Cu3.5Pd5.5
Pd8.6
6a
7a
8a
9b
10
11
12
13
14
15
16
17 [3]
18 [15]
Au/Ti-powder
Au8.7
CuAg-4/Ti-powder
CoPd-4/Ti-powder
NiPd-4/Ti-powder
Au/Cu-fiber
Cu6.2Ag2.8
Co6Pd3
Ni5.7Pd3.3
–
K–Cu–TiO2
–
Reaction conditions: temperature: 280 °C, WHSV: 20, molecular ratio of N2/O2/benzyl al-
cohol: 4.8/0.6/1, a: metal content is 5%, b: metal content is 7%, c: weight ratio is detected by
ICP, d: conversion of benzyl alcohol, e: selectivity of benzyl aldehyde, by-products are tol-
uene and benzoic acid.
2.3. Catalytic tests
The gas-phase oxidation of alcohols is performed on a fixed-bed
quartz tube reactor (600 mm length by 14 mm inner diameter) under
atmospheric pressure. Catalyst used in each test is 0.27 g (200–
300 mesh). Other conditions are described in the previous literature
elaborately [16]. The products are analyzed by Gas Chromatography
(Shimadzu GC-2014 with a Rtx-5 column) as well as GC–MS (Agilent
6890 equipped with a HP-5 column). The content of benzoic acid, ben-
zyl benzoate, toluene and COx is 0.5%, 0.2%, 0.1% and 0.6% respectively,
so the selectivity of benzylaldehyde in our reaction conditions is higher
than 98%. The carbon balance in the liquid phase is 99% and other
products are nearly negligible.
its activity after calcinating in air at 400 °C to burn away the
deposited coke (7.2 wt.% of carbon after 50 h running), which
shows promising stability characteristics (Fig. 2). However, the
benzyl alcohol conversion catalyzed by Pd/Ti-powder is just 44%
(Table 1, entries 12). Our catalyst exhibits higher activity compared
with Au/Ti-powder, CuAg-4/Ti-powder, CoPd-4/Ti-powder and
NiPd-4/Ti-powder catalyst (Table 1, entries 13–16). Compared with
Au/Cu-fiber [3], the noble metal content in our catalyst is much
lower (Table 1, entry 17). Whereas the K–Cu–TiO2 shows a very
high conversion of 99% at 210 °C, the reported lifetime is only 50 h
and its throughput is extremely low (Table 1, entry 18) [15].
Compared with Ag/SBA-15, the conversion is slightly lower but the
run-lifetime increases to 150 h [19].
Influence of temperature on benzyl alcohol conversion and benzal-
dehyde selectivity is shown in Fig. S1. The conversion of benzyl alcohol
increases with the augment of temperature from 220 °C to 300 °C. It
should be noticeable that our catalyst is still active at lower tempera-
tures. Over CuPd–Cu2O-4/Ti-powder, the benzyl alcohol conversion
decreases from 90% to 78% as the temperature is decreased from
300 °C to 260 °C. When temperature is decreased to 240 °C, conversion
reduces to 68%.
2.4. Catalyst characterization
X-ray diffraction (XRD) patterns of the catalysts are performed on a
Bruker D8 diffractometer with Cu-Kα radiation with a scan speed of
60°/min. X-ray photoelectron spectroscopy (XPS) measurements are
obtained on a PHI-5500 spectrometer with Al Kα X-ray radiation as
the X-ray source for excitation. Transmitting electron microscopy
(TEM) is performed on a JEOL 2100 F instrument operating at 30 kV.
Inductively-coupled plasma atomic emission spectroscopy (ICP-AES)
measurements are performed on the Thermo Scientific iCAP 6300 in-
strument. Surface area (SBET) is calculated by BET method using a BEL
SORP mini II analyzer at liquid N2 temperature.
We extend the experiments using various volatile alcohols
(Table S1). This catalyst could oxidize 1-phenylethanol to acetophenone
3. Results and discussion
3.1. Catalytic activity
100
90
80
70
60
50
40
100
90
80
70
60
50
40
Catalytic activity of metal Ti-powder (200–300 mesh) with excellent
heat-transfer ability and high oxidation/acid corrosion resistance is very
low (Table 1, entry 1) [16]. Increasing Cu loading from 5 to 9 wt.% signif-
icantly boosts the benzyl alcohol conversion from 65% to 88%, but the
conversion decreases expeditiously after 4 h over Cu/Ti-powder
catalyst (Table 1, entries 2–4 and Fig. 1). When the metal loading
is 5 wt.% with Pd/Cu ratio of 1/4, the benzyl alcohol conversion is
66%, which is further decreased to 6% with the increase of Pd/Cu ratio
to 1/1 (Table 1, entries 5–8). When the metal Pd/Cu ratio is 1/4,
the benzyl alcohol conversion over CuPd–Cu2O-4/Ti-powder catalyst in-
creases to 87% with the total metal loading increasing to 9 wt.% (Table 1,
entries 4, 9 and 10). Notably, the catalytic activity of CuPd–Cu2O-1/Ti-
powder is inferior when the metal content is increased to 9 wt.%
(Table 1, entry 11). For the benzyl alcohol oxidation at 280 °C, CuPd–
Cu2O-4/Ti-powder delivers a single-run lifetime of 50 h with
excellent activity and selectivity. The spent catalyst is able to restore
CuPd-Cu O-4/Ti-powder
2
Cu/Ti-powder
1
2
3
4
5
Time / h
Fig. 1. Comparison of activity between CuPd–Cu2O-4/Ti-powder and Cu/Ti-powder.

56
K. Liu et al. / Catalysis Communications 67 (2015) 54–58
100
90
80
70
60
100
beneficial to investigate the catalytic mechanism. Specific surface area
of Cu/Ti-powder after 0.5 and 4 h running is only 1.1 and 1.2 m2/g,
close to that (0.8 m2/g) for Ti powder itself (Table S2). XRD results indi-
cate that the diffraction intensity of Cu2O in Cu/Ti-powder falls by
roughly half and the conversion decreases from 89% to 46% with the in-
crease of running time from 0.5 to 4 h (Figs. 1 and 3A) (The intensity
ratio of Cu2O (111) to Ti (101) is 0.12 and 0.05 over Cu/Ti-powder
after 0.5 h and 4 h running respectively). To obtain further insight into
Cu-substrate interactions, we study Cu/Ti-powder after catalyzing ben-
zyl oxidation for 0.5 and 4 h by XPS (Table 2, Figs. 3B, C, S2A and S2B).
The lower B. E. peak at 932.4 eV suggests the presence of Cu2O or Cu0
species, which is in accordance with XRD result (Fig. 3A and B). The
presence of Cu2O at B. E. 569.6 eV is confirmed by Cu Auger LMM spectra
and its surface content in Cu/Ti-powder after 0.5 and 4 h running is 93%
and 17%, respectively (Table 2 and Figs. 3C and S2) [7,21]. TEM result in-
dicates that particle size of Cu/Ti-powder after 4 h running is below
5 nm (Fig. 3D) and the particles distribute on the Ti support randomly.
There is no deposited coke on the catalyst after 4 h due to the thermal
conductivity of Ti support [16]. We conclude that the high catalytic
activity of the Cu/Ti-powder at the early stage is due to Cu2O formed
during the reaction conditions and the catalytic activity decreases
after 4 h because of the reduction of Cu2O rather than other reasons
such as particle size effect and deposited coke.
90
80
70
60
nd
Conv.
Sel.
2
regeneration
st
1
regeneration
0
20
40
60
80
100
120
140
Time / h
Fig. 2. The stability of CuPd–Cu2O-4/Ti-powder catalyst.
at a high conversion of 83% at 300 °C, but only 55% for 2-phenylethanol
at 340 °C. The conversion of octanol is higher than 2-octanol, consistent
with a previous report [20]. Notably, cyclohexanol and cyclopropyl
carbinol are very reactive among the aliphatic alcohols. Furthermore,
1, 2-propylene glycol, which favors the formation of hydroxylketone
rather than methyl glyoxal, could be oxidized with selectivity of 67%
and conversion of 93%.
3.3. Identification of CuPd(alloy)–Cu2O species in CuPd–Cu2O-4/Ti-powder
As is mentioned above, Pd/Ti-powder is less active even the metal
content is increased to 9 wt.% (Table 1, entry 12) and Cu/Ti-powder de-
activates expeditiously after 4 h (Fig. 1). Given that the stability of
CuPd–Cu2O-4/Ti-powder is superior than Cu/Ti-powder, we use XRD,
TEM and surface-sensitive XPS technique to track the surface chemical
composition for CuPd–Cu2O-4/Ti-powder after running 4 h. Surface
3.2. Deactivation of Cu/Ti-powder
Cu/Ti-powder exhibits an acceptable yield of benzaldehyde
compared with CuPd–Cu2O-4/Ti-powder, but fast deactivation is
unavoidable. Understanding the cause of Cu/Ti-powder deactivation is
Fig. 3. XRD, XPS and TEM of Cu/Ti-powder catalyst. XRD patterns of Cu/Ti-powder after 0.5 h and 4 h running (A);Cu 2p (B), Cu Auger (C) and TEM (D) of Cu/Ti-powder after 4 h running.

K. Liu et al. / Catalysis Communications 67 (2015) 54–58
57
Table 2
In order to investigate the synergic effect between Cu2O and CuPd
alloy, we prepare CuPd–Cu2O-1/Ti-powder. The conversion of benzyl al-
cohol is 11% (Table 1, entries 11) due to the lower content of Cu2O
(Table 2), XRD indicates that CuPd alloy rather than CuO and Cu2O is
formed during the reaction conditions (Fig. 4A), which is in accordance
with XPS results (Table 2 and Fig. S4). So we conclude that CuPd alloy is
not active in alcohol oxidation, just like AuCu alloy reported by Zhao [3].
Control-experiments between CuPd–Cu2O-4/Ti-powder, Cu/Ti-powder
and CuPd–Cu2O-1/Ti-powder indicate that Cu2O is active in alcohol
oxidation, which is stabilized by CuPd alloy because CuPd–Cu2O-4/
Ti-powder exhibits excellent stability.
Metal contents of the catalysts calculated from XPS data.
Catalyst
Cu2+ (%) Cu+ (%) Cu0 (%) Pd2+ (%) Pd0 (%)
Cu/Ti-powder after running
0.5 h
Cu/Ti-powder after running 4 h
CuPd–Cu2O-4/Ti-powder after
running 4 h
Pd/Ti-powder after running 4 h
CuPd–Cu2O-1/Ti-powder after
running 4 h
0
93
7
0
0
0
0
17
78
83
22
0
5
0
95
0
0
0
2
0
98
14
0
86
100
Cu/Ti-powder fresh
Pd/Ti-powder fresh
CuPd–Cu2O-4/Ti-powder fresh
100
0
96
0
0
0
0
0
4
0
100
85
0
0
15
XRD and XPS results indicate that Pd0 particles are formed in the re-
action conditions over Pd/Ti-powder (Fig. S5A and B). Moreover, the
catalysts after 4 h running are also tested by TEM, and the results are
shown in Figs. 3D, 4D and S5C. The catalysts are not sintered in our re-
action conditions except Pd/Ti-powder catalyst, which is beneficial to
the industrial process. The nanoparticle size of Cu/Ti-powder and
CuPd–Cu2O-4/Ti-powder after 4 h running is below 5 nm and the parti-
cles distribute on Ti support randomly (Figs. 3D and 4D). So we
conclude that the particle size is not the decisive factor in alcohol oxida-
tion reaction.
area of each sample is close to that of Ti powder itself (Table S2). XRD
test indicates that Cu2O and CuPd alloy are formed in the reaction con-
ditions (Fig. 4A). Cu 2p spectrums testify that the lower B. E. at 932.5 eV
is assigned to Cu2O or Cu0 species and Auger Cu LMM spectra confirm
the presence of Cu2O at B. E. 569.6 eV (Fig. 4B and C) [7,21]. The prom-
inent peak at B. E. 335.2 eV and the ambiguous peak at B. E. 336.3 eV are
assigned to Pd0 and Pd2+, respectively (Fig. S3A) [22]. On such surface,
the Cu0 and Pd0 surface content to corresponding total surface atoms is
22% and 95%, respectively. The surface Cu0/Pd0 ratio is about 1/1
(Figs. 4B, C, S3 and Table 2). TEM and HRTEM indicate that particles
are not sintered and the lattice fringe of CuPd alloy and Cu2O is
0.185 nm and 0.246 nm, respectively (Fig. 4D and E). From the results
mentioned above, we conclude that active CuPd(alloy)–Cu2O is formed
in the reaction conditions.
3.4. Discussions of activation and regenerate process
From the results mentioned above, we know that Cu2O is an active
site in the oxidation of alcohols and CuPd alloy inhibits the reduction
of Cu2O. XPS results indicate that CuO and PdO are formed over Cu/
Ti-powder fresh (Table 2, Fig. 3B) and Pd/Ti-powder fresh respec-
tively (Table 2, Fig. S5A). Interestingly, the formation of CuO, PdO
and trace amount of CuPd alloy in CuPd–Cu2O-4/Ti-powder fresh is
Fig. 4. XRD, XPS and TEM of CuPd–Cu2O/Ti-powder catalyst. XRD patterns of CuPd–Cu2O-1/Ti-powder and CuPd–Cu2O-4/Ti-powder after 4 h running (A);Cu 2p (B), Cu Auger (C), TEM
(D) and HRTEM (E) of CuPd–Cu2O-4/Ti-powder after 4 h running.

58
K. Liu et al. / Catalysis Communications 67 (2015) 54–58
testified using the same technique (Table 2, Figs. 4B, C and S3B). The
particles in the fresh catalysts are so small that below the determina-
tion limit of XRD instruments (Figs. 3A, 4A and S5B). For the fresh
catalyst, the particles with the diameter about 2 nm distribute on
the support (Figs. S2C, S3C and S5D) randomly. BET surface area of
fresh catalyst is close to each other (Table S2). So we conclude that
in the activation process CuO is reduced in Cu/Ti-powder and PdO
transforms to Pd in Pd/Ti-powder. However, CuO–PdO generates
the active composite CuPd–Cu2O in CuPd–Cu2O-4/Ti-powder.
XRD patterns, TEM image and XPS results of CuPd–Cu2O-4/Ti-powder
after regeneration step are not changed compared with CuPd–Cu2O-4/
Ti-powder (Figs. 4A, S6A, B, C and D). The regeneration step is similar
with that of Ag/Cu-fiber catalyst reported by Y. Lu [17]. Compared with
K–Cu/TiO2, AuCu/SiO2 and AgCu/Al2O3, the thermal conductivity is excel-
lent because no crystalline TiO2 is detected by XRD, which corresponds
with the temperature difference (about 20 °C) between the setup tem-
perature and the catalyst-bed temperature in the oxidation of benzyl al-
cohol over CuPd–Cu2O-4/Ti-powder after regeneration due to the
thermal conductivity of Ti.
oxidation reaction. Cu/Ti-powder catalyst exhibits high activity in this
reaction, however, the catalyst deactivates expeditiously due to the re-
duction of active Cu2O. CuPd–Cu2O-4/Ti-powder catalyst exhibits high
stability due to the formation of CuPd (alloy)–Cu2O composites. Reac-
tion mechanism is under investigation in our lab.
Acknowledgments
The authors thank Dr. Guo Feng Zhao (East China Normal University)
in the experimental guidance, Mrs. Yan Ling Shi (National Engineering
Research Center for Nanotechnology) in the testing services. This work
is supported by the financial support from the key project of Shanghai
Science and Technology Committee (No. 14231200300), Shanghai Key
Laboratory of Green Chemistry and Chemical Processes and SRF for
ROCS, SEM.
Appendix A. Supplementary data
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.catcom.2015.04.001.
3.5. Reaction mechanism
We propose that O2 activation occurs on Cu2O sites instead of Pd NPs
or PdCu alloy, which is supported by the results that Pd/Ti-powder or
CuPd–Cu2O-1/Ti-powder is significantly less active for benzyl alcohol
oxidation than CuPd–Cu2O-4/Ti-powder (Table 1 and Fig. 1). In addi-
tion, CuPd alloy is proposed to inhibit the reduction of Cu2O to Cu0 spe-
cies because of the deactivation of Cu/Ti-powder (Table 1 and Fig. 1). In
general, the selective oxidation of alcohols by molecular oxygen over
Cu-based catalysts proceeds via the route as follows [3,7]: Cu2O cata-
lyzed alcohol dehydrogenation takes place firstly to form surface
Cu2O–H hydride species and alcoholates, which are decomposed to al-
dehydes, then the oxygen accepts the hydrogen of the Cu2O–H hybrid
by releasing the free active Cu2O sites. Cu2O is stabilized by CuPd alloy
over CuPd–Cu2O-4/Ti-powder.
References
[1] K. Liu, T.T. Chen, L.Y. Dai, Catal. Lett. 144 (2014) 314–319.
[2] K. Liu, X.J. Yan, L.Y. Dai, Catal. Commun. 58 (2015) 132–136.
[3] G.F. Zhao, H.Y. Hu, Y. Lu, Green Chem. 13 (2011) 55–58.
[4] G.F. Zhao, H.Y. Hu, Y. Lu, Chem. Commun. 47 (2011) 9642–9644.
[5] G.L. Li, L.H. Jiang, G.Q. Sun, Int. J. Hydrog.Energy 38 (2013) 12767–12773.
[6] B. Karimi, D. Elhamifar, O. Yari, Chem. Eur. J. 18 (2012) 13520–13530.
[7] P. Liu, E.J. Hensen, J. Am. Chem. Soc. 135 (2013) 14032–14035.
[8] O.A. Simakova, V.I. Sobolev, D.Y. Murzin, ChemCatChem 2 (2010) 1535–1538.
[9] Y.T. Meng, H.C. Genuino, S.L. Suib, J. Am. Chem. Soc. 135 (2013) 8594–8605.
[10] J.E. Steves, S.S. Stahl, J. Am. Chem. Soc. 135 (2013) 15742–15745.
[11] L. Heo, M.H. Wiebenga, C.H. Kim, Appl. Catal. B Environ. 160–161 (2014) 365–373.
[12] F.Y. Chen, X. Zhao, J.H. Qu, Appl. Catal. B Environ. 158–159 (2014) 85–90.
[13] C.K.P. Neeli, A. Narani, D.R. Burri, Catal. Commun. 39 (2013) 5–9.
[14] C. Wen, Y.Y. Cui, W.L. Dai, Chem. Commun. 49 (2013) 5195–5197.
[15] J. Fan, Y.H. Dai, G.D. Stucky, J. Am. Chem. Soc. 131 (2009) 15568–15569.
[16] G.F. Zhao, H.Y. Hu, Y. Lu, Appl. Catal. A Gen. 467 (2013) 171–177.
[17] G.F. Zhao, Y.K. Li, Y. Lu, AIChE J. 60 (2014) 1045–1053.
4. Conclusions
[18] Q.F. Zhang, Y.K. Li, Y. Lu, Green Chem. 50 (2014) 6343–6347.
[19] L. Ma, L.H. Jia, X.F. Guo, Chin. J. Catal. 35 (2014) 108–119.
[20] D.I. Enache, J.K. Edwards, G.J. Hutchings, Science 311 (2006) 362–365.
[21] J.F. Moulder, W.F. Stickle, K.D. Bomben, Handbook of X-ray photoelectron spectros-
copy, Physical Electronics, MN. (1992).
High stable CuPd–Cu2O-4/Ti-powder catalyst is prepared using a
simple method. XRD, HRTEM, XPS and control-experiments indicate
that active CuPd (alloy)–Cu2O is formed under reaction condition,
which is crucial for the gas-phase oxidation of alcohols. TEM results in-
dicate that the particle size of NPs is not the decisive factor in alcohol
[22] X.M. Wang, G.J. Wu, L.D. Li, Appl. Catal. B Environ. 115–116 (2012) 7–15.