Highly efficient synchronized production of phenol and 2,5-dimethylfuran through a bimetallic Ni-Cu catalyzed dehydrogenation-hydrogenation coupling process without any external hydrogen and oxygen supply

Article abstract of DOI:10.1039/c7gc01387f

2,5-Dimethylfuran (DMF) and phenol are considered as one of the new-fashioned liquid transportation biofuels and a key motif for industrial chemicals, respectively. Herein, a highly efficient vapor-phase dehydrogenation-hydrogenation coupling process over bimetallic Ni-Cu alloy nanocatalysts was established for the synchronized production of phenol and DMF with unprecedentedly high yields (>97%) from two cyclohexanol (CHL) and biomass-derived 5-hydroxymethylfurfural (HMF) substrates, without any external hydrogen and oxygen supply. Systematic characterization and catalytic experiments revealed that the production of phenol went through a consecutive triple-dehydrogenation process from CHL, while HMF was simultaneously hydrogenated into DMF using active hydrogen species generated from the dehydrogenation process. The bimetallic Ni-Cu alloy nanostructures derived from Ni-Cu-Al layered double hydroxide precursors and strong metal-support interactions play important roles in governing the present coupling process. An appropriate Ni-Cu alloy nanostructure could greatly facilitate the dehydrogenative aromatization of CHL, thus significantly improving the selectivities to both phenol and DMF. Such an unparalleled efficient, eco-friendly and versatile coupling process for the synchronized production of various substituted phenols and DMF makes it practically promising for large-scale industrial applications in terms of green chemistry and sustainable development.

Full text of DOI:10.1039/c7gc01387f

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Highly efficient synchronized production of phenol and 2,5-
dimethylfuran through a bimetallic Ni-Cu catalyzed
dehydrogenation-hydrogenation coupling process without
external hydrogen and oxygen supply
Wei Li,a,b Guoli Fan,a Lan Yang a and Feng Li*a
2,5-Dimethylfuran (DMF) and phenol are considered as one of the new-fashioned liquid transportation biofuels and the
most key structural motifs for industrial chemicals, respectively. Herein, a highly efficient vapor-phase dehydrogenation-
hydrogenation coupling process over bimetallic Ni-Cu alloy nanocatalysts was established for the synchronized production
of phenol and DMF with unprecedentedly high yields (>97%) from two cyclohexanol (CHL) and biomass-derived 5-
hydroxymethylfurfural (HMF) substrates, without external hydrogen and oxygen supply. Systematic characterizations and
catalytic experiments revealed that the production of phenol went through a consecutive triple-dehydrogenation process
from CHL, while HMF was simultaneously hydrogenated into DMF using active hydrogen species generated from the
dehydrogenation. The bimetallic Ni-Cu alloy nanostructures derived from Ni-Cu-Al layered double hydroxide precursors
and strong metal-support interactions play important roles in governing the present coupling process. An appropriate Ni-
Cu alloy nanostructure could greatly facilitate the dehydrogenative aromatization of CHL, thus significantly improving the
selectivities to both phenol and DMF. Such an unparalleledly efficient, eco-friendly and versatile coupling process for the
synchronized production of various substituted phenols and DMF makes it practical promising for large-scale industrial
applications in terms of green chemistry and sustainable development.
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
because they can provide the largest carbon source for
transportation fuels and important chemicals.4 In this regard,
biomassꢀderived 5ꢀhydroxymethylꢀfurfural (HMF) is perceived
Introduction
With the growing shortage of fossil resources and the increase
in greenhouse gas emissions, the associated energy crisis and
environmental pollution are gaining increasing attention.1 In
recent years, considerable interest has been oriented towards
the development of sustainable resources for bulk chemicals
and energy production in both academic and industrial
communities. Especially, the conversion from renewable raw
biomass resources into highꢀquality liquid biofuels and high
valueꢀadded chemicals is undoubtedly the most attractive.2,3
With the development of transportation and economics
involved, natural carbohydrates are considered as potential
candidates for the synthesis of renewable liquid biofuels
as
a versatile key platform compound in the biomass
conversion for a broad array of biofuels through reductive
upgrading, and efforts to use such building blocks have been
going on for quite some while.5 In particular, 2,5ꢀdimethylfuran
(DMF), which can be produced by the selective
hydrodeoxygenation of HMF, shows great potential as a liquid
biofuel additive, thanks to the unique properties including low
boiling point (92–94 °C), high research octane number (111),
high energy density (31.5 MJ/L) and low water solubility.6
Presently, the conversion of HMF into DMF using
molecular hydrogen has been extensively explored over various
metal and bimetallic catalysts.7 Specially, bimetallic catalysts
(e.g. CuꢀRu,3a PtꢀCo7fꢀh) usually presents higher selectivity to
DMF than monometallic analogues. Even so, in some cases,
DMF selectivities are poor as a consequence of the occurrence
of further ringꢀopened and ringꢀhydrogenated reactions.
Although noble metal catalysts show good catalytic
performance, some drawbacks, such as easy deactivation, limit
their practical applications. Therefore, for the energy
a
State Key Laboratory of Chemical Resource Engineering, Beijing Advanced
Innovation Center for Soft Matter Science and Engineering, Beijing University of
Chemical Technology, Beijing 100029, China.
E-mail: lifeng@mail.buct.edu.cn; Fax: +8610-64425385; Tel: +86-10-64451226
b
SINOPEC Beijing Research Institute of Chemical industry Yanshan Branch, Beijing
102500, China.
†Electronic supplementary
10.1039/x0xx00000x
information
(ESI)
available.
See
DOI:
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conversion, developing heterogeneous noble metalꢀfree versatile vaporꢀphase coupling process between the CHL
catalysts is highly desirable from both an economic and a dehydrogenation and the HMF hydrogenation over bimetallic
sustainable development perspective. Conventionally, the NiꢀCu alloy nanocatalysts without external hydrogen and
hydrodeoxygenation of HMF always consumes external oxygen supply, as shown in Scheme 1. Here, bimetallic NiꢀCu
hydrogen. However, there are some drawbacks in the alloy nanocatalysts were prepared from NiꢀCuꢀAl layered
hydrogenation using molecular hydrogen, such as high double hydroxide (NiCuAlꢀLDH) precursors.16 The reaction
hydrogen pressure, hydrogen flammability, and high costs of pathways and network were investigated. More intriguingly,
hydrogen transportation and storage. More recently, due to the great difference in the boiling point of phenol and
hydrogenations of HMF using formic acid or alcohols as DMF (181.9 °C and 93.1 °C under 101.3 kPa, respectively), the
hydrogen sources also have emerged.6d,8 Despite the technical
viability of these alternative hydrogen donors, the application
of this strategy, however, meets great challenges due to several
issues (e.g. the corrosiveness of formic acid, the use of large
amounts of hydrogen donators as solvents).
On the other side, phenol and its derivatives as important
precursors and core structural motifs of industrial chemicals are
employed widely to manufacture polymers, dyes,
agrochemicals, and pharmaceuticals.9 Typically, phenol can be
produced by a classical threeꢀstep cumene process involving the
electrophilic aromatic substitution between benzene and
propylene.10 However, such widely employed commercial
process also has several shortcomings including the
involvement of explosive cumene hydroperoxide intermediate
and the limitation in preparing orthoꢀ or paraꢀsubstituted
derivatives due to the strong electronic directing effects
associated with these reactions. Moreover, because of the high
Scheme 1 The dehydrogenationꢀhydrogenation coupling process for the
value of phenol, the preparation of cyclohexanol through
synchronized production of phenol and DMF, and the traditional
cyclohexane oxidation has been explored,11 instead of the
synthetic procedures for phenol and DMF.
phenol hydrogenation process. Recently, a newlyꢀdeveloped
alternative process for the production of phenol, aerobic
oxidative dehydrogenation of cyclohexanol (CHL) or
separation process of phenol and DMF would be easy, which
cyclohexanone (CHN), has received increasing attention.12 In
may be of great importance for the largeꢀscale industrial
this sense, the dehydrogenation of cyclohexanol to produce
application of the coupling process. To the best of our
phenol is meaningful. Despite remarkable progress in this
knowledge, hitherto, the present developed bimetallic NiꢀCu
process, most of the existing studies were carried out by using
alloy catalyzed vaporꢀphase dehydrogenationꢀhydrogenation
external oxidizing reagents (e.g. molecular oxygen or air) and
coupling process for synchronized production of phenol and
noble metal catalysts. Therefore, the direct production of
DMF with high yields starting from CHL and HMF substrates
phenol based on the dehydrogenation of CHL or CHN over
in the absence of hydrogen and oxygen has never been reported.
heterogeneous nonꢀnobleꢀmetal catalysts without the use of
oxidizing reagents is still a challenge.
Over the past few years, some vaporꢀphase hydrogenationꢀ
dehydrogenation coupling processes to simultaneously produce
hydrogenated and dehydrogenated products have been
occasionally reported,13 which highlights the idea of sustainable
and economical production of chemicals.14 As a typical
example, the coupling in the combination of CHL
dehydrogenation and furfural hydrogenation can produce 2ꢀ
methylfuran or furfuryl alcohol and CHN.15 Due to low
efficiency of catalysts, in some cases, however, external
hydrogen supply or cycle still is required to maintain the
hydrogen transfer process, and the desired phenol are rarely
produced. In this sense, designing highly efficient
heterogeneous catalysts is quite crucial for the feasibility of the
process.
Results and discussion
Characterization of bimetallic Ni-Cu alloy nanocatalysts
Monometallic and bimetallic NiꢀCu catalysts (NixCuy) were
prepared from NiCuAlꢀLDH precursors with different initial
Ni:Cu molar ratios of x:y (see the ESI†). Other comparison
samples with the identical metal loading to NixCuy catalysts
were also prepared by the impregnation method.
Powder Xꢀray diffraction (XRD) patterns of different
NiCuAlꢀLDH precursors show the characteristic diffractions of
hydrotalciteꢀlike materials (JCPDS 15ꢀ0087/37ꢀ0630) with well
crystallinity (Fig. S1†). Fig. 1 shows the XRD patterns of
reduced NixCuy samples under ambient conditions. Clearly, no
diffraction peaks related to hydrotalciteꢀlike materials can be
found in reduced samples due to the topological transformation
of LDH precursors. Monometallic Ni3Cu0 and Ni0Cu3 samples
exhibit the characteristic (111) and (200) diffractions of
In the present work, we for the first time report the
synchronized production of phenol and DMF with high yields
(> 97 %) through an unparalleledly efficient, ecoꢀfriendly and
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crystalline metallic nickel (JCPDS 04ꢀ0850) and metallic NiꢀCu nanostructure. This result is also supported by the
copper (JCPDS 04ꢀ0836) phases, respectively. In addition, the hydrogen temperature programmed reduction (H2ꢀTPR) results
absence of crystalline Al2O3 reveals the existence of amorphous of calcined LDH samples (Fig. S2†). Notably, TPR profiles of
alumina phase as the support in samples. Interestingly, in the all calcined NiCuAlꢀLDH samples show decreased reduction
cases of bimetallic NixCuy samples, the (111) and (200) planes temperatures of both Ni and Cu species relative to calcined
appear between those of metallic Ni and Cu peaks and their CuAlꢀLDH (278 °C for the reduction of Cu2+ species) and
positions gradually shift to the higher values of 2
θ
with the calcined NiAlꢀLDH (560 °C for the reduction of Ni2+ species)
increasing Ni/Cu molar ratios from 1:2 to 2:1, strongly samples. Especially, the CꢀNi2Cu1 sample (the precursor of
reflecting the formation of bimetallic NiꢀCu alloy phases.17
Ni2Cu1 sample) shows the lowest reduction temperature,
indicative of the improved reducibility of Ni and Cu species in
the sample. The aforementioned results verify the presence of
strong NiꢀCu interactions in calcined NiCuAlꢀLDH samples,
thereby facilitating the formation of bimetallic NiꢀCu NPs. As
shown in Table S1†, the specific surface area of samples
ranging from about 74 to 90 m2/g presents a gradual decrease
with the decreasing Ni content, whereas the pore size shows an
opposite trend.
Vapor-phase dehydrogenation-hydrogenation coupling process
Under nitrogen atmosphere, the vaporꢀphase coupling process
goes through a consecutive twoꢀpart reaction pathway: CHL
dehydrogenation to produce phenol; HMF hydrogenation to
produce DMF using active hydrogen species released from the
dehydrogenation part. Table 1 summarizes the catalytic reaction
results over different NixCuy catalysts without external
hydrogen and oxygen supply at 200 and 240 °C. It is noted that
the yields of phenol and DMF decrease in the following order
for catalysts: Ni2Cu1 > Ni3Cu0 > Ni1.5Cu1.5 > Ni1Cu2 >Ni0Cu3
(Table 1, entries 1ꢀ5). In particular, the highest yields of phenol
(41%) and DMF (95%) are gained over the Ni2Cu1 at 200 °C.
However, in the case of Ni0Cu3 catalyst, no phenol is formed
and the main dehydrogenation product is CHN. Additionally,
for Ni3Cu0, 2,5ꢀdimethyltetrahydrofuran (DMTHF) product
Fig. 1 XRD patterns of reduced NixCuy samples. (a) XRD standard card
of Ni (JCPDS 04ꢀ0850), (b) Ni3Cu0, (c) Ni2Cu1, (d) Ni1.5Cu1.5, (e)
Ni1Cu2, (f) Ni0Cu3, (g) XRD standard card of Cu (JCPDS 04ꢀ0836).
Detailed XRD patterns (right) of different samples in the 2θ range of
40°–55°.
also can be detected as
a consequence of the deep
hydrogenation of the furan ring in DMF product.
The reaction results also indicate that when the reaction
proceeds at 200 °C, high conversions of HMF (> 90%) can be
achieved in each case, while the CHL conversion seems to be
positively correlated with the Ni/Cu molar ratio in catalysts.
When the reaction temperature is raised to 240 °C, the CHL
conversion, along with the phenol yield, increases significantly.
It is worth noting that a quite high phenol yield of 98% is
achieved over the Ni2Cu1, higher than that over the Ni3Cu0
(Table 1, entries 6 and 7). Further decrease in the Ni/Cu molar
ratio leads to the decrease in both CHL conversions and phenol
yields (Table 1, entries 8 and 9). Only a low phenol yield of 8%
is obtained over the Ni0Cu3 at 240 °C (Table 1, entry 10). It
clearly demonstrates that Niꢀrich catalysts exhibit superior
catalytic activity to Cuꢀrich ones in the present coupling system;
however, an appropriate incorporation of Cu into the NiꢀCu
alloy structure can greatly facilitate the dehydrogenative
aromatization of CHL, thereby improving the selectivities to
both phenol and DMF. In addition, the coupling process also
was conducted in the absence of any solvents. It is found that
such process can be realized without any solvents (Table 1,
Fig. 2 HRTEM (A, B) and HAADFꢀSTEM (C) images of the
representative Ni2Cu1 sample; the EDS mappings of Ni (D), Cu (E) and
the overlapping of Ni and Cu (F).
Further, high resolution transmission electron microscopy
(HRTEM) and highꢀangle annular darkꢀfield scanning TEM
(HAADFꢀSTEM) analysis of representative Ni2Cu1 sample (Fig.
2) depict that bimetallic NiꢀCu nanoparticles (NPs) can highly
disperse on the surface. Elemental mapping analysis (Fig. 2Dꢀ
3F) shows the homogeneous and similar distributions of Ni and
Cu elements, further indicative of the formation of bimetallic
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entry 11), despite a certain decrease in both conversions and the physical mixture of Ni3Cu0 and Ni0Cu3 with the same Ni/Cu
product selectivities due to high concentrations of substrates. molar ratio as that of Ni2Cu1 (Table 1, entry 15), in comparison
Compared with Ni3Cu0, Ni0Cu3 and Ni2Cu1, three Ni/Al2O3, to the Ni2Cu1 catalyst. The aforementioned results verify that
Cu/Al2O3 and NiꢀCu/Al2O3 comparison catalysts prepared by both the synergy between NiꢀCu in the alloy structure and
the impregnation method show much lower activities (Table 1, strong metalꢀsupport interactions should play important roles in
entries 12ꢀ14), along with lower conversions and phenol yields. improving
catalytic
dehydrogenationꢀhydrogenation
In addition, lower yields of phenol and DMF are obtained over performance of catalysts.
Table 1 Catalytic performance of various catalysts in the coupling process between the dehydrogenation of CHL and the
hydrogenation of HMF. a
Selectivity (%) b
Selectivity (%) c
Con.%
(CHL)
Con.%
(HMF)
Entry
Catalyst
Temp. (°C)
Phenol
CHN
CHO
DMF
MFA
DMTHF
1
2
3
4
Ni3Cu0
Ni2Cu1
200
200
200
200
200
240
240
240
240
240
240
240
240
240
240
99
98
83
71
65
99
99
94
87
82
76
70
62
72
95
99
99
97
93
90
99
99
99
99
99
89
87
76
91
99
36
42
26
10
0
45
47
54
83
99
16
2
18
10
19
5
95
96
88
67
40
83
99
96
92
77
90
85
59
89
81
0
3
5
0
Ni1.5Cu1.5
Ni1Cu2
12
32
51(9)
0
0
0
5 d
Ni0Cu3
0
0
6
Ni3Cu0
78
98
46
23
10
88
52
0
6
17
0
7
Ni2Cu1
0
0
8
Ni1.5Cu1.5
Ni1Cu2
42
62
85
12
43
99
35
58
11
14
3
3
0
9
8
0
10
11 e
12
13 d
14
15 f
Ni0Cu3
23
10
15
23(18)
11
19
0
Ni2Cu1
0
0
Ni/Al2O3
Cu/Al2O3
NiꢀCu/Al2O3
Ni3Cu0+Ni0Cu3
5
0
0
0
58
37
7
0
5
0
b
a Reaction conditions: N2: 1 atm, CHL/HMF = 2 (in mole), N2/(CHL + HMF) = 13 (in mole), LHSV(CHL + HMF) = 1.0 hꢀ1. Isolated selectivity of the
c
d
dehydrogenation part. Isolated selectivity of the hydrogenation part. The numbers in parentheses refer to the selectivity of 2,5ꢀdihydroxymethylfuran
(DHMF). e No solvents, LHSV(CHL + HMF) = 0.5 hꢀ1. f The physical mixture of Ni3Cu0 and Ni0Cu3 catalysts.
The coupling process was performed over the Ni2Cu1 addition to phenol and cyclohexenꢀ1ꢀone (CHO). With the
catalyst at different temperatures and liquid hourly space reaction temperature raised up to 260 °C, the phenol selectivity
velocity (LHSV) values to investigate the product distributions. reaches about 100%. Meantime, for the HMF hydrogenation
As shown in Fig. 3a and 3b, the conversions of CHL and HMF part (Fig. 3b), low reaction temperatures (< 220 °C) results in
increase with the increasing reaction temperature. When the the formation of a small amount of 5ꢀmethylꢀ2ꢀfuranmethanol
reaction temperature is above 200 °C, almost complete (MFA) hydrogenation intermediate, besides DMF. At 240 °C, a
conversions are achieved. However, the selectivities to phenol highest DMF selectivity of 99% is achieved. As the reaction
and DMF vary substantially with the reaction temperature. For temperature is further raised to 260 °C, a certain amount of
the CHL dehydrogenation (Fig. 3a), the main dehydrogenation DMTHF is formed due to the deep hydrogenation of the furan
product is CHN at lower reaction temperatures (< 220 °C), in ring in DMF, thus causing a slight decrease in the DMF yield.
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Fig. 3c and 3d depicts the dependence of product CHN and CHO dehydrogenation products. The above results
distributions on LHSV values applied in the coupling process. verify that phenol can be formed through the dehydrogenations
It is noted that the total yields of both dehydrogenation products taking CHN and CHO as intermediates.
and hydrogenation products are low when the LHSV is below
On the other side, as shown in scheme S1†, single CHL
0.6 hꢀ1, due to the easy occurrence of the condensation between dehydrogenation to phenol is an endothermic process (+189.8
CHL and HMF or between the intermediates in a long residence kJ molꢀ1), whereas single HMF hydrogenation to DMF is
time. Moreover, a small amount of DMTHF is produced at low exothermic by about ꢀ277.5 kJ molꢀ1. Clearly, the coupling
LHSV values (< 1.0 hꢀ1). As the LHSV increases from 1.0 hꢀ1 to process combines dehydrogenation and hydrogenation into one
1.6 hꢀ1, the conversions of CHL and HMF, as well as the catalytic system, thus leading to a highly effective usage of
selectivities to phenol and DMF, decrease gradually, and the hydrogen through hydrogen transfer between two substrates, as
yields of CHN, CHO, and MFA increase remarkably. An well as a better thermal balance with a lower heat release (ꢀ87.7
appropriate LHSV value of 1.0 hꢀ1 benefits the production of kJ molꢀ1).Therefore, much easier temperature control can be
phenol with high yield, accompanied by the disappearance of achieved in the practical operation.18
Fig. 3 Change in the conversions and selectivies over Ni2Cu1 catalyst in the coupling process with the reaction temperature and LHSV in the CHL
dehydrogenation part (a and c) and in the HMF hydrogenation part (b and d). Reaction conditions: N2: 1 atm, CHL/HMF = 2 (in mole), N2/(CHL +
HMF) = 13 (in mole), LHSV(CHL + HMF) = 1.0 hꢀ1 (for a and b),
T = 240 °C (for c and d).
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Fig. 4 Conversions and selectivities as function of time on stream over
the Ni2Cu1catalyst. Reaction conditions: N2: 1 atm, CHL/HMF = 2 (in
mole), N2/(CHL + HMF) = 13 (in mole), LHSV(CHL + HMF) = 1.0 hꢀ1,
T
= 240 °C.
Fig. 4 shows the conversions of CHL and HMF and the
selectivities to phenol and DMF as functions of time on stream
over the Ni2Cu1 catalyst. During the 160 h continuous test, no
obvious decline in both the conversions and the selectivities is
observed, mirroring its excellent structural stability. The
turnover number (TON) values, which were calculated based
on the moles converted CHL or HMF per mole of Ni and Cu in
the catalyst, are about 77.9 for CHL and 48.6 for HMF,
respectively. ICPꢀAES measurements reveal that the decrease
in total content of Ni and Cu in the catalyst is less than 0.4
wt.% after reaction, indicating that there is a slight leaching of
the active composition in the catalyst during the reaction.
Therefore, the stability of the catalyst needs to be further
improved. The related investigations will be made in the future.
The above results further confirm the advantage for the present
Fig. 5 Change in the conversions and selectivies over Ni2Cu1 catalyst
with the reaction temperature (a) and the LHSV value (b) in the CHL
dehydrogenation. Reaction conditions: N2: 1 atm, N2/CHL = 13 (in
mole), LHSV(CHL) = 1.0 hꢀ1 (for a),
T = 240 °C (for b).
studied. In order to deeply investigate the reaction pathways in
the present coupling process, the following control experiments
were conducted over the Ni2Cu1 catalyst.
Firstly, the CHL dehydrogenation was carried out in the
absence of HMF under N2 atmosphere, ruling out the possible
role of HMF. The reaction results are displayed in Fig. 5.
Notably, the CHL conversions are significantly restrained at the
same temperatures as those in the coupling process (Fig. 5a). In
this case, the absence of hydrogen acceptor (HMF), however,
leads to decreased phenol selectivities at different reaction
temperatures, compared with those in the coupling process. In
addition, it is noted from Fig. 5b that the phenol selectivity
declines rapidly with the increasing LHSV value, whereas CHN
increases remarkably in yield and becomes the main product at
a high LHSV value of 1.6 hꢀ1. It suggests that the CHL
dehydrogenation can be substantially promoted by coupling
with the HMF hydrogenation, and HMF as hydrogen acceptor
drives the reaction equilibrium of the CHL dehydrogenation
toward the generation of phenol in the coupling process.
Secondly, to verify the crucial role of the dehydrogenation
playing in the HMF hydrogenation, CHN and CHO were
employed as substrates to substitute CHL in different
dehydrogenationꢀhydrogenation coupling processes over the
Ni2Cu1 catalyst (Fig. 6). Noticeably, the CHN dehydrogenation
produces both phenol in high yields and CHO in low yields
even at relatively high LHSV values. In the meantime, the
DMF selectivities (LHSV > 0.8 hꢀ1) are lower than those in the
bimetallic
NiꢀCu
alloy
catalyzed
dehydrogenationꢀ
hydrogenation coupling process for the production of phenol
and DMF.
Reaction pathways and mechanism
As we know, the HMF hydrogenation under H2 atmosphere
mainly involves the hydrogenation of C=O bond and the
hydrogenolysis of C–O bond.6,7 Previously, in most cases, CHN
was reported to be the main dehydrogenation product using
CHL as hydrogen donator in transfer hydrogenations. To date,
the production of phenol by oxygenꢀfree dehydrogenation of
CHL coupled with the HMF hydrogenation has not been
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Fig. 6 Change in the conversions and selectivities over Ni2Cu1 catalyst with the LHSV value in the coupling process starting from (a) CHN and
HMF and (b) CHO and HMF. Reaction conditions: N2: 1 atm, CHN/HMF = 2 (in mole), CHO/HMF = 2 (in mole), N2/(CHN + HMF) = 13 (in
mole), N2/(CHO + HMF) = 13 (in mole),
T = 240 °C.
Scheme 2 Plausible reaction pathways for the coupling process between the CHL dehydrogenation and the HMF hydrogenation over asꢀformed
NixCuy catalysts.
case of coupling process starting from CHL and HMF. And CHO and HMF, phenol is the only dehydrogenated product and
accordingly, the yields of MFA and 2,5ꢀdihydroxymethylfuran almost complete conversion of CHO to phenol occurs at the
(DHMF) are enhanced quickly with the increasing LHSV value LHSV value of 0.8 hꢀ1; while MFA is a major hydrogenation
at the expense of the DMF selectivity at higher LHSV values, product together with DHMF. Therefore, positive correlations
due to the lack of active hydrogen species produced from the can be established between the amount of the in-situ generated
CHN dehydrogenation. For the coupling process starting from active hydrogen species and the DMF selectivity in the HMF
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hydrogenation, implying that an appropriate substrate should be nanostructure. In order to get an insightful understanding of the
critical for the present coupling process producing phenol and synergy between NiꢀCu species in reduced catalysts, Xꢀray
HMF with high yields. The above observations clearly reflect photoelectron spectroscopy (XPS) characterizations of the
three tandem steps for the conversion of CHL through CHL to catalysts were performed (Fig. 7). Obviously, the values of
CHN, CHN to CHO, and CHO to phenol in the coupling binding energy (BE) of Ni 2p3/2 core level in bimetallic NiꢀCu
process starting from CHL and HMF, and HMF is concurrently catalysts are lower than that in the monometallic Ni one.
hydrogenated to DMF using active hydrogen species released Intriguingly, the change in the BE values of Cu 2p3/2 core level
from the dehydrogenations of CHL, CHN, or CHO.
in catalysts exhibit an opposite trend. This phenomenon
At last, the dehydrogenationꢀhydrogenation coupling suggests the presence of electron transfer from Cu to Ni in the
process starting from CHN and HMF was also conducted over alloy structure, thanks to the electronic (ligand) effect. Such
different catalysts. As shown in Table S2†, Ni2Cu1 catalyst electronic effect would benefit the βꢀhydride elimination,
exhibits the best dehydrogenation and hydrogenation thereby promoting the dehydrogenation reaction.12c,20 Therefore,
performances among all NixCuy catalysts. In contrast, much manipulating the Ni/Cu molar ratio in catalysts is capable of
lower conversions of CHN and HMF are observed over the concurrently improving the yields of phenol and DMF products
Ni0Cu3. In addition, Al2O3ꢀsupported monometallic and in the present coupling process, which has never been reported
bimetallic comparison samples show poorer catalytic before. Nevertheless, how metallic sites in bimetallic NiꢀCu
dehydrogenation and hydrogenation activities, in comparison to alloy structure cooperate in the present coupling process
their corresponding NixCuy catalysts. The above results further catalysis to dictate the high selectivities to phenol and DMF
confirm that the dehydroꢀaromatization and hydrogenation still need to be further systemically investigated.
abilities of Ni species are much stronger than those of Cu
species, and that the nanostructure of bimetallic NiꢀCu alloy path is that HMF is firstly converted to DHMF or MFA and
plays
crucial role in promoting the dehydrogenationꢀ further to DMF.6,7 This is also supported by the single HMF
hydrogenation coupling process. hydrogenation using external H2 (Fig. S3†). One can found that
For the HMF hydrogenation, a commonly accepted reaction
a
In view of the above catalytic reaction results, a plausible the content of MFA intermediate is remarkably increased with
mechanism for the dehydrogenation–hydrogenation coupling the increasing LHSV value from 1.0 to 1.8 hꢀ1, similar to that in
process through the hydrogen transfer between CHL and HMF the case of the coupling process. As described above, however,
over asꢀformed NixCuy catalysts is proposed tentatively at a the product distributions in the HMF hydrogenation is closely
molecular level (Scheme 2). For the CHL dehydrogenation, related to the amount of released active hydrogen species in the
firstly, the hydroxyl group in CHL interacts with active metallic coupling process without external hydrogen. When CHL is
sites on the catalyst, and the hydrogen atom is abstracted to converted to phenol with high yields, the amount of in situ
form the metal alkoxide species (R–O–M) (step
1
, compound produced hydrogen species is sufficient for the HMF
A). Then, the catalyst capture another βꢀH atom adjacent to the hydrogenation to form DMF. However, if CHL is incompletely
alcoholic group to form the πꢀallylic species (step 2, compound
B
), which may exist as a transitional structure between ketone
and enol and then give CHN and active hydrogen species.
Sequentially, the adsorbed CHN suffers a αꢀC–H activation
process and coordinates with the catalyst to form the metal
enolate species (step
proceeds again to give the second intermediate CHO (step
compound ). At last, the dehydrogenation of CHO, which
takes place through a similar process to that of CHN (step ),
and tautomeric transformation of CHO lead to the formation of
final phenol product (step ). During the whole
3, compound C), then the βꢀH elimination
4,
D
5
6
dehydrogenation process of CHL and intermediates, active
hydrogen species are continuously abstracted to take part in the
HMF hydrogenation for the production of DMF.
One fact should be underlined that Niꢀrich catalysts
possesses high dehydrogenation activity and are highly
selective to phenol even under relatively low reaction
temperatures, which should be correlated with the intrinsic high
aromatization activity of nickel.19 Correspondingly, the
dehydrogenation of ring easily occurs through the formation of
metalꢀcarbon bonds with σꢀ or πꢀtype character on such a kind
of “aromatizing metal”. Another phenomenon is that the
introduction of an appropriate amount of Cu into NiꢀCu alloy
system can enhance the yields of phenol and DMF. This may be
reasonably related to the synergistic effect of NiꢀCu alloy
Fig. 7 Ni 2p XPS (A) and Cu 2p XPS (B) of NixCuy catalysts. (a)
Ni3Cu0, (b) Ni2Cu1, (c) Ni1.5Cu1.5, (d) Ni1Cu2, (e) Ni0Cu3.
converted or partial dehydrogenated to CHN, high yields of
hydrogenation intermediates (e.g. DHMF or MFA) can be
formed. On the other hand, the high activity of metallic Ni puts
forward the possibility of the deep hydrogenation of furan ring
to give DMTHF, thus decreasing the DMF yield. On the
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contrary, due to the overlapping of the 3d band of Cu atoms and one. As a result, the aromatic hydrogenation is minimized and
the antiꢀbonding orbital of furan ring,8d,21 Cuꢀcontained samples high yields of DMF can be gained over bimetallic NiꢀCu alloy
usually strongly repulses the furan ring. Consequently, the C– catalysts.
OH bond can be preferentially dissociated rather than the C–C
Table 2 Catalytic reaction results over the Ni2Cu1 catalyst in the dehydrogenationꢀhydrogenation coupling processes between substituted
CHLs and HMF. a
Entry
1
Substrate (I)
Temp. (°C)
240
LHSV (hꢀ1)
1.0
Yield % (III) b
Yield % (IV) c
79
98
2
3
4
240
240
250
1.0
1.0
0.8
87
92
78
99
99
98
5
6
250
250
0.8
1.0
76
89
95
99
7
8
9
240
240
250
1.0
1.0
0.8
72
85
88
94
98
99
a Reaction conditions: N2: 1 atm, I/II = 2 (in mole), N2/(I + II) = 13 (in mole), LHSV(I + II) = 1.0 hꢀ1. b Isolated yield of the dehydrogenation part. c Isolated
yield of the hydrogenation part.
The present dehydrogenationꢀhydrogenation coupling protocol
The feasibility of NixCuy catalyst for the coupling process
was further extended to produce various substituted phenols
and DMF to verify the scope, activity, and chemoselectivity of
the Ni2Cu1 catalyst (Table 2). Notably, the Ni2Cu1 catalyst also
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exhibited good catalytic activity and chemoselectivity for the
dehydrogenation of various substituted CHLs and the
hydrogenation of HMF, with high yields of substituted phenols
and DMF. Compared with those for monomethylꢀsubstituted
CHLs (entries 1ꢀ3), dehydrogenationꢀaromatization activities
for dimethylꢀsubstituted CHLs (entries 4ꢀ6) are lower due to the
steric effect, along with higher reaction temperatures and (or)
lower LHSV values required. Furthermore, selective
dehydrogenations of substituted ethylꢀ and phenyl CHLs can
successfully proceed (entries 7ꢀ9). Meanwhile, the DMF
selectivities maintain above 94 % in all cases. The above results
clearly verify the extensive applicability of the present coupling
process between the dehydrogenation of substituted CHLs and
the hydrogenation of HMF for the highly efficient synchronized
production of DMF and various substituted phenols.
1
2
3
4
a) J. N. Chheda, G. W. Huber and J. A. Dumesic, Angew.
Chem. Int. Ed., 2007, 46, 7164–7183; b) P. P. Upare, D. W.
Hwang, Y. K. Hwang, U. ꢀH. Lee, D. ꢀY. Hong and J. ꢀS.
Chang, Green Chem., 2015, 17, 3310–3313.
a) R. ꢀJ. van Putten, J. C. van der Waal, E. de Jong, C. B.
Rasrendra, H. J. Heeres and J. G. de Vries, Chem. Rev.
,
2013, 113, 1499–1597; b) J.C. Colmenares and R. Luque,
Chem. Soc. Rev., 2014, 43, 765–778.
a) Y. RománꢀLeshkov, C. J. Barrett, Z. Y. Liu and J. A.
Dumesic, Nature, 2007, 447, 982–985; b) J. ꢀP. Lange, R.
Price, P. M. Ayoub, J. Louis, L. Petrus, L. Clarke and H.
Gosselink, Angew. Chem. Int. Ed., 2010, 49, 4479–4483.
a) M. J. Climent, A. Corma and S. Iborra, Green Chem.
2014, 16, 516–547; b) B. Zhou, J. Song, H. Zhou, T. Wu
and B. Han, Chem. Sci., 2016, , 463–468; c) F. M. A.
,
7
Geilen, B. Engendahl, A. Harwardt, W. Marquardt, J.
Klankermayer and W. Leitner, Angew. Chem. Int. Ed., 2010,
49, 5510–5514.
Conclusions
5
a) J. J. Bozell and G. R. Petersen, Green Chem., 2010, 12,
539–554; b) S. P. Teong, G. Yi and Y. Zhang, Green Chem.
2014, 16, 2015–2026; c) M. E. Zakrzewska, E. Bogelꢀ
In summary, we developed a highly efficient vaporꢀphase
coupling process between the CHL dehydrogenation and the
HMF hydrogenation to simultaneously produce phenol and
DMF with high yields (> 97%), over the noble metalꢀfree Niꢀ
Cu alloy nanocatalyst with the Ni/Cu molar ratio of 2:1 in the
absence of any external hydrogen and oxygen supply.
Systematic catalytic tests revealed that CHL could be
dehydrogenated into phenol via CHN and CHO intermediates.
Meanwhile, in situ produced active hydrogen species from the
dehydrogenation of CHL, CHN, or CHO could react with HMF
to generate DMF. Furthermore, HMF as hydrogen acceptor
derived the reaction equilibrium of the CHL dehydrogenation
toward the generation of phenol in the coupling process. It was
found that the NiꢀCu alloy nanostructure substantially
facilitated the coupling process along with high yields of both
phenol and DMF, due to the fact that the electronic effect in the
NiꢀCu alloy structure benefited the βꢀhydride elimination in the
dehydrogenation and effectively restrained the aromatic
hydrogenation. Besides, a variety of substituted phenols also
could be produced through the present coupling system. Asꢀ
developed coupling process provides a promising and simple
avenue for the green production of industrial chemicals and
biofuels from fundamental raw materials, which highlights the
idea of green chemistry and sustainable development greatly.
,
Łukasik and R. BogelꢀŁukasik, Chem. Rev., 2011, 111
,
397–417; d) M. J. Climent, A. Corma and S. Iborra, Green
Chem., 2011, 13, 520–540; e) A. A. Rosatella, S. P.
Simeonov, R. F. M. Fraude and C. A. M. Afonso, Green
Chem., 2011, 13, 754–793; f) Y. Nakagawa, M. Tamura, K.
Tomishige, ACS Catal., 2013, 3, 2655–2668; g) J. Mitra, X.
Zhou and T. Rauchfuss, Green Chem., 2015, 17, 307–313; h)
A. S. K. Hashmi, M. Wölfle, J. H. Teles and W. Frey,
Synlett, 2007, 11, 1747–1752; i) S. Tšupova, F. Rominger,
M. Rudolph and A. S. K. Hashmi, Green Chem., 2016, 18
,
5800–5805; j) A. S. K. Hashmi, T. M. Frost and J. W. Bats,
J. Am. Chem. Soc., 2000, 122, 11553–11554; k) T. Buntara,
S. Noel, P. H. Phua, I. MeliánꢀCabrera, J. G. de Vries and H.
J. Heeres, Angew. Chem. Int. Ed., 2011, 50, 7083–7087; l)
M. J. Gilkey and B. Xu, ACS Catal., 2016, 6, 1420–1436; m)
A. S. K. Hashmi, P. Haufe, C. Schmid, A. R. Nass and W.
Frey, Chem. Eur. J., 2006, 12, 5376–5382.
6
7
a) M. Chidambaram and A. T. Bell, Green Chem., 2010, 12
1253–1262; b) J. Jae, W. Q. Zheng, A. M. Karim, W. Guo,
R. F. Lobo and D. G. Vlachos, ChemCatChem, 2014,
,
6
,
848–856; c) J. B. Binder and R. T. Raines, J. Am. Chem.
Soc., 2009, 131, 1979–1985; d) J. Jae, W. Zheng, R. F.
Lobo and D. G. Vlachos, ChemSusChem, 2013, 6, 1158–
1162.
Conflicts of interest
a) G. H. Wang, J. Hilgert, F. H. Richter, F. Wang, H. J.
Bongard, B. Spliethoff, C. Weidenthaler and F. Schuth, Nat.
Mater., 2014, 13, 293–300; b) M. Chatterjee, T. Ishizaka
and H. Kawanami, Green Chem., 2014, 16, 1543–1551; c)
There are no conflicts of interest to declare.
Acknowledgements
M. Y. Chen, C. B. Chen, B. Zada and Y. Fu, Green Chem.
2016, 18, 3858–3866; d) Y. B. Huang, M. Y. Chen, L. Yan,
Q. X. Guo and Y. Fu, ChemSusChem, 2014, , 1068–1072;
,
This study was funded through National Natural Science
Foundation of China (21325624; 21521005) and Fundamental
Research Funds for the Central Universities (buctrc201528).
7
e) Y. H. Zu, P. P. Yang, J. J. Wang, X. H. Liu, J. W. Ren, G.
Z. Lu and Y. Q. Wang, Appl. Catal., B, 2014, 146, 244–248;
f) J. Luo, H. Yun, A. V. Mironenko, K. Goulas, J. D. Lee,
M. Monai, C. Wang, V. Vorotnikov, C. B. Murray, D. G.
Notes and references
Vlachos, P. Fornasiero and R. J. Gorte, ACS Catal., 2016, 6,
10 | J. Name., 2012, 00, 1-3
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ARTICLE
4095ꢀ4104; g) G.ꢀH. Wang, J. Hilgert, F. H. Richter, F. 17 a) J. G. Dickinson and P. E. Savage, ACS Catal., 2014, 4,
Wang, H.ꢀJ. Bongard, B. Spliethoff, C. Weidenthaler and F.
Schüth, Nat. Mater., 2014, 13, 293–300; h) J. Luo, L.
ArroyoꢀRamírez, J. Wei, H. Yun, C. B. Murray and R. J.
Gorte, Appl. Catal., A, 2015, 508, 86–93.
2605–2615; b) E. T. Saw, U. Oemar, X. R. Tan, Y. Du, A.
Borgna, K. Hidajat and S. Kawi, J. Catal., 2014, 314, 32–46;
c) A. Ungureanu, B. Dragoi, A. Chirieac, S. Royer, D.
Duprez and E. Dumitriu, J. Mater. Chem., 2011, 21, 12529–
12541.
8
a) T. S. Hansen, K. Barta, P. T. Anastas, P. C. Ford and A.
Riisager, Green Chem., 2012, 14, 2457–2461; b) T. 18 a) Y. Zhu, H. Xiang, G. Wu, L. Bai and Y. Li, Chem.
Thananatthanachon and T. B. Rauchfuss, Angew. Chem., Int.
Ed., 2010, 49, 6616–6168; c) S. De, S. Dutta and B. Saha,
Commun., 2002, 254–255; b) Y. Zhu, H. Xiang, Y. Li,*a H.
Jiao, G. Wu, B. Zhong and G. Guo, New J. Chem., 2003, 27
208–210.
,
ChemSusChem, 2012,
Aellig and I. Hermans, ChemSusChem, 2013,
T. Pasin, A. Lolli, S. Albonetti, F. Cavani and M. Mella, J.
Catal. 2014, 317 206–219; f) A. M. Ruppert, M. 20 a) A. Wang, X. Y. Liu, C. ꢀY. Mou and T. Zhang, J. Catal.
Jędrzejczyk, O. SnekaꢀPłatek, N. Keller, A. S. Dumon, C. 2013, 308, 258–271; b) J. K. Edwards, S. J. Freakley, A. F.
Carley, C. J. Kiely and G. J. Hutchings, Acc. Chem. Res.,
5, 1826–1833; d) D. Scholz, C.
7
, 268–275; e) 19 M. Dobrovolszky, P. Tétényi and Z. Paál, J. Catal., 1982,
74, 31–43.
,
,
,
Michel, P. Sautet and J. Grams, Green Chem., 2016, 18
,
2014–2028.
2014, 47, 845–854; c) G. J. Hutchings and C. J. Kiely, Acc.
Chem. Res., 2013, 46, 1759–1772; d) H. Zhang and N.
9
Z. Rappoport, The Chemistry of Phenols, WileyꢀVCH, New
York, 2003.
Toshima, Catal. Sci. Technol., 2013,
, 127–137; 21 a) K. L. Deutsch and B. H. Shanks, J. Catal., 2012, 285
b) P. Hanson, J. R. Jones, A. B. Taylor, P. H. Walton and A. 235–241; b) S. Sitthisa, T. Sooknoi, Y. Ma, P. B. Balbuena
W. Timms, J. Chem. Soc., Perkin Trans., 2002, , 1135–
1150; c) J. Zhang, Q. Jiang, D. Yang, X. Zhao, Y. Dong and
R. Liu, Chem. Sci., 2015, , 4674–4680. S. Yun, D. S. Park and J. Yi, Catal. Sci. Technol., 2014, 4,
3, 268–278.
10 a) C. Hoarau and T. R. R. Pettus, Synlett, 2003,
1
,
6
and D. E. Resasco, J. Catal., 2011, 277, 1–13; c) S. Sitthisa
and D. E. Resasco, Catal. Lett., 2011, 141, 784–791; d) Y.
6
11 R. Kumar, S. Sithambaram and S.L. Suib, J.Catal., 2009,
262, 304ꢀ313.
3191–3202; e) T. Wang, M. W. Nolte and B. H. Shanks,
Green Chem., 2014, 16, 548–572.
12 a) Y. Izawa, D. Pun and S. S. Stahl, Science, 2011, 333
,
209–213; b) Y. Izawa, C. Zheng and S. S. Stahl, Angew.
Chem., Int. Ed., 2013, 52, 3672–3675; c) D. Pun, T. Diao
and S. S. Stahl, J. Am. Chem. Soc., 2013, 135, 8213–8221; d)
X. Jin, K. Taniguchi, K. Yamaguchi and N. Mizuno, Chem.
Sci., 2016, 7, 5371–5383; e) T. Moriuchi, K. Kikushima, T.
Kajikawa and T. Hirao, Tetrahedron Lett., 2009, 50, 7385–
7387; f) J. Muzart, Eur. J. Org. Chem., 2010, 2010, 3779–
3790.
13 a) Q. Hu, G. Fan, L. Yang, X. Cao, P. Zhang, B. Wang and
F. Li, Green Chem., 2016, 18, 2317–2322; b) Q. Yang, Y. Z.
Chen, Z. U. Wang, Q. Xu and H. L. Jiang, Chem. Commun.
2015, 51, 10419–10422; c) Y. L. Zhu, H. W. Xiang, G. S.
Wu, L. Bai and Y. W. Li, Chem. Commun., 2002, , 254–
,
3
255; d) Y. L. Zhu, J. Yang, G. Q. Dong, H. Y. Zheng, H. H.
Zhang, H. W. Xiang and Y. W. Li, Appl. Catal., B, 2005, 57
183–190; e) J. Song, L. Wu, B. Zhou, H. Zhou, H. Fan, Y.
Yang, Q. Meng and B. Han, Green Chem., 2015, 17, 1626–
1632.
,
14 a) H. P. R. Kannapu, C. K. P. Neeli, K. S. R. Rao, V. N.
Kalevaru, A. Martin and D. R. Burri, Catal. Sci. Technol.
2016, , 5494–5503; b) H. Y. Zheng, Y. L. Zhu, L. Huang,
Z. Y. Zeng, H. J. Wan and Y. W. Li, Catal. Commun., 2008,
, 342–348.
15 a) H. Y. Zheng, Y. L. Zhu, Z. Q. Bai, L. Huang, H. W.
Xiang and Y. W. Li, Green Chem., 2006, , 107–109; b) B.
,
6
9
8
M. Nagaraja, A. H. Padmasri, P. Seetharamulu, K. H. P.
Reddy, B. D. Raju and K. S. R. Rao, J. Mol. Catal., 2007,
278, 29–37.
16 a) G. Fan, F. Li, D. G. Evans and X. Duan, Chem. Soc. Rev.
,
2014, 43, 7040–7066; b) F. Li and X. Duan, Struct. Bonding
2006, 119, 193–223.
,
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A table of contents entry
Highly efficient synchronized production of phenol and 2,5-dimethylfuran was
achieved via a bimetallic Ni-Cu catalyzed dehydrogenation-hydrogenation coupling
process.