Nickel-catalyzed intelligent reductive transformation of the aldehyde group using hydrogen

Article abstract of DOI:10.1039/c9gc01116a

The selective transformation of the aldehyde group (-CHO) in multifunctional oxygenates is a key challenge in the development of sustainable biomass feedstock. Herein, a smart Ni-MFC catalyst was developed from a 2D Ni-based metal-organic framework (MOF), which efficiently promoted the transformation of -CHO in the presence of H₂ to a methyl group (-CH₃) via the reductive etherification and hydrogenolysis of the C-O ether bond in methanol. Moreover, the catalytic process could be controlled to directionally produce methyl ether (-CH₂OR) using the reductive etherification protocol. For the catalytic reduction of vanillin, the Ni-MFC-700 catalyst guaranteed the full conversion of vanillin and 96.5% yield of the desired 2-methoxy-4-methylphenol (MMP), while the Ni-MFC-500 catalyst afforded about 82.7% yield of 4-(methoxymethyl)-2-methoxyphenol in methanol solvent. This is a novel and promising approach for the valorization of multifunctional oxygenates and biomass-derived platform compounds.

Full text of DOI:10.1039/c9gc01116a

View Article Online
View Journal
Green
Chemistry
Cutting-edge research for a greener sustainable future
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: X. Tong, P. Guo,
S. Liao, S. Xue and H. Zhang, Green Chem., 2019, DOI: 10.1039/C9GC01116A.
Volume 20
This is an Accepted Manuscript, which has been through the
Number
May 2018
Pages 1919-2160
9
7
Royal Society of Chemistry peer review process and has been
accepted for publication.
Green
Chemistry
Cutting-edge research for a greener sustainable future
rsc.li/greenchem
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
shall the Royal Society of Chemistry be held responsible for any errors
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
ISSN 1463-9262
PAPER
Paul T. Anastas et al.
The Green ChemisTREE: 20 years after taking root with the 12
principles
rsc.li/greenchem

Please do not adjust margins
Page 1 of 15
Green Chemistry
View Article Online
DOI: 10.1039/C9GC01116A
Green Chemistry
ARTICLE
Nickel-catalyzed intelligent reductive transformation of aldehyde
group with hydrogen
Xinli Tong,a Pengfei Guo,a Shengyun Liao, a Song Xue, a Haigang Zhanga
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
The selective transformation of aldehyde group (-CHO) in multifunctional oxygenate is a key challenge in the upgrading of
sustainable biomass feedstock. Herein, a smart Ni-MFC catalyst is developed from the 2D Ni-based metal-organic
frameworks (MOFs), which can efficiently promote the transformation of -CHO with H2 to methyl group (-CH3) via the
reductive etherification and hydrogenloysis of C-O ether bond route in methanol. Moreover, the catalytic process can be
controlled to directionally produce methyl ether (-CH2OR) using the reductive etherification protocol. For the catalytic
reduction of vanillin, Ni-MFC-700 catalyst guarantees the full conversion of vanillin and 96.5% yield of desirable 2-
methoxy-4-methylphenol (MMP), while Ni-MFC-500 catalyst affords about 82.7% yield of 4-(methoxymethyl)-2-
methoxyphenol in methanol solvent. It is a novel and promising approach for valorization of multifunctional oxygenate
and biomass-derived platform compound.
www.rsc.org/
In the past decades, the precious metals such as Pd, Pt, Rh, Ru
and Au supported catalysts have been applied for the
transformation of vanillin into MMP.10-16 But their widespread
Introduction
In recent years, developing the fuels and fine chemicals
production process based on the renewable biomass resource
has provoked great interests due to the continuous growth in
energy demand and security.1-3 As one of the most important
components in the lignocellulosic biomass, lignin is the sole
valuable rich in aromatic rings bio-resource that can be
converted into the aromatic-based chemical and liquid fuels
with high energy density.4, 5 The aromatic aldehyde is the main
ingredient of the crude bio-oil form pyrolysis of lignin. The
selective transformation of aldehyde groups is one of the most
attractive routes to improve the quality of liquid fuel and gain
the bio-based fine chemicals. The process of selective
hydrogenation aldehyde group (-CHO) to methyl group (-CH3)
and methyl ether (-CH2-O-R) without destroying C=C in
aromatic rings have attracted more and more attention,
recently.6-9
The selective reductive transformation of -CHO to -CH3
can afford us with the value-added methylated product, and
minimize the hydrogen consumption and loss of carbon.
Developing efficient and economical catalytic system and
probing the mechanism of the transformation in different
reaction systems are the key factors to successfully upgrade
the bio-oils. Vanillin was often chosen as a model compound
for investigation the selective transformation of –CHO to –CH3.
applications are limited by low earth-abundance and high cost.
Moreover, the high hydrogenation activities of noble metal
catalysts often result in the undesirable saturation of aromatic
ring, in which the high hydrogen consumption is necessary. On
basis of these, there is a pressing need for developing highly
active, selective and steady non-noble metal-based catalysts
with the prospects in practical application. Chen et al. used
well-dispersed Mo2C nanoparticles supported on activated
carbon to catalyse the transformation of vanillin
hydrogenation and obtained the poor selectivity for
methylated product.17 In 2018, the highly dispersed copper
nanoparticles supported on activated carbon was applied in
the processes of vanillin hydrodeoxygenation toward MMP in
aqueous-phase and the obtained 15wt%-Cu/AC-600 catalyst
can promote the transformation of vanillin to MMP with 99.9%
conversion and 93.2% selectivity of MMP under a moderate.15
In the same period, Zhang et al and Xia et al. found nitrogen-
doped carbon supported cobalt or nickel nanoparticles
displayed good activity in the process of vanillin
hydrodeoxygenation.18-19 With Co/nitrogen-doped carbon as
catalyst, 98.8 % conversion of vanillin and 58.9 % selectivity of
MMP were achieved in ethanol. However, the reduction of
aldehydes, utilization of Ni catalysts mainly focused on the
20-23
transformation of –CHO to –CH2OH.
Lee’s group
synthesized one caped Ni nanoparticles using a colloidal
method to catalyze the selective hydrogenation of furanic
aldehydes to generate furanic alcohols.24 Recently, Stella’s
a. Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion,
School of Chemistry and Chemical Engineering, Tianjin University of Technology,
No. 391 Binshuixi Road, Tianjin 300384, PR China. Tel: (+86)-22-60214259; E-mail: group reported NiO nanoparticles can effectively catalyze
tongxinli@tju.edu.cn;tongxli@sohu.com (X. T.) or mengyunliao@sina.com (S. L.).
reduction of benzaldehydes to the correspondent benzylic
alcohols.25 There are very little reports on the catalytic
†Electronic
Supplementary
Information
(ESI)
available.
See
DOI: 10.1039/x0xx00000x
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 1
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 2 of 15
ARTICLE
Green Chemistry
Path(i): the -CHO group hydrogenation/ -CH2OH group hydrogenolysis
transformation of -CHO to -CH3 or -CH2OCH3 using the Ni-
based catalysts. 19
View Article Online
DOI: 10.1039/C9GC01116A
CH3
CH2OH
CHO
For the selective hydrogenation reaction of vanillin, Xu’s
group suggested MMP could be produced via hydrogenation
and further hydrogenolysis pathway, in which the
hydrogenolysis of vanillyl alcohol occurred (path (i) in Scheme
1);8 Also, several other investigations supported that MMP was
obtained via the hydrogenation/hydrogenolysis pathway.
-H2O
H2
Catalyst
H2
OCH3
OCH3
OH
OCH3
OH
OH
Vanillyl alcohol
Vanillin
2-methoxy-4-methylphenol
Path(ii):: the reductive etherification of -CHO/the ether C-O bond hydrogenolysis
15,25,26
It is worth mentioning that Abu-Omar’s group27 and
O
CH3
CHO
Jiang et al18 performed the catalytic hydrodeoxygenation of
vanillin in alcohol. They also thought of Route (i) as the
reaction pathways and vanillyl alcohol as the reactive
intermediate. In addition, they claimed 4-(methoxymethyl)-2-
methoxyphenol (ether), which is the result of vanillyl alcohol
reaction with the solvent MeOH can protect vanillin from
hydrogenolysis.
-CH3OH
H2
Catalyst
CH3OH
OCH3
OCH3
OCH3
OH
2-methoxy-4-methylphenol
OH
OH
Vanillin
Ether
The yeild of etherification and methylation products being controllable to 82.7% and 96.5%, respectively
Scheme
1
The possible pathways of the reductive
transformation of aldehyde group under H2.
In recent years, our group has employed the novel MOFs-
based materials (MOFs: Metal-organic frameworks) to catalyze
28,29
the transformation of biomass
Distinguishing from
Results and discussion
traditional supported catalysts, the active sites of MOFs-based
catalysts can either originate from the immobilizing metal
nanoparticles or from metal linkers, and sometimes from the
functional groups on the organic ligands as well.30,31
Furthermore, MOFs can be used as precursors of carbon
matrix nanocomposites.32-35 These composites not only remain
two dimensional structure of the MOF precursor, but also
have high specific surface area and uniformly dispersed active
sites, which are essential in promoting catalytic activity. Most
important of all, some heteroatoms such S, N, Si, B, active
metal sites or some other functional groups may be
incorporated into the nodes and linkers on the MOFs in
advance resulting in co-doped porous carbon composites,
which can endow the perfectly catalytic activity. 32,33,36
In this contribution, we performed the hydrogenation
reaction of vanillin using novel Ni-based catalysts as potential
heterogeneous catalysts, which were manufactured through
calcining one 2D Ni-based MOFs ([Ni(tia)(H2O)2]) (tia2- = 5-
(1H-1,2,3-triazol-1-yl) isophthalate). With the higher
calcination temperature at 700 oC, the derived active
nanocomposites (designated as Ni-MFC-700 catalyst) show
great performance in hydrodeoxygenation of vanillin into the
desirable product MMP with 100% conversion and 96.5%
selectivity. At the same time, 4-(methoxymethyl)-2-
methoxyphenol as the intermediate was detected and the high
yield of it (82.7%) was obtained using the alternative Ni-MFC-
500 catalyst under the mild conditions, where a more atom-
economic alternative reductive etherification protocol was
proposed. Furthermore, a new possible reaction pathway of
the reduction of -CHO to -CH3, especially for the hydrogenation
of vanillin with hydrogen in methanol was explored. As shown
in path (ii) of Scheme 1, the transformation of vanillin to MMP
would proceed via the tandem reductive etherification and the
ether C-O bond hydrogenolysis steps.
Synthesis and characterizations of the catalysts. The
precursors 2D Nickel-based MOFs ([Ni(tia)(H2O)2]) has been
synthesized
using
hydrothermal
method.28
The
crystallographic data and detail structural information was
supplied in the Supporting information (Table S1). Single
crystal X-ray diffraction analysis revealed an unusual infinite
2D-dimensional layer based on Ni3 rings formed in
crystallographic ab plane and each Ni(II) ion has a slightly
distorted octahedral coordination, formed by one nitrogen
atoms and three oxygen atoms from the tia2- ligands, and two
oxygen atoms from water molecules occupied on the apical
positions (see Fig. 1a, 1b and 1c). In crystallographic bc plane,
the 2D-dimensional layers was connected by hydrogen-bond
interaction to form 3D supramolecular structure (Fig. 1(d)). Ni-
MFC catalysts were manufactured by calcining this Ni-MOF
under N2 atmosphere at different temperature.
The purity of the bulk synthesized MOFs material was
confirmed by PXRD (Supplementary Fig. S1 (a) and (b)). The
derived catalysts (designated as Ni-MFC-300, 350, 400 500,
600, 700, and 800) were manufactured by calcining the Ni-
based MOFs in the atmosphere of N2 with different calcination
temperature. The PXRD patterns of the derived catalysts
showed the frameworks of MOFs were destroyed gradually
with the calcination temperature increasing (Supplementary
Fig. S1(c), (d), (e), (f), (g), (h) and (i)). At the same time, the
diffraction intensity of Ni (111) and Ni (200) at 2 = 44 and
52, respectively, increased greatly.37,38
The X-ray photoelectron spectroscopy (XPS) spectra of the
fresh Ni-MFC-700, fresh Ni-MFC-500 and used Ni-MFC-700
were displayed in Fig. 2, Fig. S2 and S3 in Supporting
Information, respectively. The photoelectron peaks at 853 eV
(Ni2p3/2), 532 eV (O1s), 401 eV (N1s) and 285 eV (C1s) were
assigned to the main elements of the catalyst. For the fresh Ni-
MFC-700 catalyst, the best fitted peaks of Ni2p3/2 in Ni-MFC-
700 at 852.1, 853.3, 855.1 and 859.8 eV, which were
associated with the adsorption Ni(0), élément naturel, NiO and
2 / 14
Please do not adjust margins

Page 3 of 15
Green Chemistry
Please do not adjust margins
Journal Name
ARTICLE
Ni2O3, respectively (Fig. 2(a)). The best fitted peaks of O1s at
529.7, 531.4, 532.3, and 533.1 eV could be attributed to the
adsorption of NiO, Ni2O3, -C-O and -C=O, respectively (Fig.
2(b))39-42. The nicely fitted peak of N1s at 398.5eV was
generally ascribed to pyridinic N atoms, which were bound to
two C atoms at the edge of graphene layers. 43 Signals at 400.8
eV were usually attributed to N atoms, which was bound to O
atoms (Fig. 2(c)). Peaks at 401.9 eV may originate from
quaternary N, which substituted one C atom in the graphene
layer forming three σ-bonds with C atoms. A very weak peak at
404.4 eV may be assigned to the coordination interaction
between N and Ni. The best fitted peaks of C1s at 284.8, 285.5
and 289.1 eV are ascribed to the graphite C, -C-O and –C=O,
respectively (Fig. 2(d)). The peak of Ni(0) in Ni-MFC-500
catalyst is much weaker than in Ni-MFC-700 (see Fig. 2(a) and
Fig S2(a) in the Supporting Information). The best fitted peaks
of Ni2p3/2 show the content of Ni(0) in Ni-MFC-700 and Ni-
MFC-500 is 15.6% and 1.5 %, respectively. In addition, the best
fitted peaks of Ni2p3/2 in Ni-MFC-500 at 857.1 and 861.9 eV
may be assigned to the -Ni-O-, -Ni-N- of MOF’s framework (see
Fig. S2(a) in Supporting Information). At the same time, some
best fitted peaks of C1s, N1s and O1s in Ni-MFC-500 are
different from Ni-MFC-700, which indicated their existence
form in the matrix carbon may be different. In addition, Fig S3
(a) in Supporting Information indicates the existence of Ni in
Ni-MFC-700 keeps unchanged after being recycled for 5 times,
which are responsible for the good recyclability.
Ni nanoparticles are not fully grown. After beingVrieewuAsreticdlefOonrlin5e
times, the morphologies of Ni-MFC-500DcOhIa: n10g.1e0d39g/rCe9aGtCly01(1F1i6gA.
3(j), 3(k) and 3(l)). In addition, the HRSEM images of
Ni/activated showed the particle sizes are in the range of 30-
100 nm. These non-uniform particles are distributed on the
surface of the support (see Fig. S8 in Supporting Information).
To get a clear vision of the elemental distribution of Ni, N,
O and C on the fresh Ni-MFC-700, used Ni-MFC-700, fresh Ni-
MFC-500 and used Ni-MFC-500 catalyst, one representative
region was subjected to EDX mapping (see Fig. S4-S7 in
Supporting Information). It was found Ni and N elements were
uniformly distributed on each catalyst. Obviously, the
dispersion effect of the active Ni species using MOFs as
templates is better than the conventional supported catalyst
The Brunauer-Emmett-Teller (BET) results of the derived
Ni-MFC catalysts were shown in supplementary Table S2 and
Fig. S9. Their isotherm presented a type IV isotherm according
to BDDT classification. There are hysteresis loops of type H2 in
Ni-MFC-700 and Ni-MFC-800 catalysts according to IUPAC
classification.44 While the adsorption and desorption hysteresis
loop of Ni-MFC-500 belonged to H3. The hysteresis loop H2 is
attributed to the presence of relatively uniform pores in the
form of channels. Hysteresis loop H3 in Ni-MFC-500 may be
ascribed to the presence of mesopores surrounded by a matrix
of smaller pores, which is associated to the incomplete
degradation of organic skeletons. It was worth mentioning that
the pore feature of Ni-MFC-700 almost kept unchanged after 5
cycles. However, the pore size of Ni-MFC-500 became smaller
after being recycled for 5 times. The isotherm curves of them
also changed (see Fig. S10 and S11 in Supporting Information).
The ammonia desorption profile of Ni-MFC-500, 700, 800
were investigated in a normalized mode (initial coverage of
Typical morphologies of the fresh Ni-MFC-700, Ni-MFC-
500, used Ni-MFC-700, used Ni-MFC-500 and Ni/activated
carbon were displayed in Fig. 3 and Fig. S8 in the supporting
information. Ni-MFC-700 maintained the cuboid block shape
of the synthesized 2D Ni-based MOFs (see Fig. 3(a) in
Supporting Information). Meanwhile, the images of the
catalyst highlight the lamellar structure (see Fig. 3(b)). High
magnification HRSEM images revealed that the compact
morphology converted to porosity after calcination. There are
spherical nanoparticles distributed uniformly on some cotton-
shaped matrix, whose sizes fell within the range of 010 nm
(shown in Fig.3(c)). Fig. 3(d), 3(e) and 3(f) exhibit the
morphology of the used Ni-MFC-700 remained unchanged
after five cycles. It was found in Fig. 3(g), 3(h) and 3(i), the
shapes of Ni-MFC-500 are similar to those of Ni-MFC-700.
Different from the latter, no lamellar structure was found.
Comparison Fig. 3(c) with Fig. 3(i), it is found a large quantity
of Ni nanoparticles with uniform particle size are uniformly
dispersed in the lamellar in Ni-MFC-700. While in Ni-MFC-500,
o
NH3 = 1) at a heating rate of 10 C/min and the results were
shown in supplementary Fig. S12. The first broad peak of Ni-
MFC-500 may be ascribed to the two contributions: (i)
decomposition of the remnant MOFs’ framework and (ii) weak
Brønsted acidic sites. As far as the TPD profiles of Ni-MFC-500,
700, 800 were concerned, a narrow desorption peak was
o
observed around 375 C referred to Bronsted acid sites in the
catalysts. After being recycled for 5 times, the acidity of Ni-
FMC-700 became stronger. However, the number of weak
acidic sites increased (see Fig. S13 and S14 in Supporting
Information).
In addition, the Ni content of all as-obtained catalysts
were determined by quantitatively by ICP-OES technique (ICP-
OES: Inductively Coupled Plasma Optical Emission
Spectrometry) and the results were shown Table S3 in the
Supporting Information.
This journal is © The Royal Society of Chemistry 20xx
green chemistry, 2019, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 4 of 15
ARTICLE
Green Chemistry
View Article Online
DOI: 10.1039/C9GC01116A
Fig. 1. The synthesis route and the structure of 2D Ni-MOFs
9000
10000
9500
9000
8500
8000
7500
7000
(b)
(a)
Raw
Sum
Peak1
Peak2
Peak3
Peak4
8000
7000
6000
5000
4000
3000
531.4
853.3
852.1
Raw
Sum
Peak1
Peak2
Peak3
Peak4
859.8
855.1
533.1
532.3
529.7
540
535
Binding Energy(eV)
530
525
865
860
855
850
845
Binding Energy (eV)
6000
5500
5000
4500
4000
40000
30000
20000
10000
0
(c)
(d)
284.8
400.8
Raw
Sum
Peak1
Peak2
Peak3
Peak4
Raw
Sum
Peak1
Peak3
Peak2
398.5
285.5
289.1
404.4
401.9
408
406
404
402
400
398
396
394
296
292
288
Bonding Energy (eV)
284
280
Binding Energy (eV)
F
ig. 2. XPS analysis for fresh Ni-MFC-700: (a) Ni2p3/2; (b) O1s; (c) N1s; (d) C1s
4 / 14
Please do not adjust margins

Page 5 of 15
Green Chemistry
Please do not adjust margins
Journal Name
ARTICLE
View Article Online
DOI: 10.1039/C9GC01116A
This journal is © The Royal Society of Chemistry 20xx
green chemistry, 2019, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 6 of 15
ARTICLE
Green Chemistry
View Article Online
DOI: 10.1039/C9GC01116A
Fig. 3. HRSEM images of the catalysts at different magnification: (a), (b) and (c) for the fresh Ni-MFC-700; (d), (e) and (f) for the
used Ni-MFC-700; (g), (h) and (i) for the fresh Ni-MFC-500; (j), (k) and (l) for the used Ni-MFC-500.
Catalysts screening. In view of the uniformly dispersed active excellent hydrogenolysis catalysts. Here, the different
sites originated from the MOFs-based derived materials, we derivative catalytic materials (designated as Ni-MFC, Ni-MFC-
have synthesized 2D Ni-based metal-organic frameworks 300, Ni-MFC-350, etc.) were generated through the calcination
(MOFs: [Ni(tia)(H2O)2]) as the precursors for fabricating the process of [Ni(tia)(H2O)2] in the N2 atmosphere with different
6 / 14
Please do not adjust margins

Page 7 of 15
Green Chemistry
Please do not adjust margins
Journal Name
ARTICLE
temperature. We conducted the hydrogenation of vanillin the derived catalysts Ni-MFC-500700 exhibited the strong
View Article Online
reaction in methanol over these derivative catalysts under the promotion effect in producing 1 viaDOhyI:d10ro.1d03e9o/xCy9gGeCn0a1t1i1o6nA
o
condition of 2 MPa H2, 160 C and the results were shown in process (Entries 79 in Table 1). With Ni-MFC-700 catalyst, the
Scheme
2
and Table 1. MMP (1), 2-methoxy-4- conversion of vanillin and selectivity of the desirable product 1
(methoxymethyl)phenol (2) and 4-(dimethoxymethyl)-2- can be up to 100% and 26.4%, respectively. However, the
methoxyphenol (3) were detected in our reaction systems, but higher calcination temperature at 800oC, the catalytic active
the vanillyl alcohol (4) and deep hydrogenation (saturation of towards 1 decreased (Entry 10 in Table 1). So Ni-MFC-700 was
C=C) product were not observed. The calcination temperature screened as the best HDO catalyst for up-grading vanillin
of Ni-MFC catalysts shows great influence on the distribution (Entry 9 in Table 1). If we calcined 2D Ni-based MOFs in O2
of products. As shown in Table 1, the conversion of vanillin atmosphere and the derived Ni-MFC-700 showed no catalytic
increased with the calcination temperature increasing before activity on the hydrodeoxygenation and reductive
500 oC (Entries 37 in Table 1). The as-synthesized 2D Ni-based etherification process of vanillin (Entry 11 in Table 1). The full
MOF showed no activity for hydrogenation of vanillin (Entry 3 conversion of vanillin and 96.5% selectivity of 1 were obtained
in Table 1). Selectivity towards reductive etherification product using Ni-MFC-700 as the catalyst under the condition of 2 MPa
2 increased and 3 decreased with the calcination temperature H2, at 200oC for 10 h (Entry 12 in Table 1). The higher yield of 2
increasing. Ni-MFC-400 catalyst can promote the selectivity of was up to 82.7% with Ni-MFC-500 as the catalyst under the
reductive etherification product to 88.9% (Entry 6 in Table 1). condition of 2 MPa H2, at 160oC for 4 h (Entry 7 in Table 1).
For further increasing the calcination temperature of MOFs,
H3CO
OCH3
H3CO
CH2OH
CHO
CH3
CH2
+
+
+
OCH3
OCH3
OCH3
OCH3
OCH3
OH
OH
OH
OH
OH
4
3
2
Vanillin
1
Scheme 2. Hydrodeoxygenation and reductive etherification of vanillin in methanol with the Ni-based catalysts
Table 1. Hydrogenolysis of vanillin using Ni-MFC catalysts and the conventional supported catalystsa.
Sel. (%)b
TONh
TOFi
Entry
Catalyst
Conv. (%)b
(1/h)
1
2
3
Others
1
2
No
62.0
58.9
0.0
0.0
12.1
7.8
87.9
88.2
0.0
4.0
/
/
/
/
Cd-MFC-700j
3
4
Ni-MFC
Ni-MFC-300c
Ni-MFC-350c
Ni-MFC-400c
Ni-MFC-500c
Ni-MFC-600c
Ni-MFC-700c
Ni-MFC-800c
Ni-MFC-700f
62.5
82.9
81.4
62.4
100
0.0
5.2
5.3
7.4
13.1
17.2
26.4
20.6
0.0
96.5
20.0
0.0
1.5
1.1
0
11.1
43.9
61.2
88.9
82.7
80.2
72.5
59.3
7.1
88.9
50.9
30.9
3.7
0.0
0.0
2.6
0
/
/
574.8
595.1
577.2
1343.6
1859.5
2640.0
1961.9
/
143.7
148.8
144.3
335.9
464.9
660.0
490.5
/
5
6
7
3.8
0.4
1.6
0.7
0.8
0.0
0.0
0.0
0.0
1.3
1.1
1.5
4.5
0.0
8
100
1.0
9
100
0.4
10
11
12
13
14
15
16
17
18
19
100
19.3
92.9
0.4
71.5
100
Ni-MFC-700d
3.1
8772.7
4074.3
0
877.3
1018.6
0
Ni/Activated Carbone
Ni/γ-Al2O3-700e
Ni/nano graphite-700e
Ni/TiO2-700e
Ni/ZrO2-700e
Ni/nano MgO-700e
Ni/Activated Carbon usedg
71.3
70.1
71.5
64.0
60.5
74.9
65.5
30.5
29.9
23.3
31.6
19.3
46.0
10.2
49.5
70.1
73.9
66.2
79.2
48.0
89.7
286.0
234.7
0
71.5
58.7
0
1.5
0
374.5
/
93.6
/
a Reaction conditions: 0.1 g vanillin, 0.025 g catalyst, in 15 mL methanol, under 2 MPa of H2, at 160 oC for 4 h.
b The results were obtained by GC analysis with the internal standard technique, 1,3-dichlorobenzene as internal standard.
c The catalyst was obtained by calcination 2D Nickel-based MOFs ([Ni(tia)(H2O)2]) in N2 flow at 300800 oC.
d Reaction conditions: 0.1 g vanillin, 0.025 g catalyst, in 15 mL methanol, under 2 MPa of H2, at 200 oC for 10 h.
This journal is © The Royal Society of Chemistry 20xx
green chemistry, 2019, 00, 1-3 | 7
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 8 of 15
ARTICLE
Green Chemistry
eCatalysts preparation: support (0.1 g) and Ni(NO3)2·6H2O (0.04 g), and 2 mL H2O were mixed together, and theVmiewixAtruticrleeOwnlianes
treated under ultrasonic irradiation for 6 h, then the mixture was placed in an oven and dried at 80 oC for D1O2I:h1.0T.1h0e39a/Cs-9oGbCt0a1i1n1e6dA
powder was grinded and calcined under N2 flow at 700 oC for 4 h.
f The catalyst was obtained by calcination 2D Nickel-based MOFs ([Ni(tia)(H2O)2]) in O2 flow at 700 oC.
g The Ni/Activated Carbon was reused for one time.
h TON = mole of product (MMP) /mole of Ni species.
i TOF = TON/time.
j The Cd-MFC-700 catalyst was prepared by calcination 2D Cadmium-based MOFs ([Cd(tia)(H2O)2]) in N2 flow at 700 oC.
In addition, the conventional Ni-based solid catalysts were stronger than other Ni-MFC-X catalysts. Another evidence
also investigated and the experimental results were from the analysis results of XPS data. The best fitted peaks of
summarized in Table 1 (Entries 13-18). Therein, in the Ni2p3/2 show the content of Ni(0) in Ni-MFC-700 and Ni-MFC-
presence of Ni/activated carbon, a 71.3% conversion of vanillin 500 is 15.6% and 1.5%, respectively. So we speculated that
and 20.0% selectivity of 1 were obtained under the same Ni(0) is the active species for hydrogenation vanillin to product
conditions. The turnover number (TON) and turnover 1, While the nickel in oxidation state may be responsible for
frequency (TOF) of it is higher than Ni-MFC-700 (see the last producing 2, because the Ni(0) content of Ni-MFC-700 is much
two columns in Table 1).45, 46 However, when we tested the higher than Ni-MFC-500.
stability of the catalysts, we found the activity of Ni/activated
Optimization of reaction conditions. In order to improve the
yield of 1, the reaction conditions were further optimized and
the results were displayed in Supplementary Fig. S15 and S16.
It is found that the conversion of vanillin and selectivity of 1
was increased with the increase of temperature. Below 120 oC,
there is no production of desirable product 1, in which
compounds 3 and 4 were the main products. Along with the
elevation of reaction temperature, the conversion of vanillin
was gradually increased, and the total selectivity of 2 and 1
was increased, while the selectivity of 3 and 4 was decreased.
In particular, when the temperature was increased to more
than 160 oC, it should be no longer detected for 3 and 4 after 4
h. In the temperature range of 140 oC160 oC, a large quantity
of ether (2) was obtained. The full conversion of vanillin was
carbon is lost after one cycle (Entry 19 in Table 1). Furthermore,
the other supported Ni-based catalysts nearly showed no
selective conversion toward the generation of 1. Meanwhile,
the yield of reductive etherification product was not desirable.
Here, the great performance of Ni-MFC-700 was obtained
by comparison with other Ni-based catalysts supported on the
conventional porous materials. The metal-organic frameworks
are compounds consisting of metal ions or clusters
coordinated to organic ligands to form one-, two-, or three-
dimensional structures, so pyrolysis metal-organic frameworks
(MOFs: [Ni(tia)(H2O)2]) afforded us Ni-based carbon
composites, so in order to determine the active species is Ni
rather than other ingredients of the derived materials, one
isostructural Cd-based MOFs [Cd(tia)(H2O)2] has been
synthesized and used as the precursors for fabricating Cd-MFC-
700 catalyst under the same condition as Ni-MFC-700 (Entry 2
in Table 1). Cd-MFC-700 showed no activity for hydrogenolysis
vanillin to 1 or 2. So we are ascertained Nickel is the active
species for catalyzing the transformation of vanillin into 1 or 2.
Furthermore, a significant change in the catalytic activity
depending on the calcination conditions was observed (see
Entries 4-8 in Table 1), which may be ascribed to the different
existence form of Nickel under the different calcination
conditions. The Ni(II) centers in the as-synthesized 2D MOFs
([Ni(tia)(H2O)2]) are coordinated by the donor atom (N and O)
show no catalytic activity. With the calcination temperature
increased, the organic component decomposed and the Ni
centers were exposed little by little. In addition, the existence
form of Ni and the morphology of the as-obtained Ni-MFC-X
also changed. The evidence for these is from XPS spectra, XRD
patterns and HRSEM images of Ni-MFC-500 and Ni-MFC-700.
The correlation between structural properties and catalytic
activity is as follows. (i) The lamellar structure and the uniform
particles are uniformly dispersed in the lamellar in Ni-MFC-700,
while in Ni-MFC-500, Ni nanoparticles are not fully grown. This
explains a significant change in the catalytic activity depending
on the calcination conditions. (ii) The XRD patterns of Ni-MFC-
X show the intensity of Ni(0) diffraction peaks in Ni-MFC-700 is
o
acquired at 160 C. If the temperature continues to be raised,
the selectivity of 2 was gradually decreased and the selectivity
of 1 was increased.
Supplementary Fig. S16 showed the selectivity of 1
increased and 2 slowly decreased along with the prolonging of
time. As a result, a full conversion of vanillin and a 96.5%
selectivity for 1 was acquired at 200 oC for 10 h. Moreover, the
Ni-MFC-700 and Ni-MFC-500 catalyst are easily separated by
the filtration process and the activity keeps almost unchanged
after being recycled for 5 times which proves its good stability
and recyclability (see Fig. S17 in Supporting Information).
Reaction mechanism. The traditional hydrogenation and
deoxygenation route of vanillin in aqueous media could
proceed via (aa’) (The red section in Scheme 3).25, 26 However,
acetal (3), ether (2) and 2-methyl-4-methylphenol (1) were
detected as the main products in our catalytic system (vanillin
+ H2 + methanol). With this in mind, a new possible pathway
for the transformation of vanillin to 1 was proposed. The
transformation of vanillin to 1 proceeds via the ether
hydrogenolysis pathway and compound 2 should be the main
reaction intermediate, and generated from the reductive
etherification of vanillin (The green section in Scheme 3). The
detail steps may include: (i) Self-catalytic condensation into
acetal or hemiacetal. In methanol media, furfural reacted with
8 / 14
Please do not adjust margins

Page 9 of 15
Green Chemistry
Please do not adjust margins
Journal Name
ARTICLE
methanol to produce into acetal or hemiacetal via self- producing 2 was detected. Herein, the catalytic reaction
View Article Online
catalytic pathway due to the acidity of para-phenolic hydroxyl proceeds via hemiacetal and/or acetalDpOaI:t1h0w.10a3y9/(Ct9hGeC0g1r1e1e6nA
group on the substrate. (ii) Reduction acetal or hemiacetal to section path bb1 and path bb2b3 in Scheme 3) was
ether (2); (iii) Hydrogenolysis ether -CH2O-R (2) bond into proposed.47-49 Vanillin can be converted to the acetal (3)
methyl group. For further evidence, we have performed the without Ni-MFC-700 under the N2 atmosphere by comparison
kinetic experiments and the kinetic curves of the the data from Entries 2 and 4 in Table 2. We speculated that 3
transformation were shown Fig. 4. At the initial stage, was the self-catalytic condensation product, in which the
compound 3 is the main product. As reaction time was acidity of phenolic hydroxyl group on the para-position may be
prolonged, the selectivity of compound 2 and 1 increased, responsible for forming product 3.
while the selectivity of compound 3 decreased greatly. After
Generally, the transformation from vanillin to ether (2)
1.5 h, the selectivity of 2 reached the maximum value, and can be performed on the following pathways: (i)
then selectivity of compound 2 decreased. Based on the above hydrogenation of vanillin to vanillyl alcohol, then vanillyl
characters, it is concluded that the transformation of vanillin alcohol react with methanol to produce ether [see routes
to compound 1 proceeds via the ether hydrogenolysis pathway (a)(d’)] (see Entry 5 and 6 in Table 2); (ii) hydrogenation of
(path b4 in Scheme 3).
hemiacetal and acetal to ether [see routes (b) (b1) or
In addition, a series of control experiments have been (b)(b2)(b3)]. Here, when we performed the catalytic
performed and the results were shown in Table 2. The vanillin, experiments using vanillin as the substrate, no alcohol was
vanillyl alcohol (4) and ether (2) were respectively selected as detected, ether (2) and acetal (3) were the main by-products.
the substrates (Note: compound 2 was acquired from the Transformation acetal (3) to ether (2) can’t do without H2,
reaction system of vanillin and methanol with Ni-MFC-700 as while the catalyst can promote this process (Entries 1, 2 and 3
the catalyst by using silica gel column chromatography. 1HNMR in Table 2). Transformation (4) to (2) can do without H2 and
spectrum of 2 was provided in Supplementary Fig. S18). It was the catalyst (Entries 5 and 6 in table 2). If the path b2bad’
found that the yield of 1 was listed in the order of from 2 (342) is the main pathway in our reaction system, the yield
(28.4%) > from vanillin (26.4%)> from vanillyl alcohol (10.4%), of 1 would be in the order: vanillyl alcohol > vanillin. But the
which suggested that hydrogenolysis of 2 into 1 should be opposite is true. So the tandem reductive etherification
easier than the hydrogenolysis of vanillyl alcohol (Entries 3, 7 pathway was more favorable in our reaction system. But we
and 8 in Table 2). Comparison the data from Entry 9 and 12 in really can not preclude the pathway 342.
Table 1, it was found conversion 2 to 1 was feasible by
At last, we used other solvents with vanillin, vanillyl
prolonging the reaction time and raising the reaction alcohol and ether as starting materials for the determination
temperature. We also performed the following reaction: the of the mechanistic pathway and the results were shown in
vanillin was firstly reacted in the N2 atmosphere for 4 h. Then, Table 3. When the reaction with the other solvents (THF and
the N2 gas was totally replaced by H2 gas. After being further CH3CN) shows no evidence of product (2) formation, it may be to
reduced for 4 h, it was found that the full conversion of vanillin, the fact step (i) and (ii) can’t proceed in THF and CH3CN. So in the
39.3% selectivity of 1 and 56.8% selectivity of 2 were obtained methanol, hydrogenolysis vanillin into 1 may proceed in pathway
(Entry 10 in Table 2). Obviously, compound 3 can be converted (ii), While in THF and CH3CN, hydrogenolysis vanillin into 1 may
to 2, which can be further transformed to 1 during the proceed in pathway (i). At the same time, the order for producing 1
selective reduction of vanillin.
was found in tetrahydrofuran (THF): 2 (30.7%) > vanillyl alcohol
The aforementioned results exhibited that hydrogenolysis (22.8%) > vanillin (11.4%) (Entries 3, 4, 5 in Table 3). While the yield
of 2 into 1 is the most efficient route for the reduction of of 1 in methanol is: 2> vanillin > vanillyl alcohol. Hydrogenolysis
vanillin in alcohol. Compound 2 should be the main reaction ether to 1 is much easier. In methanol, the yield of 1 is from vanillin
intermediate, and generated from reductive etherification of > vanillyl alcohol, which can be ascribed to the occurrence of the
vanillin, in which acetal (3) formation as an intermediate for tandem reductive etherification.
This journal is © The Royal Society of Chemistry 20xx
green chemistry, 2019, 00, 1-3 | 9
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 10 of 15
ARTICLE
Green Chemistry
3
View Article Online
DOI: 10.1039/C9GC01116A
CH3
OH
CHO
OH
CH2OH
(a)
(a')
OCH3
OCH3
OCH3
(b)
OH
4
1
(d)
(d')
(b4
)
H3CO OH
H3CO
CH2
(b1)
OCH3
OCH3
OH
(b2
H3CO OCH3
OH
2
)
(b3)
OCH3
OH
3
Scheme 3. The different routes for hydrogenation of vanillin.
Conv. of vanillin
100
Sel. of 1
Sel. of 2
Sel. 0f 3
80
60
40
20
0
1
2
3
4
5
Reaction time/h
Fig. 4 The kinetic curves of the transformation of vanillin in methanol (reaction conditions: 0.1 g vanillin, 0.025 g catalyst, in 15
mL methanol, under 2 MPa of H2, at 200 oC).
Table 2. Some blank and controlled experiments for investigation the reaction mechanism a
Selectivity (%) b
Entry
Substrate
Catalyst
Atmosphere
Conv. (%) b
1
0.0
-
26.4
-
1.6
1.9
10.4
97.3
39.3
2
12.1
0.6
72.5
1.0
97.8
97.6
88.7
-
3
87.9
96.7
0.4
97.4
0.3
0
others
-
1
2
3
4
5
6
7
Vanillin
Vanillin
Vanillin
Vanillin
No
No
2MPa H2
1MPa N2
2MPa H2
1MPa N2
1MPa N2
2MPa H2
2MPa H2
2MPa H2
62.0
71.5
100
63.1
100
100
100
29.2
100
2.7
0.7
1.6
0.3
0.5
0.6
2.7
-
Ni-MFC-700
Ni-MFC-700
No
4
4
4
2
No
Ni-MFC-700
Ni-MFC-700
Ni-MFC-700
0.3
-
8
10 c
vanillin
1MPa N2-2MPa H2
56.8
3.9
a Reaction conditions: 0.1 g substrate, 0.025 g catalyst, in 15 mL methanol, at 160 oC for 4 h.
b The results are obtained by GC analysis with the internal standard technique, 1,3-dichlorobenzene as internal standard.
c The reaction was performed in N2 for 4 h, then N2 was replaced by H2.
10 / 14
Please do not adjust margins

Page 11 of 15
Green Chemistry
Please do not adjust margins
Journal Name
ARTICLE
View Article Online
DOI: 10.1039/C9GC01116A
Table 3. Effect of solvents on hydrogenolysis of vanillin, 4 and 2 a
Selectivity (%) b
Entry
Substrate
Solvent
Conv. (%) b
1
3
4
Others
100
7.6
13.6
9.8
0
1 c
2 c
3 d
4 d
5 d
Vanillin
Vanillin
Vanillin
4
CH3CN
THF
THF
THF
THF
96.1
13.1
13.2
25.3
30.7
0
0
0
0
0
0
0
64.9
0
0
0
27.5
86.4
90.2
100
2
a Reaction conditions: 0.1 g substrate, 0.025 g catalyst, in 15 mL solvent, for 4 h;
b The results are obtained by GC analysis with the internal standard technique, 1,3-dichlorobenzene as internal standard.
c Reaction temperature is 160 oC;
d Reaction temperature is 200 oC.
Scopes of Substrate. In order to reveal the advantage of this selective reduction of 8 and 9 at 200 oC for 10 h. The
catalytic system, the selective reduction of different aldehydes corresponding yields of methylated product are 62.1% and
such
as
4-hydroxybenzaldehyde
(6),
(5),
4-hydroxy-3,
3-chloro-4- 68.2%, respectively. For the reduction of 10, the selectivity of
5- methylated product was 34.9% where 53.0% selectivity of
hydroxybenzaldehyde
dimethoxybenzaldehyde (7), p-methoxy bezaldehyde (8), 3- alcohol and 12.1% selectivity of ether were achieved. While,
hydroxy-4-methoxybenzaldehyde (9), and 3, 4, 5-trimethoxy for the hydrogenation of 8 and 9, the selectivity of ether was
benzaldehyde (10) were studied, and the data are presented in respectively 37.9% and 29.5% in the catalytic reaction system.
Table 4. Interestingly, the hydrogenation of the substrates 5, 6 Obviously, the yield of methylated products was consistent
and 7 with phenolic hydroxyl group in the para-position with the occurrence of reduced etherification of substrates,
afforded the main methylated products. The sequence of which further verified the aforementioned reaction pathway
methylated product yield is from 7 > from 5 > from 6. Notably, (Route (b) in Scheme 3). The obtained methylated product
the reduction of compound 7 could give the methylated could mainly be attained via reductive etherification route
product in 51.5% yield at 160oC, 2 MPa H2 for 4 h in (see Table during the catalytic process, indicating that the transformation
S4 in Supporting Information), which is much higher than the of the aldehyde group to the methyl group via the
hydrogenation of vanillin under the similar reaction conditions. hydrogenolysis of ether is more favorable than that via the
However, the yields of the corresponding alcohol were mainly hydrogenolysis of alcohol.
generated and the relatively low methylated products were
In order to further verify the catalytic results, the isolated
obtained when compound 8 and 10 was used as the substrate, yields of methylated products for the reduction of vanillin,
o
which indicates that the existence of phenolic hydroxyl is compoud 5 and 7 (200 C, 10 h) were obtained based on the
beneficial to transform -CHO to CH3 in hydrogenation of silica gel column chromatography with the mixture of ethyl
aldehydes. Furthermore, the hydrogenation of compound 9 acetate and petroleum ether as eluent. Therein, the isolated
provide a moderate yield of methylated product that proves yield of MMP (1), 4-methyl phenol and 2,6-dimethoxy-4-
that the hydroxyl at the para-position is more desirable than methylphenol is 82%, 78% and 85%, respectively (see the last
that at meta position to this catalytic process. When the column in Table 4). The isolated yields are a slightly lower than
o
reaction was performed at 200 C for 10 h, the reduction of the yields obtained from GC detection, which may be ascribed
the substrates 5, 6 and 7 afforded the higher yields of to the adsorption of silica gel. But the 1HNMR spectra of
methylated products. Especially for 6 and 7, no ether as the corresponding products were attained and shown in Fig. S19,
intermediate was detected. A small quantity of unknown by- S20 and S21 of Supporting Information, which shows the data
product would be the deep hydrolysis products. Also, higher from the GC analysis are reliable.
yields of methylated products were obtained during the
This journal is © The Royal Society of Chemistry 20xx
green chemistry, 2019, 00, 1-3 | 11
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 12 of 15
ARTICLE
Green Chemistry
View Article Online
DOI: 10.1039/C9GC01116A
Table 4. Hydrogenolysis of other lignin models using Ni-MFC-700 as catalyst a
Substrates
Conv. (%)b
Product distribution (%) b
Isolated yield(%)
CHO
HO
O
O
O
Others
1.0
OH
OH
OH
OH
OH
OH
(5)
100
100
83.1
15.9
0
0
78.0
OH
CHO
O
O
O
Others
24.7
/
/
Cl
Cl
Cl
Cl
OH
Cl
OH
OH
OH
OH
75.3
0
0
0
(6)
O
O
O
HO
CHO
Others
O
O
O
O
O
O
O
O
O
O
O
O
OH
OH
OH
OH
OH
OH
(7)
CHO
92.1
0
0
0
7.9
Others
0
85.0
100
100
HO
O
O
O
/
O
O
O
O
O
62.1
37.9
0
0
/
/
(8)
HO
CHO
O
O
O
Others
OH
OH
OH
OH
OH
O
O
O
O
O
68.2
29.5
0
0
2.3
Others
0
/
/
(9)
CHO
100
100
100
HO
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
34.9
12.1
0
53.0
_
(10)
HO
CHO
O
O
O
Others
0
O
O
O
O
O
O
OH
OH
OH
OH
OH
OH
Vanillin
82.0
96.5
3.1
0.4
0
a Reaction conditions: 0.1 g substrate, 0.025 g catalyst, in 15 mL methanol, at 160 oC for 4 h.
b The results were obtained by GC analysis with the internal standard technique, 1,3-dichlorobenzene as internal standard.
Ni(NO3)2·6H2O (98.0%), NaN3 (98.0%), NaNO2·6H2O (98.0%),
sodium ascorbate (97.0%), NaOH (98.0%), CuSO4·5H2O
(98.0%), -AL2O3, activated carbon, nano graphite, ZrO2, TiO2
and MgO were purchased from Shanghai Aladding Bio-Chem.
Technology Co. Ltd. The reaction solvents were
chromatography reagents and used without further
purification.
Experimental
Materials. Vanillyl alcohol (99.0%), vanillin (98.0%), 3,4,5-
trimethoxybenzaldehyde (99.0%), p-methoxybezaldehyde
(99.0%),
hydroxybenzaldehyde
dichlorobenzene (99.0%) were purchased from Alfa Aesar.
4-hydroxybenzaldehyde
(99.0%),
3-chloro-4-
(99.0%),
MMP (99.0%),
1,3-
12 / 14
Please do not adjust margins

Page 13 of 15
Green Chemistry
Please do not adjust margins
Journal Name
ARTICLE
Catalyst preparation and characterization. Ni-MOF
([Ni(tia)(H2O)2]) was fabricated according to our previous
report 28. Ni(NO3)2·6H2O (0.4 mmol, (0.1162 g), NaOH (0.8
mmol, 0.032 g), and H3ctia (0.4 mmol, 0.1108 g) was added
into a Teflon-lined pressure vessel, and then the mixture was
heated to 180oC and kept at 180oC for 72 h. After being cooled
to room temperature at a rate of 2.5oC/h, green block-shaped
crystals were acquired, collected, washed with distilled water,
and then dried in the air.
The as-synthesized Ni-MOFs were added in a quartz boat,
and placed in the tubular furnace. The MOFs were calcined
under N2 flow (50 mL/min) for 4 h at different temperature
(300, 350, 400, 500, 600, 700 and 800oC). After being cooled to
room temperature, Ni-MFC-300, 350, 400, 500, 600, 700 and
800 catalysts were obtained.
Conclusions
View Article Online
Novel Ni-MFC catalysts have been fabricaDteOdI: 1u0s.i1n0g392/CD9NGCi-0M11O16FAs
as precursors. Owing to the well-defined architecture of MOFs,
the as-synthesized catalyst possesses the high specific surface
area and uniform mesoporous sizes. The catalytic active sites
such as Ni(0), NiO, etc., which were originated from metal
nodes of MOFs, and the functional ingredient
N was
incorporated into the co-doped porous carbon matrix
composites. All of these endowed Ni-MFC catalysts with good
catalytic performance for the efficient transformation of
vanillin to 1 or 2. Notably, Ni-MFC-700 was screened as the
efficient hydrodeoxygenation catalyst for the transformation
of -CHO group to -CH3 group while the Ni-MFC-500 was
selective to promote reductive etherification of aldehydes to
methyl ether. Moreover, the Ni-MFC catalysts kept stable and
recyclable for the catalytic reductive process under the H2
atmosphere. Furthermore, the mechanism investigations
indicated that the transformation of aldehyde group (-CHO) to
methyl group (-CH3) may proceed via the following steps: (i)
Self-catalytic condensation into acetal or hemiacetal; (ii)
Reduction acetal or hemiacetal to ether; (iii) Hydrogenolysis
ether -CH2O-R bond into methyl group. In general, this
catalytic system showed better performance for aromatic
aldehyde with phenolic hydroxyl groups in the para-position. It
provides a new and promising technique for the catalytic
valorization of biomass feedstock and biomass-derived
aldehyde and ether in chemical industry.
Ni/activated carbon, Ni/γ-Al2O3-700, Ni/nano-graphite-
700, Ni/TiO2-700, Ni/ZrO2-700 and Ni/nano-MgO-700 were
prepared according to the literature.29
X-ray single-crystal diffraction data were collected on a
Rigaku SCX-mini diffractometer at 293(2) K with MoKR
radiation (= 0.71073 Å) by -scan mode. The powder X-ray
diffraction patterns (PXRD) were recorded on Rigaku D/Max
2400 diffractometer with Cu/K radiation. Fourier transform
infrared spectra (FT-IR) were recorded using Bruker
EQUINOX55 infrared spectrometer. High resolution scanning
electron microscopy (HRSEM) was performed in a JSM 6490LV
JEOL microscope at 25 kV. X-ray photoelectron spectroscopy
(XPS) was carried out in a 5700 model Physical Electronics
apparatus. Temperature programmed desorption (TPD)
analysis were carried out using a Micromeritics ChemiSorb
2720 Pulse Chemisorption System with TCD detector. The BET
surface areas and pore volumes were measured by N2
adsorption-desorption at 77 K on a Micromeritics ASAP 2020
instrument at -196°C. Inductively Coupled Plasma Optical
Emission Spectrometry (ICP-OES: Varian 700-ES) was used to
measure the metal content of the catalytic materials.
Conflicts of interest
There are no conflicts to declare.
Acknowledgements
We are grateful for the support of the Tianjin Research
Program of Application Foundation and Advanced Technology
(No.17JCYBJC20200), the National Natural Science Foundation
of China (21878235 and 21601135), and the Natural Science
Foundation of Tianjin Municipal Education Commission
(2017KJ256).
Reaction system and product analysis. The catalytic reaction
was performed in 100 mL Parr stainless autoclave equipped
with heater and sample port. In a typical experiment, substrate
(0.1000 g), catalyst (0.025 g), and methanol (15 mL) were
charged into the autoclave and purged with N2 for several
times to remove the air. Then H2 was purged into the reactor
for 4 times to replace N2 at room temperature. Later, the
autoclave was pressurized with H2 up to 2 MPa and heated to
160 oC under vigorous stirring and held at this temperature for
4 h. After the reaction was over, the reaction mixture was
weighed and diluted with methanol. The products were
qualitatively analyzed by an Agilent 7890A-5975C gas
chromatography-mass spectrometry (GC-MS) equipped with
an capillary flow technology to detect multi signal data and
quantitatively analyzed by using a GC (Agilent 6820) equipped
with a flame ionization detector (FID) and a HP-5MS capillary
column (0.25 mm in diameter, 30 m in length). Some GC-MS
and GC spectra of the typical reactions were shown in
Supporting information (Fig. S22S37).
Notes and references
1 J. A. Melero, J. Iglesias and A. Garcia, Energy Environ. Sci.,
2012, 5, 7393-7420.
2 C. O. Tuck, E. Pérez, I. T. Horváth, R. A. Sheldon and M.
Poliakoff, Sci., 2012, 337, 695-699.
3 X. Zhao, H. Zhou, V. S. Sikarwar, M. Zhao, A.-H. A. Park, P. S.
Fennell, L. Shen and L.-S. Fan, Energy Environ. Sci., 2017, 10,
1885-1910.
4 A. J. Ragauskas, G. T. Beckham, M. J. Biddy, R. Chandra, F.
Chen, M. F. Davis, B. H. Davison, R. A. Dixon, P. Gilna, M.
Keller, P. Langan, A. K. Naskar, J. N. Saddler, T. J. Tschaplinski,
G. A. Tuskan and C. E. Wyman, Sci., 2014, 344, 709-718.
5 J. Zakzeski, P. C. A. Bruijnincx, A. L. Jongerius and B. M.
Weckhuysen, Chem. Rev., 2010, 110, 3552-3599.
This journal is © The Royal Society of Chemistry 20xx
green chemistry, 2019, 00, 1-3 | 13
Please do not adjust margins

Please do not adjust margins
Green Chemistry
Page 14 of 15
ARTICLE
Green Chemistry
6 Q. Xia, Z. Chen, Y. Shao, X. Gong, H. Wang, X. Liu, S. F. Parker, 32 J. Hao, W. Yang, Z. Zhang and J. Tang, Nanoscale, 2015, 7,
View Article Online
DOI: 10.1039/C9GC01116A
X. Han, S. Yang and Y. Wang, Nat. Commun., 2016, 7, 11162-
11171.
7 T. L. Lohr, Z. Li and T. J. Marks, ACS Catal., 2015, 5, 7004-
7007.
8 X. Xu, Y. Li, Y. Gong, P. Zhang, H. Li and Y. Wang, J Am. Chem.
Soc., 2012, 134, 16987-16990.
9 Z. Zhu, H. Tan, J. Wang, S. Yu and K. Zhou, Green Chem., 2014,
16, 2636-2643.
11055-11062.
33 Y. Yang, Z. Lun, G. Xia, F. Zheng, M. He and Q. Chen, Energy
Environ. Sci., 2015, 8, 3563-3571.
34 R. Fang, R. Luque and Y. Li, Green Chem., 2016, 18, 3152-
3157.
35 C. Li, S. Dong, R. Tang, X. Ge, Z. Zhang, C. Wang, Y. Lu and L.
Yin, Energy Environ. Sci., 2018, 11, 3201-3211.
36 R. Wang, X. Y. Dong, J. Du, J. Y. Zhao and S. Q. Zang, Adv.
Mater., 2018, 30, DOI:10.1002/adma.201703711.
10 J. L. Santos, M. Alda-Onggar, V. Fedorov, M. Peurla, K. Eränen,
P. Mäki-Arvela, M. Á. Centeno and D. Y. Murzin, Appl. Catal. 37 Q. Han, M. U. Rehman, J. Wang, A. Rykov, O. Y. Gutiérrez, Y.
A: General, 2018, 561, 137-149.
11 M. A. N. González-Borja and D. E. Resasco, Energy & Fuels,
2011, 25, 4155-4162.
12 X. Yang, Y. Liang, Y. Cheng, W. Song, X. Wang, Z. Wang and J.
Qiu, Catal. Commun., 2014, 47, 28-31.
13 Y. Han, D. N. McIlroy and A. G. McDonald, J. anal. Appl. Pyrol.,
2016, 117, 94-105.
14 Y. Zhu, H. Qian, B. A. Drake and R. Jin, Angew. Chem. Int. Ed.,
2010, 49, 1295-1298.
15 R. Fan, C. Chen, M. Han, W. Gong, H. Zhang, Y. Zhang, H. Zhao
and G. Wang, Small, 2018, 14, DOI: 10.1002/smll.201801953..
Zhao, S. Wang, X. Ma and J. A. Lercher, Appl. Catal. B:
Environ., 2019, 253, 348-358.
38 A. A. Aboul-Enein and A. E. Awadallah, Polymer Degradation
and Stability, 2019, 167, 157-169.
39 X. Fan, D. Liu, Z. Zhao, J. Li and J. Liu, Catal. Today, 2019, DOI:
10.1016/j.cattod.2019.02.036.
40 M. Li and A. C. van Veen, Appl. Catal. B: Environ., 2018, 237,
641-648.
41 Rastegarpanah, M. Rezaei, F. Meshkani, K. Zhang, X. Zhao, W.
Pei, Y. Liu, J. Deng, H. Arandiyan and H. Dai, Appl. Catal. B:
Environ., 2019, 248, 515-525.
16 A. Banerjee and S. H. Mushrif, J. Phys. Chem. C, 2018, 122, 42 K. A. Resende, A. H. Braga, F. B. Noronha and C. E. Hori, Appl.
18383-18394.
Catal. B: Environ., 2019, 245, 100-113.
43 K. Friedel Ortega, R. Arrigo, B. Frank, R. Schlögl and A.
Trunschke, Chem. Mater., 2016, 28, 6826-6839.
44 M. S. Hamdy, R. Amrollahi and G. Mul, ACS Catal., 2012, 2,
2641-2647.
45 T. Baran, I. Sargin, A. Mentes and M. Kaya, Appl. Catal. A:
Gen., 2016, 523, 12-20.
46 A. N. Marianov and Y. Jiang, Appl. Catal. B: Environ., 2019,
244, 881-888.
47 C. Zhao, C. A. Sojdak, W. Myint and D. Seidel, J. Am. Chem.
Soc., 2017, 139, 10224-10227.
48 S. Shinde and C. Rode, ChemSusChem, 2017, 10, 4090-4101.
49 Y. Wang, Q. Cui, Y. Guan and P. Wu, Green Chem., 2018, 20,
2110-2117.
17 L. He, Y. Qin, H. Lou, P. Chen, RSC Adv. 2015, 5, 43141.
18 L. Jiang, P. Zhou, C. Liao, Z. Zhang and S. Jin, ChemSusChem.,
2018, 11, 959-964.
19 R. Nie, H. Yang, H. Zhang, X. Yu, X. Lu, D. Zhou and Q. Xia,
Green Chem., 2017, 19, 3126-3134.
20 K. Li, Y. Jiao, Z. Yang and J. Zhang, J. Mater. Sci Technol., 2019,
35, 159-167.
21 L. Liu, H. Lou and M. Chen, Int. J. Hydrog. Energ., 2016, 41,
14721-14731.
22 H. Zhao, L. Chou and H. Song, React. Kinet. Mech. Catal.,
2011, 104, 451-465..
23 H. Li and Z. Liu, Bioresour. Technol. Rep., 2019, 5, 86-90.
24 H. Jeong, C. Kim, S. Yang and H. Lee, J. Catal., 2016, 344, 609-
615.
25 A. Banerjee and S. H. Mushrif, J. Phys. Chem. C, 2018, 122,
18383-18394.
26 A. Aijaz, Q. L. Zhu, N. Tsumori, T. Akita and Q. Xu, Chem.
Commun., 2015, 51, 2577-2580.
27 T. H. Parsell, B. C. Owen, I. Klein, T. M. Jarrell, C. L. Marcum, L.
J. Haupert, L. M. Amundson, H. I. Kenttämaa, F. Ribeiro, J. T.
Miller and M. M. Abu-Omar, Chem. Sci., 2013, 4, 806-813.
28 L. Ning, S. Liao, X. Liu, L. Yu, X. Zhuang and X. Tong, J. Catal.,
2017, 352, 480-490.
29 L. Ning, S. Liao, X. Liu, P. Guo, Z. Zhang, H. Zhang and X. Tong,
J. Catal., 2018, 364, 1-13.
30 A. H. Chughtai, N. Ahmad, H. A. Younus, A. Laypkov and F.
Verpoort, Chem. Soc. Rev., 2015, 44, 6804-6849.
31 S. M. J. Rogge, A. Bavykina, J. Hajek, H. Garcia, A. I. Olivos-
Suarez, A. Sepulveda-Escribano, A. Vimont, G. Clet, P. Bazin,
F. Kapteijn, M. Daturi, E. V. Ramos-Fernandez, I. X. F. X.
Llabres, V. Van Speybroeck and J. Gascon, Chem. Soc. Rev.,
2017, 46, 3134-3184.
14 / 14
Please do not adjust margins

Page 15 of 15
Green Chemistry
Nickel-catalyzed intelligent reductive transformation of
View Article Online
DOI: 10.1039/C9GC01116A
aldehyde group with hydrogen
Xinli Tong, *a Pengfei Guo, a Shengyun Liao, *a Song Xuea, Haigang Zhang a
a Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion, School of Chemistry
and Chemical Engineering, Tianjin University of Technology, No. 391 Binshuixi Road, Tianjin
300384, P. R. China. Fax: (+)86-22-60214259; Tel: (+86)-22-6024259; E-mail: tongxinli@tju.edu.cn;
tongxli@sohu.com .
Graphical Abstract
CHO
OCH3
OH
H3CO
OCH3
H3CO
OH
self-catalyzing acetalization
OCH3
H3CO
OCH3
CH2
OH
OH
OH
OCH3
Reductive ehterification
H2
Pyrolysis
N2
CH3
2D Ni-based MOFs
Ni-MFC catalyst
OCH3
OH
A highly efficient and catalytic valorization of lignin-derived aldehhydes to produce value-added
chemicals has been developed with the Ni-based catalyst under the H2 atmosphere.