Synthesis of diesel range alkanes with 2-methylfuran and mesityl oxide from lignocellulose

Article abstract of DOI:10.1016/j.cattod.2014.01.028

The alkylation of 2-methylfuran with mesityl oxide was carried out over a series of solid acid catalysts. Among the investigated candidates, Nafion-212 resin exhibited the highest catalytic efficiency and good stability, which can be rationalized by the h

Full text of DOI:10.1016/j.cattod.2014.01.028

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Synthesis of diesel range alkanes with 2-methylfuran and mesityl
oxide from lignocellulose
Shanshan Lia,b, Ning Lia,∗, Guangyi Lia,b, Aiqin Wanga, Yu Conga,
Xiaodong Wanga, Tao Zhanga
a State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, No. 457 Zhongshan Road, Dalian 116023, China
b Graduate School of Chinese Academy of Sciences, Beijing 100049, China
a r t i c l e i n f o
a b s t r a c t
Article history:
For the first time, the alkylation of 2-methylfuran with mesityl oxide was carried out over a series of
solid acid catalysts. Among the investigated candidates, Nafion-212 resin exhibited the highest catalytic
efficiency and good stability, which can be rationalized by the higher acid strength of this catalyst. The
hydrodeoxygenation (HDO) of the alkylation products of 2-methylfuran with mesityl oxide was also
studied. Ni–Mo2C/SiO2 and Ni–W2C/SiO2 were firstly used for the HDO of biomass derived oxygenates and
demonstrated excellent catalytic performance for the conversion of the alkylation products to alkanes.
Compared with Ni–W2C/SiO2, Ni–Mo2C/SiO2 exhibited higher selectivity to diesel range alkanes. Over
the Ni–Mo2C/SiO2 catalyst, high carbon yield of diesel range alkanes (77%) could be achieved by the HDO
of the alkylation products of 2-methylfuran and mesityl oxide at 573 K and 6.0 MPa H2. This value is
evidently higher than those obtained over noble metal catalysts and Ni–WxC/AC under the same reaction
conditions.
Received 6 November 2013
Received in revised form 17 January 2014
Accepted 21 January 2014
Available online xxx
Keywords:
Solid acid
Carbide
Renewable diesel
2-Methylfuran
Mesityl oxide
© 2014 Elsevier B.V. All rights reserved.
1. Introduction
HCl), or para-toluenesulfonic acid. This compound can be further
hydrodeoxygenated to diesel or jet fuel alkanes over noble metal
Energy and environment are two mostly concerned problems,
nowadays. As one of the solutions, the catalytic conversion of
renewable biomass to fuels [1–3] and chemicals [4–8] becomes a
very popular research area. Lignocellulose is the main component
of agriculture wastes or forest residues. Following the pioneering
works of Dumesic’s group [9,10] and Huber and co-workers [11,12],
the synthesis of renewable diesel or jet fuel by the C–C coupling
reactions of the lignocellulose derived platform chemicals followed
by hydrodeoxygenation (HDO) has drawn wide attention [13–19].
2-Methylfuran (2-MF) is the selective hydrogenation prod-
uct of furfural which is available on an industrial scale by the
hydrolysis–dehydration of the hemicellulose part of agriculture
wastes and forest residues [20–22]. Mesityl oxide is the self
aldol condensation product of acetone which can be produced
by the Acetone–n-Butanol–Ethanol (ABE) fermentation of ligno-
cellulose [16]. In the recent work of Corma’s group [23], it was
found that a C11 oxygenate (i.e. 4-methyl-4-(5-methylfuran-2-
yl)pentan-2-one) can be produced by the alkylation of 2-MF with
mesityl oxide under the catalysis of mineral acids (H2SO4 and
catalyst. In practical application, solid acids are more preferable
because they can be easily sperated and reused. However, to our
knowledge, there is no report on the application of solid acid as the
catalyst for the alkylation of 2-MF with mesityl oxide.
Hydrodeoxygenation (HDO) is a key step for the conversion of
alkylation product of 2-MF and mesityl oxide to diesel or jet fuel
range alkanes. In the past years, most of works about the HDO of
biomass derived oxygenates were carried out over noble metal cat-
alysts. Due to the high cost and limited reserve of non-noble metals,
the exploration of non-noble HDO catalyst is of great significance. In
our recent work, the nickel-promoted tungsten carbide (Ni–WxC/C)
catalyst was found to be highly active in conversion of cellulose to
ethylene glycol [6] and the HDO of the HAA products of 2-MF [24].
Molybdenum is cheaper and more available than tungsten. So far,
there is no report about the HDO of biomass derived oxygenates
over nickel-promoted molybdenum carbide (Ni–Mo2C) catalyst.
In this work, the alkylation of 2-MF with mesityl oxide was
carried out for the first time over a series of solid acid catalysts.
Among the investigated candidates, Nafion-212 resin exhibited the
highest catalytic efficiency and stability. The influences of reaction
conditions on the catalytic performance of Nafion-212 resin were
investigated. Finally, the HDO of the alkylation products of 2-MF
and mesityl oxide was also carried out over a series of catalysts.
∗
Corresponding author. Tel.: +86 411 84379738; fax: +86 411 84685940.
E-mail address: lining@dicp.ac.cn (N. Li).
http://dx.doi.org/10.1016/j.cattod.2014.01.028
0920-5861/© 2014 Elsevier B.V. All rights reserved.
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Scheme 1. Reaction pathways for the different products during the alkylation of 2-MF with mesityl oxide.
Among them, Ni–Mo2C/SiO2 demonstrated the highest activity and
selectivity to diesel or jet fuel range alkanes. To understand the
excellent catalytic performance of this catalyst, the fresh and used
Ni–Mo2C/SiO2 catalysts were characterized by XRD, TEM and XPS.
2. Materials and methods
2.1. Preparation of catalysts
Nafion-212 resin (average pore size about 4 nm, 51 ␮m thick)
was supplied by Dupont Company. It was cut into small pieces
(about 2 mm × 2 mm) before use. Amberlyst-15 and Amberlyst-
36 resins were purchased from Sigma–Aldrich (with average pore
diameters of 29 nm and 24 nm, respectively). H-Y (SiO2/Al2O3 = 4)
and H-Beta (SiO2/Al2O3 = 394) zeolites were provided by Nankai
University. Zirconium phosphate (ZrP) was prepared by the co-
precipitation method described in Ref. [25]. In the typical synthesis,
1 mol L−1 ZrCl2O·8H2O and 1 mol L−1 (NH4)H2PO4 aqueous solution
were mixed at a molar ratio of P/Zr = 2.0. The as-obtained precipi-
tate was filtered, washed with deionized water, dried at 333 K for
12 h and then calcined in static air at 673 K for 4 h.
100
Conversion of 2-MF
Yield of P1
Yield of P2
Yield of P3
80
60
40
20
0
The Pd/SiO2, Pt/SiO2, Pd/AC and Pt/AC catalysts used in the HDO
step were prepared by the incipient wetness impregnation of the
SiO2 (200 mesh, Qingdao Ocean Chemical Plant, SBET = 391 m2 g−1
)
or active carbon (AC, supplied by NORIT Company) with the
aqueous solutions of PdCl2 and H2PtCl6·6H2O. The precursors as
obtained were put at room temperature overnight, and then dried
at 393 K for 12 h. To facilitate the comparison, the metal contents
in the Pd/SiO2, Pt/SiO2, Pd/AC and Pt/AC catalysts were controlled
as 5 wt.%. These catalysts were reduced in-situ by hydrogen at
4
ta
rP
12
-Y
e
SO
2
Z
H
B
H
yst-36
rl
H-
yst-15
rl
on-2
i
be
be
Naf
Am
Am
Fig. 1. Conversions of 2-MF and yields of P1, P2, P3 over different catalysts; reaction
conditions: 333 K, 2 h; 1.64 g (20 mmol) 2-MF, 1.96 g (20 mmol) mesityl oxide, 0.15 g
catalyst.
Please cite this article in press as: S. Li, et al., Synthesis of diesel range alkanes with 2-methylfuran and mesityl oxide from lignocellulose,
Catal. Today (2014), http://dx.doi.org/10.1016/j.cattod.2014.01.028

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3
300
5
4
3
2
1
40
30
20
10
0
P1
Conversion of 2-MF
Yield of P1
Yield of P2
250
200
150
100
50
Yield of P3
0
12
10
8
0
P2
0.20
0.15
0.10
0.05
4
2
P
ta
-Y
36
15
SO
2
Zr
H
-21
ion
H
yst-
H-Be
yst-
l
l
f
6
a
ber
ber
N
Am
Am
4
Fig. 2. Conversions of 2-MF and yields of P1, P2, P3 under the catalysis of different
catalysts. Reaction conditions: 333 K, 2 h; 1.64 g (20 mmol) 2-MF, 1.96 g (20 mmol)
mesityl oxide, 0.015 g catalyst.
2
0
10
0.00
0.15
P3
8
6
4
2
0
623 K for 2 h before being used in the HDO reaction. The Ni-
promoted molybdenum carbide and Ni-promoted tungsten carbide
catalysts loaded on SiO2 support (denoted as Ni–Mo2C/SiO2 and
Ni–W2C/SiO2) used for the HDO process were prepared according
to Ref. [26] by the incipient wetness co-impregnation of SiO2 with
an aqueous solution of Ni(NO3)2·6H2O and (NH4)6Mo7O24·4H2O
(or ammonium molybdate). The as-obtained catalyst precursors
were kept at room temperature overnight, dried at 333 K, and cal-
cined in nitrogen atmosphere for 5 h at 773 K. After calcination,
the samples were reduced and carburized in a CH4/H2 flow under a
three-stage heating ramp (from room temperature to 623 K at a rate
of 3 K min−1, then to 973 K at a rate of 1 K min−1, and maintained
at 973 K for 3 h). Prior to exposure to air, the as-prepared carbide
catalysts were passivated with 1% O2 in N2 (V/V) for 12 h at room
temperature. The contents of Ni and Mo (or W) in the catalysts
were 5% and 13.5%, respectively. For comparison, we also pre-
pared the Ni–WxC/AC catalyst according to the method described
in our previous work [24]. Typically, the AC was impregnated with
the aqueous solution of (NH4)10W12O41·5H2O and Ni(NO3)2·6H2O.
The product as-obtained was kept at the ambient temperature
overnight, dried at 393 K for 10 h and reduced at 1023 K by H2 flow
0.10
0.05
0.00
5
6
4
ta
e
1
rP
SO
-
-3
st
Z
H-Y
st
H
2
n-212
y
y
H-B
fio
erl
Amb
erl
Amb
Na
Fig. 3. TONs and TOFs for the conversion of 2-MF to P1, P2, P3 calculated based on
the yields of P1, P2, P3 and the acid amounts of different catalysts measured by NH3
chemisorption.
was used. The liquid alkylation products of 2-MF with mesityl
oxide were directly fed into the reactor by a HPLC pump at a
rate of 0.04 mL min−1, along with a hydrogen flow at a rate of
120 mL min−1. The system pressure was controlled as 6.0 MPa by
a back-pressure regulator. The products from the HDO process
became two phases in a gas–liquid separator. The gas products were
analyzed on-line by an Agilent 6890N GC. The liquid products were
drained periodically from the separator and analyzed by an Agilent
7890 GC.
−1
−1
for 1 h. Then the catalyst was
at a flow rate of 60 mL min
cooled down to ambient temperature under hydrogen atmosphere
and passivated by 1% O2 in N2 (V/V) at a flow rate of 20 mL min−1
g
cat
.
The theoretical contents of Ni and W in the Ni–WxC/AC catalyst are
the same as those in Ni–W2C/SiO2.
The carbon yields of different alkanes from the HDO of alkylation
products were calculated according to following equations:
Carbon yield of diesel or jet fuel range alkanes (%) = Sum of car-
bon in C9–C16 alkanes detected in the liquid products/carbon fed
into the reactor × 100%
2.2. Alkylation of 2-MF with mesityl oxide
The alkylation reaction between 2-MF and mesityl oxide was
carried out in a round-bottom flask equipped with a reflux con-
denser and a magnetic stirrer [24,27,28]. The reaction temperature
was controlled by a water bath. In a typical reaction, 0.15 g catalyst,
1.64 g 2-MF (20 mmol) and 1.96 g (20 mmol) mesityl oxide were
added to the flask and then the mixture was stirred at 333 K for 2 h.
The products were analyzed by Agilent 1100 HPLC, equipped with a
ZORBAX SB-C18 column (4.6 mm × 150 mm, 5 ␮m) and a refractive
index detector (RID).
Carbon yield of gasoline range alkanes (%) = Sum of carbon in
C5–C8 alkanes detected in the gas products per unit time/carbon
fed into the reactor per unit time × 100% + sum of carbon in the
C5–C8 alkanes detected in liquid phase products/carbon fed into
the reactor × 100%
Carbon yield of light alkanes (%) = Sum of carbon in the C1–C4
alkanes detected in the gas products per unit time/carbon fed into
the reactor per unit time × 100%.
2.3. Hydrodeoxygenation (HDO)
2.4. Characterization of catalysts
The HDO process of the alkylation products was conducted at
573 K in a 316 L stainless steel tubular fixed-bed reactor under
solvent-free condition [24,27,28]. For each test, 1.80 g catalyst
The amounts of acid sites on the ZrP, H-Y and H-Beta catalysts
used in the alkylation of 2-MF with mesityl oxide were mea-
sured by NH3 chemisorption according to the method described
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Conversion of 2-MF
Yield of P2
Yield of P3
100
80
60
40
20
0
Yield of P1
100
80
60
40
20
0
Conversion of 2-MF
Yield of P1
Yield of P2
Yield of P3
Conversion of 2-MF
Yield of P1
Yield of P2
Yield of P3
100
80
60
40
20
0
273
323
303
333
Reaction temperature / K
Fig. 5. Conversions of 2-MF (ꢀ) and the yields of P1 (᭹), P2 (ꢁ), P3 (ꢂ) over Nafion-
212 resin as the function of reaction temperature. Reaction conditions: 2 h; 1.64 g
(20 mmol) 2-MF, 1.96 g (20 mmol) mesityl oxide, 0.15 g Nafion-212 resin.
Yield of P2
Yield of P3
Conversion of 2-MF
Yield of P1
100
100
80
60
40
20
Conversion of 2-MF
80
Yield of P1
Yield of P2
Yield of P3
60
40
20
0
0
1
2
3
4
5
Recycle time
Fig. 4. Yields of P1, P2 and P3 over Nafion-212 (a), Amberlyst-15 (b), and Amberlyst-
36 (c) as the function of recycle times. Reaction conditions: 333 K, 2 h; 1.64 g
(20 mmol) 2-MF, 1.96 g (20 mmol) mesityl oxide, 0.15 g catalyst.
0.05
0.15
0.015
0.3
Mass of catalyst / g
Fig. 6. Conversions of 2-MF (ꢀ) and the yields of P1 (᭹), P2 (ꢁ), P3 (ꢂ) over Nafion-
212 resin as the function of catalyst amount. Reaction conditions: 333 K, 2 h; 1.64 g
(20 mmol) 2-MF, 1.96 g (20 mmol) mesityl oxide.
in our previous work [29]. The experiments were carried out by
a Micrometeritics Autochem 2920 Automated Catalyst Characteri-
zation System. Typically, 0.1 g of catalyst was loaded into a quartz
reactor, purged in He flow at 393 K for 2 h and cooled down to 373 K.
Subsequently, pulses of NH3 were dosed in until saturation. The
amounts of acid sites on different catalysts were calculated by the
uptakes of NH3 during the tests.
3. Results and discussion
3.1. Alkylation of 2-MF with mesityl oxide
The alkylation of 2-MF with mesityl oxide was carried out over a
series of solid acid catalysts. According to the analysis of HPLC (Fig.
S1) and NMR spectra (Figs. S2–S4), 4-methyl-4-(5-methylfuran-2-
yl)pentan-2-one (i.e. P1 in Scheme 1) was identified as the main
product. Besides P1, 5,5ꢀ-(propane-2,2-diyl)bis(2-methylfuran)
(i.e. P2 in Scheme 1) and 5,5-bis(5-methylfuran-2-yl)pentan-2-one
(i.e. P3 in Scheme 1) were also detected in the liquid phase prod-
ucts. As shown in Scheme 1, P1 is the alkylation product of 2-MF
with mesityl oxide, and P2 is the HAA product of 2-MF and acetone
generated from the retro-aldol condensation of mesityl oxide. P3 is
XRD patterns of fresh and used Ni–W2C/SiO2 and Ni–Mo2C/SiO2
catalysts were recorded with a PW3040/60X’ Pert PRO (PANalyti-
cal) diffractometer using a Cu K␣ radiation source (ꢀ = 0.15432 nm)
at 40 kV and 40 mA. The Transmission Electron Microscopy (TEM)
images of the fresh and used Ni–W2C/SiO2 and Ni–Mo2C/SiO2 cata-
lysts were obtained from a TECNAI G2 Spirit FEI microscopy with an
accelerating voltage of 120 kV. The binding energies of the Ni, Mo,
and W species on the surface of the fresh and used Ni–W2C/SiO2 and
Ni–Mo2C/SiO2 catalysts were measured by an ESCALAB250 X-ray
photoelectron spectrometer (XPS).
Table 1
The average pore sizes, acid amounts and Hammett acidy function (−H0) values of the different solid acid catalysts used in the alkylation of 2-MF with mesityl oxide.
Catalyst
Average pore size (nm)
−H0
Acid amount (mmol g−1
)
Reference
Nafion-212
Amberlyst-15
Amberlyst-36
ZrP
H-Y
H-Beta
4a
11–13
2.2
2.2–2.65
−1.0 to −2.8
−1.5 to 5.6
4.4–5.7
1.1a
4.7a
5.4a
2.1b
0.9b
0.2b
[32]
[32,33]
[33]
[34]
[31,32]
[31,33]
29a
24a
7.2
0.74 × 0.74
0.66 × 0.67 0.56 × 0.56
a
According to the information provided by supplier.
Measured by NH3 chemisorption.
b
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5
100
80
60
40
20
Conversion of 2-MF
Yield of P1
Yield of P2
Yield of P3
10
20
30
40
50
o
60
70
80
0
4
0.25
0.5
1
2
Reaction time / h
Fig. 7. Conversions of 2-MF (ꢀ) and the yields of P1 (᭹), P2 (ꢁ), P3 (ꢂ) over
Nafion-212 resin as the function of reaction time. Reaction conditions: 333 K; 1.64 g
(20 mmol) 2-MF, 1.96 g (20 mmol) mesityl oxide, 0.15 g Nafion-212 resin.
the trimerization product of 2-MF through a hydrolysis-HAA route
[23].
Fig. 1 illustrates the catalytic performances of different solid
acids for the alkylation of 2-MF with mesityl oxide. As can be seen
from it, solid acid catalysts can also promoted the alkylation of
2-MF with mesityl oxide. It is very interesting that higher yields
of P1, P2 and P3 can be achieved over Nafion-212, Amberlyst-15
and Amberlyst-36 resins than those obtained under the cataly-
sis of 72% H2SO4 under the same reaction conditions. This is very
10
20
30
40
50
60
70
80
o
2
/
Fig. 9. XRD patterns of fresh and used Ni–Mo2C/SiO2 (a) and Ni–W2C/SiO2 (b) cat-
alysts.
70
(a)
Gasoline range alkanes
Light alkanes
Diesel range alkanes
4,4-Dimethylnonane
60
50
40
30
20
10
0
advantageous in practical application. As we know, solid acids are
less corrosive, easier to be separated and reused. According to the
yields of P1, P2, P3 over different solid acids at low catalyst dosage
(Fig. 2) and the amount of acid sites on different catalysts pro-
vided by supplier or measured by NH3 chemisorption described
in our previous work [24,30], we also calculated the TONs and TOFs
for the conversion of 2-MF to P1, P2 and P3 over different cat-
alysts. As shown in Fig. 3, Nafion-212 resin showed the highest
efficiency for the alkylation of 2-MF with mesityl oxide among the
investigated solid acid catalysts. In order to understand the activity
difference of the solid acid catalysts used in this work, we com-
pared their average pore sizes and acidities. From the information
shown in Table 1 and Fig. S5, the pore sizes of the zeolite cata-
Pd/SiO2
Pd/AC
Pt/SiO2
Pt/AC
100
80
60
40
20
0
˚
˚
lysts (7.4 × 5.4 A for H-Y and 6.6 × 6.7 5.6 × 5.6 A for H-Beta) used
(b)
Diesel range alkanes
4,4-Dimethylnonane
Gasoline range alkanes
Light alkanes
˚
in this work [31] are smaller than the sizes of P1 (10.6 × 5.4 A),
˚
˚
P2 (9.6 × 5.4 A) and P3 (10.7 × 9.6 A) (estimated by the software
of Materials Studio). This may be one reason for the lower activ-
ities of H-Y and H-Beta for the alkylation of 2-methylfuran with
mesityl oxide. From the Hammett acidity function (−H0) values of
different acid catalysts reported in Refs. [32–34], it was found that
the sequence for acid strength of the non-zeolite solid catalysts
is Nafion-212 > Amberlyst-15, Amberlyst-36 > ZrP. This sequence
is consistent with the activity sequence of these catalysts for the
alkylation of 2-methylfuran with mesityl oxide. According to this
information, the outstanding catalytic efficiency of Nafion-212
resin may be rationalized by its higher acid strength. To verify this
speculation, a comparative experiment on the alkylation of 2-MF
with mesityl oxide was carried out under the catalysis of acids
with different acid strength. H2SO4, H3PO4 and CH3COOH were
chosen to represent strong, medium and weak acid, respectively.
From the results shown in Table 2, the activity sequence for these
three acids in the alkylation reaction of 2-MF and mesityl oxide was
H2SO4 ꢁ H3PO4 > CH3COOH, indicating that strong acid site is the
Ni-Mo2C/SiO2
Ni-W2C/SiO2
Ni-WxC/AC
Fig. 8. Carbon yields of different alkanes from the HDO of the alkylation prod-
ucts over different catalysts. Reaction conditions: 573 K, 6.0 MPa H2, 1.8 g catalyst,
flow rate of liquid feedstock: 0.04 mL min−1 (WHSV = 1.3 h−1); hydrogen flow rate:
120 mL min−1. Diesel range alkanes, gasoline range alkanes and light alkanes corre-
spond to C9–C15, C5–C8 and C1–C4 alkanes, respectively.
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Table 2
Conversions of 2-MF and yields of P1, P2, P3 under the catalysis of H2SO4, H3PO4 and acetic acid respectively. Reaction condition: 333 K, 2 h, 1.64 g (20 mmol) 2-MF, 1.96 g
(20 mmol) mesityl oxide, the concentrations of the acid solutions are 24 wt.%.
Catalyst
Mole of acid (mmol)
Conversion of 2-MF (%)
Yield of P1 (%)
Yield of P2 (%)
Yield of P3 (%)
H2SO4
H3PO4
CH3COOH
0.6
0.6
0.6
24.4
10.8
7.3
8.9
1.0
0.0
0.0
0.0
0.0
3.0
2.0
0.0
active center for the alkylation of 2-MF with mesityl oxide. The high
acid strength of Nafion-212 resin can be explained by its chemical
structure. As we know, Nafion resin is a kind of perfluorinated sul-
fonic acid resin which is always recognized as a superacid catalyst,
while Amberlyst resin is a family of sulfonic-acid-functionalized
cross-linked polystyrene resin [19,35,36]. The presence of fluorine
increases the acid strength of –SO3H groups in Nafion resins and
makes them stronger than those in Amberlyst resins, which is the
intrinsic reason for the higher acid strength of Nafion-212 resin.
The stabilities of three most active catalysts (i.e. Nafion-212,
Amberlyst-15 and Amberlyst-36 resins) in the alkylation of 2-MF
with mesityl oxide were further compared. To exclude the disturb-
ance of residues (such as alkylation and HAA products, unreacted
2-MF and mesityl oxide), the catalysts were washed thoroughly
with methanol after each usage and then dried at 333 K for 6 h
before the next cycle. As shown in Fig. 4, Nafion-212 resin exhibited
good stability under the investigated condition. No obvious deac-
tivation was observed during the five continuous tests. In contrast,
evident decrease of activity could be noticed over Amberlyst-15
and Amberlyst-36 resins. Considering the higher catalytic efficiency
and good stability of Nafion-212 resin in the alkylation of 2-MF
with mesityl oxide, we believe it is a promising catalyst in future
application.
The effects of reaction temperature, catalyst amount and reac-
tion time on the yields of P1, P2 and P3 over Nafion-212 resin were
investigated, respectively (see Figs. 5–7). Under the optimum reac-
tion condition (0.15 g catalyst, 20 mmol 2-MF and 20 mmol mesityl
oxide reacting at 333 K for 2 h), high carbon yield of diesel precur-
sors (∼70%) can be obtained over the Nafion-212 resin.
3.2. Hydrodeoxygenation (HDO)
The alkylation products of 2-MF and mesityl oxide were
hydrodeoxygenated over a series of catalysts at 573 K and 6.0 MPa
H2. From the results shows in Fig. 8a, Pt/SiO2 and Pd/SiO2 catalysts
exhibit higher HDO activities than those of Pt/AC and Pd/AC cata-
lysts (which can been seen from the evidently higher carbon yields
of alkanes over the Pt/SiO2 and Pd/SiO2 catalysts). This result is
Fig. 10. TEM images of the fresh Ni–Mo2C/SiO2 (a), used Ni–Mo2C/SiO2 (b), fresh Ni–W2C/SiO2 (c) and used Ni–W2C/SiO2 (d).
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7
(a)
(a)
500
Ni 2p-Ni-Mo2C/SiO2-used
450
400
350
300
250
Ni 2p-Ni-Mo2C/SiO2-fresh
885
880
875
870
865
860
855
850
240
238
236
234
232
230
228
226
Binding energy / eV
Binding energy / eV
500
450
400
350
300
250
200
(b)
(b)
Ni 2p-Ni-W2C/SiO2-used
Ni 2p-Ni-W2C/SiO2-fresh
885
880
875
870
865
860
855
850
240
238
236
234
232
230
228
226
Binding energy / eV
Binding energy / eV
Fig. 11. Ni 2p XPS spectra of the fresh and used Ni–Mo2C/SiO2 (a) and Ni–W2C/SiO2
Fig. 12. Mo 3d XPS spectra of the fresh (a) and used (b) Ni–Mo2C/SiO2 catalysts.
(b) catalysts.
consistent with what we observed in the HDO of other lignocel-
lulose derived oxygenates [37]. From this result, we can see that
SiO2 is better than active carbon to be used as the catalyst support
in HDO process. In the chromatograms of the liquid HDO products
over the Pt/SiO2 and Pd/SiO2 catalysts (see Fig. S6 in supporting
information), evident peaks of oxygenates or partial HDO products
can be observed, which means that the alkylation products of 2-MF
and mesityl oxide cannot be completely hydrodeoxygenated over
the Pt/SiO2 and Pd/SiO2 catalysts under the investigated conditions.
As the emphasis of this work, we studied the performances of
Ni–W2C/SiO2 and Ni–Mo2C/SiO2 catalysts for the HDO of the alkyl-
ation products of 2-MF and mesityl oxide under the same reaction
conditions as we used for Pt and Pd catalysts (see Fig. 8b). From
the analysis of GC-MS, the alkylation products of 2-MF and mesityl
oxide were completely converted to alkanes over these catalysts.
This result indicates that the Ni–W2C/SiO2 and Ni–Mo2C/SiO2 cata-
lysts are more active than Pt/SiO2 and Pd/SiO2 catalysts for the HDO
of the alkylation products of 2-MF and mesityl oxide. For compar-
ison, we also investigated the performance of Ni–WxC/AC catalyst
prepared by the method reported in our previous work [24]. As we
found earlier on Pt and Pd catalysts, evidently lower carbon yield of
alkanes was achieved over Ni–WxC/AC catalyst than those obtained
over the Ni–W2C/SiO2 and Ni–Mo2C/SiO2 catalysts. This result fur-
ther proves that SiO2 is better than active carbon to be used as the
support for HDO catalyst. Moreover, it is worth mentioning that
higher diesel yield (77%) can be achieved over Ni–Mo2C/SiO2 than
that over Ni–W2C/SiO2 (20%) under the same condition, which can
be explained by the less C–C cleavage over Ni–Mo2C/SiO2 catalyst
during the HDO process. The carbon distributions of the alkanes
from the HDO of the alkylation products of 2-MF and mesityl oxide
over Ni–Mo2C/SiO2 and Ni–W2C/SiO2 were shown in Fig. S7. From
it, we can see that higher carbon yields of short chain alkanes
were obtained over Ni–W2C/SiO2, indicating severer C–C cleavage
occurred over Ni–W2C/SiO2 than that over Ni–Mo2C/SiO2. Accord-
ing to the carbon distributions of different alkanes, some possible
pathways for the HDO of different products from the alkylation of
2-MF with mesityl oxide were proposed in Scheme S1. As suggested
in the previous work of Corma et al. [23] and our group [38], the
C–C cracking reactions prefers taking place at the branch carbon
atoms which are also adjacent to furan ring. This can be explained
by the higher stability of carbocation at these positions (due to elec-
tron donor effect of alkyl group or the conjugation effect of furan
group). It is well known that carbocations are important interme-
diates in the C–C cleavage reactions that decrease the diesel range
alkane yield [39,40]. Along with the price advantage of Mo over W,
Ni–Mo2C/SiO2 is more promising than Ni–W2C/SiO2 in the future
application for the HDO of biomass derived oxygenates.
To find out the reason for the better performance of
Ni–Mo2C/SiO2 than that of Ni–W2C/SiO2, we characterized the
fresh and used Ni–Mo2C/SiO2 and Ni–W2C/SiO2 catalysts by XRD,
TEM and XPS. The XRD patterns of the fresh and used Ni–Mo2C/SiO2
and Ni–W2C/SiO2 catalysts were illustrated in Fig. 9. From it, we can
only see the peaks of Mo2C and W2C. No peak of molybdenum or
tungsten oxide was observed, which means that the molybdenum
and tungsten species were carburized under the assistance of nickel
[6]. The Ni species on Ni–Mo2C/SiO2 exists as metallic state. In con-
trast, the Ni species on Ni–W2C/SiO2 exists as Ni17W3 alloy. For
both catalysts, no obvious crystal structure change was observed
after being used for the HDO process.
The TEM images of the fresh and used Ni–Mo2C/SiO2 and
Ni–W2C/SiO2 catalysts were illustrated in Fig. 10. From them, we
can see that the average sizes of the Mo2C and W2C particles on
Please cite this article in press as: S. Li, et al., Synthesis of diesel range alkanes with 2-methylfuran and mesityl oxide from lignocellulose,
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Table 3
8
(a)
220
200
180
160
140
120
100
80
The ratios of oxide to carbide on the surfaces of the fresh and used Ni–Mo2C/SiO2 or
Ni–W2C/SiO2 catalysts (calculated from the XPS results).
Catalyst
Fresh
Used
Ni–Mo2C/SiO2
Ni–W2C/SiO2
0.71
5.86
0.98
10.14
be rationalized by the oxidation of Mo2C by the H2O generated
during the HDO process. Fig. 13 illustrates the W 4f XPS spec-
tra of the fresh and used Ni–W2C/SiO2 catalysts. Compared with
Ni–Mo2C/SiO2, the Ni–W2C/SiO2 catalyst is liable to be oxidized,
which is indicated by the much higher ratio of W oxide (denoted
by dot line) to W2C (denoted by dash line) on the surfaces of fresh
and used Ni–W2C/SiO2 catalysts (see Table 3). Analogous to what
we observed for Ni–Mo2C/SiO2, the ratio of W oxide to W2C on the
surface of Ni–W2C/SiO2 catalyst also increased after being used for
HDO process (see Fig. 13 and Table 3). This can be also be explained
by the oxidation of W2C on the surface of the Ni–W2C/SiO2 catalyst
by the H2O generated during the HDO process. In Refs. [46–48],
it was suggested that the tungsten oxide or molybdenum oxide
over the carbide catalysts can act as acid sites for the hydroi-
somerization and hydrocracking reactions. According to the XPS
results we obtained, evidently higher oxide to carbide ratio was
observed on the surface of Ni–W2C/SiO2 than that on the surface of
Ni–Mo2C/SiO2, which can be one reason for the higher hydrocrack-
ing activity of Ni–W2C/SiO2 during the HDO process. Furthermore,
it is well known that tungsten oxide has higher acid strength than
molybdenum oxide, which can be another reason for the higher
hydrocracking activity of Ni–W2C/SiO2 than that of Ni–Mo2C/SiO2
[49].
60
40
42
40
38
36
34
32
30
Binding energy / eV
(b)
350
300
250
200
150
100
50
0
40
38
36
34
32
30
Binding energy / eV
Fig. 13. W 4f XPS spectra of the fresh (a) and used (b) Ni–W2C/SiO2 catalysts.
4. Conclusions
In this work, a systematic research about the alkylation of 2-
MF with mesityl oxide was carried out over a series of solid acid
catalysts. Among the investigated candidates, Nafion-212 resin
exhibited the highest catalytic efficiency, which can be explained
by its higher acid strength. By the optimization of reaction con-
ditions, high carbon yield of diesel precursors (∼70%) can be
obtained over Nafion-212 resin. Moreover, nickel promoted car-
bides (Ni–Mo2C/SiO2 and Ni–W2C/SiO2) catalysts were found to be
very active for the HDO of the alkylation products of 2-MF with
mesityl oxide. Compared with Ni–W2C/SiO2, Ni–Mo2C/SiO2 has
evident advantage at the cost and the selectivity to diesel range
alkanes. Over the Ni–Mo2C/SiO2 catalyst, 77% carbon yield of diesel
range alkanes was achieved by the HDO of alkylation products of
2-MF and mesityl oxide. This value is higher than those obtained
over the noble metal catalysts and the Ni–WxC/AC catalyst which
has been reported in our previous work.
the fresh Ni–Mo2C/SiO2 and Ni–W2C/SiO2 catalyst are 8.2 nm and
5.8 nm, respectively. After being used for the HDO process, the aver-
age sizes of the Mo2C and W2C particles on the used Ni–Mo2C/SiO2
and Ni–W2C/SiO2 catalyst slightly increased to 9.3 nm and 6.3 nm,
respectively. This phenomenon can be explained by the agglomer-
ation of the molybdenum carbide or tungsten carbide during the
HDO process.
The Ni 2p XPS spectra of the fresh and used Ni–Mo2C/SiO2 and
Ni–W2C/SiO2 catalysts were shown in Fig. 11. From it, we can see
that the nickel species on the four catalysts exist as zero valent. No
evident change of the valence of nickel was observed after being
used for the HDO process. Fig. 12 shows the Mo 3d XPS spec-
tra of the fresh and used Ni–Mo2C/SiO2 catalysts. From it, we can
see that both Mo2C (denoted by the dash line) and molybdenum
oxide (denoted by the dot line) exist on the surface of fresh and
used Ni–Mo2C/SiO2 catalysts. The presence of molybdenum oxide
on the surface of Ni–Mo2C/SiO2 catalyst can be explained by the
oxidation of molybdenum carbide when catalyst was exposed to
oxygen in air or passivation gas. The molybdenum oxide attached
on the surface of molybdenum carbide may be helpful for the HDO
process. In the recent work of Tomishige group [41], high yield of
the gasoline range alkanes can be obtained by the HDO of sugars
and sugar alcohols under co-catalysis of the Ir–ReOx/SiO2 and H-
ZSM-5. In another work of the same group [42], the modification
of rhenium oxide demonstrated evident promotion effect on the
hydrogenolysis of alcohols over Ir/SiO2 catalysts. Analogously, it
has been found that molybdenum oxide and tungsten oxide have
similar promotion effects as rhenium oxide for the C–O cleavage
reactions over noble metal catalysts [43–45]. The ratio of Mo oxide
to Mo2C on the surface of Ni–Mo2C/SiO2 catalyst increased after
being used for HDO process (see Fig. 12 and Table 3). This can
Acknowledgements
This work is supported by Natural Science Foundation of China
(Nos. 21106143, 21277140) and 100-talent project of Dalian Insti-
tute of Chemical Physics (DICP), and the Independent Innovation
Foundation of State Key Laboratory of Catalysis of DICP (No.
R201113).
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/j.cattod.
2014.01.028.
Please cite this article in press as: S. Li, et al., Synthesis of diesel range alkanes with 2-methylfuran and mesityl oxide from lignocellulose,
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9
References
[28] G. Li, N. Li, S. Li, A. Wang, Y. Cong, X. Wang, T. Zhang, Chem. Commun. 49 (2013)
5727–5729.
[29] J.F. Pang, A.Q. Wang, M.Y. Zheng, T. Zhang, Chem. Commun. 46 (2010)
6935–6937.
[30] J. Pang, A. Wang, M. Zheng, Y. Zhang, Y. Huang, X. Chen, T. Zhang, Green Chem.
14 (2012) 614–617.
[31] J. Jae, G.A. Tompsett, A.J. Foster, K.D. Hammond, S.M. Auerbach, R.F. Lobo, G.W.
Huber, J. Catal. 279 (2011) 257–268.
[32] T. Okuhara, Chem. Rev. 102 (2002) 3641–3666.
[33] M. Cadenas, R. Bringué, C. Fité, E. Ramírez, F. Cunill, Top. Catal. 54 (2011)
998–1008.
[34] K.N. Rao, A. Sridhar, A.F. Lee, S.J. Tavener, N.A. Young, K. Wilson, Green Chem.
8 (2006) 790–797.
[35] R. Weingarten, G.A. Tompsett, W.C. Conner, G.W. Huber, J. Catal. 279 (2011)
174–182.
[36] K.A. Mauritz, R.B. Moore, Chem. Rev. 104 (2004) 4535–4586.
[37] J. Yang, N. Li, G. Li, W. Wang, A. Wang, X. Wang, Y. Cong, T. Zhang, Chem.
Commun. (2014), http://dx.doi.org/10.1039/c1033cc46588h.
[38] G. Li, N. Li, J. Yang, L. Li, A. Wang, X. Wang, Y. Cong, T. Zhang, Green Chem.
(2014), http://dx.doi.org/10.1039/C1033GC41356J.
[39] J. Weitkamp, ChemCatChem 4 (2012) 292–306.
[40] P.F. Britt, A.C. Buchanan Iii, K.B. Thomas, S.-K. Lee, J. Anal. Appl. Pyrol. 33 (1995)
1–19.
[41] K. Chen, M. Tamura, Z. Yuan, Y. Nakagawa, K. Tomishige, ChemSusChem 6
(2013) 613–621.
[42] Y. Nakagawa, K. Mori, K. Chen, Y. Amada, M. Tamura, K. Tomishige, Appl. Catal.
A: Gen. 468 (2013) 418–425.
[43] S. Koso, N. Ueda, Y. Shinmi, K. Okumura, T. Kizuka, K. Tomishige, J. Catal. 267
(2009) 89–92.
[44] M. Chia, Y.J. Pagán-Torres, D. Hibbitts, Q. Tan, H.N. Pham, A.K. Datye, M. Neurock,
R.J. Davis, J.A. Dumesic, J. Am. Chem. Soc. 133 (2011) 12675–12689.
[45] Z. Wang, G. Li, X. Liu, Y. Huang, A. Wang, W. Chu, X. Wang, N. Li, Catal. Commun.
43 (2014) 38–41.
[46] F.H. Ribeiro, R.A. Dalla Betta, M. Boudart, J. Baumgartner, E. Iglesia, J. Catal. 130
(1991) 86–105.
[47] E. Iglesia, J.E. Baumgartner, F.H. Ribeiro, M. Boudart, J. Catal. 131 (1991)
523–544.
[48] E.A. Blekkan, C. Pham-Huu, M.J. Ledoux, J. Guille, Ind. Eng. Chem. Res. 33 (1994)
1657–1664.
[49] V.G. Komvokis, S. Karakoulia, E.F. Iliopoulou, M.C. Papapetrou, I.A. Vasalos, A.A.
Lappas, K.S. Triantafyllidis, Catal. Today 196 (2012) 42–55.
[1] G.W. Huber, S. Iborra, A. Corma, Chem. Rev. 106 (2006) 4044–4098.
[2] D.M. Alonso, J.Q. Bond, J.A. Dumesic, Green Chem. 12 (2010) 1493–1513.
[3] T.D. Matson, K. Barta, A.V. Iretskii, P.C. Ford, J. Am. Chem. Soc. 133 (2011)
14090–14097.
[4] A. Corma, S. Iborra, A. Velty, Chem. Rev. 107 (2007) 2411–2502.
[5] P. Gallezot, Chem. Soc. Rev. 41 (2012) 1538–1558.
[6] N. Ji, T. Zhang, M.Y. Zheng, A.Q. Wang, H. Wang, X.D. Wang, J.G.G. Chen, Angew.
Chem. Int. Ed. 47 (2008) 8510–8513.
[7] A. Wang, T. Zhang, Acc. Chem. Res. 46 (2013) 1377–1386.
[8] H. Zhao, J.E. Holladay, H. Brown, Z.C. Zhang, Science 316 (2007) 1597–1600.
[9] G.W. Huber, J.N. Chheda, C.J. Barrett, J.A. Dumesic, Science 308 (2005)
1446–1450.
[10] J.Q. Bond, D.M. Alonso, D. Wang, R.M. West, J.A. Dumesic, Science 327 (2010)
1110–1114.
[11] R. Xing, A.V. Subrahmanyam, H. Olcay, W. Qi, G.P. van Walsum, H. Pendse, G.W.
Huber, Green Chem. 12 (2010) 1933–1946.
[12] H. Olcay, A.V. Subrahmanyam, R. Xing, J. Lajoie, J.A. Dumesic, G.W. Huber,
Energy Environ. Sci. 6 (2013) 205–216.
[13] A. Corma, O. de la Torre, M. Renz, N. Villandier, Angew. Chem. Int. Ed. 50 (2011)
2375–2378.
[14] C. Zhao, D.M. Camaioni, J.A. Lercher, J. Catal. 288 (2012) 92–103.
[15] A. Corma, O. de la Torre, M. Renz, ChemSusChem 4 (2011) 1574–1577.
[16] P. Anbarasan, Z.C. Baer, S. Sreekumar, E. Gross, J.B. Binder, H.W. Blanch, D.S.
Clark, F.D. Toste, Nature 491 (2012) 235–239.
[17] A.D. Sutton, F.D. Waldie, R.L. Wu, M. Schlaf, L.A. Silks, J.C. Gordon, Nat. Chem. 5
(2013) 428–432.
[18] W. Xu, Q. Xia, Y. Zhang, Y. Guo, Y. Wang, G. Lu, ChemSusChem 4 (2011)
1758–1761.
[19] B.G. Harvey, R.L. Quintana, Energy Environ. Sci. 3 (2010) 352–357.
[20] S. Sitthisa, W. An, D.E. Resasco, J. Catal. 284 (2011) 90–101.
[21] J.-P. Lange, E. van der Heide, J. van Buijtenen, R. Price, ChemSusChem 5 (2012)
150–166.
[22] Y. Nakagawa, M. Tamura, K. Tomishige, ACS Catal. 3 (2013) 2655–2668.
[23] A. Corma, O. de la Torre, M. Renz, Energy Environ. Sci. 5 (2012) 6328–6344.
[24] G. Li, N. Li, J. Yang, A. Wang, X. Wang, Y. Cong, T. Zhang, Bioresour. Technol. 134
(2013) 66–72.
[25] Y. Kamiya, S. Sakata, Y. Yoshinaga, R. Ohnishi, T. Okuhara, Catal. Lett. 94 (2004)
45–47.
[26] W. Zhang, Y. Zhang, L. Zhao, W. Wei, Energy Fuels 24 (2010) 2052–2059.
[27] G. Li, N. Li, Z. Wang, C. Li, A. Wang, X. Wang, Y. Cong, T. Zhang, ChemSusChem
5 (2012) 1958–1966.
Please cite this article in press as: S. Li, et al., Synthesis of diesel range alkanes with 2-methylfuran and mesityl oxide from lignocellulose,
Catal. Today (2014), http://dx.doi.org/10.1016/j.cattod.2014.01.028