Conversion of biomass-derived levulinate esters to γ-valerolactone with a robust CuNi bimetallic catalyst

Article abstract of DOI:10.1039/d0nj02874f

A high-performance Cu-Ni bimetallic catalyst supported on Zr-Al oxides was fabricated for catalyzing the transfer hydrogenation of levulinate esters to γ-valerolactone (GVL) under mild conditions. The Cu2Ni1/Zr3Al7Oz catalyst provided the highest ethyl levulinate conversion of 99% with 96.8% GVL yield at 150 °C in 8 h employing 2-butyl alcohol (2-BuOH) as the hydrogen source. The catalyst was also used successfully for the catalytic transfer hydrogenation (CTH) of a series of levulinate esters. Moreover, the catalyst still retained high activity after recycling for 4 times. The outstanding catalytic performance and selectivity of Cu2Ni1/Zr3Al7Oz, together with its low-cost nature, make it have great application potential as a catalyst for the fabrication of GVL on a large scale in industry.

Full text of DOI:10.1039/d0nj02874f

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Conversion of biomass-derived levulinate esters to γ-
valerolactone with robust CuNi bimetallic catalyst
Received 00th January 20xx,
Accepted 00th January 20xx
Shuai Zhang†, Jie Li†, Ning-Zhao Shang*, Shu-Tao Gao, Chun Wang*, Zhi Wang
DOI: 10.1039/x0xx00000x
A high-performance Cu-Ni bimetallic catalyst supported on Zr-Al oxides was fabricated for catalyzing the transfer
2 1 3 7 z
hydrogenation of levulinate esters to γ-valerolactone (GVL) under mild conditions. The Cu Ni /Zr Al O catalyst provided
o
the highest ethyl levulinate conversion of 99% with 96.8% GVL yield at 150 C in 8 h employing 2-butyl alcohol (2-BuOH) as
the hydrogen source. The catalyst was also used successfully for the catalytic transfer hydrogenation (CTH) of a series of
levulinate esters. Moreover, the catalyst still remained high activity after 4 times recycling. The outstanding catalytic
2 1 3 7 z
performance and selectivity of Cu Ni /Zr Al O , together with its low-cost nature, make it have a great application
potential as catalyst for the fabrication of GVL at large scale in industry.
precious metal-based catalysts, including Au-Pd/TiO
2
, Pt/C, Rh
supported on TiO active carbon and Al O 6, 9, 10. However, the
Introduction
2
2 3
high price and low stability of precious metal-based catalysts
limit their practical application potential in the production of
GVL. Developing cheap, stable, highly efficient and recyclable
catalysts for the hydrogenation of LA are urgently needed.
To solve the energy crisis and pollution problem caused by
the ever-increasing consumption of fossil fuels, it is necessary
to find sustainable resource as alternative energy to petroleum
products 1 . Biomass, as the most richest, low cost and readily
available sustainable carbon sources from photosynthesis on
the earth, provides an effective solution for alleviated pressure
-3
2
Meanwhile, H is potentially dangerous, flammable and
requires special equipment for production and storage.
2
Recently, in order to avoid employing dangerous H ,
4
on fuel shortage . Among the renewable biomasses,
catalytic transfer hydrogenation (CTH), a much security and
sustainability method, has been proposed, in which H is
replaced by a hydrogen donor, for example formic acid (FA),
lignocellulose has attracted considerable attention because it
can be readily transferred into a series of value-added
platform chemicals, such as levulinic acid (LA) and levulinate
ester. LA and its esters are regarded as the most potential
building blocks in producing various biochemicals and biofuels
2
1
1
12-14
alcohols and hydrazine hydrate
. The CTH reaction with
primary alcohols as the H-donors provided low GVL product
1
5
yields . The primary alcohols were poor H-donors in the CTH
including valerate esters, 1,4-pentanediol and γ-valerolactone
GVL) 5 . Among them, GVL has been widely used as a solvent,
reaction due to the difficult β-hydride elimination after it
formed alkoxy species on the surface of the catalyst
, 6
(
1
6
.
fuel additive, liquid fuel and raw material for the fabrication of
Dumesic et al. used ZrO
2
as catalyst for the hydrogenation of
7
, 8
other value-added chemicals . Moreover, levulinate esters
are considered as ideal substrates for synthesizing GVL
because they are energy-efficient and easier to be separated
from the ethanol reaction system than the separation of LA
from aqueous solution. So, it is more desirable to explore
highly active catalysts for hydrogenation reaction of levulinate
esters to GVL.
6
ethyl levulinate (EL) with isopropanol as H-donor at 150°C .
Lin et al. reported that metal hydroxide (such as ZrO(OH)
effectively catalyzed EL to GVL in a supercritical ethanol
2
) can
1
7
.
Song and his workers found that 94.4% yield of GVL was
achieved with Zr-HBA as the catalyst in the presence of
1
8
isopropanol . Yao et al prepared bimetallic Cu-Ni catalyst for
1
9
the CTH of EL to GVL . Rode et al. prepared the Ag-Ni
bimetallic catalyst for the hydrogenation of LA in water with
The hydrogenation of LA and its esters to the GVL mainly
conducted with hydrogen (H ) as hydrogen source over
2
2
0
high selectivity . Hence, exploring more robust and stable
heterogeneous catalysts for the hydrogenation of EL to GVL is
still desired urgently for practical application.
College of Science, Hebei Agricultural University, Baoding 071001, China. Tel.: +86
12 7528291. E-mail:wangchun@hebau.edu.cn, chunwang69@126.com (C.
Wang), ningzhao611@126.com (N. Shang).
3
In continuation of our endeavors in the exploying of
2
1-24
sustainable and efficient catalysts
, in this work, a
†
These authors contributed equally to this work.
Electronic Supplementary Information (ESI) available: Chemicals and bimetallic catalyst, Cu-Ni nanoparticles supported on the Zr-Al
characterization apparatus, XRD and EDS of the materials, effect of reaction time
oxide, was fabricated by a simple one-step co-precipitation
and reaction temperature on the conversion of EL, repetitiveness of
2 1 3 7 z
Cu Ni /Zr Al O
2 1 3 7 z
, BET surface areas, base and acid strength of prepared catalysts, method. The optimized Cu Ni /Zr Al O catalyst delivered high
comparison with reported catalysts tested for the CTH toward GVL. See
DOI: 10.1039/x0xx00000x
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activity for the conversion of levulinate esters to GVL with 2-
butyl alcohol (2-BuOH) as the hydrogen donor (Scheme 1).
Results and Discussion
Characterization of the catalysts
View Article Online
DOI: 10.1039/D0NJ02874F
The transmission electron microscopy (TEM) images of
Ni /Zr Al catalyst were displayed in Fig. 1. It can be
observed from the pictures that the metal (Cu, Ni)
nanoparticles were well dispersed on the Zr-Al oxide
composite. The average particle size of the metal
nanoparticles was about 4-5 nm as shown in Fig. 1D. In
Cu
2
1
3
7 z
O
0
1
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9
0
2 1 3 7 z
addition, metal distribution of Cu Ni /Zr Al O catalyst was
analyzed by energy dispersive spectrometer (Fig. S2). The
mapping of the elements Cu, Ni, Zr, Al and O from the selected
area revealed that Cu, Ni, Zr, Al and O were uniform
distributed on the catalyst without obvious aggregation noted
Scheme 1. Illustration of the conversion of biomass to
chemicals.
(
Fig. 2), which confirmed the formation of CuNi nanoparticles.
And the contents of Cu and Ni in the Cu Ni /Zr Al sample
2
1
3
7 z
O
was measured by inductively coupled plasma atomic emission
spectroscopy (ICP-AES) and amounted to be 8.4 wt% and 4.2
wt%, respectively.
Experimental
The reagents and instruments are provided in the
Electronic Supporting Information.
The X-ray diffraction (XRD) patterns of Al
Al (Zr Al , Zr Al , Zr Al ) supported catalysts were
revealed in Fig. 3 and Fig. S1. No apparent diffraction patterns
of metal oxides species (e.g., Ni and Cu ) were exhibited
in the XRD images, probably can be attributed to their
2 3 2
O , ZrO and
Zr
x
O
y z
3
O
7 z
5
O
5 z
7
3 z
O
Preparation of the catalysts
O
x z
x z
O
The precursor of the catalyst was fabricated by one-pot
co-precipitation method. 1 mmol Cu(NO
Ni(NO ·6H O were dissolved in 100 mL deionized water, 3
mmol ZrOCl ·8H O and 7 mmol Al(NO ·9H O were added.
3 2 2
) ·3H O and 0.5 mmol
2
5
amorphous state . All the samples were shown two obvious
)
3 2
2
o
o
broad peaks at 2θ = 30.38
corresponding to the peaks of t-ZrO
and 46.2 , which were
and Al
2
2
)
3 3
2
2
2 3
O .
-1
Then 1 mol L sodium carbonate was added dropwise under
stirring vigorously until the pH of solution reach to 9-10. The
resulted precipitate was filtered and washed with water until
no chloride ions. The obtained solid was dried at 100°C for 12
h, calcined and reduced in a flow of 5% H
with a rate of 10°C/min. This catalyst was denoted as
2 2
/N for 4 h at 400°C
Cu
Cu
2
Ni
Ni
1
/Zr
/Zr
3
Al
Al
7
O
O
z
. For comparison, Cu/Zr
3 7 z 3 7 z
Al O , Ni/Zr Al O and
were fabricated with the same procedure
1
1
3
7
z
except that the mole ratios of Cu and Ni were 1:0, 0:1 and 1:1,
respectively. Cu Ni /Zr Al Cu Ni /Zr Al , Cu Ni /Al and
Cu Ni /ZrO were prepared according to the above method
except the mole ratios of ZrOCl ·8H O and Al(NO ·9H O were
:3, 5:5, 0:10 and 10:1, respectively.
Cu Ni /TiO were prepared with the above method except
that according to the above method except that 750 mg TiO
instead of ZrOCl ·8H O and Al(NO ·9H O was added.
2
1
7
O
3 z
2
1
5
O
5 z
2
1
2 3
O
2
1
2
2
2
)
3 3
2
7
2
1
2
2
2
2
3
)
3
2
Fig. 1 TEM images of Cu
2
Ni
1 3 7 z
/Zr Al O (A, B, C), corresponding
General procedure for the hydrogenation of levulinic acid and size distribution of Cu Ni nanoparticles (D).
its esters
2 1
The hydrogenation of levulinic acid and its esters was
conducted in a 50 mL Teflon-sealed autoclave under magnetic
stirring. In the model reaction, 0.5 mmol of ethyl levulinate, 3
mL of 2-butanol, 50 mg catalyst were added and heated at
1
50°C for 8 h. When the reactor was cooled down to room
temperature, the product was subjected to analysis by gas
chromatography (GC). After reaction, the catalyst was
separated by filtration and washed with 2-butanol for three
times. The recycled catalyst was directly added to the
autoclave for the next experiment.
2
| J. Name., 2012, 00, 1-3
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Fig. 2 SEM images and element mapping of Cu
catalyst.
2
Ni
1
/Zr
3
Al
7
O
z
revealed that all catalysts displayed the weak and medium-
View Article Online
DOI: 10.1039/D0NJ02874F
strength acid sites (Table S1, entries 1-5), and the acid strength
o
of Cu
2
Ni
1
/Zr
3
Al
7
O
z
at 400 C was higher than that of the other
The pore structures, textural properties and Brunauer-
Emmett-Teller (BET) surface areas of the catalysts were
characterized by N
were summarized in Fig. 4 and Table S1 (entries 1-5). As shown
in Fig. 4, the isotherms of Zr Al and Cu Ni /Zr Al
exhibited a typical type IV isotherm with a large hysteresis
loop, suggesting the presence of mesoporous structures,
which is beneficial for exposing more catalytic active sites and
the mass transfer of the reactant, which will lead to a better
catalysts. To our surprise, similar to the curve of acidity, the
base strength of these catalysts also belongs to weak and
medium levels (Table S2). The results demonstrated that the
2
sorption measurements and the results
addition of certain amount of ZrO
acid and base strength of the Cu Ni
2
is beneficial to enhance the
/Zr Al
3
7
O
z
2
1
3
7 z
O
0
1
2
3
4
5
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0
1
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9
0
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3
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0
2
1
3
7 z
O .
catalytic performance. The BET surface areas of Zr
3
Al
were 110 and 78 m /g , respectively. The
lower surface area of Cu Ni /Zr Al can be attributed to that
a certain amount of Cu-Ni occupied partially the porous
channel of Zr Al . Apart from Cu Ni /Al , the surface area
of Cu Ni /Zr Al and Cu Ni /ZrO were
lower than that of Cu
7 z
O and
2
-1
2 1 3 7 z
Cu Ni /Zr Al O
2
1
3
7 z
O
3
7
O
z
2
1
2 3
O
Fig. 5 NH
calcined at 400 C.
1. Cu Ni /Al
Cu Ni /Zr Al
3 2
-TPD (A) and CO -TPD (B) profiles of the catalysts
2
1
7
3
O
z
, Cu
Ni
2
Ni
/Zr
1
/Zr
Al
5
Al
5
O
z
2
1
2
o
2
1
3
7
O
z
.
2
1
2
O
3
,
2. Cu
, 5. Cu Ni /Zr
2
Ni
Al
1
/ZrO
O .
7 z
2
.
3-Cu
2
Ni
1
/Zr
7
3 z
Al O ,
4.
2
1
5
5
O
z
2
1
3
2 1 3 7 z
Metal composition of the Cu Ni /Zr Al O catalyst was
characterized by the X-ray photoelectron spectroscopy (XPS),
and the results were shown in Fig. 6. The two peaks of the Cu
2p3/2 were observed in Fig. 6A, the peaks at 933 and 952 eV
0
corresponded to the Cu in the Cu
2
Ni
1
/Zr
Al
3 7
O
z
. The peaks at
936 eV and the satelite peak around 956 eV in the catalyst
surface which reflecting the existence of CuO. The XPS of Ni
2p3/2 and Ni 2p1/2 was exhibited in Fig. 6B, the peaks at 857
Fig. 3 XRD images of the catalysts and the reused and 875 eV together with the peaks at 865 and 882 eV were
Cu
2 1
Ni /Zr
3 7
Al Oz.
0
assigned to the Ni and NiO species, respectively. The Al 2p
binding energy located at around 74 eV indicating the
presence of Al O in the catalyst (Fig. 6C). As shown in Fig. 6D,
2 3
Zr 3d spectra of the catalyst located at 182 and 184.5 eV can
be corresponded to the Zr 3d 5/2 and Zr 3d 3/2, respectively,
4
+
2 1 3 7 z
which indicated the presence of Zr in the Cu Ni /Zr Al O .
Fig. 4 The N
2
sorption isotherm of Cu
2
Ni
1
/Zr
3
Al
7
O
z
and Zr
3
Al
7
O .
z
The surface acidity and basicity of Cu
2
Ni /Al
1
2
O ,
3
Cu
2 1
Ni /ZrO
2
,
Cu
were conducted by Ammonia-Temperature
-TPD) and Carbon dioxide-
Temperature Programmed Desorption (CO -TPD), as displayed
in Fig. 5, Table S1 and Table S2, respectively. Fig. 5A presented
2
Ni
1
/Zr
7
Al
3
O
z
,
Cu
2
Ni
1
/Zr
5
Al
5
O
z
and
Cu
2
Ni
1
/Zr Al O
3
7 z
Fig. 6 XPS images of the Cu
p (B), Al 2p (C) and Zr 3d (D).
2 1 3 7 z
Ni /Zr Al O catalyst, Cu 2p (A), Ni
Programmed Desorption (NH
3
2
2
3
the NH -TPD results of these as-prepared catalysts at the Catalytic performance of the catalyst.
o
tested temperature ranging from 110 to 400 C. It obviously
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The catalytic hydrogenation of EL to GVL was subjected as unchanged. Only 44% yield of GVL and 47% conversion of EL
a model reaction to evaluated the activity of the catalysts, were obtained when the dosage was 25 mg (entries 12). As the
which was performed at 150 C with 2-BuOH as hydrogen amount of the catalyst increased to 40 mg, 69.1% yield of GVL
source. Series of blank experiments were executed with ZrO2, was obtained (entry 13).
View Article Online
DOI: 10.1039/D0NJ02874F
o
2 3 3 7 z
Al O and Zr Al O as catalysts, the reactions only provided 4%,
1
8% and 14% yields of GVL after 24 h (Table 1, entries 1-3). To
Table 2. The hydrogenation of LA and its esters with different
our delight, high yield (96.8%) of GVL was achieved with
excellent selectivity catalyzed by Cu
o
hydrogen source.
Ni
1
/Zr
3
Al
7
O
z
at 150 C for 8
0
1
2
3
4
5
6
7
8
9
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3
4
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Entry
Substrates
H-source
MeOH
EtOH
2-PrOH
2-BuOH
tert-BuOH
2-BuOH
2-BuOH
2-BuOH
Conv. (%)
Yield. (%)
h (Table 1, entry 4). For comparison, the hydrogenation of EL
over Cu/Zr Al Ni/Zr Al and Cu Ni /Zr Al were
investigated (Table 1, entries 5-7), the yields of GVL were
0.3%, 13% and 36.5%, respectively. Those also have been
1
2
3
4
5
6
7
8
EL
EL
EL
EL
EL
ML
BL
LA
4
6
3.8
5.1
3
7
O
z
,
3
7
O
z
1
1
3
7 z
O
65
99
8
99
96
38
63.2
96.8
7.63
95.3
91.6
35.6
8
testified that the catalytic performance enhances as the
increasing Cu content, however, the yield of GVL increasing
gradually with Ni content and basic sites
Our research found that apart from the Cu-Ni
nanoparticles, the composition of the support also plays an
2
6, 27
.
a
Conditions: 0.5 mmol substrate, 50 mg Cu
mL, 150 C, 8 h, GC yield.
2
1
Ni /Zr
3
7
Al O
z
, solvent 3
important role for the activity of the catalysts. With ZrO
Al as the support, 90% and 83.2% yields of GVL can be
obtained (Table 1, entries 8 and 9). However, only 3% yield of
GVL was gained with Cu Ni1/TiO as the catalyst (Table 1, entry
0). Compared with Cu Ni /Zr Al , Cu Ni /Zr Al exhibited
2
and
o
2 3
O
The effect of reaction temperature and time were also
examined (Fig. S3). When the reaction was carried out at
130 C, 65% conversion of EL and 56% GVL yield was gained
(Fig. S2A). The conversion of EL and the yield of GVL increased
with increasing the temperature until the yield of GVL reached
its maximum (96.8%) at 150°C. When the reaction
2
2
1
2
1
3
7
O
z
2
1
7
O
3 z
o
relative lower catalytic performance (Table 1, entry 11). The
above results clearly revealed that the component of the
supports also play very important role for the hydrogenation
of EL. Moreover, the results demonstrated that the acid-base
property of the supports may affect the performances of the
concordant catalysts. More acid-base sites may facilitate the
alcohols’ dehydrogenation and form alkoxide on the surface of 29
catalysts, and then assist the unsaturation migration of H on
metal active sites 1 (Table 1, entries 6-11). The only by-
products detected in the product mixtures were those formed
through the transesterification of the levulinate ester with the
secondary alcohol solvent (e.g., isobutyl levulinate as the
o
temperature increased to 170 C, a slight decline of the yield of
GVL was observed. We speculate that other intermediates may
have been produced during the reaction at higher temperature
o
. Thus, the reaction temperature was maintained at 150 C in
the following reactions. Furthermore, we also investigated to
the impact of the reaction time for the reaction (Fig. S3B).
When the reaction time reached to 8 h, the yield of GVL was
96.8%.
The possible catalytic mechanism is proposed. Secondary
alcohol was first absorbed on the surface of the catalyst and
formed alkoxide species by dissociation its O-H bond. The
alkoxide species subsequently underwent β-hydride
elimination to form metal hydride species and release the side
product. The unsaturated C-O bond of EL was then
hydrogenated by the active metal hydride species to yield
ethyl 4-hydroxypentanoate, which finally underwent
intramolecular cyclization and formed GVL.
7
2
8
product) .
Table 1. Different catalysts for the CTH of EL to GVL a.
Entry
Catalysts
ZrO
Al
Zr Al
Conv. (%)
Yield (%)
b
1
2
3
2
5
21
21
99
50
25
99
90
85
5
4
18
14
96.8
36.5
13
80.3
90
83.2
3
79
44
69.1
b
b
2
O
3
3
7
O
z
4
Cu
Cu
2
Ni
Ni
1
/Zr
/Zr
3
Al
Al
7
O
O
z
z
5
6
7
8
9
1
1
3
7
We also screened the hydrogen sources of CTH of LA and
its esters. The primary alcohols as the hydrogen sources can
only provide lower yield of GVL (Table 2, entries 1 and 2),
Ni/Zr
Cu/Zr
Cu Ni
Ni
Ni
3
Al
Al
/ZrO
/Al
/TiO
7
O
z
3
7
O
z
30
2
1
2
which is consistant with the previous work . For secondary
alcohols, the reaction with 2-PrOH as hydrogen donor afforded
63.2% yield of GVL, whereas 2-BuOH provided 96.8% yield of
GVL (Table 2, entries 3 and 4). Besides, only 7.6% yield of GVL
was offered with tert-BuOH as the hydrogen donor (Table 2,
entry 5). In summary, the 2-Butanol was considered to be the
most suitable hydrogen source from the yield and activity
views.
Cu
Cu
2
1
2
O
3
1
1
0
1
2
1
2
Cu
Cu
Cu
2
2
2
Ni
Ni
Ni
1
1
1
/Zr
/Zr
/Zr
7
3
3
Al
Al
Al
3
O
O
O
z
z
z
82
47
71.8
c
1
2
7
7
d
1
3
a
o
Conditions: 0.5 mmol EL, 50 mg catalyst, 3 mL 2-BuOH, 150 C, 8 h,
b
c
d
GC yield; 24 h; 25 mg catalyst; 40 mg catalyst.
2 1 3 7 z
To evaluate the applicability of the Cu Ni /Zr Al O
The effect of amount of catalyst on the reaction efficiency
of the CTH was also explored by changing the dosage of
Cu Ni /Zr Al O from 25 to 50 mg while other conditions
2 1 3 7 z
catalyst, different levulinate esters were also employed as the
substrate for the fabrication of GVL. ML and BL were
converted to GVL successfully, offered 95.3% and 91.6% yields
4
| J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
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Ple Na es we dJ oo u nr no at l ao df jCu hs et mm i as tr rgy ins
Journal Name
of GVL in the same reaction conditions, respectively (Table 2, 3.
ARTICLE
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
4
4
4
4
4
5
5
5
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5
5
5
6
C. O. Tuck, E. Pérez, I. T. Horváth, R. A. ShVeieldwoAnrticalenOdnlMine.
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entries 6 and 7). The catalytic activity of Cu
surpassed the performance of most reported oxide catalysts
Table S3). However, when LA was selected as the reactant,
only 38% of GVL was gained (Table 2, entry 8). Overall, the
Cu Ni /Zr Al catalyst exhibited outstanding performance for
a series of levulinate esters to GVL in the CTH reaction.
The stability of Cu Ni /Zr Al was also examined and
the results were shown in Fig. S4. The fresh Cu Ni /Zr Al
provided 96.8% yield of GVL under the optimized conditions.
2 1 3 7 z
Ni /Zr Al O
4
.
1
06, 4044-4098.
(
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7 z
O
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
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2
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4
5
6
7
8
9
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1
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7 z
O
Then the used catalyst was separated by centrifugation, 9.
washed with water and ethanol, respectively. Finally, the
1
1
0.
1.
recovered catalyst was dried at 80°C for 12 h to the next cycle.
The yield of GVL decreased slightly after four cycles. After
being reused for four consecutive runs, the recovered
1
1
14.
15.
2.
3.
2 1 3 7 z 2
Cu Ni /Zr Al O to be calcined in the flow of H at 400°C for 4 h
exhibited GVL yield (92.4%) equivalent to the fresh catalyst
(
96.8%) 3 . Compared with the fresh Cu
1, 32
Ni /Zr Al O catalyst,
2 1 3 7 z
no obvious diffraction peak change can be observed for the
recycled catalyst (Fig. 3). The BET surface area of the reused
catalyst decreased slightly due to a slight agglomeration of the 16.
2
4
catalyst after five recycles (Table S1) .
1
7.
2
013, 3, 10277-10284.
Conclusions
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Cu-Ni bimetal supported on Zr-Al oxides was fabricated and
which exhibited superior catalytic activity for the
hydrogenation of levulinate esters into γ-valerolactone with 2-
BuOH as hydrogen source. These results proved that the
1
2
9.
0.
introducing of ZrO
2
in the Al O
2 3
support increased the effective 21.
acid and basic sites on the surface of the catalyst, which is
beneficial for the transformation reaction. This paper provides
a feasible approach to design efficient catalyst for the
hydrogenation of levulinate esters, and will inspire the
development of Zr-Al oxides-based heterogeneous catalysts.
2
2
2
2
2.
3.
4.
5.
Conflicts of interest
There are no conflicts to declare.
26.
27.
Acknowledgements
Financial supports from the National Natural Science
Foundation of China (31671930) the Natural Science
Foundation of Hebei Province (B2020204003, B2019204023,
1
0453.
2
8.
M. Chia and J. A. Dumesic, Chem Commun (Camb), 2011,
47, 12233-12235.
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I. G. Solorzano, Metall Mater Trans A, 2017, 48, 2643-
653.
Y. Kuwahara, W. Kaburagi and T. Fujitani, RSC Adv, 2014,
, 45848-45855.
J. He, H. Li, Y. M. Lu, Y. X. Liu, Z. B. Wu, D. Y. Hu and S.
Yang, Appl Catal A-Gen, 2016, 510, 11-19.
B2018204145, B2016204136, B2015204003) and the Natural 29.
Science Foundation of Hebei Agricultural University
2
(
ZD201613,
LG201709,
LG201711)
are
gratefully
3
0.
acknowledged.
4
31.
32.
Notes and references
T. Xing, H. Chen, H. Lei, W. Hao, S. Yong, X. Zeng, L. Lu and
S. Liu, Appl Catal B-Environ, 2014, 147, 827-834.
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This journal is © The Royal Society of Chemistry 20xx
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View Article Online
DOI: 10.1039/D0NJ02874F
Conversion of biomass-derived levulinate esters to γ-valerolactone
with robust CuNi bimetallic catalyst
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*
Jie Li†, Shuai Zhang†, Ning-Zhao Shang*, Shu-Tao Gao, Chun Wang , Zhi Wang
College of Science, Hebei Agricultural University, Baoding 071001, China
College of Science, Hebei Agricultural University, Baoding 071001, China
College of Science, Agricultural University of Hebei, Baoding 071001, China