Selective conversion of furfural into value-added chemical commodity in successive fixed-bed reactors

Article abstract of DOI:10.1016/j.catcom.2019.105836

Successive hydrogenation of furfural in two fixed-bed reactors connected in tandem with Cu/SiO₂ and Ni/SiO₂ as the catalysts was achieved under atmospheric pressure. Various targeting products including furfuryl alcohol (yield: 98.8%), 2-methylfuran (yield: 95.1%), 2-methyltetrahydrofuran (yield: 96.2%) and tetrahydrofurfuryl alcohol (yield: 78.2%) could be obtained by variation of the reactor configurations.

Full text of DOI:10.1016/j.catcom.2019.105836

Journal Pre-proof
Selective conversion of furfural into value-added chemical
commodity in successive fixed-bed reactors
Qianhe Liu, Qing Liu, Xun Hu
PII:
S1566-7367(18)30382-0
DOI:
https://doi.org/10.1016/j.catcom.2019.105836
CATCOM 105836
Reference:
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
22 September 2018
1 April 2019
26 September 2019
Please cite this article as: Q. Liu, Q. Liu and X. Hu, Selective conversion of furfural
into value-added chemical commodity in successive fixed-bed reactors, Catalysis
Communications (2019), https://doi.org/10.1016/j.catcom.2019.105836
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Selective Conversion of Furfural into Value-added Chemical
Commodity in Successive Fixed-bed Reactors
a
b
*a
Qianhe Liu , Qing Liu , Xun Hu
a
School of Material Science and Engineering, University of Jinan, Jinan, 250022, P. R.
China
b
Key Laboratory of Low Carbon Energy and Chemical Engineering, College of
Chemical and Environmental Engineering, Shandong University of Science and
Technology, Qingdao, 266590, P. R. China
*
Corresponding author: Tel./Fax. +86 89736201; Email: Xun.Hu@outlook.com
1

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Abstract
Successive hydrogenation of furfural in two fixed-bed reactors connected in tandem
with Cu/SiO and Ni/SiO as the catalysts was achieved under atmospheric pressure.
2
2
Various targeting products including furfuryl alcohol (yield: 98.8%), 2-methylfuran
(
(
yield: 95.1%), 2-methyltetrahydrofuran (yield: 96.2%) and tetrahydrofurfuryl alcohol
yield: 78.2%) could be obtained by variation of the reactor configurations.
Keywords: Hydrogenation, Furfural, 2-methylfuran, Furfuryl alcohol, Reactor
configuration.
2

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1
. Introduction
Currently, production of fine chemicals from biomass has attracted substantial
1
,2
attention. For example, the selective conversion of biomass-derived furfural has
3
become a research focus in recent years. Furfural can be produced by the dehydration
4
-6
of the xylan and pentosans formed from the hydrolysis of hemicellulose. Furfural is
a representative compound for the investigation of the selectivity for hydrogenation of
7
,8
C=C and C=O groups with varied formulation of catalysts or reactor configuration.
Typically, hydrotreatment of furfural involves the hydrogenation and hydrogenolysis
of the C=O group, the hydrogenation of the C=C group in the furan ring, the breaking
of C-C bonds and so on. Generally, the Cu-based catalyst could be used for the
hydrogenation of furfural to produce furfuryl alcohol (FOL) and 2-methylfuran
9
-13
(2-MeF) in a fixed-bed reactor at atmospheric pressure.
Ni-based catalyst,
especially Raney nickel, is used for the hydrogenation of FOL and 2-MeF to
tetrahydrofurfuryl alcohol (THFOL) and 2-methyltetrahydrofuran (2-MeTHF) in a
1
4-18
batch reactor at high H pressure.
The direct conversion of furfural to 2-MeTHF
2
via one-step was also realized under atmospheric pressure over two-stage-packed
1
9
Cu-Pd catalysts in a fixed-bed reactor. However, via such process the separation of
the 2-MeTHF from the water that is produced in the hydrogenation of furfural is
difficult, as water and 2-MeTHF are azeotropic (the moisture content in commercial
2
-MeTHF should be less than 300 ppm). On the other hand, the use of
palladium-based catalyst make the process costly. Moreover, there may be differences
in the lifetime for the two catalysts. In other words, when one kind of catalyst is
deactivated, another non-deactivated catalyst has to be replaced together. To solve
such issues, we designed a successive process for the conversion of furfural under
atmospheric pressure, in which two fixed-bed reactors were used in series. Various
3

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products such as FOL, 2-MeF, 2-MeTHF and THFOL could be obtained by variation
of the reactor configurations.
2
. Experimental
Cu(NO ) ·3H O (AR), Ni(NO ) ·6H O (AR), ammonia (AR) and urea (AR)
3
2
2
3 2
2
were purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd. SiO was
2
purchased from Qingdao Ocean Chemical Industry Co., Ltd. Furfural and other
chemicals were purchased from Sinopharm Chemical Reagent Co., Ltd.
The preparation method of Cu/SiO was detailed as follows: Firstly, an aqueous
2
solution of Cu(NO ) ·3H O (1.0 mol/L) was mixed with SiO support (Silica gel
3
2
2
2
type B). After that, under vigorous stirring, the mixed aqueous of urea (2.0 mol/L)
and ammonia (5.0 mol/L) was dropped into the above mixed suspension at 100ºC.
+
2+
The amount of NH4 was four times more than that of Cu . After 1 h, the slurry
was filtrated and washed with deionized water. After this, the precipitant was
dried in air at 120ºC for 6 h. Subsequently, the obtained precursor was calcined at
5
50ºC in air and the Cu/SiO catalyst was obtained. The preparation method of
2
Ni/SiO was similar to that of Cu/SiO . The difference was that the Cu(NO ) ·3H O
2
2
3 2
2
+
was replaced by Ni(NO ) ·6H O. The amount of NH was six times more than
3
2
2
4
2
+
that of Ni .
The hydrogenation of furfural was performed in two series fixed-bed reactor.
Before reaction, 10 % (v/v) H /N was introduced into the reactor to reduce the
2
2
catalysts. The reduction temperatures of the Cu/SiO and Ni/SiO catalysts (40~50
2
2
mesh) are 200 and 550ºC, respectively. After the reduction, furfural was continuously
pumped into a preheater, while H was also introduced into the preheater. Thereafter,
2
the vaporized furfural and H were mixed and introduced into reactors. The effects of
2
4

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internal and external diffusion have been excluded (Table S1 and S2). The final
products were condensed and trapped by N, N-dimethylformamide. The carbon
balance could be greater than 99%. Isopropanol acted as an internal standard in the
analysis of products. The products were analyzed by using a Shimadzu GC-2010 Plus
chromatography equipped with a Rtx-5 capillary column.
X-ray diffraction patterns (XRD) were recorded on a PANalytical X’Pert PRO
diffractometer using nickel-filtered Cu K α radiation. The bulk elemental analysis was
carried out on a Philips Magix601 X-ray fluorescence (XRF) analysis apparatus. The
N adsorption-desorption isotherms were measured at 77 K on a Pioneer SSA–6000
2
physical adsorption instrument. Before N adsorption, the samples were degassed in
2
vacuum at 300ºC for 2 h. Temperature-programmed-reduction (H -TPR) was
2
performed on a Vodo VDSorb–91x instrument. The catalyst (50 mg) was pretreated in
Ar flow (50 mL/min) at 550ºC for 1 h. After that, a flow of 5 vol.% H /Ar (20
2
mL/min) was used as the reducing agent, and the temperature was increased from 50
to 700ºC for Cu/SiO catalyst or 900ºC for Ni/SiO catalyst at 20ºC/min. Water
2
2
content in the products was measured on a Karl Fischer Moisture Titrator.
3
. Results and discussion
A water separator and a desiccator were used and located in between of the two
fixed-bed reactors (Figure 1). Cu/SiO catalyst was employed in the first reactor and
2
Ni/SiO catalyst was employed in the second reactor. Desiccant was anhydrous
2
calcium chloride. In this process, FOL, 2-MeF, THFOL and 2-MeTHF could be
produced selectively by manipulating the experimental variables. For the purpose of
production of 2-MeTHF, path 1 was preferred. The generated H O during the first step
2
5

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could be almost completely removed by the water separator and desiccator. For the
purpose to produce THFOL, path 2 was preferred because there was little water
generated in the first step of the reaction. Interestingly, the yield of 2-MeTHF
achieved 96.2% under an optimized conditions through path 1. Moreover, both
Cu/SiO and Ni/SiO catalysts showed the excellent stability. From the perspective of
2
2
industrialization, this process was also economical and could adjust target products,
according to the need from market, conveniently. Furthermore, we also performed a
detailed research of the Cu/SiO and Ni/SiO catalysts prepared by ammonia
2
2
evaporation method and the influence of reaction conditions on the conversion of
furfural.
The catalyst with good activity and stability was the key to achieve the high
efficiency transformation of furfural. In the hydrogenation reaction, furfural was
transformed into FOL on a Cu-based catalyst. FOL was subsequently converted into
2
-MeF on the Cu-based catalyst or into THFOL on a Ni-based catalyst via
hydrogenation. 2-MeF could also be hydrogenated into 2-MeTHF over the Ni-based
catalyst. In industry, Cu-Cr catalyst was usually used for the conversion of furfural
into FOL and 2-MeF. However, only about 100 gram products could be produced by 1
gram catalyst (Figure S3). The catalyst suffered from the quick deactivation because
of the polymerization of furfural, sintering of copper or poisoning of the active sites
by probably sulfur (about 40 ppm sulfur in furfural). Fortunately, the Cu/SiO catalyst
2
prepared by ammonia evaporation method had a large specific surface area and high
dispersion of copper (Figure S1, S2 and Table S3). It showed excellent activity and
stability in the hydrogenation of furfural into 2-MeF in the first fixed-bed reactor. The
yield of 2-MeF was always above 92% during the 150 h stability test, and 2-MeTHF
was the major by-product but with only 4% of yield (Figure 2). It could be estimated
6

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that at least 270 gram 2-MeF could be produced by 1 gram Cu/SiO catalyst.
2
Reaction conditions affected the distribution of the products (Table S4) and it could
be found that the yield of FOL was 98.8% at the low temperature and low WHSV (T
-1
=
140ºC, WHSV = 0.50 h ). The Cu/SiO catalyst was responsible for the
2
hydrogenation of the HC=O bonds at the low temperature and could break
deoxygenation) HC=O bands at high temperature. However, Cu/SiO catalyst was
(
2
hardly active for the hydrogenation of the -C=C bonds in the furan ring. For the
hydrogenation of C=C bonds, Pd-based and Ni-based catalysts exhibited good activity
2
0, 21
and selectivity.
However, the cost of using Pd-based catalyst was high and hence
Ni-based catalysts would be the better choice for the successive hydrogenation of
2
-MeF or FOL in the second fixed-bed reactor.
The Ni/SiO catalyst prepared by ammonia evaporation method also had large
2
specific surface area, which helps to achieve the high dispersion of Ni (Figure S1, S2
and Table S3). It showed good activity and selectivity for the hydrogenation of C=C
bonds (Table 1). The yield of 2-MeTHF was high (ca. 96.2%) through path 1. The
water had a significant influence on the activity of the catalyst and the distribution of
the product (Table S5). If the final target product was 2-MeTHF, the intermediate
product in the first fixed-bed reactor should be 2-MeF. Accordingly, the production of
1
mole H O was accompanied by the production of 1 mole 2-MeF. The water would
2
reduce the activity of the Ni/SiO catalyst and cause the generation of 2-pentanol and
2
2
2
1
, 4-pentanediol. The solubility of 2-MeF in water was about 0.3 wt% at 25ºC.
Therefore, 2-MeF and water could be easily separated into two phases (the upper
phase was 2-MeF). In the water separator, 2-MeF could be brought into a desiccator
(
filled with anhydrous calcium chloride) by excess H and then brought into the
2
second fixed-bed reactor The water content in 2-MeF could be lower than 0.5 wt%
.
7

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after this treatment. It was known that the solubility of 2-MeTHF in water was about
2
3
1
5 wt% at 25ºC, and 2-MeTHF and water are azeotropic. Therefore, nearly no water
was introduced into the second reactor, which would make the subsequent purification
of 2-MeTHF easier. Thus, the water content of less than 300 ppm in purified
2
-MeTHF could be achieved at a low cost. If the final target product was THFOL, the
intermediate product in the first fixed-bed reactor should be FOL. There was no much
water in this process and the path 2 could be used. However, a small amount of water
still led to the generation of 1, 4-Pentanediol.
From the view of industrial application, the stability was one of the most important
factors determining applications of the catalysts. Figure 3 and 4 showed that both
Cu/SiO and Ni/SiO catalysts had good stability for the production of 2-MeTHF and
2
2
THFOL. There might be some difference in the lifetime between the Cu/SiO and the
2
Ni/SiO catalyst in industrial operations. The Cu/SiO catalyst, which was relatively
2
2
inexpensive in the first fixed-bed reactor, could absorb sulfur to avoid the deactivation
of Ni/SiO catalyst in the second fixed-bed reactor. Therefore, only the Cu/SiO
2
2
catalyst was needed to be replaced if the Ni/SiO still maintained the activity.
2
4
. Conclusions
In summary, a highly efficient process for the catalytic conversion of furfural was
developed by means of two fixed-bed reactors connected in series with Cu/SiO and
2
Ni/SiO as catalysts, respectively. This strategy provided a successive hydrogenation
2
of furfural to produce 2-MeTHF and THFOL with a high yield. Notably, the yield of
2
-MeTHF and THFOL achieved were up to 96.2% and 78.2%, respectively. More
importantly, both Cu/SiO and Ni/SiO catalysts exhibited excellent stability. In
2
2
addition, the water separator between the first and the second reactor reduced the
8

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difficulty for the separation of 2-MeTHF. This strategy could also be applied to other
cascade reactions.
Acknowledgement
This work was supported by the National Natural Science Foundation of China (No.
5
1876080), the Strategic International Scientific and Technological Innovation
Cooperation Special Funds of National Key R&D Program of China (No.
016YFE0204000), the Program for Taishan Scholars of Shandong Province
2
Government, the Recruitment Program of Global Young Experts (Thousand Youth
Talents Plan), the Natural Science Fund of Shandong Province (ZR2017BB002) and
the Key R&D Program of Shandong Province (2018GSF116014). This work was also
supported by the Doctoral Fund of University of Jinan (160100340).
References
1
A. J. Ragauskas, C. K. Williams, B. H. Davison, G. Britovsek, J. Cairney, C. A.
Eckert, W. J. Frederick, Jr., J. P. Hallett, D. J. Leak, C. L. Liotta, J. R. Mielenz,
R. Murphy, R. Templer, T. Tschaplinski, The Path Forward for Biofuels and
Biomaterials, Science 311(2006) 484-489.
2
3
C. Zhang, X. Hu, H. Guo, T. Wei, D. Dong, G. Hu, S. Hu, J. Xiang, Q. Liu, Y.
Wang, Pyrolysis of poplar, cellulose and lignin: Effects of acidity and alkalinity
of the metal oxide catalysts, J. Anal. Appl. Pyrol., 134 (2018) 590-605.
L. Zhang, G. Hu, S. Hu, J. Xiang, X. Hu, Y. Wang, D. Geng, Hydrogenation of
fourteen biomass-derived phenolics in water and in methanol: their distinct
reaction behaviours, Sustainable Energy & Fuels, 2 (2018) 751-758.
9

Journal Pre-proof
4
5
S. Dutta, S. De, B. Saha, M. I. Alam, Advances in conversion of hemicellulosic
biomass to furfural and upgrading to biofuels, Catal. Sci.Technol, 2(2012)
2
025-2036.
C. Garcia-Sancho, I. Agirrezabal-Telleria, M. B. Guemez, P. Maireles-Torres,
Dehydration of D-xylose to furfural using different supported niobia catalysts,
Appl. Catal. B: Environ. 152(2014) 1-10.
6
7
J. P. Lange, E. van der Heide, J. van Buijtenen, R. Price, Furfural, a promising
platform for lignocellulosic biofuels, ChemSusChem 5( 2013) 150-166.
G. W. Huber, S. Iborra and A. Corma, Synthesis of transportation fuels from
biomass:ꢀchemistry, catalysts, and engineering, Chem. Rev. 106(2006)
4
044-4098.
8
X. Hu, R.J.M. Westerhof, L.P. Wu, D.H. Dong, C.Z. Li*, Upgrading
biomass-derived furans via acid-catalysis/hydrogenation: the remarkable
difference between water and methanol as the solvent, Green Chem., 17(2015)
2
19-224.
9
1
1
Y. Nakagawa, K. Takada, M. Tamura and K. Tomishige, Total Hydrogenation
of Furfural and 5-Hydroxymethylfurfural over Supported Pd–Ir Alloy Catalyst,
ACS Catal. 4(2014) 2718-2726.
0 S.Y. Hwang, E.Yurchekfrodl, C. L. Zhang, Z. M. Peng, Low‐ Temperature
Preferential Oxidation of Carbon Monoxide on Pt Ni Alloy Nanoparticle
3
Catalyst with Engineered Surface, CHEMCATCHEM 8(2016) 97-101.
1 J. Cui, J. Tan, X. Cui, Y. Zhu, T. Deng, G. Ding, Y. Li, Conversion of Xylose
to Furfuryl Alcohol and 2‐ Methylfuran in a Continuous Fixed‐ Bed Reactor,
ChemSusChem 9(2016) 1259-1262.
1
0

Journal Pre-proof
1
1
1
2 G. S. Hutchings, W. Luc, Q. Lu, Y. Zhou, D. G. Vlachos, F. Jiao, Nanoporous
Cu–Al–Co Alloys for Selective Furfural Hydrodeoxygenation to 2-Methylfuran,
Ind. Eng. Chem. Res. 56(2017) 3866-3872.
3 X.H. Yang, X. M. Xiang, H. M. Chen, H.Y. Zheng, Y. W. Li, Y. L. Zhu,
Efficient Synthesis of Furfuryl Alcohol and 2-Methylfuran from Furfural over
Mineral-Derived Cu/ZnO Catalysts, ChemCatChem 9(2017) 3023-3030.
4 C. P. Jimenez-gomez, J. A. Cecilia, R. Moreno-Tost, P. Maireles-Torres,
Selective Production of 2‐ Methylfuran by Gas‐ Phase Hydrogenation of
Furfural on Copper Incorporated by Complexation in Mesoporous Silica
Catalysts, ChemSusChem 10(2017) 1448-1459.
1
1
1
1
5 F. Dong, G. Ding, H. Zheng, X. Xiang, L. Chen, Y. Zhu, Y. Li, Highly
dispersed Cu nanoparticles as an efficient catalyst for the synthesis of the
biofuel 2-methylfuran, Catal. Sci. Technol. 6(2016) 767-779.
6 J. Wu, G. Gao, J. Li, P. Sun, X. Long, F. Li, Efficient and versatile CuNi alloy
nanocatalysts for the highly selective hydrogenation of furfural, Appl. Catal. B.
2
03(2017) 227-236.
7 S. Sitthisa, W. An, D. E. Resasco, Selective conversion of furfural to
methylfuran over silica-supported NiFe bimetallic catalysts, J. Catal. 284(2011)
9
0-101.
8 R. J. Huang, Q. Q. Cui, Q. Q. Yuan, H. H. Wu, Y. J. Guan, P. Wu, Total
Hydrogenation of Furfural over Pd/Al O and Ru/ZrO Mixture under Mild
2
3
2
Conditions: Essential Role of Tetrahydrofurfural as an Intermediate and
Support Effec, ACS Sustainable Chem. Eng. 6(2018) 6957-6964.
11

Journal Pre-proof
1
9 F. Dong, Y. Zhu, G. Ding, J. Cui, X. Li, Y. L, One‐ step Conversion of
Furfural into 2‐ Methyltetrahydrofuran under Mild Conditions, ChemSusChem
8
(2015) 1534-1537.
2
2
0 W. Zhang, Y. Zhu, S. Niu, Y. Li, A study of furfural decarbonylation on
K-doped Pd/Al O catalysts, J. Mol. Catal. A 335(2011) 71-81.
2
3
1 Y. Nakagawa, K. Tomishige, Total hydrogenation of furan derivatives over
silica-supported Ni–Pd alloy catalyst, Catal. Commun. 12(2010) 154-156.
2 http://www.aladdin-e.com/zh_cn/m110932.html
2
2
3 http://www.aladdin-e.com/zh_cn/m106688.html
1
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Artwork
Table 1: The hydrogenation of furfural over the Cu/SiO and Ni/SiO catalyst in two
2
2
series fixed-bed reactors.
Figure 1: The diagram of two fixed-bed reactors in series for the conversion of
furfural.
Figure 2: The hydrogenation of furfural in the first fixed-bed reactor with the Cu/SiO2
catalyst.
Figure 3: The hydrogenation of furfural to produce 2-MeTHF.
Figure 4: The hydrogenation of furfural to produce THFOL.
1
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Table 1 The hydrogenation of furfural over the Cu/SiO
2
and Ni/SiO
2
catalyst in two series fixed-bed reactors.
Yield [%]
a
Reaction Conditions
Conv. [%]
Furfural
99.9
b
c
Entry
Path
T
1
[ºC]
T
2
[ºC]
H
2
/Furfuralmol
2-MeF
20
2-MeTHF
79.3
FOL
0
THFOL
2-Pentanol
1,4-Pentanediol
1
2
3
4
5
6
7
8
9
Path 1
Path 1
Path 1
Path 1
Path 1
Path 1
Path 1
Path 1
Path 2
Path 2
200
200
200
200
200
190
180
170
160
160
100
10
10
10
10
10
10
10
10
10
10
0
0
0.6
3.5
2.7
3
0
0
110
120
130
140
120
120
120
120
130
99.9
6.7
0.9
0.6
0.4
0.9
0.9
0.8
1
89.4
0
99.9
96.2
0
0
0
99.9
96.1
0
0
0
99.9
95.3
0
0
4.4
2.4
2.8
4.3
2.9
3
0
99.9
95.9
0
0
0
99.9
95.6
0
0
0
99.9
94.9
0
0
0
99.9
13.1
9.1
0
70
78.2
3.8
4.1
10
99.9
0.9
13.7
a
b
c
Reaction conditions: atmospheric pressure; the mass of catalyst is 2 g, the flow rate of furfural is 4.6 g/h.
the reaction temperature in the second fixed-bed reactor.
T
1
was the reaction temperature in the first fixed-bed reactor.
T
2
was
1
4

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Figure 1 The diagram of two fixed-bed reactors in series for the conversion of furfural.
1
5

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Figure 2 The hydrogenation of furfural in the first fixed-bed reactor with the Cu/SiO catalyst.
2
Reaction conditions: T = 200ºC, P = 1 atm, the mass of catalyst is 2 g, the flow rate of furfural is
4.6 g/h.
1
6

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Figure 3 The hydrogenation of furfural to produce 2-MeTHF.
Reaction conditons:,T = 200ºC, T = 200ºC, P = 1 atm, H /Furfural = 10:1, the mass of catalyst
1
2
2
mol
is 2 g, the flow rate of furfural is 4.6 g/h.
1
7

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Figure 4 The hydrogenation of furfural to produce THFOL.
Reaction conditons: T = 160ºC, T = 130ºC, P = 1 atm, H /Furfural = 10:1, the mass of catalyst
1
2
2
mol
is 2 g, the flow rate of furfural is 4.6 g/h.
1
8

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Highlights



A successive hydrogenation of furfural in two fixed-bed reactors was realized.
Cu/SiO and Ni/SiO showed well activity and stability.
Various products could be obtained by variation of the reaction strategy.
2
2
1
9

Figure 1

Figure 2

Figure 3

Figure 4