Selective conversion of furfural to cyclopentanol over cobalt catalysts in one step

Article abstract of DOI:10.1016/j.cclet.2017.03.017

A series of cobalt catalysts with different supports were prepared for the selective conversion of biomass-derived furfural to cyclopentanol (CPL) in one step. The best CPL yield was 82?mol% at 160?°C, 2?MPa H₂, 4?h when cobalt was supported on ZrO₂-La₂O₃. The supports were characterized by X-ray diffraction (XRD) and temperature-programmed desorption of ammonia (NH₃-TPD). The XRD results indicated that the more stable t-ZrO₂ formed by doping La₂O₃. The amount of acid sites of the catalyst increased, too. The influences of parameters such as reaction temperature, hydrogen pressure, and reaction time on the catalytic activity were also investigated. The polymer formed during the reaction may cause the deactivation of the Co/ZrO₂-La₂O₃ catalyst. This work provides a possibility to prepare the stable t-ZrO₂ and apply with cobalt metal for biomass valorization.

Full text of DOI:10.1016/j.cclet.2017.03.017

Accepted Manuscript
Title: Selective conversion of furfural to cyclopentanol over
cobalt catalysts in one step
Authors: Yan-Fu Ma, Hao Wang, Guang-Yue Xu, Xiao-Hao
Liu, Ying Zhang, Yao Fu
PII:
S1001-8417(17)30094-3
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.cclet.2017.03.017
CCLET 4012
To appear in:
Chinese Chemical Letters
Received date:
Revised date:
Accepted date:
13-1-2017
22-2-2017
9-3-2017
Please cite this article as: Yan-Fu Ma, Hao Wang, Guang-Yue Xu, Xiao-Hao Liu, Ying
Zhang, Yao Fu, Selective conversion of furfural to cyclopentanol over cobalt catalysts
in one step, Chinese Chemical Lettershttp://dx.doi.org/10.1016/j.cclet.2017.03.017
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Original article
Selective conversion of furfural to cyclopentanol over cobalt catalysts in one step

Yan-Fu Ma, Hao Wang, Guang-Yue Xu, Xiao-Hao Liu, Ying Zhang , Yao Fu
iChEM, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory for Biomass Clean Energy and
Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
ARTICLE INFO Article history:
Received 16 January 2017
Received in revised form 22 February 2017
Accepted 2 March 2017
Available online

Corresponding author.
E-mail address: zhzhying@ustc.edu.cn
Graphical abstract
A series of cobalt catalysts with different supports were prepared for the selective conversion of biomass-derived furfural to
cyclopentanol in one step. The best CPL yield was 82 mol% at 160 °C, 2 MPa H
zirconia that can be obtained by doping La
2
, 4 h when cobalt was supported on tetragonal
2
3
O .
ABSTRACT A series of cobalt catalysts with different supports were prepared for the selective conversion of biomass-derived furfural to
cyclopentanol (CPL) in one step. The best CPL yield was 82 mol% at 160 °C, 2 MPa H , 4 h when cobalt was supported on ZrO -La . The
supports were characterized by X-ray diffraction (XRD) and temperature-programmed desorption of ammonia (NH -TPD). The XRD results
indicated that the more stable t-ZrO formed by doping La . The amount of acid sites of the catalyst increased, too. The influences of parameters
such as reaction temperature, hydrogen pressure, and reaction time on the catalytic activity were also investigated. The polymer formed during the
2
2
2 3
O
3
2
2 3
O
reaction may cause the deactivation of the Co/ZrO
metal for biomass valorization.
2 2 3 2
-La O catalyst. This work provides a possibility to prepare the stable t-ZrO and apply with cobalt
—
——

Keywords:
Furfural
Cobalt
Cyclopentanol
Hydrogenation
Tetragonal Zirconia
1
.
Introduction
Biomass is the most attractive alternative feedstock of fossil resource to produce fuels and bulk chemicals since it is a widely
available carbon source [1]. Furfural is an important biomass platform chemical that can be produced by acid-catalyzed dehydration
from pentose [2-6]. In addition, it can also be prepared from hexose via isomerization step to form a ketose prior to the retro-aldol
reactions [7-9]. Basically, furfural can be converted into many useful chemicals such as furan, furfuryl alcohol (FAL),
tetrahydrofurfuryl alcohol (THFAL), 2-methylfuran, pentanediol, levulinic acid, etc. [11]. As a new route, furfural could be
transformed into cyclopentanol (CPL) which is used for the production of fragrance chemicals and pharmaceuticals. Traditionally, CPL
was obtained from an extra hydrogenation process of cyclopentanone (CPO) which was prepared by the pyrolysis of adipic acid or its
derivatives and the oxidation of cyclopentene [12-14]. Therefore, the direct synthesis of CPL form biomass-derived furfural by
rearrangement is meaningful, which could reduce the social dependence on fossil resource. However, there were only a few related
researches. The possible reason is that it is hard to fulfill the hydrogenation of CPO to CPL without the saturation of furan ring to side-
product THFAL.
As another rearrangement product, CPO has been studied widely. In 2012, Hronec et al. proposed the method to produce CPO
from lignocellulose-derived furfural in the presence of metal catalysts and water [15]. The best yield of CPO was 76.5 mol% over 5%
Pt/C catalyst and water was an essential part in the ring rearrangement. Then, they found the support had an influence on the product
distribution [16]. A 44.7% CPO yield was obtained over the 1% Pt/Al
at 160 °C, 8 MPa H , 30 min. Other noble metal catalysts such as Ru/MIL-101 [17], Pd-Cu
20] were also reported and the CPO yield was more than 91%. Considering the high price and low reserves of noble metals, many
2
O
3
while the main product was furfuryl alcohol over 1% Pt/MgO
2
2
O/C [18], Au/TiO -A [19] and Ru/CNTs
2
[
non-noble metals had also been investigated, especially Cu and Ni. NiCu-50/SBA-15 [21], Cu-Ni-Al [22] and CuNi@C [23] were
synthesized and exhibited good catalytic activity for the conversion of furfural into CPO. Our group developed CuZnAl catalyst for the
conversion of furfural to CPO and achieved a 62% of CPO yield at 150 °C and 4 MPa H [24]. Among these catalysts, CPO is the main
2
rearrangement product instead of CPL, which means an additional hydrogenation process is necessary.
The reaction mechanism was proposed by Hronec et al. and shown in Scheme 1 [16,25]. After the hydrogenation of furfuryl,
furfuryl alcohol was obtained and converted by different pathways: rearrangement, polymerization and over-hydrogenation, which
were competitive reactions. Through the rearrangement pathway, furfuryl alcohol was protonated by hydrogen ions and cationic
intermediate was formed. Subsequently, it opened the ring by interacting with water, the furan ring was rearranged to 4-hydroxy-2-
cycloentenone (4-HCP). It is an unstable intermediate and can be found in the spontaneous hydrolysis of furfuryl alcohol under N
2
atmosphere without any catalyst [16]. Thus 4-HCP was hardly detected in the reaction system. Then 4-HCP was dehydrated to 2-
cyclopentenone on Lewis acid sates. These two intermediates are high reactivity and the conversion was fast in the catalytic system
[
17]. 2-cyclopentenone underwent further hydrogenation to CPO and CPL. Polymerization and over-hydrogenation should be avoided.
Therefore, the catalytic metals should be able to hydrogenate furfural and 2-cyclopentenone but not saturate the furan ring to THFAL.
The weak Lewis acid support can contribute to dehydration [26].
It is a challenge to catalyze furfural into CPL directly. Therefore, it will be significant to develop new catalytic systems, especially
catalysts with high activity to fulfill the conversion of CPL in one step without THFAL. Xiao’s group reported the CPL was obtained
as the main product over some non-noble metal catalysts. The yield of CPL was 83.6% at 140 °C, 5 MPa H
High loading of Ni was required to obtain CPL. CuMgAl [28] and CuZnAl [29] were highly active and the yield of CPL was 93.4% at
40 °C, 4 MPa H , 10 h and 84% at 150 °C, 4 MPa H , 10 h, respectively. Except for the high H pressure and long reaction time, these
catalysts agglomerated during the recycling. Li et al. used Cu-Co catalysts to convert furfural into CPL under mild H pressure and
, methanol can also be used as
2
over 30% Ni/CNTs [27].
1
2
2
2
2
short reaction time (2 MPa H
hydrogen donor [31].
2 2
, 1 h). The CPL yield was 67 mol% at 170 °C [30]. Besides molecular H
According to previous reported [32,33], Co is a promising hydrogenation metal. In this study, we prepared several supported
cobalt catalysts for the selective conversion of furfural to CPL in one step under mild conditions. The supports were the typical weak
Lewis acid materials. Except for TiO
ray diffraction (XRD) and temperature-programmed desorption of ammonia (NH
including reaction temperature, hydrogen pressure and reaction time on the catalytic activity were also investigated. The deactivation
of the Co/ZrO -La catalyst was also studied.
2
and Al
2
O
3
, we also studied ZrO
2
2 3
and changed its phase by doping La O and characterized by X-
3
-TPD). The influences of various reaction conditions
2
2 3
O
2
. Results and discussion
.1. Effect of different supports on the hydrogenation of furfural
2

Based on the previous reports [15], the rearrangement of furfuryl alcohol to form CPL or CPO occurred only in aqueous-phase.
Thus, water was employed as the solvent in the following reactions. Table 1 showed the results of furfural conversion in water by using
different cobalt catalysts. The supports include Al O , TiO , ZrO and ZrO -La O . After the reaction, the main products were CPL,
2 3 2 2 2 2 3
CPO and THFAL. CPL and CPO were the rearrangement products. THFAL came from over-hydrogenation of furfuryl alcohol.
Furfural and furfuryl alcohol could be converted to oligomeric and polymeric compounds by heat [34,35] or acid sites [36] when they
were accumulated in the reaction system. The loss of carbon was related to polymerization. As showed in Table 1, furfural could be
converted to polymer with a 24% carbon loss. The polymerization product was hardly detected, so we count the loss of carbon as its
ratio. When Co/Al
acid support, which was consistent with the previous reports [15,37,38]. It indicated that rearrangement reaction was hindered by the
polymerization and over-hydrogenation. As for Co/TiO , because the cobalt particles were encapsulated in the TiO in the effect of
SMSI [39], the polymer formed by heat could block the some caves resulting in the partial loss of hydrogenation activity. Hence, the
yield of CPO was higher than CPL. When Co was supported on ZrO , the polymerization reduced and the main product of CPL
2 3
O was used as catalyst, the by-product THFAL was 17 mol%. Most of furfuryl alcohol was polymerized on the
2
2
2
increased to 49 mol%. Changing the temperature to 160 °C, the yield of THFAL reduced to 2 mol%, which showed high temperature
contributed to the rearrangement by increasing the concentration of hydrogen ions which was related to temperature. The catalytic
activity increased and product distribution tended to be CPL. Therefore, the furfuryl alcohol underwent the rearrangement reaction
instead of over-hydrogenation and polymerization. After doping La
into CPL. The 82 mol% yield of CPL was obtained at 160 °C, 2 MPa, 4 h over Co/ZrO
2
O
3
, the catalytic activity raised and CPO was further hydrogenation
-La
2
2 3
O .
The reason of high catalytic activity with the addition of La
characterized by XRD patterns to study the crystal morphology. As showed in Fig. 1, the diffraction peaks of ZrO
two different phases: the diffraction peaks at 24.3°, 28.1°, 31.3°, 34.6°, 41.2° and 50.1° were monoclinic zirconia (m-ZrO
0.3°, 35.2°, 50.6°, 60.0° and 62.23° were tetragonal zirconia (t-ZrO ). The mixture phases were existed in ZrO . However, after
adding some La, the diffraction peaks of m-ZrO were disappeared. Only the diffraction peaks of t-ZrO were observed without La
species appeared. The shift of diffraction peaks in ZrO -La to lower angle suggested that La had been doped into ZrO lattice and
increased the interplanar spacing. Thus, t-ZrO can be obtained from the mixture phase of t-ZrO and m-ZrO by doping La , which
may be the main reason for the good performance. After impregnation and calcination, Co/ZrO -La was synthesized and the t-ZrO
phase did not change compared with ZrO -La . There was not the diffraction peak contributed by metallic Co, which demonstrated
that Co species were highly dispersed on the surface of supports. Then, Co/ZrO -La was investigated at different conditions.
2
O
3
was studied by XRD and NH
3
-TPD. All Zr-based supports were
could be indexed to
) while
2
2
3
2
2
2
2
2
2
O
3
2
2
2
2
2 3
O
2
2
O
3
2
2
2 3
O
2
2 3
O
The acidic properties of the synthesized supports were investigated by NH
can be classified as weak acid sites (<200 °C), medium acid sites (200-400 °C) and strong acid sites (>400 °C) depending on NH
desorption temperatures [40]. The sample showed a desorption peak at about 120 °C, which meant the existence of weak acid sites. It
was obvious that the peaks increased after doping of La . This could be explained that the amount of acid sites in t-ZrO was more
than that in m-ZrO , which was consistent with previous reports [41]. This phenomenon indicated the dispersion of La species in ZrO
lattice was important for the increase of the acidity which may contributed to the conversion of furfural to CPL
3
-TPD. The results were shown in Fig. 2. The acid sites
3
2
O
3
2
2
2
2
.2. Effect of reaction conditions on the conversion of furfural to CPL
The yields of furfural at different temperature catalyzed by Co/ZrO
CPL could be recognized. The results showed that temperature had an influence on the product distribution during the hydrogenation
2
2 3
-La O were illustrated in Fig 3a. The volcanic type curve of
process. In the investigated temperature range, the yield of CPL reached the maximum at 160 °C. Some CPO and furfural alcohol were
remained at 150 °C. Lower temperature limited both the hydrogenation activity of the catalyst and the dissociation constant of water
[
42]. When the temperature was at 170 °C or higher, the polymerization was dominant. Based on the previous studies, furfuryl alcohol
could polymerize [43]. It occurred at α-position and β-position of furan ring in the reaction system [36]. The polymer could attach on
the surface of the catalyst and impair the activity. Therefore, 160 °C was optimal temperature for the rearrangement and hydrogenation.
This moderate temperature not only produced enough hydrogen ions but also minimized the polymerization of furfural and furfuryl
alcohol by heat.
The hydrogen pressure was one of the important factors affecting the final products. The initial hydrogen pressure was studied for
the hydrogenation of furfural by Co/ZrO -La O . Fig. 3b showed the results of furfural hydrogenation carried out on different hydrogen
2 2 3
pressure. When the initial pressure was 1 MPa, the main product was CPO. When the initial pressure raised to 2 MPa, CPO was
hydrogenated to CPL. The yield of CPL improved obviously when the initial pressure raised from 1 MPa to 2 MPa, which was similar
to the Ni/CNTs [27]. Thus, the low pressure was suitable for producing CPO while the high pressure can increase the selectivity to
CPL. A further increase in hydrogen pressure showed no improvement in selectivity, but a slight slip for CPL. A part of furfuryl
alcohol was over-hydrogenated and 6 mol% THFAL was obtained when the pressure was up to 4 MPa. Therefore, the higher pressure
could lead to a high selectivity to THFAL, which was the product of over-hydrogenation of furfuryl alcohol during the competing
reaction with rearrangement. Therefore, 2 MPa was the optimal pressure for the high selectivity for CPL.

The kinetics curves could reflect the reaction pathway clearly. The Fig. 3c exhibited the product distribution for the conversion of
furfural at different reaction time. The zero time was the moment that the reaction temperature reached 160 °C. Firstly, furfural was
fast hydrogenated into furfuryl alcohol and then CPO began to accumulation by rearrangement. With the extension of time, CPL was
obtained by the hydrogenation of CPO. The carbon balance was decreased significantly at the beginning since furfuryl alcohol
polymerized partly to the compounds having conjugated diene structures with 5 to 30 furanic moieties [44]. It increased a little owing
to the decomposition reaction according to the former report [45]. When the polymer formed, it would deposit on the surface of the
catalyst, which could block the active sites for hydrogenation and decrease the catalytic activity [46].
2
.3. The study of deactivation
2 2 3
A series of experiments were designed over Co/ZrO -La O to study the deactivation in Table 2. When the reaction was preform
at 80 °C for 2 h, the conversion was 95% without carbon loss. There wasn’t polymer. The products were furfuryl alcohol and THFAL.
The rearrangement didn’t occur duo to lower concentration of hydrogen ions. After the recycle, the catalyst activity didn’t change.
Then, when the reaction was carried out at 160 °C, reaction time was set at 1 h to show the difference obviously. The conversion was
1
00% and the main product was CPL with a 42 mol% yield. There was 24% carbon loss which was caused by polymerization.
However, after the reuse of catalysts, the main product was CPO without further hydrogenation and the conversion reduced to 92%.
When CPO was the substrate, the conversion was 65% without polymerization under the same conditions. The catalytic activity was
almost unchanged after the recycle, indicating the structure of the catalyst was intact. Therefore, the polymer could be the reason for
the decrease the catalytic activity and the inhibition of the polymer formation should improve over the supported Co catalysts
3
. Conclusion
In summary, cobalt catalysts loading on different supports were synthesized and applied in the hydrogenation of furfural into CPL
in one step. Among the different supports, t-ZrO obtained by doping La was high-efficient for the conversion of furfural into CPL
after loading cobalt metal. Under the optimized conditions (160 °C, 2 MPa H pressure and 4 h), the yield of CPL could reach up to 82
mol%. The change of phase in ZrO was proved by XRD and the increase of acidity was demonstrate by NH -TPD that could improve
the catalytic activity. Further studies to control the polymer formation during the reaction are currently undergoing.
2
2 3
O
2
2
3
4
. Experiment
4
.1. Chemicals materials
Furfural was purified by vacuum distillation and stored at -15°C. Furfuryl alcohol was not purified. Furfural (AR, >99%) Furfuryl
alcohol (AR, >99%), tetrahydrofurfuryl alcohol (AR, >97%), cyclopentanone (AR, >97%), cyclopentanol (AR, >97%),
Co(NO ·6H O (AR, >99%), La(NO ·6H O (AR, >44%), ZrOCl ·8H O (AR, >99%), (NH Ce(NO (AR, >99%) and CTAB (AR,
99%) were from Sinopharm Chemical Reagent Co., Ltd. Al was purchased from Aladdin Chemical Reagent Co., Ltd. TiO was
purchased from Sigma-Aldrich Chemical Reagent Co., Ltd.
3
)
2
2
3
)
3
2
2
2
4
)
2
3 6
)
>
2
O
3
2
4
.2. Catalyst preparation
ZrO was synthesized by co-precipitation/hydrothermal crystallization with a modification. Typically, a certain amount of
hexadecyltrimethylammonium bromide (CTAB) was dissolved in deionized water at 60 °C with agitation. Zirconium oxychloride
solution was added to give a clear homogeneous solution. The mixed solution contains Zr, CTAB and H O with molar ratio of
:0.5:100, respectively. After 0.5 h, 1 mol/L sodium hydroxide solution was prepared and added dropwise under vigorous stirring to a
2
2
1
constant pH of 9. Then, the mixture was aged at 90 °C for 10 h and followed by filtration and washing with deionized water and
ethanol. Finally, the precipitate was dried at 105 °C overnight and then calcined in air at 550 °C for 4 h.
ZrO
The mixed solution contains Zr, La, CTAB and H
as that for preparing ZrO
The Co based catalysts were prepared by impregnation method. Al
the impurities. The support (0.5 g) was dispersed in acetone (45 mg) with stirring at 45 °C. Cobalt nitrate (0.246 mg) was dissolved in
ml acetone and then added drop by drop to the above solution. After stirring for 24 h, acetone was removed by rotary evaporation.
The catalyst was dried at 105 °C overnight and calcined at 300 °C for 2 h to remove the nitrates with a heating rate of 1 °C/min.
Finally, the catalyst was calcined at 600 °C for 2 h at a rate of 1 °C/min again. The calcined catalysts were reduced in a H atmosphere
2
-La
2
O
3
was synthesized by adding zirconium oxychloride solution and lanthanum solution to the clear homogeneous solution.
2
O with a molar ratio of 1:0.2:0.5:100, respectively. After that, the process was same
2
.
2
3 2
O and TiO were calcined in air at 750 °C for 4 h to remove
5
2
at 600 °C for 2 h with a heating rate of 1 °C/min before reaction. All the loadings were 8.8 wt% for the Co based catalysts according to
ICP-AES.
Catalytic hydrogenation of furfural was carried out in a 25 ml stainless steel autoclave equipped with a magnetic stirrer. Typically,
a mixture of furfural (1 mmol), catalyst (50 mg) and water (10 ml) were put into the reactor and purged with H
reactor was pressured with H to 2 MPa. Then the autoclave was heated to the desired temperature for 4 h. After reaction, the reactor
was cooled to ambient temperature. The liquid products were extracted by ethyl acetate and then analyzed by a gas chromatograph
GC, Kexiao 1690) with a HP-INNOMAX capillary column (30 m×0.25 mm×0.25 μm) and GC-MS (Agilent 7890A). The GC
2
for several times. The
2
(

detecting conditions were as follows: nitrogen was the carrier gas; injection port temperature was 280 °C; detector (FID) temperature
was 280 °C. Column temperature heated from 40 °C to 250 °C with a heating rate of 10 °C/min. The n-hexanol was used as internal
standard to quantify the products.
4
.3. Characterization methods
X-ray diffraction (XRD) was conducted on an X-ray diffractometer (TTR-III, Rigaku Corp, Japan) using Cu Kα radiation (λ=
.54056 Å). The data were recorded over 2θ ranges of 20-70°.
1
Temperature-programmed desorption was carried out in a home-built reactor system coupled to a gas chromatograph. All the gas
flow was set to 40 mL/min. Temperature-programmed desorption of ammonia (NH
of the catalysts. Prior to absorption of ammonia, 80 mg catalyst sample was heated at 500 °C for 1 h under Ar flow and then cooled to
0 °C followed by saturating with pure NH for 1 h. Then after flushing with Ar for 1 h, the NH -TPD was performed from 80 to 650
C with a heating rate of 10 °C/min. Desorbed ammonia was monitored by an on-line gas chromatograph equipped with a thermal
3
-TPD) was employed to determine the total acidity
8
3
3
°
conductivity detector (TCD).
Acknowledgments
The authors appreciate financial support from the NSFC (No. 21572213), the National Basic Research Program of China (No.
2
013CB228103), Program for Changjiang Scholars and Innovative Research Team in University of the Ministry of Education of China
and the Fundamental Research Funds for the Central Universities (No. wk 2060190040).
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[
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(


t-ZrO2
m-ZrO2




c
b
a






20
30
40
50
60
70
o
2
θ ( )
Fig. 1. XRD patterns of (a) ZrO
2
2
, (b) ZrO -La
O
2 3
and (c) Co/ZrO
2
2 3
-La O .
b
a
0
100
200
300
400
500
600
700
o
Temperature ( C)
Fig.2. NH
3
-TPD profiles of (a) ZrO
2
, (b) ZrO
2
2 3
-La O .
1
00
80
60
40
20
0
100
80
60
40
20
0
100
100
80
60
40
20
0
1
00
100
(b)
(c)
(
a)
80
8
6
4
2
0
0
0
0
0
80
60
40
20
0
60
40
20
0
Carbon Balance
furfural
FAL
Carbon Balance
CPL
Carbon Balance
CPL
CPO
THFAL
FAL
CPO
FAL
THFAL
CPO
CPL
THFAL
150
160
170
180
1
2
3
4
0
1
2
3
4
Temperature (℃)
Hydrogen pressure (MPa)
Time (h)
Fig. 3. Catalytic performance of Co/ZrO
2
2 3
-La O at different temperature (a), hydrogen pressure (b), reaction time (c).
Scheme 1. The reaction mechanism for the conversion of furfural into CPL

Table 1 Hydrogenation of furfural with various cobalt catalysts.
Temperature
Yield (mol%)
CPL
0
32
21
49
68
82
Carbon
Balance (%)
Entry
Catalyst
Conversion (%)
(°C)
CPO
0
1
36
2
14
4
FAL
THFAL
0
17
5
8
1
2
3
4
5
6
-
150
150
150
150
160
160
24
0
0
8
0
0
0
76
50
70
61
84
88
2
Co/Al O
3
100
100
100
100
100
Co/TiO
2
Co/ZrO
Co/ZrO
Co/ZrO
2
2
2
2
2
-La
O
2 3
2 2
Reaction condition: Furfural (1 mmol), catalyst (50 mg), 2 MPa H , H O (10 mL), 4 h.
Table 2 Hydrogenation of furfural and CPO at different conditions over Co/ZrO
2
2 3
-La O
Temperature
°C)
80
Time
(h)
Pressure
(MPa)
Conversion
(%)
Yield (mol%)
Carbon
balance (%)
100
100
76
80
100
100
Entry
1
Substrate
(
CPL
0
CPO
0
FAL
94
94
4
14
0
THFAL
Furfural
Furfural
Furfural
Furfural
CPO
2
2
1
1
1
1
2
2
2
2
2
2
95
95
100
92
65
64
1
1
4
0
0
0
a
2
80
0
0
3
4
160
160
160
160
42
2
65
64
26
56 b
35
a
5
6
a
b
CPO
36
0
a
Recycle experiment.
b
The yield of CPO means the unreacted CPO.