Selective hydrogenation of furfural to furfuryl alcohol in the presence of a recyclable cobalt/SBA-15 catalyst

Article abstract of DOI:10.1002/cssc.201403398

The hydrogenation of furfural to furfuryl alcohol was performed in the presence of a Co/SBA-15 catalyst. High selectivity (96%) at a conversion higher than 95% is reported over this catalytic system. As the conversion of furfural to furfuryl alcohol occurs over metallic Co sites, the effect of reduction temperature, H₂ pressure, and reaction temperature were studied. Optimum reaction conditions were: 150C, 1.5 h, 2.0 MPa of H₂. The catalyst was recyclable, and furfuryl alcohol was recovered with a purity higher than 90%. The effect of the solvent concentration was also studied. With a minimum of 50 wt% of solvent, the selectivity to furfuryl alcohol and the conversion of furfural remained high (both over 80%). Likewise, the activity of the catalyst is maintained even in pure furfural, which confirms the real potential of the proposed catalytic system. This catalyst was also used in the hydrogenation of levulinic acid to produce γ-valerolactone selectively.

Full text of DOI:10.1002/cssc.201403398

DOI: 10.1002/cssc.201403398
Full Papers
Selective Hydrogenation of Furfural to Furfuryl Alcohol in
the Presence of a Recyclable Cobalt/SBA-15 Catalyst
[
a]
[a, b]
[a]
[a]
Ma ¨ı tꢀ Audemar, Carmen Ciotonea,
Karine De Oliveira Vigier,* Sꢀbastien Royer,
[b]
[b]
[b]
[a]
Adrian Ungureanu, Brindusa Dragoi, Emil Dumitriu, and FranÅois Jꢀrꢁme
The hydrogenation of furfural to furfuryl alcohol was per-
formed in the presence of a Co/SBA-15 catalyst. High selectivi-
ty (96%) at a conversion higher than 95% is reported over this
catalytic system. As the conversion of furfural to furfuryl alco-
hol occurs over metallic Co sites, the effect of reduction tem-
ered with a purity higher than 90%. The effect of the solvent
concentration was also studied. With a minimum of 50 wt% of
solvent, the selectivity to furfuryl alcohol and the conversion of
furfural remained high (both over 80%). Likewise, the activity
of the catalyst is maintained even in pure furfural, which con-
firms the real potential of the proposed catalytic system. This
catalyst was also used in the hydrogenation of levulinic acid to
produce g-valerolactone selectively.
perature, H pressure, and reaction temperature were studied.
2
Optimum reaction conditions were: 1508C, 1.5 h, 2.0 MPa of
H . The catalyst was recyclable, and furfuryl alcohol was recov-
2
Introduction
The concept of biorefinery is the use of biomass as a renewable
feedstock for the production of fuels and fine chemicals. Ligno-
cellulosic biomass is made of polymeric components such as
cellulose, hemicellulose, and lignin. After the fractionation of
biomass, these three main components can be isolated and
converted to commodities. Among the molecules that can be
obtained from biomass, furanic
of FAL. However, many side compounds (Scheme 1) are often
produced simultaneously from secondary or side reactions
(e.g., hydrogenation to tetrahydrofurfuryl alcohol (THFA), hy-
drogenolysis of FAL to methylfuran, decarbonylation of FAL to
[3–5]
furan).
Consequently, the development of an efficient cata-
lytic system for the selective production of FAL is challenging.
compounds are of prime indus-
trial interest. In particular, the hy-
drogenation of furfural (FAL; ob-
tained by the hydrolysis/isomeri-
zation/dehydration of hemicellu-
lose) is a relevant reaction that
gives access to furfuryl alcohol
(FOL), a valuable chemical used
in the production of liquid
resins, fine chemicals, lysine, vi-
tamin C, lubricants, dispersant
[
1,2]
agents, and fibers.
FAL is in-
dustrially available with a produc-
tion of 400000 t per year. In
principle, FOL can be produced
selectively through the catalytic
hydrogenation of the C=O bond
Scheme 1. Hydrogenation of FAL.
FOL is mainly produced by the hydrogenation of FAL in either
gas- or liquid-phase processes. The gas-phase hydrogenation
of FAL has two main drawbacks: the amount of byproducts is
higher than that in the liquid-phase process and it has a high
[
a] M. Audemar, C. Ciotonea, Dr. K. D. O. Vigier, Dr. S. Royer, Dr. F. Jꢀrꢁme
UMR 7285 CNRS, IC2MP, Universitꢀ de Poitiers
rue Marcel Dorꢀ TSA 41105- 86 073 POITIERS Cꢀdex 9 (France)
E-mail: karine.vigier@univ-poitiers.fr
1
[6]
[
b] C. Ciotonea, A. Ungureanu, Dr. B. Dragoi, Prof. E. Dumitriu
Faculty of Chemical Engineering and Environmental Protection
Gheorghe Asachi Technical University of Iasi
energy consumption because of the need to vaporize FAL. In
the liquid phase, solvent and high H pressures are generally
2
required for the hydrogenation of FAL to FOL with high selec-
7
3 D. Mangeron Bvd., 700050 Iasi (Romania)
[7,8]
tivity.
In this context, copper chromite (Cu-Cr) catalysts are
Supporting Information for this article is available on the WWW under
http://dx.doi.org/10.1002/cssc.201403398.
the most widely used commercial catalysts for the hydrogena-
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tion of FAL. Conversions and selectivities to FOL of 98% and
3
5–98% were claimed in liquid- and gas-phase reactions, re-
[
7]
spectively.
However, the toxicity of Cu-Cr catalysts that can cause envi-
ronmental pollution after the final disposal of the catalyst rep-
[
8]
resents a serious shortcoming. In addition, although these
catalysts are very selective to FOL, they exhibit moderate activ-
[
9]
ity. Consequently, the liquid-phase hydrogenation of FAL has
been studied using catalysts based on Ni, Co, Ru, Pt, and Pd as
[
2c,4,10–14]
alternatives to the Cu-Cr catalytic system.
However,
a major disadvantage of the proposed catalytic systems is that
they always promote side reactions and are difficult to recycle.
In most cases, the use of promoters is required to improve the
[
15,16]
activity and/or selectivity of these catalysts.
For example,
[
12]
Chen et al. used a Mo-doped Co-B amorphous catalyst (Co-
Mo-B) prepared by the chemical reduction of mixed CoCl and
2
Na MoO with KBH in aqueous solution. This catalyst exhibited
2
4
4
excellent activity and nearly 100% selectivity to FOL in the
liquid-phase hydrogenation of FAL at 1008C under 1.0 MPa of
H . This high selectivity and activity is rarely observed in the
2
presence of a monometallic catalyst. Clearly, the design of
non-noble monometallic catalysts able to hydrogenate FAL to
FOL selectively in the liquid phase with an acceptable activity
remains an important issue.
Figure 1. Representative TEM images recorded of a, c) calcined Co
3
O
4
/SBA-
0
15 and b, d) Co /SBA-15 obtained by reduction at 8008C.
Herein, we demonstrate that monometallic non-noble Co-
based nanoparticles confined in the mesopores of SBA-15 silica
are active and selective in the hydrogenation of FAL to FOL at
a moderate reaction temperature (1508C) and H2 pressure
Scherrer equation. As expected, TEM analysis demonstrates the
formation of oxide nanoparticles confined in the mesopores
with only the minor formation of external aggregates (Fig-
ure 1a and c).
(2.0 MPa). An important benefit of the use of such confined
catalysts is the control of the stability of the nanoparticles be-
cause of the special microenvironment of SBA-15 nanopores
that inhibits their growth during high-temperature catalyst ac-
N2 adsorption/desorption isotherm measurements per-
formed on the calcined Co O /SBA-15 exhibit a type IV iso-
3
4
therm with an H1 hysteresis loop comparable with that record-
ed for the SBA-15 support (Figure S2). Pore periodicity seems
to be unaltered upon preparation, as confirmed by low-angle
XRD analysis (Figure S1). Sensible decreases in specific surface
area and total pore volume are observed upon impregnation
and calcination (Table S1). Such a result is consistent with pore
filling by a secondary phase to result in a partial plugging of
the intrawall micropores and mesopores that occurs if particles
grow to a size comparable with the pore size of the SBA-15
[
17–19]
tivation and/or catalytic reaction.
The effects of reduction
temperature of the catalyst, H pressure, reaction time, and re-
2
action temperature were investigated specifically. Catalytic re-
sults showed that the proposed catalytic system is recyclable,
and the reaction can take place either in ethanol or under sol-
vent-free conditions. At the end of the reaction, the purity of
FOL was higher than 90%, which facilitates downstream purifi-
cation. Moreover, the Co/SBA-15 catalyst was active in the hy-
drogenation of levulinic acid to g-valerolactone (GVL) to lead
to a selectivity of 88% to GVL.
[17–20]
host (Figure S2).
Based on these characterization results,
we can conclude that the oxide material consists of homoge-
neously size-distributed cobalt oxide nanoparticles confined in
the SBA-15 main mesochannels.
Results and Discussion
Oxide material properties
Reducible properties of the cobalt oxide particles confined
in the channels of SBA-15
The catalytic material consists of 10 wt% equivalent Co metal
dispersed over the SBA-15 silica support, a content verified by
inductively coupled plasma optical emission spectroscopy (ICP-
OES). The catalyst was prepared by an incipient wetness im-
pregnation (IWI) route proposed previously as this process en-
sures the homogeneous infiltration of the precursors inside the
pores without a significant enrichment of active phase on the
The reducibility of the cobalt oxide was monitored by H tem-
2
perature-programmed reduction (TPR), and the crystal struc-
ture evolution under a reducing atmosphere was followed by
in situ XRD (Figure 2). The TPR profile exhibits three distinct re-
[19–21]
duction stages (Figure 2A) as reported previously.
Below
3508C, the reduction of large, mesopore-confined Co O parti-
3
4
[
17]
3+
2+
0
external silica surface. XRD analysis of the calcined precursor
shows the presence of a Co O crystalline phase (Figure S1)
cles in two steps (Co !Co !Co ) is supposed to occur.
Small Co O particles, with a moderate interaction with the
3
4
3
4
with an average crystallite size of 10.9 nm as evaluated by the
support, are supposed to reduce at higher temperatures, with
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2
.0 MPa of H without any cata-
2
lyst, a FAL conversion of 13%
was obtained and no production
of FOL was observed (Table 1,
entry 1). Similar results were ob-
tained in the presence of neat
SBA-15. In both cases, the low
conversion of FAL was attributed
to the acetalization of FAL with
ethanol, as shown by MS and
NMR spectroscopy (Figures S3
and S4). The hydrogenation re-
action was next investigated in
the presence of 5 wt% Co/
SBA15 reduced at 5008C under
ꢁ
1
3
Lh
of H2 for 10 h. After
90 min, 92% conversion of FAL
was obtained along with a selec-
tivity to FOL of 96% (Table 1,
entry 6).
Figure 2. a) Reducible properties of calcined Co
3 4
O /SBA-15 and b) Co structure evolution under a reducing atmos-
phere (vertical bars: Co ICDD 42-1467; CoO, ICDD 02-8505; #, metallic Co, ICDD 15-0806).
3
O
4
The conversion of FAL re-
mained very low (18%) and no
a maximum H consumption at 4578C. Finally, the reduction at
high temperature, above 6008C, suggests the formation of
formation of FOL was observed if the reaction was performed
over the oxide form (Co O ) of the catalyst (Table 1, entry 3).
2
3
4
a third fraction of Co species that interact strongly with the
The only product obtained was always the acetal formed by
the reaction between FAL and ethanol. If the catalyst was re-
duced at low temperature (Table 1, entry 4), below the temper-
ature needed to form metallic species, the conversion of FAL
remained low and no FOL was produced. A minimal reduction
temperature of 3008C is needed to convert FAL into FOL sig-
nificantly (Table 1, entry 5). At this reduction temperature, H2-
TPR and in situ XRD results suggest the formation of metallic
Co sites, although the reduction was still not complete
(Figure 2). As expected, the best results were obtained in the
presence of Co/SBA15 reduced at 5008C. This catalyst present-
ed the highest degree of reduction and thus had the highest
number of active sites (Table 1, entry 6). Together, these results
showed that:
[
22]
support, such as that in phyllosilicate phases. Reduction pro-
cesses were further validated by in situ XRD (Figure 2B). The
in situ XRD experiment showed that the Co O phase is ob-
3
4
served until reduction at 3008C. Above 3008C, the Co O4
3
phase signal decreases along with the appearance of charac-
teristic reflections of the CoO phase. The CoO signal decreases
progressively in intensity along with the appearance of weak
0
Co phase signals (ICDD 15-0806) at high temperatures. Char-
acterization of the material by TEM, after reduction at 8008C,
0
evidenced the formation of Co metallic particles of a compara-
ble size to that of precursor oxide particles that remain con-
fined in the support channels (Figure 1b and d).
·
·
reduced Co species are required for the hydrogenation of
FAL,
Impact of the reducing conditions on activity
FAL of high purity (ꢀ99%) was used in the experiments. If an
ethanolic solution of FAL (10 wt%) was heated at 1508C under
FAL can be hydrogenated selectively to FOL in the presence
of metallic Co sites without the addition of a promoter
(
Scheme 2).
[a]
Two mechanism pathways can occur during this reaction
Table 1. Hydrogenation of FAL. Effect of the Co reduction conditions.
after the adsorption of the carbonyl group on the metallic Co
species. Hence, a hydroxyalkyl species can be formed by H
attack on the O atom of the carbonyl group or an alkoxy inter-
mediate can be obtained by H attack on the C atom of the car-
bonyl group. In the literature, the formation of a hydroxyalkyl
Entry Reduction temperature FAL conversion FOL selectivity FOL yield
[
8C]
[%]
[%]
[%]
[
[
b]
c]
1
2
3
4
5
6
–
–
NR
150
300
500
13
15
18
20
75
92
–
–
–
–
88
96
–
–
–
–
66
88
[
d]
intermediate is favored in the presence of a Cu/SiO catalyst
2
based on the stabilization of this intermediate by the furanic
[22]
ring. In this study further investigations are performed to de-
[
a] Conditions: 9 g of ethanol, 1 g of FAL, catalyst=5 wt%, 1508C, 2 MPa
of H , 90 min. [b] Reaction without catalyst. [c] Reaction in the presence
of neat SBA-15. [d] NR=not reduced.
termine the exact mechanism of the hydrogenation of FAL in
the presence of Co/SBA-15.
2
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76 to 96%). This can be ascribed
to the limitation of secondary re-
actions that can occur during
the hydrogenation of FAL upon
prolonged reaction time because
of the stability of FOL in the re-
action media. Hence, there are
several compounds derived from
side reactions (i.e., the hydroge-
nation of the furan ring to THFA,
hydrogenolysis
of
the
C=O bond to methylfuran, de-
carbonylation to furan, and fur-
ther hydrogenation to THF
[3,6,23]
(
Scheme 1).
Resinous mate-
rial and ring-decomposed prod-
[24]
ucts are also produced. If the
reaction time was further de-
creased to 1 h, the conversion
was only 80% and the selectivity
remained higher than 95%.
From these results, it is clear
that a maximum reaction time of
Scheme 2. Hydrogenation of FAL to FOL.
1.5 h is required for FAL hydro-
genation to FOL under 2.0 MPa of H at 1508C. The purity of
2
Table 2. Effect of H
nation of FAL to FOL.
2
pressure and reaction temperature on the hydroge-
the FOL obtained was higher than 90%.
[
a]
Entry
T
P
H2
t
FAL conversion FOL selectivity FOL yield
[
8C] [MPa] [h]
[%]
[%]
[%]
1
2
3
4
5
6
7
8
9
2.0
2.0
2.0
2.0
5.0
5.0
2
100
99
92
76
84
96
96
78
75
40
95
84
85
87
89
76
90
88
76
83
88
77
78
75
40
77
74
83
66
63
26
18
45
Effect of H pressure
2
1.75
1.5
1
1
2
4
2
3
2
2
2
2
2
150
An increase of the H pressure was beneficial for the conver-
2
80
sion of FAL. Indeed, after 1 h of reaction at 1508C, the conver-
sion of FAL was complete under 5.0 MPa of H2 (Table 2,
entry 5) versus only 80% under a H2 pressure of 2.0 MPa
100
100
100
81
88
97
76
71
34
20
150 5.0
1.0
(Table 2, entry 4). However, an increase in the H pressure led
2
1.0
concomitantly to a decrease in the FOL selectivity from 96 to
1
0
140 2.0
130 2.0
120 2.0
110 2.0
100 2.0
100 2.0
75% as supported by the formation of dark brown products.
1
1
1
1
1
1
2
3
4
5
This decrease of selectivity can be ascribed to i) the formation
of polymers from the polymerization of FOL or FAL or ii) the
degradation of FOL or FAL, which can be favored at high H
2
6
51
[15,16]
pressure as described previously.
tion was continued after the complete conversion of FAL from
to 4 h at 5.0 MPa of H (Table 2, entries 6 and 7), the selectivi-
In evidence, if the reac-
[a] Conditions: 9 g of ethanol, 1 g of FAL, 5 wt% catalyst reduced under
H
2
flow at 5008C.
2
2
ty to FOL decreased significantly from 75 to 40%, which sup-
ports the relative instability of FOL under a high pressure of
H . Hence, byproducts of the condensation of FOL can be pro-
2
In subsequent experiments, the reduction temperature was
duced as shown previously. This result was further confirmed
kept at 5008C.
by conducting experiments at only 1.0 MPa of H (Table 2, en-
2
tries 8 and 9). Under 1.0 MPa of H , the conversion of FAL was
2
incomplete even after 2 h of reaction (81%), and the selectivity
to FOL reached 95%. At this pressure, the increase of the reac-
tion time from 2 to 3 h led to an increase of the conversion of
FAL from 81 to 88%, along with a decrease of the selectivity to
FOL from 95 to 84% (Table 2, entries 8 and 9). Therefore, in the
presence of monometallic Co/SBA-15, FAL can then be con-
verted selectively to FOL even under a pressure of 1.0 MPa H2.
Effect of reaction time
The effect of the reaction time on the hydrogenation of FAL
(
1508C, 2.0 MPa of H , 5 wt% catalyst) is presented in Table 2
2
(entries 1–4). If the reaction time was decreased from 2 to
1.5 h, the conversion decreased from 100 to 92%. However,
a beneficial effect on the FOL selectivity was observed (from
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during the recycling process. A decrease in
the conversion from 92 to 81% was ob-
served between the two first runs
[
a]
Table 3. Hydrogenation of FAL. Effect of the catalyst and FAL content.
Entry FAL content Catalyst content FAL conversion FOL selectivity FOL yield Productivity
Coꢁ
1
ꢁ1
[
wt%]
[wt%]
[%]
[%]
[%]
[molFOL mol
h ]
(
Figure 3). Thereafter, the conversion re-
1
2
3
4
5
6
10
10
10
30
50
5
3
3
5
5
5
100
63
84
100
90
37
76
87
85
88
78
84
76
55
71
88
70
31
46
56
48
161
214
190
mained almost constant (around 80%)
during the next two runs. After the fourth
cycle, the conversion decreased slightly
run by run. However, the conversion of FAL
remained higher than 70% up to the ninth
cycle. In all runs, the selectivity to FOL was
similar. These results show that the per-
formances of the active sites are main-
tained under recycling, despite the slight
[
b]
100
2
[a] Conditions: 1508C, 2.0 MPa of H , t=2 h. [b] t=3 h.
Effect of reaction temperature
progressive decrease in conversion. To elucidate this point, the
leaching of Co during the reaction was evaluated. Co in solu-
tion at the end of each run was ~10ꢂ2 ppm. Hence, Co leach-
ing can be the origin of the loss of activity as after 11 runs ap-
proximately 110 ppm of Co is lost from the catalyst surface.
However, to validate that the process is purely heterogeneous
(i.e., Co in solution is not responsible for FAL conversion in
a homogeneous process), an additional test was performed.
Thus, the catalyst was removed from the reaction media when
the conversion reached 50%. After the removal of the catalyst,
The reaction was performed at temperatures lower than 1508C
Table 2 entries 10–15). A decrease of the reaction temperature
(
from 150 to 1408C led to 97% conversion of FAL with a selec-
tivity to FOL of 96% after 2 h of reaction versus 1.5 h at 1508C
(Table 2, entry 3). If the reaction temperature was further de-
creased from 140 to 130 and 1208C, the conversion decreased
logically from 97 to 76 and 71% with a similar selectivity to
FOL (around 87%; Table 3, entries 10–12). At lower tempera-
tures of 110 and 1008C, a significant decrease of the FAL con-
version was observed (20% after 2 h). At such low tempera-
tures, the conversion can be increased by increasing the reac-
tion time. For instance, the conversion of FAL increased from
H was reintroduced and the reaction was performed for a fur-
2
ther hour. No additional conversion of FAL was observed,
which shows that Co in solution did not allow the formation of
FOL. This is probably because Co in solution has a cationic
character, which is inactive for the hydrogenation reaction.
The activation of the catalyst after the fifth cycle was per-
formed by calcination under air for 6 h at 1008C and then re-
20 to 51% if the reaction time was increased from 2 to 6 h
(
(
Table 3, entry 15). The selectivity to FOL remained high
around 90%), which shows that side reactions are limited at
low reaction temperatures.
duction under H for 10 h at 5008C. This activated catalyst was
2
used in the hydrogenation of FAL to FOL at 1508C under
2
.0 MPa of H for 1.5 h. A FAL conversion of 90% and a selectiv-
Stability in reaction
2
ity to FOL of 96% were obtained, which shows that this cata-
lyst can be reactivated.
The recyclability of the catalyst is a key aspect for the viability
of a heterogeneously catalyzed pathway. The catalyst was recy-
cled after the reaction performed at 1508C under 2.0 MPa of
H2 for 1.5 h. The catalyst was recovered simply based on its
magnetic properties and was reused without washing and/or
reactivation. The weight percentage of fresh FAL added was
always 10 wt% in EtOH. The amount of FAL was not adjusted
Optimization studies
The catalyst content can be decreased without affecting the
selectivity to FOL. Indeed, with a catalyst content as low as
3
wt%, the FAL conversion was 84% with 85% selectivity to
FOL (Table 3, entries 1–3). The productivity was similar for both
ꢁ
1
ꢁ1
catalyst contents (around 50 molFOL molCo h ). The effect of
the FAL/solvent ratio on the FAL conversion and selectivity to
FOL was studied. Several reactions were performed (5 wt% cat-
alyst, reaction temperature 1508C, 2.0 MPa of H , 2 h; Table 3,
2
entries 1 and 4–6). The conversion of FAL remained above
9
0% and the selectivity to FOL is around 80% up to 50 wt%
FAL content. In addition, if FAL was used without solvent
100 wt%), the selectivity remained unchanged, and a conver-
(
sion of 37% was measured. This is clear evidence that this cat-
alytic system can work without solvent and maintain a high
productivity to FOL. Hence, the productivity was
ꢁ
1
ꢁ1
1
2
61 molFOL molCo
h
h
for 30 wt% of FAL and increased up to
for 50 wt% of FAL. We were pleased to
Figure 3. Evolution of FAL conversion and FOL selectivity during recycling
ꢁ
1
ꢁ1
14 molFOL molCo
tests over Co/SBA-15 (10 wt% of FAL in ethanol, 1508C, 2.0 MPa of H
.5 h).
2
,
ꢁ
1
ꢁ1
1
see that a productivity of 190 molFOL molCo
h
was obtained
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in the absence of solvent, which shows the excellent produc-
tivity that can be obtained using this catalyst.
tion that function at low temperature and H pressure can be
2
designed. Moreover, compared to other systems, a similar yield
of FOL can be obtained without the promotion of another
metal, and Co-SBA-15 can be recovered easily and recycled,
which is of prime interest in such reactions.
Hydrogenation of levulinic acid to GVL
We were interested to study the use of this catalyst in another
hydrogenation reaction. With this aim, the hydrogenation of
levulinic acid was performed in the presence of Co/SBA-15 cat-
Experimental Section
Catalyst preparation
[
a]
The SBA-15 support was synthesized according to the procedure
Table 4. Hydrogenation of levulinic acid.
[27]
used by Zhao et al.
Pluronic P123 (PEO PPO PEO , MW=
20 70 20
ꢁ1
Entry
Reaction time
h]
Levulinic acid
GVL selectivity
[%]
GVL yield
[%]
5800 gmol , 4 g) and HCl (1.6m) were stirred at 408C until the
complete dissolution of the templating agent. The silica source,
tetraethyl orthosilicate (8.5 g), was added dropwise, and the mix-
ture was stirred for 24 h. The resulting gel was submitted to hydro-
thermal treatment for 48 h at 1008C. The SBA-15 support was ob-
tained by calcination at 5508C for 6 h in a muffle oven (heating
[
conversion [%]
1
2
3
4
2
2
100
89
81
69
88
73
69
78
59
[
b]
[
a] Conditions: 1508C, 5.0 MPa of H
2
. [b] 1508C, 2.0 MPa of H
2
.
ꢁ1
ramp 1.58Cmin ). Freshly calcined support was impregnated with
ꢁ1
an aqueous solution of Co(NO ) ·6H O (0.8 molL ). The volume of
3
2
2
solution was adjusted to obtain a metal loading of 10 wt%. Under
these conditions, the volume of impregnation solution ensures the
complete wetting of the support (IWI ). The impregnated powder
alyst to produce GVL. GVL, a frequently used food additive, ex-
hibits the most important characteristics of an ideal sustainable
liquid, which include the possibility to be utilized in the pro-
[28]
was dried at 1208C for 12 h in stagnant air and was calcined at
ꢁ
1
5
008C in a muffle oven (heating ramp 1.58Cmin ).
[25]
duction of energy or carbon-based consumer products. The
reaction was performed under 2.0 MPa of H at 1508C for 2 h
2
in the presence of 1 g of levulinic acid in 9 g of ethanol. A se-
lectivity to GVL of 88% was obtained at 89% levulinic acid
conversion (Table 4, entry 2). Ethyl levulinate was observed as
a byproduct (Figure S5). If the reaction time was prolonged to
Physicochemical characterization of Co/SBA-15
Materials were characterized by ICP-OES, XRD, TEM, N physisorp-
2
tion, H -TPR, and in situ XRD after programmed reduction. A de-
2
scription of the procedures is provided in the Supporting Informa-
tion.
4
h, the conversion was complete but the selectivity to GVL
decreased from 88 to 69% (Table 4, entry 1) because of the for-
mation of ethyl valerate, as shown by GC–MS analysis (Fig-
[
26]
Hydrogenation of FAL
ure S6), along with traces of ethyl levulinate. If the pressure
of H was decreased from 4.0 to 2.0 MPa at 1508C for 2 h, the
selectivity to GVL was 73% for a conversion of levulinic acid of
2
The hydrogenation of FAL was performed in the liquid phase by
using a batch reactor. In a typical experiment FAL (1 g) was added
to ethanol (9 g), and Co/SBA-15 (5 wt%) was added to the solution.
81% (Table 4, entry 3). These results show that Co/SBA-15 can
The reactor was then filled with the desired pressure of H (e.g.,
be used in the hydrogenation of levulinic acid to obtain GVL
with a selectivity of 88%.
2
5
.0 MPa) at RT, and the temperature was increased to 1508C. The
reaction time was 1–4 h. At the end of the reaction, the liquid
phase was recovered and analyzed by HPLC. FAL and FOL were
quantified by external calibration at 258C using HPLC equipped
with a nucleosil 100–5 C18 column (250ꢃ4.6 mm), a Shimadzu LC-
Conclusions
Herein, we have demonstrated that furfuryl alcohol (FOL) can
be produced selectively from the hydrogenation of furfural
2
0AT pump, and a Shimadzu RID-10 A detector using acetonitrile/
ꢁ1
water (10:90) as the mobile phase (0.6 mLmin ). The productivity
[molFOL molCo h ] was evaluated by the ratio of the moles of FOL
produced over the moles of Co species per hour.
ꢁ
1
ꢁ1
(FAL) in the presence of a monometallic Co/SBA-15 catalyst.
The presence of a metallic Co species is required for the hydro-
genation of FAL to FOL. The effect of the reaction conditions
(
temperature, pressure, reaction time) was studied. Optimal
conditions to achieve high conversions and selectivity were
508C under 2.0 MPa of H for 1.5 h. The catalyst was recycla-
Hydrogenation of levulinic acid
1
The hydrogenation of levulinic acid was performed in the liquid
phase by using a batch reactor. Typically, levulinic acid (1 g) was
added to ethanol (9 g), and Co/SBA-15 (5 wt%) was added to the
solution. The reactor was then filled with the desired pressure of
2
ble, with a limited decrease in activity in up to nine cycles. The
effect of the FAL to EtOH ratio was also studied. The catalyst
works even without solvent. Despite the decrease in conver-
sion, selectivity remains high (above 80%) and productivity to
FOL can be increased significantly. Co/SBA-15 can be consid-
ered as a promising catalyst for FOL production and also for g-
valerolactone production from levulinic acid with a low envi-
ronmental impact as processes with limited solvent consump-
H (5.0 or 2.0 MPa) at RT, and the temperature was increased to
2
1
508C. The reaction time was 2–4 h. Levulinic acid and GVL were
quantified by external calibration at 258C by using HPLC equipped
with a nucleosil 100–5 C18 column (250ꢃ4.6 mm), a Shimadzu LC-
20AT pump, and a Shimadzu RID-10 A detector using acetonitrile/
ꢁ1
water (10:90) as the mobile phase (0.6 mLmin ).
&
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Full Papers
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Published online on && &&, 0000
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&
These are not the final page numbers! ÞÞ

FULL PAPERS
M. Audemar, C. Ciotonea, K. D. O. Vigier,*
S. Royer, A. Ungureanu, B. Dragoi,
E. Dumitriu, F. Jꢀrꢁme
&& – &&
Selective Hydrogenation of Furfural to
Furfuryl Alcohol in the Presence of
a Recyclable Cobalt/SBA-15 Catalyst
The fast and the furfural: Furfuryl alco-
hol is produced from furfural with
1508C under H pressure in ethanol.
2
This catalyst is also active and selective
in the hydrogenation of levulinic acid to
g-valerolactone.
a yield of 88% in the presence of a recy-
clable and stable Co/SBA-15 catalyst at
&
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8
ꢂ 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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