Base-free conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid over a Ru/C catalyst

Article abstract of DOI:10.1039/c5gc01584g

The catalytic conversion of 5-hydroxymethyl furfural (HMF) to 2,5-furandicarboxylic acid (FDCA) over a commercial Ru/C catalyst in a base-free aqueous solution was studied with 88% FDCA yield. A self-catalyzed system using FDCA for the dehydration of fructose to HMF followed by base-free conversion of HMF to FDCA was also demonstrated with 53% overall yield.

Full text of DOI:10.1039/c5gc01584g

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Base-free conversion of 5-hydroxymethylfurfural to 2,5-
furandicarboxylic acid over Ru/C catalyst
Guangshun Yi, Siew Ping Teong, and Yugen Zhang*
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
The catalytic conversion of 5-hydroxymethyl furfural (HMF) to 2,5- where FDCA will then be precipitated from the solution as
furandicarboxylic acid (FDCA) over commercial Ru/C catalyst in white precipitate.14 In contrast, the conversion of HMF to
base-free aqueous solution was studied with 88% FDCA yield. A FDCA under base-free conditions would eliminate the need to
self-catalyzed system using FDCA for the dehydration of fructose convert FDCA salt to FDCA, making the system greener with
to HMF followed by base-free conversion of HMF to FDCA was also less waste generated.
demonstrated with 53% overall yield.
The base-free conversion of HMF to FDCA has been
investigated using homogenous Co(OAc)2/Mn(OAc)2/HBr
catalysts in acetic acid system with 60% yield under rather
Today, over 90% of the world‘s organic chemicals are
produced from petroleum, and 85% of crude oil is used for the
production of transportation fuel.1 Due to the depletion of
fossil resources and global warming concern, considerable
attention was focused on the conversion of renewable
biomass to chemicals and fuels.2 Among these chemicals, 2,5-
furandicarboxylic acid (FDCA) has received significant
attention3 as potential replacement for terephthalic acid for
o
harsh reaction conditions (125 C, 70 bar air).15 The base-free
conversion of HMF to FDCA in a bench-scale flow reactor with
Pt/ZrO2 was also studied,16 but low HMF concentration was
necessary to avoid FDCA precipitation. Very recently, the
conversion of HMF to FDCA in base-free condition has also
been demonstrated with carbon nanotube supported Au-Pd
alloy nanoparticles catalyst17 as well as a free-standing Pt
nanoparticle catalyst.5 Ru is the least expensive catalyst when
compared to Au, Pt and Pd.9b Hence, Ru catalyst has also been
investigated in the HMF oxidization reaction under basic
condition, to give diformyl furan (DFF)18 or FDCA slats.19 Here,
we report the conversion of HMF to FDCA in aqueous solution
under base-free condition with commercial Ru/C catalyst.
Under optimized conditions, 88% yield of FDCA was directly
obtained as white precipitate. Reaction pathway and various
co-catalysts were also studied in this system. Interestingly,
FDCA itself could also promote the dehydration of fructose to
HMF, where 65% HMF yield was obtained. The obtained HMF
was further converted to FDCA under the base-free conditions
with an overall yield of 55%.
the production of poly(ethylene terephthalate) (PET).4,5
A
FDCA-based polymer poly(ethylene-2,5-furandicarboxylate)
(PEF) has been prepared and investigated, which showed
comparable properties to PET.6 FDCA was also listed as one of
the 12 key value-added chemicals from biomass by the US
Department of Energy.7
FDCA can be prepared by oxidation of HMF, while HMF is
prepared by acid-catalyzed dehydration of sugars or
cellulose.4b,8 HMF could be oxidized to FDCA with
stoichiometric oxidants,8a metal catalysts,3f,9 or enzyme.10
Among these, the catalytic conversion of HMF with oxygen is
more attractive. The most studied catalysts are Au,9b,11 and
Pt,3a,9b,9d,12 usually with base additive and at elevated
temperature. High or even quantitative yield of FDCA can be
obtained. However, the product obtained from these catalytic
systems under basic condition is the salt form of FDCA which
cannot be directly used in polymer industry.6b,13 The
separation of FDCA from aqueous system usually requires the
addition of strong mineral acids such as HCl and H2SO4 pH =1,
In fact, our study for the conversion of HMF to FDCA with
Ru/C catalyst started with the addition of equivalent amount
of base. As shown in Table 1, it was found that stronger base
led to lower FDCA yield. For example, when NaOH was used as
base, it gave only 69% FDCA yield. The color of the reaction
mixture turned brownish due to the degradation of HMF at
higher pH.20 To minimize this side effect, weak bases were
tested in the reaction system.
It is clear that the weaker the base used, the higher the
FDCA yield was obtained. Eventually, the system with CaCO3
additive gave highest yield of 95%. CaCO3 remained as solid in
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the initial stage of the reaction and was gradually dissolved as to FDCA/FFCA mixture. As shown in Figure 1, with more runs of
it reacted with FDCA to form FDCA calcium salt. The addition reaction, the yield of FDCA kept on decreasing while the FFCA
of CaCO3 acted more like a neutralizer to FDCA, rather than a kept on increasing. However, the total yield of FDCA and FFCA
base to promote the reaction from HMF to FDCA. The initial pH is almost constant. This indicates that there is some
value of the solution with CaCO3 is 5.6. This indicates that deactivation of Ru/C catalyst occurred during recycle
pH>7 is not necessary for this reaction. Therefore, a base-free experiment, but only the second step reaction was affected.
condition was tested.
ICP-MS testing showed 3.4% of Ru species leached to the
solution after 5 rounds of reaction, which should not be the
main cause for catalyst deactivation. TEM results showed
there’s no obvious change for Ru particles (Figure S4).
However, after 5 rounds reaction, we have also noticed some
weight increase of catalyst, which should be due to some
unknown impurities. After re-activation of the Ru/C catalyst
(Table S1, entry 6), the catalyst resumed a full conversion. So it
was believed that the impurities and/or the oxidation of the Ru
species is the main reason for catalyst deactivation.
Table 1. The conversion of HMF to FDCA with different bases.
Entry
Base
Conv. (%)
100
Yield (%) Observation
1
2
3
4
5
NaOH
K2CO3
Na2CO3
HT
69
80
93
90
95
Brown solution
Clear solution
Clear solution
Clear solution
Clear solution
100
100
100
CaCO3
100
Table 2. Base-free conversion of HMF to FDCA over Ru/C
Reaction conditions: 1 mmol HMF, 10 ml H2O, equiv. base, 0.1 g Ru/C (5
mol%), 0.2 MPa O2, 120 oC, 5 h.
In a typical reaction, 1 mmol of HMF, 10 ml water, 0.2 g
Ru/C catalyst (10 mol%), and O2 were loaded into a 50 ml parr
reactor. The reaction mixture was then conducted under
different conditions. As shown in Table 2, the best result was
obtained at 120 oC, 0.2 Mpa O2 after 10 hours, with 88% FDCA
yield. There is no other products could be identified by crude
product NMR analysis. However, it has been observed weight
increase of catalyst that indicated some insoluble by-product
formed. Pure FDCA was directly obtained as white precipitate,
as shown in Figure S1. NMR analysis confirmed that the white
precipitate is pure FDCA (Figure S2). The pH of the solution at
the end of the reaction was 2.4, indicating the formation of
FDCA diacid.
Entry
Temp. ( oC) /O2
Pressure (MPa)
80 /0.2
Conv.
(%)
FDCA FFCA
DFF
(%)
0
(%)
14
60
87
88
88
(%)
85
37
0
1
2
3
4
5
100
100
100
100
100
100 /0.2
0
120 /0.1
0
120 /0.2
0
0
120 /0.5
0
0
Reaction conditions: 1 mmol HMF, 10 ml H2O, 0.2 g Ru/C (10 mol%), O2, 10 h.
100
80
As the catalyst loading was decreased (Ru/C 0.1 g, 5 mol%),
the reaction became slower and stopped at FFCA or DFF
intermediates after 5 h at 120 oC (Figure S3). Further study
showed that it is due to the FDCA precipitation which blocked
the active site of Ru, and slowed down the reaction. To
confirm this, FDCA with Ru/C was collected by filtration. FDCA
precipitate was washed away with methanol. Then, Ru/C was
added back into the reaction. The reaction then resumed at
60
FDCA@5h
FFCA@5h
40
20
0
1
2
3
4
5
o
Rounds
120 C and completed within 5 h. When 10 mol% catalyst was
applied, reaction completed after 10 h without washing of
catalyst.
Fig 1. Recycle of Ru/C catalyst at 5h (half of completion time).
To test the recyclability of the catalyst, we have conducted 6
rounds of experiments. After each round of reaction, the
catalyst was washed with methanol and used for the next
round of reaction. Experiments showed that for the first 3
rounds, no catalyst deactivation was observed. For the 4th and
5th rounds, slightly slow reaction rate was observed, which
may be due to the oxidation of Ru species. Therefore the
catalyst was re-activated by H2/Ar, and, the catalyst resumes
its original catalytic performance, as shown in Table S1. To
further study the stability of the catalyst, recyclability of Ru/C
catalyst within kinetic-controlled region (5 h, half of
completion time) was tested. At 5 h, HMF was fully converted
The kinetics of the reaction was also studied, as shown in
Figure 2. At the initial stage of reaction, DFF and FFCA are
increased quickly and then slowly decreased after 1 h reaction.
Concurrently, FDCA was produced after 1 h which clearly
indicated the reaction pathway where the conversion of HMF
to FDCA proceeded via the formation of DFF and FFCA
intermediates. A similar behaviour was also demonstrated in
the Au/Pd-CNT system.17 During this process, Ru catalysed the
oxidation of -OH to -CHO, and further oxidized -CHO to -COOH.
It showed that the conversion of HMF to DFF/FFCA is a fast
reaction which was completed within 2 hours, with nearly
quantitative overall yield. However, the conversion of the
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remaining -CHO to -COOH became slower, requiring 8 hours to mixture solution (5/5, v/v),21 peracetic acid was added through
complete. During the reaction, no HFCA was detected, a syringe pump at room temperature over 12 h. An overall
suggesting the oxidation of HMF always occurred from the – 95% FDCA yield was obtained as white precipitate, as shown in
OH side rather than –CHO, as shown in Figure 2B.
Figure S5.
Although the one-pot two-step reaction using peracetic acid
achieved excellent FDCA yield under mild reaction conditions,
peracetic acid was used as an oxidant which will be sacrificed
during the reaction. Alternatively, transition metal co-catalysts
were also screened in the Ru/C base-free system. Co(OAc)2
and Mn(OAc)2 have been used in the catalytic conversion of
HMF to FDCA.15 Co(OAc)2 and/or Mn(OAc)2 were then added
into current reaction system as a co-catalyst of Ru/C. As shown
in Table S3, the addition of Co(OAc)2 and/or Mn(OAc)2 have no
significant effect on FDCA yield. This may be due to the fact
that Co(OAc)2/Mn(OAc)2 was used in HOAc solution, while
water was being used in the current reaction system.
100
80
HMF Conversion
FDCA Yield
FFCA Yield
DFF Yield
60
40
20
0
0
2
4
6
8
10
Time / Hour
It has been demonstrated here that HMF was converted to
FDCA by Ru/C catalyst in the base-free condition. HMF is a
biomass-derived product and is typically prepared by acid
catalyzed sugar dehydration.8b Strong acids like HCl,8c and
Amberlyst-15,22 have been successfully used for this process.
Since FDCA being an acid itself has a pKa of 2.28, it will be
interesting and useful if FDCA can be used as acid catalyst to
promote the conversion of sugar to HMF, then further oxidized
to FDCA. In this way, no additional acid will be used in the
reaction system, forming a closed self-catalyzed system to
convert sugars to FDCA.
(A)
The conversion of fructose to HMF using FDCA as acid
catalyst was studied in iPrOH/H2O or THF/H2O systems.8c,23 As
shown in Figure 3, the reaction rate in iPrOH/H2O is faster than
in THF/H2O, where 64% HMF yield was obtained after 30 mins,
with full fructose conversion and full recovery of FDCA. While
for THF/H2O, the full conversion of fructose occured after 2 h,
with 51% HMF yield. Together with Sn-beta or AlCl3, FDCA was
also tested in glucose dehydration. As shown in Table S4,
glucose was almost fully converted after 170 oC for 30 mins.
The best HMF yield of 30% was obtained for Sn-Beta (2 h), and
35% for AlCl3 (5 h).
(B)
Fig. 2 (A) Kinetics study from HMF to FDCA. (B) Reaction pathway from HMF to FDCA.
Reaction conditions: 1 mmol HMF, 0.2 g Ru/C, 10 ml water, 0.2 MPa O2, 120 oC.
From Figure 2, we understand that for the reaction of HMF
to FDCA, the conversion of -OH to -CHO is a fast step while the
oxidation of -CHO to -COOH is the rate-limiting step. To make
the reaction faster, the key is to accelerate the reaction from –
CHO to -COOH. Although the conversion of -CHO to -COOH is
very fast with the existence of base, it is a challenge under
base-free condition. Herein, a one-pot two-step reaction with
peracetic acid as oxidant21 for the second step was proposed,
as illustrated in Scheme 1.
100
80
60
40
Fructose Conversion in THF/H2O
HMF Yield in THF/H2O
20
Scheme 1: Two-step reaction for the production of FDCA
Fructose Conversion in iPrOH/H2O
HMF Yield in iPrOH/H2O
0
For the first step, HMF was fully converted to DFF/FFCA in
1.2 h in water system, with 84% FFCA and 13% DFF. When the
reaction was conducted in other organic solvents like MeCN,
HOAc, and MeOH, excellent selectivity towards DFF was
obtained, as shown in Table S2. After the first step, Ru/C
catalyst was removed. DFF/FFCA intermediates were
recovered by evaporation and re-dissolved in tBuOH/EtOAc
0
1
2
3
4
5
Reaction time / Hour
Fig. 3 FDCA promoted conversion of fructose to HMF. Reaction conditions: 1 mmol
fructose, 1 mmol FDCA, iPrOH/H2O (4.85/0.15 ml), or THF/H2O (4.5/0.5 ml), 170 oC.
The HMF formed was then further oxidized to FDCA. After
the conversion of fructose to HMF in iPrOH/H2O, the solvent
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3786; (e) J. Y. Cai, H. Ma, J. J. Zhang, Q. Song, Z. T. Du, Y. Z.
Huang and J. Xu, Chem.-Eur. J., 2013, 19, 14215-14223; (f) A.
Villa, M. Schiavoni, S. Campisi, G. M. Veith and L. Prati,
was removed by evaporation and the crude HMF together with
FDCA was obtained. The HMF was recovered by water
extraction using the method we reported earlier (5 ml x 2, 0.64
mmol, >99% HMF recovery).14b The HMF in aqueous solution
was then directly transferred to a Parr reactor for the
oxidation reaction. Under base-free conditions with Ru/C
catalyst, the reaction was conducted and completed in 15
hours with an overall FDCA yield of 53% obtained (83% yield in
the second step). It should be noted that the Ru/C catalyzed
oxidization reaction of freshly synthesized HMF (from sugar) is
slower than the reaction of pure commercial HMF (15 h vis 10
h), which may be due to some minor water soluble impurities
in the freshly synthesized HMF solution.
Chemsuschem, 2013,
Abu-Omar, A. Modak and A. Bhaumik, J. Catal., 2013, 299
316-320; (h) G. S. Yi, S. P. Teong and Y. G. Zhang,
Chemsuschem, 2015, , 1151-1155.
(a) T. Pan, J. Deng, Q. Xu, Y. Zuo, Q.-X. Guo and Y. Fu,
Chemsuschem, 2013, , 47-50; (b) S. Dutta, S. De and B. Saha,
ChemPlusChem, 2012, 77, 259-272; (c) A. Gandini, Polym.
Chem., 2010, , 245-251; (d) J. Deng, H. J. Song, M. S. Cui, Y.
P. Du and Y. Fu, Chemsuschem, 2014, , 3334-3340.
6, 609-612; (g) B. Saha, D. Gupta, M. M.
,
8
4
6
1
7
5
6
S. Siankevich, G. Savoglidis, Z. F. Fei, G. Laurenczy, D. T. L.
Alexander, N. Yan and P. J. Dyson, J. Catal., 2014, 315, 67-74.
(a) A. Eerhart, A. P. C. Faaij and M. K. Patel, Energy Environ.
Sci., 2012, 5, 6407-6422; (b) A. Gandini, A. J. D. Silvestre, C. P.
In conclusion, the base-free conversion of HMF to FDCA over
commercially available Ru/C catalyst in water was investigated.
FDCA yield of 88% was obtained with full HMF conversion.
Under base-free condition with Ru/C catalyst, the oxidation
process prefers the DFF/FFCA pathway rather than HFCA
pathway. The oxidization of –OH to –CHO of HMF was much
faster (<2h), while further conversion of the remaining–CHO to
–COOH was the rate-limiting step (8h). To further accelerate
this reaction, a one-pot 2-step method was proposed where
HMF was first converted to FFCA and DFF intermediates, and it
was further oxidized to FDCA by the titration with peracetic
aicd at room temperature. In this way, 95% FDCA was
obtained. Finally FDCA promoted conversion of fructose and
glucose to HMF was also studied, and the freshly obtained
HMF was further oxidized to FDCA. An overall FDCA yield of
53% was obtained from fructose under base-free condition.
The lower price of Ru catalyst and base-free reaction condition
make this method a very competitive process for the FDCA
production.
Neto, A. F. Sousa and M. Gomes, J. Polym. Sci. A Polym.
Chem., 2009, 47, 295-298; (c) S. Thiyagarajan, W. Vogelzang,
R. J. I. Knoop, A. E. Frissen, J. van Haveren and D. S. van Es,
Green Chem., 2014, 16, 1957-1966.
7
8
T. Werpy and G. Petersen, DOE report, 2004, 1-76.
(a) R. J. van Putten, J. C. van der Waal, E. de Jong, C. B.
Rasrendra, H. J. Heeres and J. G. de Vries, Chem. Rev., 2013
113, 1499-1597; (b) S. P. Teong, G. S. Yi and Y. G. Zhang,
Green Chem., 2014, 16, 2015-2026; (c) L. K. Lai and Y. G.
Zhang, Chemsuschem, 4, 2011, 1745-1748; (d) W. H. Peng, Y.
Y. Lee, C. N. Wu and K. C. W. Wu, J. Mater. Chem. 2012, 22
,
23181-23185; (e) X. Cao, S. P. Teong, D. Wu, Di, H. Su, Y.
Zhang, Green Chem., 2015, 17, 2348-2352; (f) S. P. Teong, G.
Yi, H. Zeng, Y. Zhang, Green Chem., 2015, 17, 3751-3755; (g)
S. P. Teong, G. Yi, X. Cao, Y. Zhang, Chemsuschem, 2014, 7,
2120-2124.
(a) N. K. Gupta, S. Nishimura, A. Takagaki and K. Ebitani,
Green Chem., 13, 824-827; (b) S. E. Davis, L. R. Houk, E. C.
Tamargo, A. K. Datye and R. J. Davis, Catal. Today, 160, 55-
60; (c) B. Siyo, M. Schneider, J. Radnik, M.-M. Pohl, P. Langer
and N. Steinfeldt, Appl. Catal. A-Gen., 2014, 478, 107-116;
(d) S. E. Davis, B. N. Zope and R. J. Davis, Green Chem., 2012,
14, 143-147.
9
10 (a) F. Koopman, N. Wierckx, J. H. de Winde and H. J.
Ruijssenaars, Bioresource Technol., 2010, 101, 6291-6296; (b)
W. P. Dijkman, D. E. Groothuis and M. W. Fraaije, Angew.
Chem.-Int. Edit., 2014, 53, 6515-6518; (c) S. M. McKenna, S.
Leimkuhler, S. Herter, N. J. Turner and A. J. Carnell, Green
Chem., 2015, 17, 3271-3275.
Acknowledgements
This work was supported by the Institute of Bioengineering
and Nanotechnology (Biomedical Research Council), Biomass-
to-Chemicals program (Science and Engineering Research
Council), Agency for Science, Technology and Research,
Singapore.
11 (a) Y. Y. Gorbanev, S. K. Klitgaard, J. M. Woodley, C. H.
Christensen and A. Riisager, Chemsuschem, 2009, 2, 672-675;
(b) O. Casanova, S. Iborra, A. Corma, Chemsuschem, 2009, 2,
1138-1144.
12 H. A. Rass, N. Essayem and M. Besson, Green Chem., 2013,
15, 2240-2251.
13 M. Jiang, Q. Liu, Q. Zhang, C. Ye and G. Zhou, J. Polym. Sci. A
Polym. Chem., 2012, 50, 1026-1036.
14 (a) J. M. R. Gallo, D. M. Alonso, M. A. Mellmer and J. A.
Dumesic, Green Chem., 2013, 15, 85-90; (b) G. S. Yi, S. P.
Notes and references
‡ Footnotes relating to the main text should appear here. These
might include comments relevant to but not central to the
matter under discussion, limited experimental and spectral data,
and crystallographic data.
Teong; X. K. Li and Y. G. Zhang, ChemSusChem, 2014,
2131-2137
7,
1
2
D. R. Dodds, R. A. Gross, Science, 2007, 318, 1250-1251.
(a) R. A. Sheldon, Green Chem., 2014, 16, 950-963; (b) A. M.
Ruppert, K. Weinberg, R. Palkovits, Angew. Chem.-Int. Edit.,
2012, 51, 2564-2601; (c) D. S. van Es, J. Renew. Mater., 2013,
15 W. Partenheimer and V. V. Grushin, Adv. Synth. Catal., 2001,
343, 102-111.
16 M. A. Lilga, R. T. Hallen and M. Gray, Top. Catal., 2010, 53
1264-1269.
,
1
, 61-72; (d) Y. Zhang, J. Y. G. Chan, Energy Environ. Sci.,
2010, , 408-417; (d) J. J. Bozell, Science, 2010, 329, 522-523.
(a) H. A. Rass, N. Essayem, M. Besson, Chemsuschem, 2015,
, 1206-1217; (b) A. Jain, S. C. Jonnalagadda, K. V.
Ramanujachary, A. Mugweru, Catal. Commun., 2015, 58
17 X. Y. Wan, C. M. Zhou, J. S. Chen, W. P. Deng, Q. H. Zhang, Y.
H. Yang and Y. Wang, ACS Catal., 2014, , 2175-2185.
3
4
3
18 (a) P. Vinke, W. van der Poel and H. Van Bekkum., Stud. Surf.
Sci. Catal., 1991, 59, 385-394; (b) A. Takagaki, M. Takahashi,
S. Nishimura and K. Ebitani, ACS Catal., 2011, 1, 1562-1565;
8
,
179-182; (c) B. Liu, Y. S. Ren, Z. H. Zhang, Green Chem., 2015,
17, 1610-1617; (d) D. J. Chadderdon, L. Xin, J. Qi, Y. Qiu, P.
Krishna, K. L. More, W. Z. Li, Green Chem., 2014, 16, 3778-
(c) J. F. Nie and H. C. Liu, J. Catal., 2014, 316, 57-66; (d) J. F.
Nie, J. H. Xie and H. C. Liu, J. Catal., 2013, 301, 83-91.
4 | Green Chem., 2015, 00, 1-3
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19 (a) J. H. Xie, J. F. Nie and H. C. Liu, Chin. J. Catal., 2014, 35
COMMUNICATION
,
937-944; (b) Y. Y. Gorbanev, S. Kegnaes and A. Riisager,
Catal. Lett., 2011, 141, 1752-1760.
20 K. R. Vuyyuru and P. Strasser, Catal. Today, 2012, 195, 144-
154.
21 M. Krystof, M. Perez-Sanchez and P. D. de Maria,
Chemsuschem, 2013, 6, 826-830.
22 K. Shimizu, R. Uozumi and A. Satsuma, Catal. Commun.,
2009, 10, 1849-1853.
23 J. M. R. Gallo, D. M. Alonso, M. A. Mellmer and J. A. Dumesic,
Green Chem., 2013, 15, 85-90.
This journal is © The Royal Society of Chemistry 20xx
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Table of Contents
The catalytic conversion of 5-hydroxymethyl furfural (HMF) to 2,5-
furandicarboxylic acid (FDCA) over commercial Ru/C catalyst in
base-free aqueous solution was studied with up to 88% FDCA
yield.
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