Reactive Extraction Enhanced by Synergic Microwave Heating: Furfural Yield Boost in Biphasic Systems

Article abstract of DOI:10.1002/cssc.202000966

Reactive extraction is an emerging operation in the industry, particularly in biorefining. Here, reactive extraction was demonstrated, enhanced by microwave irradiation to selectively heat the reactive phase (for efficient reaction) without unduly heating the extractive phase (for efficient extraction). These conditions aimed at maximizing the asymmetries in dielectric constants and volumes of the reaction and extraction phases, which resulted in an asymmetric thermal response of the two phases. The efficiency improvement was demonstrated by dehydrating xylose (5 wt percent in water) to furfural with an optimal yield of approximately 80 mol percent compared with 60–65 mol percent under conventional biphasic conditions, which corresponds to approximately 50 percent reduction of byproducts.

Full text of DOI:10.1002/cssc.202000966

Chemistry–Sustainability–Energy–Materials
Accepted Article
Title: Reactive Extraction Enhanced by Synergic Microwave Heating -
Furfural Yield Boost in Biphasic Systems
Authors: Luca Ricciardi, Willem Verboom, Jean-Paul Lange, and
Jurriaan Huskens
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: ChemSusChem 10.1002/cssc.202000966
Link to VoR: https://doi.org/10.1002/cssc.202000966
01/2020

10.1002/cssc.202000966
ChemSusChem
COMMUNICATION
Reactive Extraction Enhanced by Synergic Microwave Heating -
Furfural Yield Boost in Biphasic Systems
Luca Ricciardi, [a] Willem Verboom, *,[a] Jean-Paul Lange,*,[b],[c] and Jurriaan Huskens*,[a]
Abstract: Reactive extraction is an emerging operation in the industry,
particularly in biorefining. We show here reactive extraction enhanced
by microwave irradiation to selectively heat the reactive phase (for
efficient reaction) without unduly heating the extractive phase (for
efficient extraction). These conditions aim at maximizing the
asymmetries in dielectric constants and volumes of the reaction and
extraction phases, which results in an asymmetric thermal response
of the two phases. We demonstrate the efficiency improvement by
dehydrating xylose (5 w% in water) to furfural with an optimal yield of
approx. 80 mol%, vs. 60-65 mol% under conventional biphasic
conditions, which corresponds to ~50% reduction of by-products.
Reactive extraction has emerged recently as a promising
[1,2,3]
technology for the conversion of bio-based feedstock.
This
Figure 1. Visualization of the effect of having a asymmetric response in the
biphasic system on reative extraction of furfural. Furfural is formed in the
microwave active “hot“ aqueous phase and extracted and stored in the MW
silent “cold“ toluene phase.
technique is a cost-effective way to circumvent problems in biorefinery,
such as recovering and recycling catalysts, separating products and
suppressing side reactions. [1,2,3] Reactive extraction shows a wide
scope of applications and can be also used in the conversion of
sugars into furans (e.g. furfural).[3]
microwave heating does not result in improvement of the
selectivity but only in a rate enhancement. [9]
This has been explained through purely thermal effects
such as inhomogeneous heating. [9,22,23,24]
Furfural is recognized as a top added value chemical. It has a
rich source of derivatives and it can be used as an additive for fuels
with promising performance.[4,5] Furfural can be obtained from the
acid-catalyzed dehydration of D-xylose, a monomeric sub-unit of
hemicellulose, which is a component of lignocellulosic feedstock.[4,5,6,7]
The industrial approach for furfural production, which employs
aqueous medium and mineral acid catalysis (H2SO4), does not deliver
furfural yields beyond approx. 45 mol% on xylose base.[4,5,7,8,9] This
shortcoming is mainly caused by the formation of insoluble by-
products called ‘humins’, resulting from furfural-xylose condensation
and direct resinification of furfural at high conversion.[4,5,8]
Incidentally, biphasic operation has been combined with
microwave heating, but no specific effects have been
recognized.[25,26] We nevertheless reasoned that the combination
of microwave heating and biphasic operation could have a
synergic effect on the selectivity of the furfural production (Figure
1). Microwave heating could heat up the aqueous phase to
accelerate the dehydration of xylose, while leaving the organic
phase colder to favor the extraction of furfural. We will show here
that the combination of microwave heating and biphasic operation
can indeed create a synergic effect that permits operation at
higher xylose conversions than normally applied and pushes the
yield into a section of the reaction parameter space that cannot
be attained by one of the conditions alone (Figure 2a). Application
to the combined microwave-biphasic operation may thus yield a
further enhancement due to the synergic effect, moving the
optimal operation point to high xylose conversion, with an effect
that is related with the microwave responsiveness of the two
phases (Figure 2b). By unravelling the basis of this effect, we
believe we open the door to improving a wide range of reactive
extraction processes.
Several examples of high-yield (>80 mol%) furfural production
have been reported, using polar aprotic organic solvents.[10,11]
However, such approaches suffer from the need to extract the xylose
from the aqueous phase to resolubilise it in the polar organic solvent.
An alternative approach, based on reactive extraction in biphasic
operation, reached furfural yields of approx. 65 mol%.[11,12,13] This
selectivity enhancement is generally assigned to ‘continuous
extraction’ of furfural into the organic phase, with the consequent
inhibition of furfural degradation. [8,12,14,15,16,17]
Microwave heating has been widely applied to organic
synthesis in general, and has been abundantly used for the
dehydration of sugars to furans, e.g. of xylose to furfural.[18,19,20,21]
When applied to monophasic aqueous xylose solution,
University of Twente, P.O. Box 217, 7500 AE Enschede, The
Netherlands
[a]
L. Ricciardi, Dr. W. Verboom, Prof. Dr. Ir. J. Huskens
Molecular NanoFabrication group
Email: j.p.lange@utwente.nl
Prof. Dr. Ir. J.-P. Lange
Shell Technology Center
MESA+ Institute for Nanotechnology
University of Twente, P.O. Box 217, 7500 AE Enschede, The
Netherlands
[c]
Grasweg 31, 1031 HW Amsterdam, The Netherlands
Supporting information for this article is given via a link at the end of the
document.
E-mail: w.verboom@utwente.nl , j.huskens@utwente.nl
Prof. Dr. Ir. J.-P. Lange
Sustainable Process Technology group
[b]
1
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10.1002/cssc.202000966
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Figure 2. (a) Visualization of the selectivity and yield enhancement in relation with the reaction conditions. The blue and cyan curves correspond to the monophasic
system at traditional and microwave heating conditions, respectively. Moving from monophasic to biphasic conditions results in an overall improvement at traditional
heating conditions (green curve). The maximum furfural yield is reported to raise from approx. 45 mol% to 65 mol%. When implementing microwave heating at
biphasic conditions (red curve, current work) at the optimal operation point, represented by high xylose conversion (>90%) there is a further improvement in selectivity
and yield, which is also related to the dielectric constants of the two phases. (b) Visualization of the ‘yield boost’ at biphasic conditions in relation with the difference
in polarity between the two phases of the system, where εA is the dielectric constant of the aqueous phase and εO is that of the organic phase. The ‘yield boost’ at
microwave conditions will arise at a higher ratio (red line), as the microwave responsiveness changes accordingly, while at traditional heating conditions the
difference in dielectric properties does not have any influence on the heating profile, resulting in an unvaried final yield (black line).
Figure 3. (a) Furfural yield (mol%) vs xylose conversion (%), at pH = 1, 1:1 water-toluene ratio, under traditional and microwave heating at 200 oC. (b) Zoom-in of
the graph of (a) at xylose conversions > 85% for the visualization of the ‘yield boost’ (approx. 10 mol%) and the maximum selectivity shift to higher xylose conversion
(%). Lines are guides to the eye.
In biphasic systems, the microwave responsiveness of each
phase is strongly dependent on its dielectric properties: a higher
polarity corresponds to a higher dielectric loss at microwave
conditions, which results in a more efficient heating.[27,28] The
monitored the temperature using an IR temperature control system.
The accuracy of this control system was ensured following a
calibration procedure prior to use, showing a standard deviation of
±1°C.[9] Under microwave heating, more information about the global
temperature of the medium is obtained by comparing the operating
pressure (approx. 18-20 bar) to the equivalent saturated pressure
(Figure S1).The operating pressure measured in the presence of the
biphasic water-toluene mixture of 1:1 volume ratio suggests a bulk
liquid temperature that deviates less than ±10 °C from that measured
by the IR sensor.[29] Yet, we fully realize that these calibration data do
not give any quantitative information on local temperature differences
between the two liquid phases.[9]
combination of
a non-polar organic solvent (e.g., toluene or
methylcyclohexane) and a highly polar aqueous phase (e.g., water
with a high ionic strength) might lead to an inhomogeneous
temperature distribution between the two phases, as the aqueous
phase gets selectively heated by the microwave irradiation.[12,16]
It is crucially important to monitor the reaction temperature
under microwave conditions accurately.[9,22,23,24] Fiber-optic sensors
are commonly used to internally monitor the temperature but, when
the homogeneity of the mixing cannot be ensured, such sensors show
surprisingly large temperature gradients throughout the reaction
medium.[22] Due to the high operation temperatures applied in this
study and the necessity to seal the pressurized reaction vessels, we
For this study a biphasic system of an aqueous solution of
xylose (350 mM, pH = 1 from H2SO4) and an organic solvent of choice
was heated to 200 °C both at traditional batch and microwave heating
conditions. To tune the microwave responsiveness of the biphasic
2
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Figure 4. (a) Furfural yield (mol%) vs xylose conversion (%), at pH = 1, at various water-toluene ratios, under microwave heating at 200 oC (section at conversions
>90% shown). The multiple points at 100% xylose conversion represent the progressive degradation of furfural with increasing reaction time. (b) Visualization of
the ‘yield boost’ obtained at the optimal operation points (at high xylose conversion) varying the toluene vol%. The data point at 90% toluene is the result of a
single experiment so is reported without an error bar.
Figure 5. (a) maximum furfural yield (mol%) at xylose conversions > 90% as a function of the ratio of the dielectric constants of the aqueous and organic phases
(15-20 min, 200 oC, 1:1 solvent ratio, pH = 1). The line is a guide to the eye. (b) Visualization of the xylose-to-furfural ‘yield boost’ in the reaction of xylose
dehydration observed when varying the water-toluene ratio from 1:1 to 1:4 (200 oC, microwave heating), in relation with the ionic strength of the aqueous phase
(dependent on acid and salt concentrations); data obtained at the optimal operation point (i.e., at maximum yield).
system, the volume ratio of the two phases and their chemical
composition was varied. Toluene, commonly used as organic phase
under biphasic conditions, was chosen as a benchmark hydrophobic
solvent for its low dielectric constant (εr = 2.4), which results in
negligible microwave activity, and for its aromaticity that ensures high
affinity for the extraction of furfural. The toluene phase will be heated
slightly being in contact with the aqueous phase, but this effect is
minimized by operating at high toluene:water ratio. Our experimental
setup did not allow us to gather information on the temperature of the
two different phases. However, in the biphasic system the two phases
remained immiscible also at high temperature (Figure S2).
At a 1:1 water-toluene ratio, both traditional heating and
microwave heating can achieve full xylose conversion. Under
traditional heating full xylose conversion was obtained after 360
min, at microwave conditions in 15 min (Figure S4), illustrating the
rate enhancement obtained under microwave conditions. The two
heating methods can also be compared in terms of furfural
selectivity and yield, and their optimal points of operation. At
xylose conversions from 0% to 85-90%, selectivity and yield run
parallel for both heating methods (Figures 3a and S4). In contrast,
for xylose conversions >90% a higher furfural yield is recorded
with microwave heating (Figure 3b), reaching a yield of approx.
75 mol% (at a conversion >95%), whereas traditional heating
provides maximally approx. 65 mol%, reached at approx. 85%
conversion, as has also been observed in literature.[4,5,7,8,9]
Correspondingly, at traditional heating conditions the selectivity
maximum is obtained at approx. 85% xylose conversion (after 240
min of reaction; Figure S4), while under microwave heating the
maximum is reached at >95% xylose conversion (after approx. 13
min of reaction; Figure S4).
Since the dehydration of xylose is acid catalyzed, the
composition of the aqueous phase (pH = 1 from H2SO4) will ensure
both optimal catalytic conditions for furfural formation and high ionic
strength for microwave responsiveness. [30,31] The concentrations of
furfural and unreacted xylose in the crude reaction mixture were
evaluated through 1H NMR spectroscopy (Figure S3) in order to
determine the rate and the selectivity of the xylose dehydration into
furfural at biphasic conditions, which can also be compared with the
monophasic system (Figures S4-S5).
3
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This observed rate enhancement cannot simply be
assigned to a higher bulk temperature of the medium under
microwave heating.[9] Such differences in the reaction rate would
correspond to effective bulk temperatures up to 50 °C higher than
the measured ones. Not only do these values exceed the
deviations shown by the calibration, they would result in an
excessive saturated pressure that is not observed experimentally.
The observed ‘yield boost’ is thus a result of a shift of the
optimal operating point (maximum furfural yield) to higher xylose
conversions. This can be rationalized by inhibition of furfural
degradation pathways in the late stage of the reaction, provided
by an improved furfural extraction from the highly reactive
aqueous phase. The selectivity enhancement upon microwave-
assisted biphasic operation appeared to depend on the toluene
volume fraction (Figure S6). Varying the solvent volume ratio will
affect the overall dielectric properties of the system as well as the
extraction capacity. As a result, the maximum yield at high xylose
conversions slightly increased with the toluene volume fraction
when operated under microwave irradiation, and these higher
yields were again achieved at higher xylose conversions (Figure
4a). Thus, a maximum ‘yield boost’ of approx. 30 mol% is
achieved when changing operation from monophasic to biphasic
at 90 vol% toluene (Figure 4b). Control experiments showed that
the toluene fraction does not affect the final furfural yield under
traditional heating (Figure S6b).
aqueous solution (Figure S9).[30] Two new sets of experiments
were performed, one at pH = 3 from H2SO4 (at a significantly lower
ionic strength) and one additional control where a passive, non-
reactive ion source (Na2SO4), was added to achieve the high ionic
strength of the solution at pH = 1, used above but keeping the pH
= 3. Both sets were performed at 1:1 and 1:4 water-toluene ratios
(Figures S10 and S111).
As described above, at pH = 1 under microwave heating,
the toluene vol% clearly influenced the process (Figure 4b). In
contrast, at pH = 3 no yield enhancement was observed (Figures
5b and S10) when varying the solvent ratio. Yet, upon adding an
inert salt to the solution at pH = 3, to reach the same ionic strength
of the experiment performed at pH = 1 (Figure S11), a similar
‘yield boost’ is observed when varying the solvent ratio (Figure
5b). This enhancement is, however, always limited, as in the
previous cases, at high xylose conversions and the optimal
operation point is reached in approx. 15-20 min of reaction
(Figures S10 and S11). This shows that the microwave
responsiveness of the aqueous phase, which is directly related to
the ionic strength, is crucial to achieve the conditions that lead to
a selectivity enhancement.[30,31] However, the best results in terms
of furfural yield (mol%) are obtained in the system at pH = 1,
indicating that a fast reaction is mandatory to prevent degradation
and humins formation. This is arguably due to the reaction rate
outcompeting the rate of heating the toluene phase upon
contacting the aqueous phase.
The observed ‘yield boost’ can be explained by the
suppression of the acid-catalyzed degradation and condensation
reactions of furfural, i.e., by a ‘medium effect’. The furfural is
extracted and stored safely in the organic phase (Figure S7),
which at microwave conditions has a lower temperature than the
aqueous phase. This difference in temperature arises only at
microwave conditions because the selective heating of the
aqueous phase cannot be observed under traditional heating
conditions, resulting in no selectivity enhancement under
traditional heating. No significant yield enhancement could be
obtained by raising the toluene percentage over 80% (Figure 4b).
This upper limit for the yield can be rationalized by the fact that
furfural partitions between the organic phase and the aqueous
phase, in the latter of which acid-catalyzed degradation can occur.
As mentioned above, the relative polarity of the two phases
is important (Figure 2b) and it can be influenced by independently
varying the dielectric constants of the organic phase and of the
aqueous phase. Various organic solvents with different polarities
were employed to show the effect of varying the dielectric
constant of the organic phase on this ‘selectivity boost’ (Figure
5a).
In conclusion, we report a consistent yield improvement of
approx. 10-15 mol% in the dehydration of xylose by synergistically
combining two different factors: microwave heating and reactive
extraction using two phases with asymmetric polarity and
volumes. Generally, the improvement of the yield of a chemical
process is obtained by the development and optimization of a
catalyst, possibly assisted by plasmonics or ultrasound, or by
varying the solvent system and using membranes or other
components for the in situ separation of the various products.[32-
38]
In this study we show how a more optimal section of the
reaction parameter space can be reached by the combination of
microwave heating and specific biphasic conditions and by
varying the dielectric properties of both phases. Such forms of
synergism can become an important tool for organic synthesis
and chemical processes. By unravelling the critical parameters of
this process optimization, we believe this approach can be applied
to improve other reactive extraction processes.
Acknowledgements
As expected, based on the previous experiments, at
microwave conditions the polarity of the solvent appears to
strongly affect the conversion of xylose to furfural (Figures 5a and
S8). At 1:1 biphasic conditions a maximum furfural yield of approx.
75 mol% is obtained for low-polarity solvents such as toluene (εr
= 2.4), methylcyclohexane (MCH, εr = 0.7) or perfluorotoluene (εr
approx. 0). When moving to solvents with a higher polarity and
significantly higher microwave absorption, the furfural yield
decreases significantly, e.g. to approx. 60 mol% with
methylisobutylketone (MIBK, εr = 4.3) and octanol (εr = 10). In
comparison, 45 mol% is achieved for the monophasic water
system under microwave heating. When using toluene-water at
traditional heating, only 65 mol% yield is achieved.
Financial support from Royal Dutch Shell plc is gratefully
acknowledged. L.R. is grateful for the fruitful discussions with
Richard J. M. Egberink and for part of the experimental work by
Matthijs van Berkel.
Conflict of interest
The authors declare no conflict of interest.
Keywords: biomass • biphasic • furfural • microwave chemistry •
synergy
The microwave responsiveness of the aqueous phase can
also be tuned by varying the pH and/or salt concentration of the
4
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[1]
[2]
[3]
[4]
[5]
[6]
H.-J. Huang, S. Ramaswamy, U. W. Tschirner, B.V. Ramarao, Sep. Purif.
Technol. 2008, 62, 1–21.
[38] R. S. Varma, K. P. Naicker, D. Kumar, J. Mol. Catal. A Chem. 1999, 149,
153-160.
S. Ramaswamy, H.-J. Huang, B.V. Ramarao, Separation and Purification
Technologies in Biorefineries, Wiley, Chichester, UK, 2013.
A. A. Kiss, J.-P. Lange, B. Schuur, D. W. F. Brilman, A. G. J. van der
Ham, S. R. A. Kersten, Biomass Bioenergy 2016, 95, 296-309.
J.-P. Lange, E. van der Heide, J. van Buijtenen, R. Price, ChemSusChem
2012, 5, 150-166.
R. Mariscal, P. Maireles-Torres, M. Ojeda, I. Sádaba, M. López
Granados, Energy Environ. Sci. 2016, 9, 1144-1189.
J.-P. Lange, I. Lewandowski, P. Ayoub, in “Sustainable Development in
the Process Industry – cases and impacts”, (Harmsen, Powell, eds)
Wiley, 2010, 171-208.
[7]
[8]
[9]
P. Priecel, J. E. Perez Mejia, P. D. Carà, J. A. Lopez-Sanchez, Green
Chem. 2018, 56, 243-299.
J. E. Romo, N. Bollar, C. J. Zimmermann, S. G. Wettstein,
ChemCatChem 2018, 10, 4805-4816.
L. Ricciardi, W. Verboom, J.-P. Lange, J. Huskens, ACS Sustain. Chem.
Eng. 2019, 7, 14273-14279.
[10] L. Shuai, J. Luterbacher, ChemSusChem 2016, 9,133–155.
[11] C. Sener, A. H. Motagamwala, D. M. Alonso, J. A. Dumesic,
ChemSusChem 2018, 11, 2321–2331.
[12] Y. Román-Leshkov, J. N. Chheda, J. A. Dumesic, Science 2006, 312,
1933-1937.
[13] B.F.M. Kuster, Starch Starke 1990, 42, 314-321.
[14] M. Peters, M. F. Eckstein, G. Hartjen, A. C. Spiess, W. Leitner, L. Greiner,
Ind. Eng. Chem. Res. 2007, 46, 7073-7078.
[15] F. Delbecq, Y. Takahashi, T. Kondo, C. C. Corbas, E. R. Ramos, C. Len,
Catal. Commun. 2018, 110, 74-78.
[16] R. Weingarten, J. Cho, W. C. Conner, Jr., G. W. Huber, Green Chem.
2010, 12, 1423-1429.
[17] G. G. Millán, S. Hellsten, A. W. T. King, J.-P. Pokki, J. Llorca, H. Sixta, J.
Ind. Eng. Chem. 2019, 72, 354-363.
[18] A. K. Rathi, M. B. Gawande, R. Zboril, R. S. Varma, Coord. Chem. Rev.
2015, 291, 68-94.
[19] M. B. Gawande, S. N. Shelke, R. Zboril, R. S. Varma, Acc. Chem. Res.
2014, 47, 1338-1348.
[20] F. Delbecq, Y. Takahashi, T. Kondo, C. Cara Corbas, E. Ruiz Ramos, C.
Len, Catal. Commun. 2018, 110, 74-78.
[21] Y. Wang, F. Delbecq, R. S. Varma, C. Len, Mol. Catal. 2018, 445, 73–
79.
[22] Á. Díaz-Ortiz, P. Prieto, A. de la Hoz, Chem. Rec. 2018, 18, 85-97.
[23] C. O. Kappe, Acc. Chem. Res. 2013, 46, 1579-1587.
[24] M. A. Herrero, J. M. Kremsner, C. O. Kappe, J. Org. Chem. 2008, 73, 36-
47.
[25] K. Hayashi, S. Kim, Y. Kono, M. Tamura, K. Chiba, Tetrahedron Lett.
2006, 47, 171-174.
[26] D. Bogdal, S. Bednarz, M. Łukasiewicz, M. Kasprzyk, Chem. Eng.
Process. 2018, 132, 208-217.
[27] Y. Wang, M. N. Afsar, Prog. Electromagn. Res. 2003, 42, 131-142.
[28] L. Gai, L. Guo, Q. An, Z. Xiao, S. Zhai, Z. Li, Micropor. Mesopor. Mat.
2019, 288, 1-13.
[29] F. E. Anderson, J. M. Prausnitz, Fluid Phase Equilibr. 1986, 32, 63-76.
[30] C. Gabriel, S. Gabriel, E. H. Grant, B. S. J. Halstead, D. M. P. Mingos,
Chem. Soc. Rev. 1998, 27, 213-224.
[31] C. O. Kappe, Angew. Chem. Int. Ed. 2004, 43, 6250-6584.
[32]
E. S. Isbrandt, R. J. Sullivan, S. G. Newman, Angew. Chem. Int. Ed.
2019, 58, 7180–7191.
[33] N. Jiang, Y. Zhao, C. Qiu, K. Shang, N. Lu, J. Li, Y. Wu, Y. Zhang, Appl.
Catal. B 2019, 259, 1-15.
[34] C. Guerrero, C. Vera, F. Acevedo, A. Illanes J. Biotechnol. 2015, 209,
31-40.
[35] G. Zeng, Y. Wang, D. Gong, Y. Zhang, P. Wu, Y. Sun, ACS Cent. Sci.
2019, 5, 1834-1843.
[36] R. Joncour, A. Ferreira, N. Duguet, M. Lemaire, Org. Process Res. Dev.
2018, 22, 312-320.
[37] C. Zhan, X. J. Chen, Y. F. Huang, D. Y. Wu, Z. Q. Tian, Acc. Chem. Res.
2019, 52, 2784-2792.
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Entry for the Table of Contents
Reactive extraction of xylose to furfural is boosted by a synergic combination of microwave heating and biphasic operation to deliver
a hot aqueous phase for reaction and a colder organic phase for extraction.
6
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