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A Facile Solid-Phase Route to Renewable Aromatic Chemicals from
Biobased Furanics
Shanmugam Thiyagarajan, Homer C. Genuino, Jan C. van der Waal, Ed de Jong,*
Bert M. Weckhuysen, Jacco van Haveren, Pieter C. A. Bruijnincx,* and Daan S. van Es*
Abstract: Renewable aromatics can be conveniently synthe-
sized from furanics by introducing an intermediate hydro-
genation step in the Diels–Alder (DA) aromatization route, to
effectively block retro-DA activity. Aromatization of the
hydrogenated DA adducts requires tandem catalysis, using
a metal-based dehydrogenation catalyst and solid acid dehy-
dration catalyst in toluene. Herein it is demonstrated that the
hydrogenated DA adducts can instead be conveniently con-
verted into renewable aromatics with up to 80% selectivity in
a solid-phase reaction with shorter reaction times using only an
acidic zeolite, that is, without solvent or dehydrogenation
catalyst. Hydrogenated adducts from diene/dienophile combi-
nations of (methylated) furans with maleic anhydride are
efficiently converted into renewable aromatics with this new
route. The zeolite H-Y was found to perform the best and can
be easily reused after calcination.
ing increased attention.[4–9] The DA aromatization strategy
typically involves two steps, that is, cycloaddition of a furanic
diene with an appropriate dienophile, followed by acid-
catalyzed dehydration of the intermediate DA adduct. A
prominent example of this approach is the reaction of 2,5-
dimethylfuran (DMF) and (excess of) ethylene over
Brønsted-acid-containing BEA- and FAU-type zeolites to
produce renewable p-xylene, a precursor to terephthalic acid
(TA) and polyethylene terephthalate (PET), with yields as
high as 90%.[4] Wang et al. showed that solid acid oxides, such
as WOx-ZrO2 and niobic acid, also demonstrate high catalytic
activities for this reaction.[5] Pacheco and Davis later explored
DA aromatization of various oxidized derivatives of 5-
hydroxymethylfurfural (HMF) with ethylene over Lewis-
acidic molecular sieves, Sn-Beta in particular.[6]
DA aromatization of 2-methylfuran (MF) and ethylene
proved less efficient over either H-Beta or Sn-Beta, with
toluene selectivities not exceeding 46%, because MF was
consumed by side reactions such as dimerization.[7] Indeed,
selectivity for aromatization typically decreases as the furan
ring becomes less substituted.[8] Related to the challenges
associated with controlling such furan-dependent side reac-
tions, careful control over the second catalytic aromatization
step is often critical as the intermediate DA adducts are
typically unstable and prone to retro-DA reaction, especially
at more elevated temperatures.[8,9] Consequently, one has to
run the aromatization reaction at either low temperature[10]
or, if ethylene is the dienophile, at high pressure.[4–6] Mah-
moud et al. addressed the issue of DA adduct instability and
furan reactivity by using a mixture of methanesulfonic acid
and acetic acid anhydride to synthesize (substituted) phthalic
anhydride with high selectivity at 808C.[8] In an alternative
approach, we recently reported on a new three-step strategy
and dealt with this general challenge in DA aromatization by
including a mild intermediate hydrogenation step of the
oxabicyclic adduct 1.[9]
T
he development of new routes for the production of ꢀdrop-
inꢁ aromatic chemicals from renewable resources is currently
receiving considerable attention because of the increased
demand, finite fossil resources, and the recognized need for
more sustainable production routes.[1] This attention is further
compounded by the challenges associated with the changes in
bulk aromatics supply caused by the increased use of shale-
gas-derived feeds in steam cracker facilities.[2] Of the various
potential routes to biobased aromatics, Diels–Alder (DA)
conversions of sugar-derived furanic compounds[3] are receiv-
[*] Dr. S. Thiyagarajan, Dr. H. C. Genuino, Prof. Dr. B. M. Weckhuysen,
Dr. P. C. A. Bruijnincx
Inorganic Chemistry and Catalysis
Debye Institute for Nanomaterials Science, Utrecht University
Universiteitsweg 99, 3584 CG Utrecht (The Netherlands)
E-mail: p.c.a.bruijnincx@uu.nl
Dr. S. Thiyagarajan, Dr. J. van Haveren, Dr. D. S. van Es
Food & Bio-based Research
Wageningen University and Research Centre
P.O. Box 17, 6700 AA Wageningen (The Netherlands)
E-mail: daan.vanes@wur.nl
This new route, which is run in the liquid phase, is shown
in Scheme 1.[9a] The hydrogenated DA adduct 2 is thermally
stable and efficiently aromatized in a tandem catalytic
reaction using a mixture of a solid acid dehydration catalyst
(e.g., zeolites or resins) and a dehydrogenation catalyst (e.g.,
metal on a carbon support). For example, catalytic aromati-
zation of 2 in toluene at 2008C with H-VUSY (SiO2:Al2O3 =
11.5) and Pd/C resulted in a combined yield of 84% for all
aromatics.[9a] Formal catalytic oxidation would then give the
desired aromatic di- and tricarboxylic acid end products.[11]
Notably, if this solution-phase reaction was run with only the
zeolite catalyst, very low aromatics yields were obtained, with
the g-lactone intermediate 3 being the major product
Dr. J. C. van der Waal, Dr. E. de Jong
Avantium Chemicals
Zekeringstraat 29, 1014 BV Amsterdam (The Netherlands)
E-mail: ed.dejong@avantium.com
Supporting information for this article is available on the WWW
ꢀ 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co.
KGaA. TThis is an open access article under the terms of the Creative
Commons Attribution-NonCommercial-NoDerivs License, which
permits use and distribution in any medium, provided the original
work is properly cited, the use is non-commercial and no modifica-
tions or adaptations are made.
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ꢀ 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2016, 55, 1368 –1371