CHEMSUSCHEM
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DOI: 10.1002/cssc.201300190
Heterogeneous Palladium Catalysts for Decarbonylation of
Biomass-Derived Molecules under Mild Conditions
Yao-Bing Huang, Zhen Yang, Meng-Yuan Chen, Jian-Jun Dai, Qing-Xiang Guo, and Yao Fu*[a]
The effective use of renewable
carbohydrates derived from
lignocellulosic biomass to gen-
erate chemicals and fuels is im-
portant in order to establish
sustainable energy systems for
the future.[1] However, these car-
bohydrates are primarily avail-
able as highly oxygenated bio-
polymers, making their utiliza-
tion difficult.[2] Recent efforts
have focused on depolymeriza-
tion into small molecules and
subsequent conversion into
chemicals or fuels through
methods such as fast pyrolysis,[3]
Scheme 1. Elementary reactions involved in the lignocellulosic biomass transformations.
gasification/Fischer–Tropsch
synthesis,[4] and fermentation.[5]
Another appealing route involves the direct conversion of
lignocellulosic biomass into platform chemicals [e.g., 5-hy-
droxymethylfurfural (HMF), levulinic acid (LA), furfural],[6] fol-
were developed, allowing milder decarbonylation conditions
(ca. 2008C).[13] Apart from the catalysts, several key technolo-
gies were explored to further improve the reaction efficien-
cy;[14] however, these routes still have limitations such as harsh
conditions or low efficiencies. In addition, these catalytic sys-
tems may not be suitable for other platform molecules, such
as HMF which would easily form humins at the elevated reac-
tion temperatures.[15] Recently, Leitner et al. reported a success-
ful example of selective decarbonylation of HMF to furfuryl al-
cohol (FFA) by using an [IrCl(cod)]2/PCy3 catalyst in the pres-
ence of compressed CO2, reporting a yield of up to 95%.[16]
Inspired by their findings, we were interested in the develop-
ment of highly efficient catalytic systems for the selective de-
carbonylation of biomass-derived molecules under milder con-
ditions, especially with a recyclable solid catalyst.
lowed by conversion into
a range of useful molecules
(Scheme 1).[7,8] The selective modification/removal of oxygen
from these compounds is the main challenge of this route.
Various types of elementary reactions have been developed
to achieve the transformation of biomass-derived platform
molecules, such as dehydration, hydrogenolysis, decarboxyla-
tion, and decarbonylation. For example, polyols can be dehy-
drated into unsaturated compounds,[9] C6 and C5 sugars can be
hydrogenolyzed into alkanes (light fuels),[10] and long-chain or-
ganic acids derived from plant oils can be converted into
diesel-range alkanes by decarboxylation reactions.[11] Among
these methods, decarbonylation involves the conversion of
biomass-derived aldehydes by releasing a CO moiety, which
not only enriches the types of transformations available but
also produces a diversity of new chemicals.
Herein, we demonstrate that a system comprising palladium
nanoparticles (NPs) deposited on porous SBA-15 can serve as
a highly efficient heterogeneous catalyst for the selective de-
carbonylation of HMF to FFA (Scheme 2). The reaction pro-
ceeds under ambient, atmospheric conditions at a relatively
low temperature (110–1308C) with high yields (up to 96%).
The catalysts can be readily recovered and reused at least four
times, with a final yield of 87%. The catalytic system is effec-
tive when applied to other aldehydes derived from biomass,
also.
A typical decarbonylation reaction in biomass conversion is
the selective decarbonylation of furfural to furan. An earlier
process used to achieve this goal in industry is based on metal
oxide catalysts and high temperatures (usually >3008C).[12]
In the following years, various supported-noble-metal catalysts
[a] Y.-B. Huang, Z. Yang, M.-Y. Chen, J.-J. Dai, Prof. Q.-X. Guo, Prof. Y. Fu
Anhui Province Key Laboratory of Biomass Clean Energy
Department of Chemistry
We set out by examining the decarbonylation of HMF in the
presence of different solvents and supported-metal catalysts.
Considering that solvents are crucial in the conversion of HMF
at elevated reaction temperatures, we firstly investigated the
stability of HMF in different solvents (A.R. grade or anhydrous)
in the absence of catalyst (Table 1; Supporting Information
University of Science and Technology of China
Hefei 230026 (PR China)
Supporting Information for this article is available on the WWW under
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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