a
b
Table 2 Conversion of saccharides individually in the biphasic system
the amorphous form displays strong acid properties which
1
4
increases the catalytic activity.
The catalyst upon treatment of 1 M H PO and calcination at
Saccharide
t/min
Yield (%)
Conv. (%)
TOF
3
4
Fructose
Glucose
Inulin
100
140
150
150
120
90
58
87
50
79
94
70
95
91
91
36.1
16.7
23.4
13.5
16.3
300 1C had larger surface area and more acid sites which led to
the polysaccharide hydrolysis and monosaccharide dehydration
to occur smoothly. As for polysaccharides, it seems that the
glucosidic bond was weakened by the acid sites of the catalyst,
thus producing fructose and glucose, which would dehydrate into
HMF at the acidic sites of TA-p. A putative pathway for glucose
as reactant catalyzed by TA-p is that the basic sites of TA-p
catalyzed the isomerization of glucose into fructose which was
then converted into HMF catalyzed by acidic sites of TA-p.
In conclusion, HMF, the most important intermediate
between bio-based chemicals and petroleum-based chemicals,
was efficiently obtained from monosaccharides, polysaccharides
and Jerusalem artichoke juice by a simple heterogeneous catalyst.
The catalyst made the process favorable so facilitating
environment-friendly and cost effective conversion of biomass
into bio-fuels and chemicals.
c
JA1
JA2
d
a
Reaction conditions: saccharide: 1.2 g, TA-p: 0.1 g, 20 ml of water,
3
0 ml of 2-butanol, 160 1C, 800 rpm. Yields were determined by HPLC
b
analysis. Turnover frequency (TOF): expressed as mmol of HMF/
c
d
(
g of catalyst ꢂ h). JA1: juice of Jerusalem artichoke tuber. JA2:
juice of Jerusalem artichoke tuber processed by ultrafiltration dialysis,
to remove protein, and pretreated by cation and anion exchange resin
to remove ions.
16
governments. Now the main challenge is how to convert it into
fuels and useful building blocks. Thus the Jerusalem artichoke
juice was used as reactant to produce HMF, and the HMF yield
reached to 50% when Jerusalem artichoke juice was hydrolyzed
by exoinulinase without other pretreatment. Considering that a
certain amount of ions are in Jerusalem artichoke juice, they might
be disadvantageous to the activity of the catalyst. Therefore,
further treatment was applied to eliminate the ions in the
Jerusalem artichoke juice through cation and anion exchange
resins. An improved HMF yield of 79% was obtained (Table 2)
using hydrolysed ion-free Jerusalem artichoke juice as reactant.
In order to have a better understanding of the catalyst, surface
The authors are grateful to HKXC (China) for their generous
providing the tantalum hydroxide samples for the present work.
This work was supported by The Main Direction Program of
Knowledge Innovation of the Chinese Academy of Science (Grant
No. KSCX2-EW-G-5) and Project supported by the National
Science and Technology Major Project of the Ministry of Science
and Technology of China (Grant No. 2009ZX09501-011).
properties, BET, CO
2 3
- and NH -TPD, XRD and FTIR measure-
Notes and references
ments were performed. The untreated sample TA had a surface
2
area of 41.6 m g , while the surface area of TA-p was found to
ꢀ1
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ꢀ1
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showed little change. Most of the acid sites
1
1
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2
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This journal is c The Royal Society of Chemistry 2011
Chem. Commun., 2011, 47, 4469–4471 4471