444
7 Conversion of Carbohydrates to 5-Ethoxymethylfurfural
Alkoxymethyl furfurals are used as flavours in tobacco in early 1960, and they
remained unmapped until they were recently explored as additive for diesel fuel.
Among alkoxymethyl furfurals, 5-ethoxymethylfurfural (EMF) is considered as an
exceptional additive for diesel as it has high energy density (8.7 kWh L
−1
), as good
as that of diesel fuel (9.7 kWh L
−1
) and gasoline (8.8 kWh L
−1
). EMF has high boiling point (508 K) than gasoline, ethanol, DMF and 2-MF, which helps in improving
the fuel’s density, stability and flow properties [62]. EMF is a favourable biofuel
recognized as an alternative energy source. The preparation of EMF in high scale is
not easy as it requires selective catalyst and huge production cost. Therefore the
synthesis of EMF in industrial scale is a big challenge present in front of researchers.
Basically EMF is synthesized from carbohydrates which are the major compounds derived from biomass. The preparation of EMF from carbohydrates was a
multistep transformation as carbohydrates are initially transformed into HMF and
then the separated HMF on ethanolysis is converted into EMF. A considerable yield
of EMF had been obtained from 5-chloromethylfurfural (CMF), which was
Table 3 Effect of reaction
temperature
on
fructose
dehydration
Catalyst
HMF conv. (%) Acidity (mmol/g)
20%TPA/Ta 2 O 5 85
0.41
20%TPA/Nb 2 O 5 65
0.13
20%TPA/SiO 2
63
0.10
20%TPA/ZrO 2
60
0.09
Reaction conditions: fructose (0.36 g), dimethyl sulfoxide (5 g), catalyst weight (0.05 g), reaction temperature
(120 °C), reaction time (3 h)
Table 4 Literature review on HMF synthesis over modified heteropoly acid catalysts
S.
no.
Feed
Catalyst
Temperature
(°C)
Time
(h)
HMF yield
(%)
Refs.
1
Fructose Zn 0.5 TPA/ɣ-Al 2 0 3
120
2
88
[52]
2
Fructose Cs 2.5 H 0.5 PW 12 O 40
115
1
74
[50]
3
Cellulose Cr[(DS)H2PW12O40]3
150
2.5
57
[53]
4
Sucrose Cs 2.3 H 0.7 PW 12 O 40
180
3
92
[57]
5
Fructose [MIMPS] 3 PW 12 O 40
120
2
99
[54]
6
Glucose [MimAM] 2 PW 12 O 40
160
7.5
54
[56]
7
Glucose TPA/boric acid in [BMIM]
Cl
140
0.66
52
[55]
8
Fructose HPW/MCM-41
120
1
80
[58]
9
Fructose Ag 3 PW 12 O 40
120
1
78
[51]
10
Fructose Mesoporous Zr-MPA
120
0.5
80
[61]
11
Fructose AlTPA/SnO 2
120
4
86
[59]
12
Fructose TPA/Ta 2 O 5
120
3
85
[60]
B. S. Rao et al.
7 Conversion of Carbohydrates to 5-Ethoxymethylfurfural
Alkoxymethyl furfurals are used as flavours in tobacco in early 1960, and they
remained unmapped until they were recently explored as additive for diesel fuel.
Among alkoxymethyl furfurals, 5-ethoxymethylfurfural (EMF) is considered as an
exceptional additive for diesel as it has high energy density (8.7 kWh L
−1
), as good
as that of diesel fuel (9.7 kWh L
−1
) and gasoline (8.8 kWh L
−1
). EMF has high boiling point (508 K) than gasoline, ethanol, DMF and 2-MF, which helps in improving
the fuel’s density, stability and flow properties [62]. EMF is a favourable biofuel
recognized as an alternative energy source. The preparation of EMF in high scale is
not easy as it requires selective catalyst and huge production cost. Therefore the
synthesis of EMF in industrial scale is a big challenge present in front of researchers.
Basically EMF is synthesized from carbohydrates which are the major compounds derived from biomass. The preparation of EMF from carbohydrates was a
multistep transformation as carbohydrates are initially transformed into HMF and
then the separated HMF on ethanolysis is converted into EMF. A considerable yield
of EMF had been obtained from 5-chloromethylfurfural (CMF), which was
Table 3 Effect of reaction
temperature
on
fructose
dehydration
Catalyst
HMF conv. (%) Acidity (mmol/g)
20%TPA/Ta 2 O 5 85
0.41
20%TPA/Nb 2 O 5 65
0.13
20%TPA/SiO 2
63
0.10
20%TPA/ZrO 2
60
0.09
Reaction conditions: fructose (0.36 g), dimethyl sulfoxide (5 g), catalyst weight (0.05 g), reaction temperature
(120 °C), reaction time (3 h)
Table 4 Literature review on HMF synthesis over modified heteropoly acid catalysts
S.
no.
Feed
Catalyst
Temperature
(°C)
Time
(h)
HMF yield
(%)
Refs.
1
Fructose Zn 0.5 TPA/ɣ-Al 2 0 3
120
2
88
[52]
2
Fructose Cs 2.5 H 0.5 PW 12 O 40
115
1
74
[50]
3
Cellulose Cr[(DS)H2PW12O40]3
150
2.5
57
[53]
4
Sucrose Cs 2.3 H 0.7 PW 12 O 40
180
3
92
[57]
5
Fructose [MIMPS] 3 PW 12 O 40
120
2
99
[54]
6
Glucose [MimAM] 2 PW 12 O 40
160
7.5
54
[56]
7
Glucose TPA/boric acid in [BMIM]
Cl
140
0.66
52
[55]
8
Fructose HPW/MCM-41
120
1
80
[58]
9
Fructose Ag 3 PW 12 O 40
120
1
78
[51]
10
Fructose Mesoporous Zr-MPA
120
0.5
80
[61]
11
Fructose AlTPA/SnO 2
120
4
86
[59]
12
Fructose TPA/Ta 2 O 5
120
3
85
[60]
B. S. Rao et al.