A. Yamaguchi et al. / Catalysis Communications 67 (2015) 59–63
61
Table 2
Table 4
Product yields obtained from conversion of milled cellulose using 2%Pt/C and Amberlyst
70 at 453 K with 5 MPa H2 for 16 h (milled cellulose 0.324 g, 2%Pt/C 0.2 g).
Product yields obtained from conversion of milled cellulose using 4%Ru/C and Amberlyst
70 with 5 MPa H2 for 16 h (milled cellulose 0.324 g, 4%Ru/C 0.2 g, Amberlyst 70 3.0 g).
Resina (g)
Yield (%)
ISb
Ta (K)
Yield (%)
ISb
1,4-AHSOc
SOd
IMe
MAf
Other WSg
1,4-AHSOc
SOd
IMe
MAf
Other WSg
0.5
7.0
9.3
16.1
2.7
0.3
9.2
20.1
12.4
2.2
0.2
0.5
0.7
3.4
1.1
0.2
19.7
21.5
8.9
443
453
463
31.8
39.6
55.8
42.5
35.4
16.1
3.2
0.8
0.0
1.8
2.0
3.3
0.1
0.0
0.0
5.0
1.2
2.3
1.0h
3.0
a
a
Amount of Amberlyst 70.
Isosorbide.
1,4-Anhydrosorbitol.
Sorbitol.
Isomannide.
Mannitol.
Reaction temperature.
Isosorbide.
1,4-Anhydrosorbitol.
Sorbitol.
Isomannide.
Mannitol.
b
c
b
c
d
e
f
d
e
f
g
h
g
Other water-soluble products.
Same data in Table 1.
Other water-soluble products.
inhibited by Amberlyst 70; on the other hand, the Ru/C catalyst worked
well for cellulose hydrogenolysis even with Amberlyst 70. Zhao et al.
also reported the similar results that Ru/C was more active for cellulose
conversion to isosorbide with hydrochloric acid or sulfuric acid [24]. The
reported maximum isosorbide yield from one-pot conversion of cellu-
lose was 52% using Ru/C and heteropoly acid [26] and Ru/niobium phos-
phate [27]. The one-pot conversion of cellulose to isosorbide consists of
cellulose hydrolysis, glucose hydrogenation, and sorbitol dehydration.
5-Hydroxymethylfurfural (HMF) is also reported as one of the promis-
ing chemicals from cellulosic biomass, which is reviewed in some arti-
cles [32,33]. HMF can be obtained by cellulose hydrolysis, glucose
isomerization, and fructose dehydration. These reactions also proceed
using acid catalysts; however, the HMF yield is not so high (ca. 30%)
unless ionic liquid or organic solvent was used [32,33]. In this study,
we obtained isosorbide (yield 55.8%) and a trace amount of HMF can
be obtained, indicating that glucose hydrogenation into sorbitol was
faster than glucose isomerization to fructose under the reaction condi-
tion with acid catalyst, supported metal catalyst, and high-pressure
hydrogen. We also investigated the effects of Ru loadings and catalyst
amounts on the isosorbide yield from the cellulose (Table 5). The
isosorbide yields using 4%Ru/C 0.1 g (29.4%) or 0.3 g (42.1%) were
lower than that using 4%Ru/C 0.2 g (55.8%), indicating that optimum
amount of 4%Ru/C was 0.2 g. In the case of 0.1 g of 4%Ru/C, the yield
of the other water-soluble products was higher than those using 0.2
or 0.3 g, implying that the hydrogenation of glucose was slow because
of less number of ruthenium metal sites. Interestingly, the isosorbide
yield using 2%Ru/C 0.4 g (24.1%) was much lower than that using
4%Ru/C 0.2 g (55.8%) despite the same amount of Ru atoms on these cat-
alysts. The metal dispersion of 2%Ru/C catalyst was 50.7% (Ru metal size
2.6 nm), which was twice larger than that of 4%Ru/C (25.0%, Ru metal
size 5.3 nm); thus, the number of surface Ru atoms in 4%Ru/C 0.2 g
(isosorbide yield 55.8%) was almost the same as that in 2%Ru/C 0.2 g
to 24.7% by an increase of 2%Pt/C catalyst amount from 0.2 to 0.3 g. On
the other hand, the isosorbide yield over 0.1 g of 4%Pt/C (16.8%) was
almost the same as that over 0.2 g of 2%Pt/C (16.1%) when the amounts
of Pt surface atoms were almost the same. The isosorbide yield over
4%Pt/C increased with increasing catalyst amount and reached 29.9%
using 0.3 g of 4%Pt/C; however, the obtained yield of isosorbide was
still lower than the expected yield in the case of Pt/C catalysts.
The supported ruthenium catalysts were also reported to be active
for the cellulose hydrogenolysis to sorbitol [5–7,11,29,31]. The sorbitol
yield from cellulose was 51.2% at 463 K for 16 h, using supported ruthe-
nium catalyst (4%Ru/C) and hydrogen (5 MPa) (Table S3 and character-
ization result of the Ru/C catalyst are shown in ESI). The Ru/C catalyst
was comparably active to the Pt/C catalyst for the cellulose hydroly-
sis to sorbitol (Tables S1 and S3) in agreement with the previous
reports [29,31]. We carried out one-pot conversion of cellulose to
isosorbide using 4%Ru/C catalyst and Amberlyst 70 for 16 h (Table 4).
The isosorbide yields using Ru/C were much higher than those using
Pt/C catalysts. The total yield of sorbitol-derived materials, which
were sorbitol, 1,4-anhydrosorbitol, and isosorbide, decreased with in-
creasing reaction temperature. On the other hand, the isosorbide yield
was higher at higher reaction temperature, indicating that the dehydra-
tion of sorbitol to isosorbide proceeded at high reaction temperature
and at the same time side reaction also proceeded slightly. The
isosorbide yield (55.8%) over 4%Ru/C and Amberlyst 70 was higher
than the expected yield (32%) from stepwise reactions (first step
51.2% and second step 62.9%). We found that the Ru/C catalyst was
more active than the Pt/C catalyst for the direct cellulose conversion
to isosorbide with Amberlyst 70. The activity for cellulose into sorbitol
using Ru/C was almost the same as that using Pt/C; however, the activ-
ity for cellulose into isosorbide using Ru/C and Amberlyst 70 was higher
than that using Pt/C and Amberlyst 70. The activity of platinum was
Table 3
Table 5
Product yields obtained from conversion of milled cellulose using Pt/C and Amberlyst 70 at
453 K with 5 MPa H2 for 16 h (milled cellulose 0.324 g, Amberlyst 70 3.0 g).
Product yields obtained from conversion of milled cellulose using Ru/C and Amberlyst
70 at 463 K with 5 MPa H2 for 16 h (milled cellulose 0.324 g, Amberlyst 70 3.0 g).
Cata
Yield (%)
ISb
Cata
Yield (%)
ISb
1,4-AHSOc
SOd
IMe
MAf
Other WSg
1,4-AHSOc
SOd
IMe
MAf
Other WSg
2%Pt/C, 0.2 gh
2%Pt/C, 0.3 g
4%Pt/C, 0.1 g
4%Pt/C, 0.2 g
4%Pt/C, 0.3 g
16.1
24.7
16.8
27.3
29.9
9.2
13.2
9.9
16.9
16.8
2.2
0.5
7.7
2.8
0.7
0.7
0.8
0.8
1.0
1.1
0.2
0.1
0.3
0.3
0.1
8.9
5.5
16.7
8.6
5.4
2%Ru/C, 0.2 g
2%Ru/C, 0.4 g
4%Ru/C, 0.1 g
4%Ru/C, 0.2 gh
4%Ru/C, 0.3 g
13.2
24.1
29.4
55.8
42.1
3.5
0.1
0.6
0.6
0.0
0.6
0.5
0.5
0.4
3.3
2.4
0.4
0.0
0.6
0.0
0.0
14.2
6.4
15.6
2.3
15.7
18.6
16.1
24.4
3.1
a
a
Catalysts.
Isosorbide.
1,4-Anhydrosorbitol.
Sorbitol.
Isomannide.
Mannitol.
Catalysts.
Isosorbide.
1,4-Anhydrosorbitol.
Sorbitol.
Isomannide.
Mannitol.
b
b
c
c
d
e
f
d
e
f
g
h
g
h
Other water-soluble products.
Same data in Table 2.
Other water-soluble products.
Same data in Table 4.