PRODUCTION OF METHANE, METHANOL BY SUPERCRITICAL WATER TREATMENT
- FORMIC ACID AND HYDROGEN PRODUCTION FROM LIGNOCELLULOSICS This work has been done in
the Kyoto University 21 COE
program “Establishment of
COE on Sustainable-Energy
System” and METI KANSAI.
Graduate School of Energy Science,
Kyoto University, Japan
Tel/Fax : +81(0)75 753 4738
E-mail : [email protected]
Seiya SAKAGUCHI Prof. Shiro SAKA
Summary
The chemical conversion of cellulose (avicel) as treated in hot-compressed water with and without hydrogen peroxide was studied with a batch-type reaction
vessel at the designated temperature (210˚C to 330˚C) and pressure (1.9MPa to 12.9MPa) for 15 to 30s. Though hot-compressed water could hardly convert
cellulose to organic acids at the subcritical state, the use of hydrogen peroxide aqueous solution could convert it to organic acids, with major product being formic
acid.
Introduction
Formic acid is included in organic acids converted from woody biomass by hot-compressed water treatment, and it is a good substrate for hydrogen production
with Escherichia coli genetically engineered with formate hydrogenlyase. The hydrogenlyase activity is catalyzed by formate dehydrogenase and hydrogenase
functioning together as a coupled electron transfer system[1]. In this study, therefore, we have studied the effect of hydrogen peroxide (H2O2) addition to hotcompressed water to increase the yield of formic acid.
1. Hydrogen Production Process from
Lignocellulose by using Hot-compressed Water
Formic acid
Cellulose
Hot compressed water treatment
with and without H2O2
2. Experimental
Cellulose (Avicel)
Hot-Compressed
Water Treatment
210~330ºC
1.9~12.9MPa
15~30s
H2O2 0~30v%
NaOH 0~10mM
Bio-Hydrogen
Treated Sample
Formate Hydrogenlyase
Filtration
2e-
E. Coli
Cell Membrane
FDH：Formate Dehydrogenase
H2ase：Hydrogenase
HCOO-
CO2 + H+
2H+
Hot-Compressed
Water-soluble
Gaseous Products
H2ase
FHD
H2
CE
3. Effect of H2O2 on Production of Formic Acid
o
●
○
HPLC
4. Chemical Composition of the Treated Cellulose
(270oC / 5.5MPa / 20s)
Lactic acid
Acetic acid
Formic acid Glycolic acid
(a) 380 C, 100MPa, 5s
Hot-Compressed
Water-insoluble
160
H2
CH4
CO2
CO
5-Hydroxymethyl furfural
Levoglucosan
Glycolaldehyde
Dihydroxyacetone
Erythrose
Fructose
Glucose
Oligomers
Other organic acids
Formic acid
Water-insoluble
■ □
140
o
(b) 220 C, 2.3MPa, 30s
120
●
Pyruvic acid
△
○
100
Yield (wt%)
o
(c) 220 C, 2.3MPa, 30s
20v% H2O2
■
o
(d) 210 C, 1.9MPa, 30s
O2 saturated
5
40
Migration time (min)
5. Treatments under Various Conditions
15s
0v%
6v%
10v%
15v%
20v%
25v%
30v%
30
Yield (wt%)
Untreated
0
10
20
H2O2 (v%)
30
6. Effect of Additional NaOH on Production of
Formic Acid
15s
30s
30
20
10
0
0
240
270
300
330
240
o
30s
0v%
6v%
10v%
15v%
20v%
25v%
30v%
20
10
0
270
300
10
15s NaOH
15s
20s NaOH
20s
30s NaOH
30s
10
330
Temperature ( C)
30
240
270
20
o
Temperature ( C)
Yield (wt%)
20s
0
Yield (wt%)
10
20
0v%
6v%
10v%
15v%
20v%
25v%
30v%
20
Yield (wt%)
Yield (wt%)
20
60
10
Supercritical water treatment (380˚C, 100MPa, 5s) for cellulose gave a small amount of
several organic acids (a). Lower temperature (220˚C, 2.3MPa, 30s) also resulted in no
organic acids formed (b). However, the use of 20v% H2O2 aqueous solution under the
same condition of (b), resulted in high formic acid production with a few other organic
acids produced (c). The use of water saturated with oxygen in reaction vessel revealed
little organic acids formed, despite of the condition similar to (c) and (d).
30
80
300
330
Under H2O2 concentration below 15v%,
formic acid was found to be higher in
yield as higher in temperature, higher in
pressure and longer in treatment time.
However, in its concentration over 15v%
with longer treatment for 20s and 30s, the
yield of formic acid was decreased due to
the decomposition to gaseous products
which is mainly carbon dioxide of formic
acid formed.
o
Temperature ( C)
Reference
[1] Peck H.D., Jr. et al; J. Bacteriol, 73, 706-721, (1957).
300oC, 8.6MPa, H2O2 6v%
0
0
0 10-3
-2
10
10
-1
10
0
1
10
NaOH (mM)
The yield of formic acid was slightly
increased at the concentration below
0.1mM. However, over 0.1mM, the
yield of formic acid was decreased, and
dramatically decreased over 1mM.
270
300
330
o
Temperature ( C)
At the temperature of 250oC, the yields
of formic acid were nearly equal with
and without NaOH. At 300oC the yields
were more with NaOH.