Environmental Engineering Reference
In-Depth Information
Corn stover
Acid mix tank
Pump
Feed hopper
Mixer
Condenser
Vent steam
Condenser
Steam
Collection tank
Discharge
valve
Reaction tank
Pretreated corn
stover slurry
Figure 3.3
Simplified diagram of the process of dilute acid hydrolysis of corn stover in a pilot-
scale reactor. Reproduced from [30], with kind permission from Springer Science and Business
Media.
Furan derivatives
Organic acids
OHH
O
O
O
CHO
HOH
2
C
CHO
H
3
CC
CCC
H
O
HH
HCOH
Furfural
Hydroxymethylfurfural
Formic acid
Levulinic acid
Figure 3.4
Chemical structures of some common fermentation inhibitors (furan derivatives
and organic acids) generated from acid hydrolysis of lignocellulose.
3.2.3.2
Alkaline Hydrolysis
Alkaline hydrolysis is one of the most commonly used chemical pretreatment
processes, which can remove primarily lignin and some hemicellulose from ligno-
cellulosic biomass. Pretreatment of biomass with alkalis causes saponification of
intermolecular ester bonds that crosslink lignin and xylem. This subsequently
leads to delignification [33, 34]. Sodium hydroxide, calcium hydroxide (lime),
