Page 212 - Lignocellulosic Biomass to Liquid Biofuels

Biobutanol from lignocellulosic biomass: bioprocess strategies 175

Figure 5.2 Schematic representation of various types of pretreatment process for lig-
nocellulosic biomass feedstocks.

(hydrothermolysis, uncatalyzed solvolysis, aquasolv, aqueous fraction), and
wet air oxidation [7,77,87,90].
In biological pretreatment the microorganisms (brown, white, and
soft-rot fungi) are widely utilized for the treatment of lignocellulosic bio-
mass feedstocks, which subsequently increase the enzymatic hydrolysis for
enhancing the fermentable sugar moieties with high yield and effective
delignification (removal of lignin from biomass feedstocks) process
[91 93]. The main biological pretreatment process includes fungal,
microbial consortium, and enzymatic techniques. Even though, such pre-
treatments possess several benefits as they are inexpensive, safer, belonging
to low hydrolysis rate, of low energy input, eco-friendly, effective to
delignification, of high yields without generating any inhibitory by-
products, easy to recover the microorganisms, etc.

5.4 Biobutanol as a valuable fuel and chemical source
Since 1916 the production of n-butanol, which has been considered an
excellent solvent, as well as chemical feedstocks in many industries and all
the isomers of n-butanol (except tert-butanol) are the most competitive
fuel stabilizers for replacing petroleum-based gasoline, directly as well as
superior to bioethanol [94 96]. Butanol is a colorless and highly flamma-
ble alcohol. In the 20th century, butanol has been widely utilized in the
production of raw material (butadiene) of natural rubber in the rubber
industry. Butanol has four different types of isomeric structures (Fig. 5.3),
namely, (1) n-butanol or 1-butanol or butyl alcohol or primary butanol,