Page 227 - Lignocellulosic Biomass to Liquid Biofuels

Biobutanol from lignocellulosic biomass: bioprocess strategies 183

Figure 5.3 Schematic representation of different isomeric structures of butanol.

(2) 2-butanol or sec-butanol, (3) 2-methyl-1-propanol or iso-butanol, and
(4) 2-methyl-2-propanol or tert-butanol [97], and all the isomers possess
the same chemical formula but differ in terms of their manufacturing
approach, energy content, and combustion characters.
Compared to ethanol, biobutanol shows superior biofuel properties as
well as is considered as a next-generation biofuel as it (1) is more easily
miscible with gasoline, thus being easy to directly blend (even at 100%)
with gasoline at a higher concentration; (2) directly utilized in convention
without any or very little modification in automobile engines; (3) easily
stored and safely distributed due to its less or nonhygroscopic (thus does
not pick up water) nature; (4) readily mixed with gasoline in any propor-
tion; (5) safer to handle due to low Reid vapor pressures (7.5 times lower
than ethanol) and flash point; (6) has a lower volatility than other conven-
tional fuels [13.9, 13.5, and 6 times lesser than MeOH (methanol), gaso-
line, and EtOH (ethanol), respectively]; hence, it can be utilized safely in
summer or winter conditions; (7) able to reduce the NO x and approxi-
mately 20% of GHG emissions and soot creations from fuel evaporation
or combustion in warm conditions; and (8) has higher energy content
(B30% more energy than ethanol), polarity, combustion value, air-to-
fuel ratio, and octane rating due to the presence of twice the number of
C atoms (as compared to ethanol) in their molecular structure, that is,
biobutanol is directly utilized in internal combustion engines. In addition,
butanol and its blends are easily transported in existing fuel pipelines,
tanks, and related infrastructures due to its soluble nature as well as very
less corrosiveness, compared to ethanol, etc. [95,98,99]. Moreover, biobu-
tanol can be utilized as a high value-added chemical feedstock in numer-
ous industrial uses, such as paints, cosmetics (eye makeup, nail care
products, lipsticks, shaving products), adhesives, inks, food flavors, sol-
vents, surface coating (enamel and lacquer) materials, fragrances, and
swelling agent in garments, and in pharmacological fields [94,100,101].