Page 250 - Lignocellulosic Biomass to Liquid Biofuels

206 Lignocellulosic Biomass to Liquid Biofuels

Table 6.2 Reactions involved for acetic acid and ethanol production.
Reactions Products Reference
Acetic acid [4,44,45]
4CO 1 2H 2 O-CH 3 COOH 1 2CO 2
3CO 1 H 2 1 H 2 O-CH 3 COOH 1 CO 2
2CO 1 2H 2 -CH 3 COOH
CO 1 3H 2 1 CO 2 -CH 3 COOH 1 H 2 O
H 2 1 2CO 2 -CH 3 COOH 1 2H 2 O
Ethanol [4,44]
6CO 1 3H 2 O-CH 3 CH 2 OH 1 4CO 2
5CO 1 H 2 1 2H 2 O-CH 3 CH 2 OH 1 3CO 2
4CO 1 2H 2 1 H 2 O-CH 3 CH 2 OH 1 2CO 2
3CO 1 3H 2 -CH 3 CH 2 OH 1 CO 2
2CO 1 4H 2 -CH 3 CH 2 OH 1 H 2 O
CO 1 5H 2 1 CO 2 -CH 3 CH 2 OH 1 2H 2 O
6H 2 1 2CO 2 -CH 3 CH 2 OH 1 3H 2 O
1 2
CO 1 CO 2 1 6H 1 6e -CH 3 COOH 1 H 2 O Acetic [44]
2
1
CO 1 CO 2 1 10H 1 10e -CH 3 CH 2 OH 1 2H 2 O acid,
ethanol

(Table 6.2, Fig. 6.6). Each reaction involved some microbial metabolism
process within the microbial cell that occurred in the cytoplasm or surface
of the cell membrane. The cells act individually, but integral action of all
cells sets condition in the fermentation bulk liquid. The reactions occur
under certain optimum condition (pH and temperature) for various
microorganisms. The inorganic substrates, CO, H 2 , and CO 2 , are con-
verted to acetyl-CoA and then organic products of acetic acid and ethanol
(Fig. 6.6). Moreover, acetyl-CoA is converted to complex organic cell
components, carbohydrates, proteins, and lipids. Most of the gas mole-
cules provide the energy for cell function and finally resulting in the acetic
acid and ethanol.

6.4 Syngas impurities

Syngas is the main product produced from the gasification and consists of
hydrogen (H 2 ), carbon monoxide (CO), carbon dioxide (CO 2 ), and meth-
ane (CH 4 ) [5,6,9,10,47].However,producedsyngascontained some
by-products that can be expected along with the syngas. In general, these
by-products are ash (solid product), tars (liquid products) and ethane,
hydrogen sulfide, benzene, acetylene, ammonia, hydrogen cyanide, sulfur
dioxide, nitrous oxide, nitrogen, methane, ethylene, etc. (gaseous products)