is desirable, because less hydrogen will be needed during hydrogenation. The index
determining unsaturation of fatty acids is known as iodine value (IV).
It has to be also considered that the CO and CO 2 formed during
hydrodecarboxylation reactions may be converted into CH4 through a methanation
reaction, and further addition of hydrogen would be necessary, as shown in
equations (1.6) and (1.7) (Melero et al. 2012; Kaewmeesri et al. 2015):
CO þ 3H 2 ! CH 4 þ H 2 O
ð1:6Þ
CO 2 þ 4 H 2 ! CH 4 þ 2H 2 O
ð1:7Þ
This implies that globally hydrodecarboxylation route will demand three more
molecules of hydrogen than the hydrodeoxygenation pathway.
Depending of the composition of the final n-alkanes produced though the
hydrotreatment process, they need to be subjected to either isomerization, cracking,
or cyclization, to improve their combustion properties and obtain isoalkanes, lighter
hydrocarbons, and aromatics, respectively (Veriansyah et al. 2012; Kiatkittipong
et al. 2013).
Fig. 1.10 Reactions happening during catalytic hydrotreatment (Vásquez et al. 2017); n, odd
number; x,y,z, number of double bonds; ¼, double bonds; -, single bond; HDO, exothermic; DCOx,
endothermic
24
P. Bartocci et al.