1.6.2 Transesterification by Supercritical Methanol
Supercritical methanol transesterification is a procedure where the feedstock reacts
with supercritical methanol and fats are transformed to biodiesel with extremely
condensed time without the usage of a catalyst. Washing and neutralization, owing
to the lack of catalyst, aren’t wanted.
With this technique, the issue related with this procedure is the prerequisite of
great pressure and temperature. The contrast of the change proficiency of diverse
feedstock with distinct approaches was displayed in Table 1.5 (Shahid and Jamal
2011).
Several factors such as the molar ratio of alcohol to plant oil, free fatty acid
quantity, types of catalysts used, amount of catalyst, temperature, reaction time, and
water content have an important effect on the manufacture speed and the quality of
the biofuels (Hassan and Abul Kalam 2013; Bojan et al. 2011).
1.7 Algae Biofuel Production
Cultivation, harvesting, drying, cell disruption, lipid extraction, transesterification,
hydrolysis, and fermentation are the diverse and complex stages in biofuel production from microalgae.
Cultivation of microalgae is achieved in either an indoor or an outdoor system.
Microalgal culture desires to be ventilated with CO 2 and replaced with a growth
medium involving nitrogen, phosphorus, and iron (Halim et al. 2012). The lipid
extraction method contains mechanical and chemical extractions (Fig. 1.9)
(Mubarak et al. 2015).
The chemical manner uses biological solvents such as n-hexane and chloroform,
which are poisonous and disturb health and the environment. The supercritical
extraction skill reduces the usage of poisonous solvents and uses non-toxic CO 2
gas as a solvent. Ultrasonication and microwave-assisted methods can remove the
supreme amount of algae lipids (Mubarak et al. 2015).
Table 1.5 Assessment of yields of methyl esters with distinct approaches (Shahid and Jamal 2011)
Raw material
FFA content wt
%
Yields of methyl esters wt%
Alkaline
catalyzed
Acid
catalyzed
Supercritical
methanol
Palm oil
5.3
94.4
97.8
98.9
Rapeseed oil
2.0
97
98.4
98.5
Used frying oil
5.6
94.1
97.8
96.9
Discarded palm
oil
>20.0
No reaction
No reaction
95.8
1 Biofuel Production Technologies, Comparing the Biofuels and Fossil Fuels
15
Supercritical methanol transesterification is a procedure where the feedstock reacts
with supercritical methanol and fats are transformed to biodiesel with extremely
condensed time without the usage of a catalyst. Washing and neutralization, owing
to the lack of catalyst, aren’t wanted.
With this technique, the issue related with this procedure is the prerequisite of
great pressure and temperature. The contrast of the change proficiency of diverse
feedstock with distinct approaches was displayed in Table 1.5 (Shahid and Jamal
2011).
Several factors such as the molar ratio of alcohol to plant oil, free fatty acid
quantity, types of catalysts used, amount of catalyst, temperature, reaction time, and
water content have an important effect on the manufacture speed and the quality of
the biofuels (Hassan and Abul Kalam 2013; Bojan et al. 2011).
1.7 Algae Biofuel Production
Cultivation, harvesting, drying, cell disruption, lipid extraction, transesterification,
hydrolysis, and fermentation are the diverse and complex stages in biofuel production from microalgae.
Cultivation of microalgae is achieved in either an indoor or an outdoor system.
Microalgal culture desires to be ventilated with CO 2 and replaced with a growth
medium involving nitrogen, phosphorus, and iron (Halim et al. 2012). The lipid
extraction method contains mechanical and chemical extractions (Fig. 1.9)
(Mubarak et al. 2015).
The chemical manner uses biological solvents such as n-hexane and chloroform,
which are poisonous and disturb health and the environment. The supercritical
extraction skill reduces the usage of poisonous solvents and uses non-toxic CO 2
gas as a solvent. Ultrasonication and microwave-assisted methods can remove the
supreme amount of algae lipids (Mubarak et al. 2015).
Table 1.5 Assessment of yields of methyl esters with distinct approaches (Shahid and Jamal 2011)
Raw material
FFA content wt
%
Yields of methyl esters wt%
Alkaline
catalyzed
Acid
catalyzed
Supercritical
methanol
Palm oil
5.3
94.4
97.8
98.9
Rapeseed oil
2.0
97
98.4
98.5
Used frying oil
5.6
94.1
97.8
96.9
Discarded palm
oil
>20.0
No reaction
No reaction
95.8
1 Biofuel Production Technologies, Comparing the Biofuels and Fossil Fuels
15