100
80
60
40
20
0
Water content, %
0
1
2
3
4
5
Methyl ester, %
Acid catalyst
Alkaline catalyst
Supercritical methanol
Biodiesel
53
methyl esters and glycerol from the reaction mixture becomes much easier.
The glycerol is more soluble in water than methanol, which moves to the
lower portion whereas biodiesel moves to the upper layer. The effect of water
content on the yield of methyl esters in the supercritical methanol process is
shown in Figure 3.8 (Sharma et al. 2008).
Lee, Hubble, and Saka (2006) developed a supercritical methanolysis process for transesterification of vegetable oils in a continuous process. In the
first stage, triglycerides rapidly hydrolyze to FFAs under 100 bar pressure and
at 270ºC temperature. When the pressure is reduced, the mixture promptly
separates into two phases and the water phase can be separated to recover
glycerol. Methanol becomes supercritical at a pressure of 100 bar and a temperature of 270ºC and the supercritical conditions favor rapid formation of
methyl esters from the fatty acids. Figure 3.9 shows two-stage continuous
biodiesel production process with supercritical methanol (Lee, Hubble, and
Saka 2006).
Wrabi, Kusdiana, and Saka (2004) analyzed the reactivity of the triglyceride and the fatty acids of the rapeseed oil. They reported that with an
increase in reaction duration, the yield of the alkyl esters was increased. For
the same reaction duration treatment, the alcohols with shorter alkyl chains
gave better conversion than that of longer alkyl chains. Increase in the reaction temperature, especially at supercritical temperatures, increases the
yield of the process. Advantages of supercritical methanol process include
1. Simpler purification process
2. Lower reaction time
3. Less energy intensive and hence, the supercritical methanol method
would be more efficient than the conventional processes
Figure 3.8
Effect of water content on yield of the process. (From Sharma, Y. C., Singh, B., and Upadhyay,
S. N., Fuel, 87, 2355–73, 2008. Reprinted with permission from Elsevier Publications.)
80
60
40
20
0
Water content, %
0
1
2
3
4
5
Methyl ester, %
Acid catalyst
Alkaline catalyst
Supercritical methanol
Biodiesel
53
methyl esters and glycerol from the reaction mixture becomes much easier.
The glycerol is more soluble in water than methanol, which moves to the
lower portion whereas biodiesel moves to the upper layer. The effect of water
content on the yield of methyl esters in the supercritical methanol process is
shown in Figure 3.8 (Sharma et al. 2008).
Lee, Hubble, and Saka (2006) developed a supercritical methanolysis process for transesterification of vegetable oils in a continuous process. In the
first stage, triglycerides rapidly hydrolyze to FFAs under 100 bar pressure and
at 270ºC temperature. When the pressure is reduced, the mixture promptly
separates into two phases and the water phase can be separated to recover
glycerol. Methanol becomes supercritical at a pressure of 100 bar and a temperature of 270ºC and the supercritical conditions favor rapid formation of
methyl esters from the fatty acids. Figure 3.9 shows two-stage continuous
biodiesel production process with supercritical methanol (Lee, Hubble, and
Saka 2006).
Wrabi, Kusdiana, and Saka (2004) analyzed the reactivity of the triglyceride and the fatty acids of the rapeseed oil. They reported that with an
increase in reaction duration, the yield of the alkyl esters was increased. For
the same reaction duration treatment, the alcohols with shorter alkyl chains
gave better conversion than that of longer alkyl chains. Increase in the reaction temperature, especially at supercritical temperatures, increases the
yield of the process. Advantages of supercritical methanol process include
1. Simpler purification process
2. Lower reaction time
3. Less energy intensive and hence, the supercritical methanol method
would be more efficient than the conventional processes
Figure 3.8
Effect of water content on yield of the process. (From Sharma, Y. C., Singh, B., and Upadhyay,
S. N., Fuel, 87, 2355–73, 2008. Reprinted with permission from Elsevier Publications.)