Summary: | Biodiesel is an environmentally friendly and renewable alternative
biofuel derived from renewable sources. However, biodiesel cost is more
expensive than that of fossil diesel due to high price of virgin vegetable oil. The
possible way of reducing biodiesel cost is by using low cost feedstocks containing
high level of Free Fatty Acid (FFA). Palm Fatty Acid Distillate (PFAD) is byproduct
of palm oil refining process which contains 80-90% FFA and 10-20%
triglycerides. Therefore, it can be used as low-cost feedstock for biodiesel
production.
Biodiesel production from PFAD via esterification using sulfated
zirconia prepared by solvent-free method as heterogeneous solid acid catalys has
been studied. The esterification reaction was carried out in a stirred-batch reactor
at the different temperature to obtain the kinetic data. The effect of reaction
condition such as methanol to PFAD molar ratio (5-15), stirring speed (700-950
rpm) and catalyst concentration (1%-3%) on FFA conversion were also
investigated.
The experimental data was interpreted with a second order heterogeneous
kinetic model involving the rate of mass transfer and the rate of reaction. The
proposed kinetic model and the experimental data show a good agreement.
Activation energy of 144,9194 kJ/mol and pre-exponential factor of 5,1362x1018
dm6.gkat-1.mol-1.s-1 were obtained in the range of temperature of 328-338 K. The
optimum condition for the esterification of PFAD was as follows: 83,3% FFA
conversion within 180 minute reaction time, temperature of 333 K, catalyst
concentration of 3%, methanol to PFAD molar ratio of 10, and stirring speed of
800 rpm.
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