Production Of Biodiesel From Waste Cooking Oil Using Sulfated Tin Oxide Catalyst
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Date
2010-04
Authors
Lam, Man Kee
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Biodiesel is a renewable, biodegradable and non-toxic fuel which can be
easily produced through transesterification reaction. However, current commercial
usage of refined vegetable oils for biodiesel production is impractical and
uneconomical due to high feedstock cost and priority as food resources. Low-grade
oil, typically waste cooking oil can be a better alternative; however, the high free
fatty acids (FFA) content in waste cooking oil does not allow efficient production of
biodiesel via current commercial homogeneous transesterification process. Therefore,
in the present study, superacid sulfated tin oxide catalyst, SO4 2-/SnO2 has been
prepared using impregnation method for biodiesel production via heterogeneous
transesterification process. The bimetallic effect of the catalyst was also studied, in
which SnO2 was mixed with SiO2 and Al2O3, respectively at different weight ratio in
order to enhance the catalytic activity of SnO2. The effect of different reaction
parameters such as calcination temperature and period of the catalyst, reaction
temperature, catalyst loading, methanol to oil ratio and reaction time were studied to
optimize the reaction conditions. It was found that SO4 2-/SnO2-SiO2 with weight ratio of 3 exhibited an exceptional high activity with an optimum yield of 92.3% at reaction temperature of 150oC, catalyst loading of 3 wt % (referred to weight of oil), methanol to oil molar ratio of 15 and reaction time of 3 hours. The physical and chemical properties of the catalysts were also characterized using XRD analysis,
NH3-TPD, Pulse Chemisorptions, FT-IR and SEM imaging. On deactivation and
regeneration study, the catalysts were found to deactivate after the first reaction cycle
due to high accumulation of carbonaceous species on the catalyst surface. In addition,
the carbonaceous species were not removed completely even after the regeneration
step. Apart from that, a kinetic model has been developed and the overall order of the
transesterification reaction catalyzed by modified SO4
2-/SnO2 was found to be third
order in which second order for triglyceride and first order for methanol.
Furthermore, the activation energy obtained in the present work was comparable to
reaction catalyzed by homogeneous base catalyst. This study therefore demonstrates
that waste cooking oil can be a potential source of biodiesel via heterogeneous
catalyst using modified SO4 2-/SnO2.
Description
Keywords
Production of biodiesel from waste cooking oil , using Sulfated tin oxide catalyst