Production Of Biodiesel From Waste Cooking Oil Using Sulfated Tin Oxide Catalyst

Loading...
Thumbnail Image
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
Citation