Transesterification of Castor Oil to Biodiesel by using Mg-AI Hydrotalcites as a Catalyst

Production of biodiesel via transesterification of castor oil using metal oxides as as solid
catalysts is investigated. Finding a suitable catalyst that is active, selective and stable
under the high free fatty acids (FFA> 0.5 %) is the major challenge. In this study, castor
oil has been chosen as feedstock because it is readily available in Malaysia and non
food. Castor oil is constituted mainly by triglycerides which consist of three fatty acids
molecule in one molecule of glycerol. These triglycerides are converted to the
corresponding alkyl ester and glycerol by transesterification with short chain alcohols;
typically methanol. Heterogeneously catalyzed offers advantages over the homogeneous
catalyst. Usage of homogeneous catalyst for transesterification is problematic because it
can produce large amounts of unwanted soap by product, which create problem in
product separation. Biodiesel production costs could certainly be reduced by using a
heterogeneous catalyst for transesterification reaction instead of a homogeneous catalyst.
This heterogeneous process provides higher quality esters and glycerol, which are more
easily separated and further expensive refining operations are not needed. In this
study,hydrotalcite derived Mg-Al mixed oxide which is a heterogeneous catalyst will be
use as catalyst. The effect of reaction parameters in transesterification reaction is
observed through conducting an experiment. Gas Chromatography (GC) has been used
to analyze biodiesel product.
Keywords: Biodiesel, transesterification, Mg-Al hydrotalcite, castor oil