Abstract:
Homogeneous catalysts are promising for the transesterification reaction of vegetable oil to produce biodiesel since this catalyst offer certain advantages such as high activity, easily reached reaction condition and less expensive; however homogeneous catalyst has some drawbacks such as high energy consumption, costly separation of catalyst from the reaction mixture and the purification of the product. The use of bubble column reactor (BCR) in producing biodiesel fuel without catalyst has been developed. In the BCR, the role of catalyst was replaced by high operating temperature, while the role of agitation was taken over by the formed vapor bubbles. The experimental result concluded that the higher the operating temperature, the higher the product conversion as well as the reaction yield, although it lowers the biodiesel’s purity. Nowadays, heterogeneous catalysts have been more widely favoured over the homogeneous one since they are easily separated from reaction mixture and reused for many times. In this study, transesterification reaction of refined palm oil (palm frying oil) was conducted in a bubble column reactor using sulphated zirconia (SO,/ZrO,)as the solid heterogencous catalyst. The experiment was carried out at 250° C. At first, the influence of methanol flow rate towards vapor bubble formation was investigated, the experiments were then run catalytic and non-catalytically by varying the catalyst to reactant mass ratio. The experimental result showed at 5 mL/min of methanol flow rate, the amount of methanol vapor bubbles were continuously produced and uniformly distributed in the oil phase. This condition was then selected for the remaining study. It was noted that the highest yield of biodiesel product was achieved at 0.5 % (m/m) of catalyst concentration, meanwhile yield of product that run without catalyst was the lowest among all experimental results. However, at 1% (w/w) of catalyst to reactant mass ratio, the product phase was changed to solid.
