KI/Al2O3 AS HETEROGENEOUS CATALYST IN BIODIESEL PREPARATION: K+ KEY FACTOR FOR CATALYST EFFICIENCY

Biodiesel has been considered as the best candidate for a diesel fuel substitution, because it is non-toxic, renewable, biodegradable; it produces less harmful gases emissions and can be used without modifying existing engines. Biodiesel is most commonly produced by transesterification of vegetable oils. Base catalysed transesterification process over heterogeneous catalyst has numerous advantages, the catalyst can be reused, there is no wastewater, and separation of biodiesel from glycerol is much easier. In this paper, the KI/Al2O3 catalyst was synthesised by modified sol-gel procedure, and it was tested in the transesterification of sunflower oil with methanol. The effects of different process parameters were considered. The results show that the incorporation of potassium iodide into the structure of gamma-Al2O3 significantly influences textural and structural properties of the catalyst as well as its basic strength and positively affects the activity of the catalyst in the reaction of transesterification of sunflower oil with methanol. The usage of the KI/Al2O3 catalyst under relatively mild process conditions resulted in very high FAME yield of 99.99%. The surface properties of the catalyst have an essential impact on its catalytic performance, the impregnation of alumina with potassium iodide resulted in the formation of basic catalytically active sites.