Catalytic Activity of Reused SiO₂–TiO₂ on Biodiesel Production from Waste Cooking Oil in Various Catalyst Loading

The reusability of silica-titania catalyst on biodiesel production from waste cooking oil in various of catalyst loading has been investigated. The reused silica-titania catalyst has been obtained by washing the previous catalyst used in biodiesel production from palm and waste cooking oils based on various of catalysts loading. The DR UV-Vis has been used for characterization of reused silica-titania catalyst to investigate the existence of titanium tetrahedral coordination in that given catalyst. In order to get information about the catalytic activity of reused silica-titania catalyst, several analyses were carried out on biodiesel products such as density, flow rate and acid number, as well as FTIR for characterization. The results show that the fraction of titanium tetrahedral coordination decreased after silica-titania catalyst reused in reaction of transesterification between waste cooking oil and methanol. The decrease of titanium tetrahedral fraction in reused silica-titania catalyst yields a reduction in its catalytic activity in biodiesel production. The density, flow rate, and acid number analyses show the 7% of catalyst loading was the optimum condition for biodiesel production from palm and waste cooking oils using reused silica-titania catalyst. The FTIR spectra of biodiesel products are almost similar to that of waste cooking oil, however, there is dissimilarity on band area in the wave number range of 1250–1000 cm-1 attributed to vibration of C–O–C or C–O–H.